JP2019134280A - Cr oscillation circuit, semiconductor integrated circuit and remote controller - Google Patents

Abstract

To provide a CR oscillation circuit obtaining a high-precision frequency irrespective of the change of a power voltage and an environmental temperature and the dispersion of a circuit constant, in a short inspection time and low inspection cost.SOLUTION: A CR oscillation circuit 100 includes: a constant voltage supply unit 10 which transforms a power voltage to supply a constant operation voltage regardless of the power voltage; a CR oscillation unit 20 which receives the supply of the operation voltage to perform oscillation operation; a temperature detector unit 50 which receives the supply of the operation voltage to detect an environmental temperature; storage means 61 which can write into a data table in which the resistance value of a resistance 24 in the CR oscillation unit 20 is associated with the environmental temperature; and a control unit 60 which changes the resistance value of a resistor 24 into the resistance value read from the data table stored in the storage means 61 according to the detection temperature acquired from the temperature detector unit 50. The resistor 24 has a plurality of series connections of parallel circuits including resistive elements and switches. The control unit 60 switches over a switch according to the read resistance value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a CR oscillation circuit that oscillates at a frequency determined based on a capacitance value of a capacitor and a resistance value of a resistor, a semiconductor integrated circuit including the CR oscillation circuit, and a remote control device.

  When the environmental temperature at which the CR oscillation circuit operates changes, the capacitance value of the capacitor inside the circuit and the resistance value of the resistor change, so that the oscillation frequency of the CR oscillation circuit has temperature characteristics. Further, even if the power supply voltage for operating the oscillation circuit varies, for example, the charging current to the capacitor is affected, so the oscillation frequency varies. Therefore, conventionally, as described in, for example, Patent Document 1, in a CR oscillation circuit including a power supply voltage detection circuit and an environmental temperature detection circuit, capacitance values and / or resistance values corresponding to different power supply voltages and different environmental temperatures are used. As a data table, stored in advance in a storage means in the circuit, and during circuit operation, the detected power supply voltage and environmental temperature are changed to a capacitance value or resistance value determined with reference to the data table. A method for correcting the frequency is known. With this method, even when the power supply voltage or the environmental temperature changes, the capacitance value or resistance value corresponding to the changed power supply voltage or environmental temperature is changed, so that a highly accurate frequency can be obtained.

Japanese Patent No. 5573781

  However, the CR oscillation circuit described in Patent Document 1 needs to create a data table by measuring capacitance values and resistance values corresponding to different power supply voltages and different environmental temperatures during inspection at the time of product manufacture or shipment. Since there are two frequency fluctuation factors, the power supply voltage and the environmental temperature, it is necessary to measure a lot of data to create a data table according to this combination, and there is a problem that the cost increases as the inspection time increases. there were.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A CR oscillation circuit according to this application example includes a capacitor and a resistor, and oscillates at a frequency determined based on the capacitance value of the capacitor and the resistance value of the resistor when supplied with a power supply voltage. In the oscillation circuit, the resistor is configured to be changeable to a specified value from among a plurality of different resistance values, and transforms the power supply voltage to obtain a constant operating voltage regardless of the power supply voltage. A constant voltage supply unit that supplies power, a CR oscillation unit that oscillates when supplied with the operating voltage, a temperature detection unit that detects environmental temperature when supplied with the operating voltage, and an environmental temperature of oscillation operation Non-volatile storage means capable of writing a data table in which the resistance values of the resistors are associated, and detected temperatures from the temperature detection unit at predetermined control cycles, respectively, and the data stored in advance in the storage means. A control unit that reads a resistance value of the resistor corresponding to the detected temperature from the data table and controls the resistance value of the resistor to be equal to the read specified value, and the resistor includes a resistance element and a switch. A plurality of parallel circuits are connected in series, and the control unit switches the switch according to the resistance value read from the data table of the storage means.

  According to this application example, the CR oscillation unit and the temperature detection unit in the CR oscillation circuit operate at a constant operating voltage that does not depend on the power supply voltage supplied by the constant voltage supply unit, and therefore the output frequency depends on the power supply voltage. Therefore, it is only necessary to create a data table of resistance values corresponding to the environmental temperature, not to the combination of the power supply voltage and the environmental temperature. As a result, the amount of measurement data at the time of inspection is reduced and the inspection time is shortened, so that the cost can be reduced as compared with the prior art.

  Application Example 2 A CR oscillation circuit according to this application example includes a capacitor and a resistor, and oscillates at a frequency determined based on the capacitance value of the capacitor and the resistance value of the resistor when supplied with a power supply voltage. An oscillation circuit, wherein the capacitor is configured to be changeable to a specified value from among a plurality of different capacitance values, and transforms the power supply voltage to provide a constant operating voltage regardless of the power supply voltage. A constant voltage supply unit that supplies power, a CR oscillation unit that oscillates when supplied with the operating voltage, a temperature detection unit that detects environmental temperature when supplied with the operating voltage, and an environmental temperature of oscillation operation Non-volatile storage means capable of writing a data table in which the capacitance values of the capacitors are associated, and a detected temperature from the temperature detection unit at a predetermined control cycle, respectively, and pre-stored in the storage means A controller that reads the capacitance value of the capacitor corresponding to the detected temperature from the stored data table, and controls the capacitance value of the capacitor to be equal to the read designated value, and the capacitor includes: A plurality of series circuits of a capacitor element and a switch are connected in parallel, and the control unit switches the switch according to a capacitance value read from a data table of the storage means.

  According to this application example, the CR oscillation unit and the temperature detection unit in the CR oscillation circuit operate at a constant operating voltage that does not depend on the power supply voltage supplied by the constant voltage supply unit, and therefore the output frequency depends on the power supply voltage. Therefore, it is only necessary to create a data table of capacitance values corresponding to the environmental temperature, not to the combination of the power supply voltage and the environmental temperature. As a result, the amount of measurement data at the time of inspection is reduced and the inspection time is shortened, so that the cost can be reduced as compared with the prior art.

  Application Example 3 A CR oscillation circuit according to this application example includes a capacitor and a resistor, and receives a supply voltage to oscillate at a frequency determined based on the capacitance value of the capacitor and the resistance value of the resistor. In the oscillation circuit, the capacitor is configured to be changeable to a specified value from a plurality of different capacitance values, and the resistor is set to a specified value from a plurality of different resistance values. A constant voltage supply unit that transforms the power supply voltage and supplies a constant operating voltage regardless of the power supply voltage; a CR oscillation unit that oscillates in response to the supply of the operating voltage; A temperature detection unit that detects the environmental temperature upon receiving the operating voltage, and a data table in which the capacitance value of the capacitor and the resistance value of the resistor are associated with the environmental temperature of the oscillation operation can be written. Non-volatile storage means, and the detected temperature from the temperature detection unit at a predetermined control cycle, respectively, the capacitance value of the capacitor and the resistance corresponding to the detected temperature from the data table stored in advance in the storage means And a control unit that controls the capacitance value of the capacitor and the resistance value of the resistor to be equal to the read specified value, and the capacitor includes a series circuit of a capacitor element and a switch. The resistor is configured by connecting a plurality of parallel circuits of a resistor element and a switch in series, and the control unit is configured to read a capacitance value read from the data table of the storage unit and The switch is switched according to a resistance value.

  According to this application example, the CR oscillation unit and the temperature detection unit in the CR oscillation circuit operate at a constant operating voltage that does not depend on the power supply voltage supplied by the constant voltage supply unit, and therefore the output frequency depends on the power supply voltage. Thus, it is only necessary to create a data table of capacitance values and resistance values corresponding to the environmental temperature, not to the combination of the power supply voltage and the environmental temperature. As a result, the amount of measurement data at the time of inspection is reduced and the inspection time is shortened, so that the cost can be reduced as compared with the prior art.

  Application Example 4 A semiconductor integrated circuit according to this application example includes the CR oscillation circuit described in the application example.

  According to this application example, the inspection time of the CR oscillation circuit in the semiconductor integrated circuit is shortened and the cost is reduced, so that the inspection time of the entire semiconductor integrated circuit can be shortened. In addition, since the inspection cost is reduced as the inspection time is shortened, the product cost of the semiconductor integrated circuit can be reduced.

  Application Example 5 A remote control device according to this application example includes the semiconductor integrated circuit described in the application example.

  According to this application example, it is possible to use a semiconductor integrated circuit whose price has been reduced by reducing the inspection cost, and the product cost of the remote control device can be reduced.

Configuration of CR Oscillator Circuit According to Embodiment 1 Configuration of constant voltage supply unit Waveform diagram of capacitor voltage Vc Data table used to select resistance values Configuration of CR Oscillator Circuit According to Embodiment 2 Data table used to select the capacity value Configuration of CR Oscillator Circuit According to Embodiment 3

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is made different from the actual scale so that each member can be recognized.

(Embodiment 1)
FIG. 1 is a configuration diagram of a CR oscillation circuit 100 according to the first embodiment. First, a schematic configuration of the CR oscillation circuit 100 according to the first embodiment will be described.

  The CR oscillation circuit 100 includes a constant voltage supply unit 10, a CR oscillation unit 20, a temperature detection unit 50, and a control unit 60.

  The constant voltage supply unit 10 operates by receiving the power supply voltage Vcc from the power supply lines 1 and 2. The power supply line 1 is the power supply voltage Vcc, and the power supply line 2 is GND. Between the power supply lines 1 and 2, a MOS transistor 4, a resistor 5 and a resistor 6 are connected in series. A reference voltage Vref 1 that does not depend on the power supply voltage Vcc is applied to the inverting input terminal of the operational amplifier 3, and the non-inverting input terminal is connected to a node Na between the resistors 5 and 6. The output of the operational amplifier 3 is connected to the gate terminal of the MOS transistor 4. With this configuration, a constant voltage according to the resistance ratio of the resistors 5 and 6 can be output.

  The CR oscillation unit 20 operates by receiving a constant operating voltage V 1 output to the node Nb between the drain terminal of the MOS transistor 4 of the constant voltage supply unit 10 and the resistor 5 between the power supply line 2. Between the node Nb and the power supply line 2, MOS transistors 22 and 23 and a resistor 24 are connected in series. The resistor 24 is configured by connecting a parallel circuit of a resistive element 25a and a switch 26a, a parallel circuit of a resistive element 25b and a switch 26b, a parallel circuit of a resistive element 25c and a switch 26c, and a resistive element 25d in series. Here, the resistance values of the resistance elements 25a, 25b, and 25c are set to r, 2r, and 4r according to the power of 2. Since the resistance element 25d that does not have a switch in parallel always remains in the resistance 24, the resistance value of the resistance element 25d determines the upper limit value of the oscillation frequency. Eight different resistance values are generated depending on the on / off states of the switches 26a to 26c.

  The operational amplifier 21 constitutes a constant current circuit together with the MOS transistor 22 and the resistor 24. A reference voltage Vref2 independent of the power supply voltage Vcc is input to the non-inverting input terminal, and the inverting input terminal is connected to the source (node Nc) of the MOS transistor 22. The reference voltage Vr2 (≈Vref2) is applied to the resistor 24 by the operation of the operational amplifier 21. Therefore, when the switches 26a to 26c are switched to change the resistance value R of the resistor 24, the current flowing through the MOS transistor 22 changes in inverse proportion to the resistance value R.

  A charging MOS transistor 26, a switch 27, and a capacitor 28 are connected in series between the node Nb and the power supply line 2. The gates and sources of the MOS transistors 23 and 26 are connected in common to form a current mirror circuit. In the MOS transistor 26, a current proportional to the current flowing in the MOS transistor 23 (MOS transistor 22) flows according to the ratio of the size W / L of the MOS transistors 23 and 26. A discharge MOS transistor 29 is connected to the capacitor 28 in parallel.

  The comparator 30 compares the voltage Vc of the capacitor 28 with the voltage Vr2 of the node Nc and outputs an output voltage VOUT2 that is an oscillation signal. The output voltage VOUT2 is applied to the gate of the MOS transistor 29 and controls the on / off of the switch 27 via the inverter 31. The switch 27 is provided to cut off the current from the charging MOS transistor 26 by the L level signal from the inverter 31 while the discharging MOS transistor 29 is on.

  The temperature detection unit 50 operates by receiving a constant operating voltage V1 output from the constant voltage supply unit 10 to the node Nb with the power supply line 2. The temperature detection unit 50 includes a resistor 51 and diodes 52a, 52b, and 52c connected in series between the node Nb and the power supply line 2, and the forward voltage Va of the diodes 52a to 52c that changes depending on the environmental temperature. Output.

  The control unit 60 forms a waveform of the oscillation signal (output voltage VOUT2) input from the CR oscillation unit 20, and operates using it as a clock signal. The control unit 60 includes a nonvolatile memory 61 (storage means) and an A / D conversion circuit 62.

Next, the operation of the constant voltage supply unit 10 will be described with reference to FIG. Due to the operation of the operational amplifier 3, the voltage Vr1 at the node Na becomes equal to the reference voltage Vref1. The voltage Vr1 is a voltage obtained by dividing the voltage V1 of the node Nb between the drain terminal of the MOS transistor 4 and the resistor 5 by the resistor 5 and the resistor 6. Therefore, if the resistance values of the resistors 5 and 6 are r1 and r2, respectively, the relationship is expressed by the equation (1). Moreover, V1 can be represented as (2) Formula from (1) Formula.
Vr1 = V1 · {r2 / (r1 + r2)} (1)
V1 = {(r1 + r2) / r2} · Vr1 (2)
Since Vr1 in equation (2) is equal to the reference voltage Vref1 and is a constant voltage, V1 is determined by the resistance values of the resistors 5 and 6. For example, by fixing the resistance value of the resistor 6 and changing the resistance value of the resistor 5, the voltage value of V 1 is adjusted to an arbitrary value within the variable range of the resistance value of the resistor 5. It becomes possible to do. Alternatively, the resistance value of the resistor 5 may be fixed and the resistance value of the resistor 6 may be changed, or the resistance value of both the resistor 5 and the resistor 6 may be changed. Since there is no term of the power supply voltage Vcc in V1 expressed by the equation (2), a constant voltage value can be output without depending on the power supply voltage Vcc. That is, the constant voltage supply unit 10 transforms the power supply voltage Vcc and supplies a constant operating voltage V1 regardless of the power supply voltage Vcc.

Next, the oscillation operation of the CR oscillation unit 20 will be described with reference to FIG. FIG. 3 shows the waveform of the voltage Vc of the capacitor 28. For example, when the currents flowing in the MOS transistors 23 and 26 are equal, the capacitor 28 is charged with a constant current of the expression (3).
Ic = Vr2 / R (3)
Assuming that the capacitance value of the capacitor 28 is C, the voltage Vc of the capacitor 28 increases with a constant slope according to the constant 1 / C during the charging period. Eventually, when the voltage Vc reaches the voltage Vr2, the output voltage VOUT2 of the comparator 30 changes to H level, the switch 27 is turned off, and the MOS transistor 29 is turned on. As a result, the voltage Vc of the capacitor 28 is reduced to 0V. Due to this voltage drop, the output voltage VOUT2 of the comparator 30 changes to the L level again, the MOS transistor 29 is turned off, and the switch 27 is turned on. As a result, an oscillation signal having a narrow H pulse with a period T is obtained.

  Next, a frequency correction method of the CR oscillation circuit 100 of FIG. 1 will be described with reference to FIG. In an inspection process at the time of manufacture or shipment of a semiconductor device in which the CR oscillation circuit 100 is incorporated, the semiconductor device is placed in a thermostatic bath, and the power supply voltage Vcc is supplied from the inspection device. For the reference voltages Vref1 and Vref2, it is necessary to supply the reference voltage in the actual use state of the CR oscillation circuit 100. Therefore, as the reference voltages Vref1 and Vref2, a voltage equal to the actual use state is supplied from the inspection device. Or you may supply from the reference voltage circuit etc. which are used in an actual use condition. The inspection device can monitor the output voltage VOUT2 of the CR oscillation circuit 100 and can instruct the control unit 60 to turn on and off the switches 26a to 26c.

  The inspection device sequentially changes the temperature of the thermostatic chamber by a plurality of points within a range that can occur in the actual use state of the CR oscillation circuit 100, and controls the oscillation frequency to be closest to the target frequency with each temperature being given. The switches 26a to 26c are switched via the unit 60.

  At this time, when the oscillation frequency is higher than the target frequency, switching is performed to increase the resistance value of the resistor 24, and when the oscillation frequency is lower than the target frequency, switching is performed to decrease the resistance value of the resistor 24. In the switching state where the oscillation frequency is closest to the target frequency, the resistance value is associated with the temperature at that time. The temperature is an A / D conversion value of the voltage Va by the control unit 60.

  FIG. 4 is a correction data table created in this way. R1 to R8 in the figure are any of the above eight resistance values related to the combination. Instead of the resistance value, the on / off information of the switches 26a to 26c may be associated as, for example, 3-bit data. A data table in which the resistance value (or the on / off state of the switches 26a to 26c) is associated with this temperature (A / D conversion value of the voltage Va) is written in the nonvolatile memory 61 in accordance with a command from the inspection device.

  In an actual use state after the semiconductor device is shipped, the control unit 60 receives the voltage Va from the temperature detection unit 50 and performs A / D conversion at every predetermined control cycle. As described above, the A / D conversion value of the voltage Va corresponds to the detected temperature. Subsequently, the resistance value of the resistor 24 corresponding to the voltage Va is read from the correction data table stored in advance in the memory 61, and the switches 26a to 26c are set so that the resistance value R of the resistor 24 becomes equal to the read specified value. Switch.

  By this control, it is possible to correct a frequency error with respect to a change in the environmental temperature of the CR oscillation circuit 100. Further, according to the present embodiment, the CR oscillation unit 20 and the temperature detection unit 50 operate by receiving a constant operating voltage V1 that does not depend on the power supply voltage Vcc generated by the constant voltage supply unit 10. Conventionally, the output frequency has changed due to fluctuations in the power supply voltage Vcc. However, since the operating voltage V1 of the CR oscillation unit 20 becomes constant regardless of the power supply voltage Vcc, the change in the output frequency due to fluctuations in the power supply voltage Vcc. I'm not getting up. In the temperature detection unit 50, since the operating voltage V1 is constant regardless of the power supply voltage Vcc, the voltage Va corresponding to the detected temperature due to the fluctuation of the power supply voltage Vcc does not occur. Further, Vref1 and Vref2 are input as reference voltages into the CR oscillation circuit 100, and these are also constant voltages that do not depend on the power supply voltage Vcc. Therefore, it is not necessary to consider the influence of the power supply voltage Vcc when creating the data table. Therefore, in the present embodiment, correction of the frequency error with respect to the power supply voltage Vcc, which has been conventionally performed, is unnecessary, and a highly accurate frequency can be obtained only by correcting the frequency error with respect to the environmental temperature described above.

  According to the above-described embodiment, the resistance value of the resistor 24 with respect to the environmental temperature is tabulated while actually oscillating the CR oscillation circuit 100 in the inspection process and adjusting the oscillation frequency. Further, regarding the tabulation of the resistance value of the resistor 24 with respect to the oscillation frequency of the CR oscillation circuit 100, the supplied reference voltages Vref1 and Vref2, and the environmental temperature, there is no influence even if the power supply voltage Vcc varies. Therefore, even if the environmental temperature and the power supply voltage Vcc fluctuate in the actual usage state of the CR oscillation circuit 100, the oscillation frequency matches the target frequency with high accuracy including the constant variation of the capacitor 28, the resistor 24 and other circuit components. Can be made. In this case, since it is not necessary to correct the frequency error with respect to the fluctuation of the power supply voltage Vcc, which has been necessary in the prior art, a highly accurate frequency can be obtained only by correcting the frequency error with respect to the environmental temperature. Therefore, it is not necessary to create a frequency correction data table for the power supply voltage Vcc in the inspection process, the amount of measurement data can be reduced, and the inspection time can be shortened. Moreover, it can be expected to reduce the inspection cost as the inspection time is shortened.

  The resistor 24 includes resistance elements 25a to 25c connected in parallel to the switches 26a to 26c, respectively. The resistance elements 25a to 25c have resistance values r, 2r, and 4r weighted by a power of two. As a result, eight resistance values for each resistance value r can be generated area-efficiently using a small number of resistance elements.

(Embodiment 2)
FIG. 5 is a configuration diagram of a CR oscillation circuit 200 according to the second embodiment. A CR oscillation circuit 200 according to the present embodiment will be described with reference to FIG. In addition, about the component same as Embodiment 1, the same number is used and the overlapping description is abbreviate | omitted. The CR oscillation circuit 200 shown in FIG. 5 includes a capacitor 40 instead of the capacitor 28 and a resistor 43 instead of the resistor 24 in the first embodiment. The CR oscillation circuit 200 is configured to change the capacitance value of the capacitor 40, thereby correcting the frequency error. The resistor 43 has a certain resistance value.

  The capacitor 40 is configured by connecting in parallel a series circuit of a capacitor element 41a and a switch 42a, a series circuit of a capacitor element 41b and a switch 42b, and a series circuit of a capacitor element 41c and a switch 42c. Here, the capacitance values of the capacitor elements 41a, 41b, and 41c are set to c, 2c, and 4c, respectively, according to powers of 2. Since the capacitor element 41d that does not have a switch in series always remains in the configuration of the capacitor 40, the capacitance value of the capacitor element 41d determines the upper limit value of the oscillation frequency. The capacitance value of the capacitor 40 is determined by eight different capacitance values depending on the on / off states of the switches 42a to 42c.

  Next, a frequency correction method of the CR oscillation circuit 200 of FIG. 5 will be described with reference to FIG. In an inspection process at the time of manufacture or shipment of a semiconductor device in which the CR oscillation circuit 200 is incorporated, the semiconductor device is placed in a thermostatic bath, and the power supply voltage Vcc is supplied from the inspection device. As for the reference voltages Vref1 and Vref2, it is necessary to supply the reference voltage in the actual use state of the CR oscillation circuit 200. Therefore, as the reference voltages Vref1 and Vref2, a voltage equal to the actual use state is supplied from the inspection device. Or you may supply from the reference voltage circuit etc. which are used in an actual use condition. The inspection device can monitor the output voltage VOUT2 of the CR oscillation circuit 200 and can instruct the control unit 60 to turn on and off the switches 42a to 42c.

  The inspection apparatus sequentially changes the temperature of the thermostatic chamber at a plurality of points within a range that can occur in the actual use state of the CR oscillation circuit 200, and controls the oscillation frequency to be closest to the target frequency in a state where each temperature is given. The switches 42a to 42c are switched via the unit 60.

  At this time, when the oscillation frequency is higher than the target frequency, the capacitance value of the capacitor 40 is switched to be increased, and when the oscillation frequency is lower than the target frequency, the capacitance value of the capacitor 40 is switched to be decreased. In the switching state where the oscillation frequency is closest to the target frequency, the capacitance value is associated with the temperature at that time. The temperature is an A / D conversion value of the voltage Va by the control unit 60.

  FIG. 6 is a correction data table created in this way. C1 to C8 in the figure are any of the above eight capacitance values related to the combination. Instead of the capacitance value, on / off information of the switches 42a to 42c may be associated as, for example, 3-bit data. A data table in which the capacitance value (or the on / off state of the switches 42a to 42c) is associated with this temperature (A / D conversion value of the voltage Va) is written in the nonvolatile memory 61 in response to a command from the inspection device.

  In an actual use state after the semiconductor device is shipped, the control unit 60 receives the voltage Va from the temperature detection unit 50 and performs A / D conversion at every predetermined control cycle. As described above, the A / D conversion value of the voltage Va corresponds to the detected temperature. Subsequently, the capacitance value of the capacitor 40 corresponding to the voltage Va is read from the correction data table stored in advance in the memory 61, and the switches 42a to 42c are set so that the capacitance value C of the capacitor 40 becomes equal to the read specified value. Switch.

  With this control, it is possible to correct a frequency error with respect to a change in the environmental temperature of the CR oscillation circuit 200. Further, according to the present embodiment, the CR oscillation unit 20 and the temperature detection unit 50 operate by receiving a constant operating voltage V1 that does not depend on the power supply voltage Vcc generated by the constant voltage supply unit 10. Conventionally, the output frequency has changed due to fluctuations in the power supply voltage Vcc. However, since the operating voltage V1 of the CR oscillation unit 20 becomes constant regardless of the power supply voltage Vcc, the change in the output frequency due to fluctuations in the power supply voltage Vcc. I'm not getting up. In the temperature detection unit 50, since the operating voltage V1 is constant regardless of the power supply voltage Vcc, the voltage Va corresponding to the detected temperature due to the fluctuation of the power supply voltage Vcc does not occur. Further, Vref1 and Vref2 are input as reference voltages into the CR oscillation circuit 200, and these are also constant voltages that do not depend on the power supply voltage Vcc. Therefore, it is not necessary to consider the influence of the power supply voltage Vcc when creating the data table. Therefore, in the present embodiment, correction of the frequency error with respect to the power supply voltage Vcc, which has been conventionally performed, is unnecessary, and a highly accurate frequency can be obtained only by correcting the frequency error with respect to the environmental temperature described above.

  According to the above-described embodiment, the capacitance value of the capacitor 40 with respect to the environmental temperature is tabulated while actually oscillating the CR oscillation circuit 200 and adjusting the oscillation frequency in the inspection process. Further, regarding the tabulation of the capacitance value of the capacitor 40 with respect to the oscillation frequency of the CR oscillation circuit 200, the supplied reference voltages Vref1 and Vref2, and the ambient temperature, there is no effect even if the power supply voltage Vcc varies. Therefore, even if the environmental temperature and the power supply voltage Vcc fluctuate in the actual usage state of the CR oscillation circuit 200, the oscillation frequency matches the target frequency with high accuracy, including the constant variation of the capacitor 40, the resistor 43 and other circuit components. Can be made. In this case, since it is not necessary to correct the frequency error with respect to the fluctuation of the power supply voltage Vcc, which has been necessary in the prior art, a highly accurate frequency can be obtained only by correcting the frequency error with respect to the environmental temperature. Therefore, it is not necessary to create a frequency correction data table for the power supply voltage Vcc in the inspection process, the amount of measurement data can be reduced, and the inspection time can be shortened. Moreover, it can be expected to reduce the inspection cost as the inspection time is shortened.

  The capacitor 40 includes capacitor elements 41a to 41c connected in series to the switches 42a to 42c in parallel, respectively, and the capacitor elements 41a to 41c have capacitance values c, 2c, and 4c weighted by a power of two. As a result, eight capacitance values for each capacitance value c can be generated with a high area efficiency using a small number of capacitor elements.

(Embodiment 3)
FIG. 7 is a configuration diagram of a CR oscillation circuit 300 according to the third embodiment. The CR oscillation circuit 300 has a configuration in which the resistor 24 included in the CR oscillation circuit 100 according to the first embodiment and the capacitor 40 included in the CR oscillation circuit 200 according to the second embodiment are combined.

  Next, a frequency correction method for the CR oscillation circuit 300 in FIG. 7 will be described. In an inspection process at the time of manufacture or shipment of a semiconductor device in which the CR oscillation circuit 300 is incorporated, the semiconductor device is placed in a thermostatic bath, and the power supply voltage Vcc is supplied from the inspection device. For the reference voltages Vref1 and Vref2, it is necessary to supply the reference voltage in the actual usage state of the CR oscillation circuit 300. Therefore, as the reference voltages Vref1 and Vref2, a voltage equal to the actual use state is supplied from the inspection device. Or you may supply from the reference voltage circuit etc. which are used in an actual use condition. The inspection device can monitor the output voltage VOUT2 of the CR oscillation circuit 300 and can instruct the controller 60 to turn on and off the switches 26a to 26c and the switches 42a to 42c.

  The inspection apparatus sequentially changes the temperature of the thermostatic chamber by a plurality of points within a range that can occur in the actual use state of the CR oscillation circuit 300, and controls the oscillation frequency to be closest to the target frequency with each temperature being given. The switches 26a to 26c and the switches 42a to 42c are switched via the unit 60.

  At this time, if the oscillation frequency is higher than the target frequency, the resistance value of the resistor 24 is increased, the capacitance value of the capacitor 40 is increased, or both the resistance value of the resistor 24 and the capacitance value of the capacitor 40 are increased. When the oscillation frequency is lower than the target frequency, the resistance value of the resistor 24 is decreased, or the capacitance value of the capacitor 40 is decreased, or both the resistance value of the resistor 24 and the capacitance value of the capacitor 40 are reduced. Switch to lower. In the switching state where the oscillation frequency is closest to the target frequency, the resistance value and the capacitance value are associated with the temperature at that time. The temperature is an A / D conversion value of the voltage Va by the control unit 60.

  In this way, a data table for correction is created. Instead of the resistance value and the capacitance value, the on / off information of the switches 26a to 26c and the switches 42a to 42c may be associated as, for example, 6-bit data. A data table in which the resistance value (or the on / off state of the switches 26a to 26c) and the capacitance value (or the on / off state of the switches 42a to 42c) are associated with this temperature (A / D conversion value of the voltage Va) is an inspection device. Is written in the non-volatile memory 61 in response to a command from

  In an actual use state after the semiconductor device is shipped, the control unit 60 receives the voltage Va from the temperature detection unit 50 and performs A / D conversion at every predetermined control cycle. As described above, the A / D conversion value of the voltage Va corresponds to the detected temperature. Subsequently, the resistance value of the resistor 24 and the capacitance value of the capacitor 40 corresponding to the voltage Va are read from the correction data table stored in advance in the memory 61, and the resistance value R of the resistor 24 and the capacitance value C of the capacitor 40 are obtained as follows. The switches 26a to 26c and the switches 42a to 42c are switched so as to be equal to the read designated value.

  With this control, it is possible to correct a frequency error with respect to a change in the environmental temperature of the CR oscillation circuit 300. Further, according to the present embodiment, the CR oscillation unit 20 and the temperature detection unit 50 operate by receiving a constant operating voltage V1 that does not depend on the power supply voltage Vcc generated by the constant voltage supply unit 10. Conventionally, the output frequency has changed due to fluctuations in the power supply voltage Vcc. However, since the operating voltage V1 of the CR oscillation unit 20 becomes constant regardless of the power supply voltage Vcc, the change in the output frequency due to fluctuations in the power supply voltage Vcc. I'm not getting up. In the temperature detection unit 50, since the operating voltage V1 is constant regardless of the power supply voltage Vcc, the voltage Va corresponding to the detected temperature due to the fluctuation of the power supply voltage Vcc does not occur. Furthermore, although Vref1 and Vref2 are input as reference voltages in the CR oscillation circuit 300, these are also constant voltages that do not depend on the power supply voltage Vcc. Therefore, it is not necessary to consider the influence of the power supply voltage Vcc when creating the data table. Therefore, in the present embodiment, correction of the frequency error with respect to the power supply voltage Vcc, which has been conventionally performed, is unnecessary, and a highly accurate frequency can be obtained only by correcting the frequency error with respect to the environmental temperature described above.

  According to the above-described embodiment, the resistance value of the resistor 24 and the capacitance value of the capacitor 40 with respect to the environmental temperature are tabulated while actually oscillating the CR oscillation circuit 300 in the inspection process to match the oscillation frequency. . Further, regarding the tabulation of the oscillation frequency of the CR oscillation circuit 300, the supplied reference voltages Vref1 and Vref2, the resistance value of the resistor 24 with respect to the environmental temperature and the capacitance value of the capacitor 40, there is no effect even if the power supply voltage Vcc varies. . Therefore, even if the environmental temperature and the power supply voltage Vcc fluctuate in the actual usage state of the CR oscillation circuit 300, the oscillation frequency can be set to the target frequency with high precision including the constant variation of the resistor 24, the capacitor 40, and other circuit components. Can be matched. Further, in this embodiment, since both the resistor 24 and the capacitor 40 are controlled, the degree of freedom of correction is increased compared to the above embodiments, and the oscillation frequency can be matched with the target frequency with higher accuracy. According to this embodiment, since it is not necessary to correct the frequency error with respect to the fluctuation of the power supply voltage Vcc, which has been necessary in the past, it is possible to obtain a highly accurate frequency only by correcting the frequency error with respect to the environmental temperature. Therefore, it is not necessary to create a frequency correction data table for the power supply voltage Vcc in the inspection process, the amount of measurement data can be reduced, and the inspection time can be shortened. Moreover, it can be expected to reduce the inspection cost as the inspection time is shortened.

  The resistor 24 includes resistance elements 25a to 25c connected in parallel to the switches 26a to 26c, respectively. The resistance elements 25a to 25c have resistance values r, 2r, and 4r weighted by a power of two. As a result, eight resistance values for each resistance value r can be generated area-efficiently using a small number of resistance elements.

  The capacitor 40 includes capacitor elements 41a to 41c connected in series to the switches 42a to 42c in parallel, respectively, and the capacitor elements 41a to 41c have capacitance values c, 2c, and 4c weighted by a power of two. As a result, eight capacitance values for each capacitance value c can be generated with a high area efficiency using a small number of capacitor elements.

(Embodiment 4)
A semiconductor integrated circuit according to the fourth embodiment includes the CR oscillation circuit described in the above embodiments. A signal output from the CR oscillation circuit in the semiconductor integrated circuit is used as a source signal of an operation clock used in other circuits, for example. Further, the constant voltage supply unit and the control unit in the CR oscillation circuit may each be configured to generate an operation voltage and control in the circuit in another circuit in the semiconductor integrated circuit. According to this embodiment, the inspection time of the CR oscillation circuit portion in the semiconductor integrated circuit is shortened, and as a result, the inspection time of the entire semiconductor integrated circuit can be shortened. Further, as the inspection time is shortened, the product cost of the semiconductor integrated circuit can be reduced.

(Embodiment 5)
A remote control device according to the fifth embodiment includes the semiconductor integrated circuit described in the fourth embodiment. This remote control device is for operating an air conditioner device, for example, and a semiconductor integrated circuit inside the remote control device performs control accompanying the operation of the remote control device. According to this embodiment, since the semiconductor integrated circuit whose product cost has been reduced is used for the remote control device, the product cost of the remote control device can be reduced.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be added to the above-described embodiment. A modification will be described below.

(Modification 1)
This modification is a modification of the frequency correction method described in the first to third embodiments. In the actual use state, the control unit 60 determines that the voltage corresponding to the detected temperature acquired from the temperature detection unit 50 so that the fluctuation value in one control cycle of the resistance value and / or the capacitance value is within a predetermined range. A variable voltage width in one control cycle of Va may be provided as a limit. In the case shown in FIG. 4, for example, the voltage width that can be varied in one control cycle with respect to the voltage Va corresponding to the detected temperature is limited to ± 0.02V. After that, the resistance value of the resistor 24 corresponding to the voltage Va after the limitation is read out from the memory 61. When the resistance value read in the previous control cycle is R4, the resistance values that can be read in the current control cycle are R3 and R5.

  According to this configuration, the rapid change of the voltage Va acquired from the temperature detection unit 50 is limited, and the oscillation frequency can be gradually corrected in units of control cycles. Therefore, the rapid change of the oscillation frequency can be prevented. In addition, when the voltage Va changes beyond the maximum change that can normally occur during the control period due to noise intrusion or the like, the change is limited, so that the oscillation frequency can be prevented from greatly deviating from the target frequency.

(Modification 2)
This modification is a modification of the frequency correction method described in the first to third embodiments. In the inspection process, a data table is created for each of a plurality of different target frequencies (X MHz, Y MHz, Z MHz,...) And stored in the memory 61 in advance. Accordingly, the data table used for reading may be switched. Thereby, one CR oscillation circuit can be oscillated at a plurality of frequencies.

(Modification 3)
This modification is a modification of the frequency correction method described in the first to third embodiments. In the inspection process, etc., a data table is created and stored for each target oscillation frequency used in a plurality of different operation modes of a device that uses an oscillation signal as a clock signal, etc. Accordingly, the data table used for reading may be switched. The operation mode here is, for example, a power saving operation mode (for example, a low power mode, a sleep mode, a standby mode), a normal power operation mode (for example, a normal mode), a startup operation mode (a wake-up mode), or the like. Thereby, one CR oscillation circuit can be oscillated at various frequencies suitable for each operation mode.

(Modification 4)
In the first and third embodiments, the resistance value of the resistor 24 can be switched to eight resistance values, but if the number n of series connections of the parallel circuit of the resistor element and the switch is increased, a larger 2n resistance value is set. It becomes possible. Similarly, in the second and third embodiments, the capacitance value of the capacitor 40 can be switched to eight capacitance values, but if the number n of parallel connections of the series circuit of the capacitor element and the switch is increased, more 2n capacitance values can be obtained. The value can be set. By increasing the settable value in this way, accuracy (frequency resolution) when correcting the oscillation frequency can be increased.

(Modification 5)
As the capacitor and resistance that determine the oscillation frequency, the gate capacitance and on-resistance of a MOS transistor may be used. In this case, the control unit 60 may control the gate-source voltage of the MOS transistor based on the capacitance value and the resistance value read from the data table stored in the memory 61.

  DESCRIPTION OF SYMBOLS 1, 2 ... Power supply line 3 ... Operational amplifier 4 ... MOS transistor 5, 6 ... Resistance, 10 ... Constant voltage supply part, 20 ... CR oscillation part, 21 ... Operational amplifier, 22, 23 ... MOS transistor, 24 ... Resistance, 25a, 25b, 25c, 25d ... resistance elements, 26 ... MOS transistors, 26a, 26b, 26c ... switches, 27 ... switches, 28 ... capacitors, 29 ... MOS transistors, 30 ... comparators, 31 ... inverters, 40 ... capacitors, 41a, 41b, 41c, 41d ... capacitor elements, 42a, 42b, 42c ... switches, 43 ... resistors, 50 ... temperature detectors, 51 ... resistors, 52a, 52b, 52c ... diodes, 60 ... control units, 61 ... memory ( Storage means), 62... A / D conversion circuit, 100, 200, 300... CR oscillation circuit

Claims (5)

A CR oscillation circuit comprising a capacitor and a resistor, and oscillating at a frequency determined based on a capacitance value of the capacitor and a resistance value of the resistor upon receiving a supply voltage;
The resistor is configured to be changeable to a specified value from among a plurality of different resistance values,
A constant voltage supply unit that transforms the power supply voltage and supplies a constant operating voltage regardless of the power supply voltage;
A CR oscillator that oscillates in response to the supply of the operating voltage;
A temperature detection unit that receives the operating voltage and detects an environmental temperature;
Non-volatile storage means capable of writing a data table in which the resistance value of the resistor is associated with the environmental temperature of the oscillation operation;
The detection temperature is acquired from the temperature detection unit at a predetermined control period, the resistance value of the resistor corresponding to the detection temperature is read from the data table stored in advance in the storage unit, and the resistance value of the resistance is A control unit that controls to be equal to the read specified value,
The resistor is configured by connecting a plurality of parallel circuits of a resistor element and a switch in series.
The CR oscillation circuit, wherein the control unit switches the switch according to a resistance value read from a data table of the storage means. A CR oscillation circuit comprising a capacitor and a resistor, and oscillating at a frequency determined based on a capacitance value of the capacitor and a resistance value of the resistor upon receiving a supply voltage;
The capacitor is configured to be changeable to a specified value from among a plurality of different capacitance values,
A constant voltage supply unit that transforms the power supply voltage and supplies a constant operating voltage regardless of the power supply voltage;
A CR oscillator that oscillates in response to the supply of the operating voltage;
A temperature detection unit that receives the operating voltage and detects an environmental temperature;
Nonvolatile storage means capable of writing a data table in which the capacitance value of the capacitor is associated with the environmental temperature of the oscillation operation;
The detection temperature is acquired from the temperature detection unit at a predetermined control period, the capacitance value of the capacitor corresponding to the detection temperature is read from the data table stored in advance in the storage unit, and the capacitance value of the capacitor is A control unit that controls to be equal to the read specified value,
The capacitor is configured by connecting a plurality of series circuits of a capacitor element and a switch in parallel.
The CR oscillation circuit, wherein the control unit switches the switch according to a capacitance value read from a data table of the storage unit. A CR oscillation circuit comprising a capacitor and a resistor, and oscillating at a frequency determined based on a capacitance value of the capacitor and a resistance value of the resistor upon receiving a supply voltage;
The capacitor is configured to be changeable to a specified value from among a plurality of different capacitance values,
The resistor is configured to be changeable to a specified value from among a plurality of different resistance values,
A constant voltage supply unit that transforms the power supply voltage and supplies a constant operating voltage regardless of the power supply voltage;
A CR oscillator that oscillates in response to the supply of the operating voltage;
A temperature detection unit that receives the operating voltage and detects an environmental temperature;
Non-volatile storage means capable of writing a data table in which the capacitance value of the capacitor and the resistance value of the resistor are associated with the environmental temperature of the oscillation operation;
The detection temperature is acquired from the temperature detection unit at a predetermined control period, and the capacitance value of the capacitor and the resistance value of the resistor corresponding to the detection temperature are read from the data table stored in advance in the storage unit, A control unit that controls the capacitance value of the capacitor and the resistance value of the resistor to be equal to the read designated value, and
The capacitor is configured by connecting a plurality of series circuits of a capacitor element and a switch in parallel.
The resistor is configured by connecting a plurality of parallel circuits of a resistor element and a switch in series.
The CR oscillation circuit, wherein the control unit switches the switch according to a capacitance value and a resistance value read from a data table of the storage unit.   A semiconductor integrated circuit comprising the CR oscillation circuit according to claim 1.   A remote control device comprising the semiconductor integrated circuit according to claim 4.

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