JPH04288609A - Supply voltage detecting circuit - Google Patents

Abstract

PURPOSE:To generate a reset pulse independent of temperature by eliminating the dependency upon temperature of a desired reset release voltage. CONSTITUTION:A potential V2 of a second node 2 is a supply voltage VDD until the potential of a fourth node 4 reaches the threshold voltage of a MOSFET 14 by the rise of the supply voltage VDD from a ground potential VSS. A potential V1 of a first node 1 is the ground potential VSS until the potential of a third node 3 reaches the threshold voltage of a MOSFET 11. When third and fourth nodes 3 and 4 exceed threshold voltages of MOSFETs 11 and 14 respectively by the rise of the supply voltage VDD, the potential divided by a first resistance 12 and the saturation characteristic of the MOSFET 11 is outputted to the first node 1, and that divided by a second resistance 13 and the saturation characteristic of the MOSFET 14 is outputted to the second node 2. A comparator 50 outputs the reset pulse till arrival at the reset release voltage after application of the supply voltage VDD.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply voltage detection circuit for detecting the application of a power supply voltage.

0002

2. Description of the Related Art In semiconductor integrated circuits, there are some circuits whose operation becomes unstable when the power is turned on, so that the initial output is not determined. In some cases, it is necessary to determine the initial output of this circuit. A power supply voltage detection circuit that supplies a control signal for determining the output to a circuit having such an undetermined initial output will be described below with reference to the drawings.

FIG. 6 is a circuit diagram of a conventional power supply voltage detection circuit. In FIG. 6, 33 and 34 are resistors, and 35 and 36 are P-channel MOS field effect transistors (hereinafter referred to as "
37, 38, 39 are N-channel MOS field effect transistors (hereinafter referred to as "N-type MOSFETs"), 50 is a comparator, 51,
52 is an input terminal of the comparator 50, 53 is an output terminal of the comparator 50, 60 is a waveform shaping amplifier, and 61 is an output terminal of the waveform shaping amplifier 60.

The operation of the conventional power supply voltage detection circuit configured as described above will be explained below. As shown in FIG. 6, by resistors 33 and 34 connected in series between power supply voltage VDD and ground potential VSS, power supply voltage VDD
The reference potential obtained by dividing the voltage is applied to the input terminal 51 of the comparator 50.
supplied to P-type MOSFETs 35, 36 and N-type MOSFETs 37, 38, 39 constitute a current mirror circuit, and the drain potential of N-type MOSFET 39 is supplied to an input terminal 52 of a comparator 50. The voltage value input to the input terminal 52 of this comparator 50 becomes higher than a certain value of the power supply voltage VDD, and the P-type MOSFET 36
In the state where current flows through the N-type MOSFETs 37 and 39, the threshold voltage of the N-type MOSFET 37 is set to VTN,
Letting the threshold voltage of the P-type MOSFET 36 be VTP, it is set to approximately VDD-|VTP|-|VTN|.

FIG. 7 shows the temperature dependence of each input terminal potential of the comparator 50 with respect to the power supply voltage VDD. In FIG. 7, V52N and V52H are the potential V52 of the input terminal 52 at room temperature and high temperature, respectively, and V51 is the potential of the input terminal 51 as shown in FIG. The same is true at high temperatures. At room temperature, increase the power supply voltage VDD until it reaches a certain value (
When VCN (hereinafter referred to as "reset release voltage") is reached,
The voltage value V52 (V52N) of the input signal input to the input terminal 52 of the comparator 50 becomes larger than the voltage value V51 of the input signal input to the input terminal 51 of the comparator 50, and the voltage value V52 (V52N) of the input signal input to the input terminal 52 of the comparator 50 becomes larger than the voltage value V51 of the input signal input to the input terminal 51 of the comparator 50, and the voltage value V52 (V52N) is output from the output terminal 53 of the comparator 50. The value of the output signal changes and becomes the reset release signal. This output signal is amplified by an amplifier 60 and output from an output terminal 61.

As described above, by applying the power supply voltage VDD, a reset signal is applied to each circuit in the semiconductor device to determine the initial output value, and the power supply voltage VDD becomes the reset release voltage V.
When reaching CN, the reset is canceled due to a change in the output of the output terminal 61.

[0007]

However, in the above conventional configuration, the voltage value V52 input to the input terminal 52 of the comparator 50 is different from the power supply voltage VDD, the P-type MOSFE
Threshold voltage VTP of T36 and N-type MOSFET3
7, the temperature dependence of the threshold voltages VTP and VTN is reflected in the voltage value V52 input to the input terminal 52, and the reset release voltage is no longer constant. Threshold voltage VTP, VT at high temperature
N becomes smaller, and as shown in FIG. 6, the voltage value V52H of the input terminal 52 at high temperature becomes larger than the voltage value V52N at normal temperature. Therefore, the reset release voltage VCH when outputting the reset release signal to the output terminal 53 of the comparator 50 becomes smaller than the reset release voltage VCN set at room temperature, and the pulse width of the reset signal may be narrow and not recognized as a reset pulse. .

An object of the present invention is to provide a power supply voltage detection circuit that can eliminate the temperature dependence of a desired reset release voltage and generate a reset pulse that is independent of temperature.

[0009]

Means for Solving the Problems The power supply voltage detection circuit according to claim 1 has a first active element connected between one power supply terminal and a first node, and a first active element connected between the first node and the other power supply terminal. A first resistor is connected between the terminal, a second resistor is connected between one power supply terminal and a second node, and a second resistor is connected between the second node and the other power supply terminal. connecting the active element and connecting a third resistor between one power supply terminal and a third node;
A fourth resistor is connected between the third node and the fourth node, a fifth resistor is connected between the fourth node and the other power supply terminal, and the control terminal of the first active element is connected to the control terminal of the first active element. is connected to the third node, and the control end of the second active element is connected to the fourth node. The device also includes a comparator that detects whether the potentials of the first node and the second node match.

In the power supply voltage detection circuit according to a second aspect of the present invention, a sixth resistor is connected between one power supply terminal and the fifth node, and a third resistor is connected between the fifth node and the other power supply terminal. a seventh resistor is connected between one power supply terminal and the sixth node, an eighth resistor is connected between the sixth node and the seventh node, and a seventh resistor is connected between the sixth node and the seventh node. A ninth resistor is connected between the node No. 7 and the other power supply terminal, and the control end of the third active element is connected to the seventh node. The device also includes a comparator that detects whether the potentials of the fifth node and the sixth node match.

[0011]

According to the structure described in claim 1, the potentials of the first node and the second node, which are the input voltages of the comparator, have no temperature dependence with respect to a desired power supply voltage. Therefore, the temperature dependence of the desired reset release voltage can be removed, and the reset pulse that is the output of the comparator also does not have temperature dependence.

According to the second aspect of the present invention, the potentials of the fifth node and the sixth node, which are input voltages of the comparator, have no temperature dependence with respect to a desired power supply voltage. Therefore, the temperature dependence of the desired reset release voltage can be removed, and the reset pulse that is the output of the comparator also does not have temperature dependence.

[0013]

[Embodiments] [First Embodiment] A first embodiment of the present invention will be described based on the drawings. FIG. 1 is a circuit diagram of a power supply voltage detection circuit according to a first embodiment of the present invention. This power supply voltage detection circuit detects between the power supply voltage VDD and the ground voltage VSS.
A P-type MOSFET (first active element) 11 and a first resistor 12 are connected in series via a first node 1, and a second resistor 13 and an N-type MOSFET (second
active elements) 14 are connected in series, and the third node 3 and the fourth
The third resistor 15 and the fourth resistor 16 are connected to the node 4 of
and a fifth resistor 17 are connected in series. Further, the third node 3 is connected to the gate of the P-type MOSFET 11, and the fourth node 4 is connected to the gate of the N-type MOSFET 14. Then, the first node 1 is connected to the comparator 5
0, the second node 2 is connected to the input terminal 51 of the comparator 50, and the output terminal 53 of the comparator 50 is connected to the waveform shaping amplifier 60. 61 is an output terminal of the waveform shaping amplifier 60.

The operation of the power supply voltage detection circuit configured as described above will be explained with reference to FIGS. 1 and 2. Note that FIG. 2 shows the comparator 5 for the power supply voltage VDD.
The temperature dependence of the potentials V1 and V2 of the first node 1 and the second node 2, which are inputs of 0, is shown. In FIG. 2, V1N and V1H are the potential V1 of the first node 1 at room temperature and high temperature, respectively, and V2N and V2H are the potential V2 of the second node 2 at room temperature and high temperature, respectively.

The potential of the third node 3 and the potential of the fourth node 4 have a value obtained by dividing the power supply voltage VDD by the third resistor 15, the fourth resistor 16, and the fifth resistor 17. Until the power supply voltage VDD rises from the ground potential VSS and the potential of the fourth node 4 reaches the threshold voltage of the N-type MOSFET 14, the N-type MOSFET 14 is in a non-conducting state and the second node 2 is in a non-conductive state. Potential V2 (V2N, V2H)
is the power supply voltage VDD. Further, until the potential of the third node 3 reaches the threshold voltage of the P-type MOSFET 11, the P-type MOSFET 11 is also in a non-conductive state, and the potential V1 (V1N, V1H) of the first node 1 is set to the ground potential VS
It is S.

[0016] The power supply voltage VDD rises and the third node 3
and the fourth node 4 become equal to or higher than the threshold voltages of the MOSFETs 11 and 14, respectively, the P-type MOSFET 11 becomes conductive, and the first resistor 12 and the P-type MOSFET 11
The potential divided by the saturation characteristic of is output to the first node 1. On the other hand, the N-type MOSFET 14 becomes conductive, and the voltage divided by the saturation characteristics of the second resistor 13 and the N-type MOSFET 14 is output to the second node 2 .

There is a point where the potentials V1 and V2 of the first node 1 and the second node 2 with respect to the power supply voltage VDD do not depend on temperature changes. Therefore, P-type MOSFE
T11, N-type MOSFET14 and resistors 12, 13,
By appropriately selecting 15, 16, and 17, the power supply voltage VDD can be adjusted to the desired reset release voltage VC, as shown in FIG.
When the first node 1 and the second node 2 reach
The potentials V1 and V2 can be made to have no temperature dependence.

Further, when the power supply voltage VDD becomes equal to or higher than the desired reset release voltage VC, the magnitude relationship of the potentials (V2, V1) of the input terminals 51 and 52 of the comparator 50 is reversed. The comparator 50 outputs a reset pulse during the period from when the power supply voltage VDD is applied until the reset release voltage VC is reached. This output is waveform-shaped by a waveform-shaping amplifier 60 and transmitted from an output terminal 61 to other circuits as a reset signal.

As described above, according to this embodiment, when the power supply voltage VDD reaches the desired reset release voltage VC, the potentials V1, V1, and V1 of the first node 1 and the second node 2 are
By making V2 independent of temperature,
The temperature dependence of the reset release voltage VC can be removed, and the reset pulse that is the output of the comparator 50 also does not have temperature dependence.

Note that in this embodiment, MO is used as an active element.
Although SFETs 11 and 14 are used, bipolar transistors may also be used. [Second Embodiment] A second embodiment of the present invention will be described based on the drawings. FIG. 3 is a circuit diagram of a power supply voltage detection circuit according to a second embodiment of the present invention.

This power supply voltage detection circuit detects the power supply voltage VDD.
and the ground voltage VSS through the fifth node 5 and the sixth resistor 18 and the N-type MOSFET (third active element) 1.
9 are connected in series, and a seventh resistor 20, an eighth resistor 21, and a ninth resistor 22 are connected in series via the sixth node 6 and the seventh node 7. Furthermore, the seventh node 7 is connected to the gate of an N-type MOSFET 19. Then, the fifth node 5 is connected to the input terminal 51 of the comparator 50, the sixth node 6 is connected to the input terminal 52 of the comparator 50, and the waveform shaping amplifier 60 is connected to the output terminal 53 of the comparator 50. There is. 61 is an output terminal of the waveform shaping amplifier 60.

The operation of the power supply voltage detection circuit configured as described above will be explained with reference to FIGS. 3 and 4. Note that FIG. 4 shows the comparator 5 for the power supply voltage VDD.
The temperature dependence of the potentials V5 and V6 of the fifth node 5 and the sixth node 6, which are 0 inputs, is shown. In FIG. 2, V5N and V5H are the potential V5 of the fifth node 5 at normal temperature and the potential V6 of the sixth node 6 at high temperature, respectively.
is the same at room temperature and at high temperature.

The potential of the sixth node 6 and the potential of the seventh node 7 have a value obtained by dividing the power supply voltage VDD by the seventh resistor 20, the eighth resistor 21, and the ninth resistor 22. Until the power supply voltage VDD rises from the ground potential VSS and the potential of the seventh node 7 reaches the threshold voltage of the N-type MOSFET 19, the N-type MOSFET 19 is in a non-conducting state and the fifth node 5 is in a non-conductive state. Potential V5 (V5N, V5H)
is the power supply voltage VDD.

[0024] The power supply voltage VDD rises and the seventh node 7
When becomes equal to or higher than the threshold voltage of the MOSFET 19, the N-type MOSFET 19 becomes conductive, and a potential divided by the saturation characteristics of the sixth resistor 18 and the N-type MOSFET 19 is output to the fifth node 5. There is a point where the potential V5 (V5N, V5H) of the fifth node 5 with respect to the power supply voltage VDD does not depend on temperature changes. Therefore, by appropriately selecting the N-type MOSFET 19 and the resistors 18, 20, 21, and 22, the power supply voltage V
When DD reaches the desired reset release voltage VC, the potential V5 of the fifth node 5 no longer has temperature dependence and can be made the same as the potential V6 of the sixth node 6.

Furthermore, when the power supply voltage VDD exceeds the desired reset release voltage VC, the magnitude relationship of the potentials (V5, V6) of the input terminals 51, 52 of the comparator 50 is reversed. The comparator 50 outputs a reset pulse during the period from when the power supply voltage VDD is applied until the reset release voltage VC is reached. This output is waveform-shaped by a waveform-shaping amplifier 60 and transmitted from an output terminal 61 to other circuits as a reset signal.

As described above, according to this embodiment, when the power supply voltage VDD reaches the desired reset release voltage VC, the potentials V5,
By making V6 independent of temperature,
The temperature dependence of the reset release voltage VC can be removed, and the reset pulse that is the output of the comparator 50 also does not have temperature dependence.

Note that in this embodiment, MO is used as an active element.
Although SFET 19 is used, a bipolar transistor may also be used. [Third Embodiment] A third embodiment of the present invention will be described based on the drawings. FIG. 5 is a circuit diagram of a power supply voltage detection circuit according to a third embodiment of the present invention.

This power supply voltage detection circuit detects the power supply voltage VDD.
and the ground voltage VSS via the fifth node 8.
type MOSFET (third active element) 23 and sixth resistor 2
4 are connected in series, and a seventh resistor 27, an eighth resistor 26, and a ninth resistor 25 are connected in series via the sixth node 10 and the seventh node 9. Furthermore, the seventh node 9
is connected to the gate of the P-type MOSFET 23. Then, the fifth node 8 is connected to the input terminal 52 of the comparator 50.
The sixth node 10 is connected to the input terminal 51 of the comparator 50, and the waveform shaping amplifier 60 is connected to the output terminal 53 of the comparator 50. 61 is an output terminal of the waveform shaping amplifier 60.

[0029] This power supply voltage detection circuit is a P-type MOSFE
By appropriately selecting T23 and resistors 24, 25, 26, and 27, a potential that does not have temperature dependence can be set to the comparator 50.
The principle and effect are the same as in the second embodiment, so detailed explanation will be omitted.

[0030]

In the power supply voltage detection circuit according to the first aspect of the present invention, the potentials of the first node and the second node, which are the input voltages of the comparator, have no temperature dependence with respect to a desired power supply voltage. Therefore, the temperature dependence of the desired reset release voltage can be removed, and the reset pulse that is the output of the comparator also does not have temperature dependence.

In the power supply voltage detection circuit according to the second aspect of the present invention, a fifth voltage, which is the input voltage of the comparator, is
The potentials of the node and the sixth node have no temperature dependence. Therefore, the temperature dependence of the desired reset release voltage can be removed, and the reset pulse that is the output of the comparator also does not have temperature dependence.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a power supply voltage detection circuit according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the potential applied to the input terminal of the comparator and the power supply voltage in the first embodiment of the invention.

FIG. 3 is a circuit diagram of a power supply voltage detection circuit according to a second embodiment of the invention.

FIG. 4 is a characteristic diagram showing the relationship between the potential applied to the input terminal of the comparator and the power supply voltage in a second embodiment of the invention.

FIG. 5 is a circuit diagram of a power supply voltage detection circuit according to a third embodiment of the present invention.

FIG. 6 is a circuit diagram of a conventional power supply voltage detection circuit.

FIG. 7 is a characteristic diagram showing the relationship between the potential applied to the input terminal of a comparator and the power supply voltage in a conventional power supply voltage detection circuit.

[Explanation of symbols]

1 First node 2 Second node 3 Third node 4 Fourth node 5, 8 Fifth node 6, 10 Sixth node 7, 9 Seventh node 11 P-type MOSFET (first active element) 12
First resistor 13 Second resistor 14 N-type MOSFET (second active element) 15
Third resistor 16 Fourth resistor 17 Fifth resistor 18, 24 Sixth resistor 19 N-type MOSFET (third active element) 20
, 27 seventh resistor 21, 26 eighth resistor 22, 25 ninth resistor 23 P-type MOSFET (third active element) 50
Comparator VDD Power supply voltage VSS Ground potential

Claims (2)

[Claims] 1. A first active element connected between one power supply terminal and a first node; a first resistor connected between the first node and the other power supply terminal; a second resistor connected between one power supply terminal and a second node; a second active element connected between the second node and the other power supply terminal; and a second resistor connected between the one power supply terminal and the second power supply terminal; a third resistor connected between the third node and the third node, a fourth resistor connected between the third node and the fourth node, and the fourth node and the other power supply terminal. the fifth connected between
and a comparator for detecting matching of potentials between the first node and the second node, the control end of the first active element is connected to the third node, and the second A power supply voltage detection circuit in which a control end of an active element is connected to the fourth node. 2. A sixth resistor connected between one power supply terminal and a fifth node; a third active element connected between the fifth node and the other power supply terminal; a seventh resistor connected between one power supply terminal and the sixth node; an eighth resistor connected between the sixth node and the seventh node; and a seventh resistor connected between the seventh node and the seventh node. a ninth resistor connected between the other power supply terminal and a comparator that detects matching of potentials between the fifth node and the sixth node; A power supply voltage detection circuit connected to the seventh node.