JP2000148264A - Power source drop circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the power source drop circuit which stably drives a circuit element, makes the current consumption in standby mode small, and reduces a DC current leak by making it possible to switch an internal source voltage generated from an external source voltage among >=3 voltage values. SOLUTION: The power source drop circuit is set to a desired internal source voltage VDDin such as a source voltage VDD for normal driving, a source voltage for a burn-in test, etc., or a standby source voltage Vstby in standby mode through logical operation wherein voltage-division level signals divided by resistances are selected by switches (Pch transistors Tr1 to Tr3) while the constant external source voltage supplied from outside is maintained without being varied and supplies the desired internal source voltage by stably driving an amplification part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply dropping circuit formed on a semiconductor substrate and supplied to a circuit element as an internal power supply voltage obtained by reducing an externally supplied power supply voltage to a plurality of voltages.

[0002]

2. Description of the Related Art In general, various circuit elements are formed on a semiconductor substrate, and with the demand for miniaturization of the circuit elements, the withstand voltage is reduced due to downsizing of the elements themselves and narrowing of the wiring width. It is necessary to lower the voltage in order to reduce the current consumption and the current consumption. The power supply voltage, for example, 5 V supplied from the outside is reduced to 3 to 4 V by a step-down circuit provided on the substrate and supplied to each circuit element. I was

[0003] However, if a design in which only a low-voltage power supply voltage is merely mounted is used, when a large voltage is required for a test such as burn-in or aging, it must be separately supplied from the outside each time. Was.

Therefore, a technique for switching between an external power supply voltage and a low power supply voltage generated internally by stepping down is used, for example,
Japanese Patent Application Laid-Open No. 7-57472 discloses that a low power supply voltage used for driving circuit elements is newly generated by stepping down an external power supply voltage, and a switch circuit is used to switch between the low power supply voltage and the original external power supply voltage. There has been proposed a semiconductor integrated circuit device provided with a step-down circuit having a voltage dividing function for switching and supplying the voltage to an internal circuit element.

[0005]

However, the step-down circuit disclosed in the above-mentioned publication inputs a signal having an input level different from a normal signal level given from an external terminal and operates a power supply voltage supplied to a circuit element in a normal operation. Since the two values are switched between the time and the time of a test operation such as burn-in, the switching control becomes complicated.

In addition, since selection is made from only two voltage values, ie, a normal driving voltage and a test voltage such as burn-in,
Even when the circuit is in the standby state, the voltage of the normal drive level is maintained and the direct current path is wasted.

Accordingly, the present invention provides an internal power supply voltage generated from an external power supply voltage that can be switched to a plurality of voltage values of three or more, thereby stably driving circuit elements, reducing current consumption during standby, and reducing DC current. It is an object of the present invention to provide a power supply drop circuit that reduces leakage.

[0008]

According to the present invention, in order to attain the above object, the present invention forms an internal power supply voltage on a semiconductor substrate by lowering an external power supply voltage supplied from the outside. A power supply dropping circuit for supplying a circuit element, a voltage dividing means for generating at least three different voltage division level signals from the external power supply voltage, and selectively outputting any one of the voltage division level signals Switching means for reducing the external power supply voltage to a desired internal power supply voltage level based on the selected divided voltage level signal, at least in the drive state and the standby state in the circuit element. Alternatively, there is provided a power supply dropping circuit for generating an internal power supply voltage having a different voltage value to be supplied in any of the burn-in (aging) states.

The power supply dropping circuit having the above-described configuration performs a normal driving by a logical operation of selecting at least three or more divided level signals generated from an external power supply voltage of a constant voltage supplied from the outside by a switch. And the internal power supply voltage VDDin including the standby power supply voltage Vstby at the time of standby, which is a low power consumption current, and the drive power supply voltage VDD for burn-in and aging. To supply a desired internal power supply voltage to the circuit element.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows and describes the configuration of a power supply dropping circuit according to a first embodiment of the present invention.

This power supply dropping circuit includes a voltage dividing section 1 for dividing an external power supply voltage VDD supplied from outside by a resistance value ratio.
A switch unit 2 for applying an external power supply voltage VDD to the voltage dividing unit 1 and selectively outputting any one of a plurality of voltage dividing level signals (Vref1 to Vref3); Voltage drop (Pch) based on signals (Vref1 to Vref3)
An amplifier unit 4 that performs feedback control on the level of the internal power supply voltage output from the transistor 3.

The voltage dividing section 1 has different values of 3
The three resistor rows R1 to R3 are connected in parallel, and divide the external power supply voltage VDD according to a resistance value ratio with the resistor Ra. The switch unit 2 is connected to a power supply line (external power supply voltage VDD), and includes Pch transistors Tr1 to Tr3 that selectively apply the external power supply voltage VDD to one resistor string according to instruction signals CTL1 to CTL3 of a control unit (not shown). Be composed.

In such a configuration, one of the three divided level signals Vref1, Vref2, and Vref3 corresponding to the resistance value ratio is selected by the selection switch unit 2, and the selected one is selected. The internal power supply voltage VDDin based on the divided level signal is output from the voltage drop transistor 3 including a Pch transistor.

In the present embodiment, for example, a drive power supply voltage for normally driving a circuit element is 2.5 V, a test power supply voltage for performing burn-in, aging, and the like is an external power supply voltage VDD, and further, a standby state of the circuit element. The standby power supply voltage Vstby supplied in the state can be considered. Of course, the power supply voltage value is not limited to this.

With the above configuration, the power supply dropping circuit according to the present embodiment can operate the switch (Pch transistor T) while maintaining the external power supply voltage supplied from the outside without changing.
r1 to Tr3), a driving power supply voltage VDD for performing normal driving, a test power supply voltage for burn-in or the like, or a standby power supply voltage Vstby at the time of standby with low current consumption, by a logical operation for selecting any one of r1 to Tr3). Such a desired internal power supply voltage VDDin is set. This eliminates the change in power supply voltage due to switching as in the prior art,
The amplifier unit incorporated in the power supply drop circuit can be driven stably under a constant voltage environment.

FIG. 2 shows an example of the configuration of the power supply dropping circuit according to the second embodiment.

This power supply dropping circuit includes a voltage dividing section 11 for dividing a power supply voltage VDD supplied from the outside, and a selecting switch section 12 for selecting a divided voltage level signal (VDD = Vref0, Vref1 to Vref3). And an amplifier unit 14 that feedback-controls the level of the internal power supply voltage output from the voltage drop transistor 13 based on the selected divided voltage level signal.
It is composed of

The voltage dividing section 11 includes a resistor R connected in series.
1, R2, R3, and R4, each of which has a resistance value corresponding to a desired voltage division ratio. Selection switch section 12
Are composed of inverters 15a to 15d and transfer gates 16a to 16d, which operate according to an instruction signal from a control unit such as a CPU (not shown). The divided voltage level signal from the voltage dividing unit 11 is transmitted to the transfer gates 16a to 16
6d, and is input to the amplifier unit 14.

The amplifier section 14 includes a selection switch section 12.
Transistor 1 based on the divided voltage level signal from
3 is driven to convert the supplied external power supply voltage to a desired internal power supply voltage VDDin and supply it to a circuit element (not shown).

In such a configuration, the divided voltage level signal Vre
f0 and the divided voltage level signals Vref1 and Vre corresponding to the ratio of the resistance values.
One of the four level signals f2 and Vref3 is selected by the selection switch section 2, and the internal power supply voltage VDDin corresponding to the selected level signal is output from the voltage drop transistor 13.

In the present embodiment, for example, a drive power supply voltage for normally driving a circuit element is 2.5 V, a test power supply voltage for performing burn-in, aging and the like is an external power supply voltage VDD, and further, a standby state of the circuit element is set. The standby power supply voltage Vstby supplied in the state can be considered. Of course, it is not limited to this.

In this embodiment, the same operation and effect as those of the first embodiment can be obtained.

Next, FIG. 3 shows an example of the configuration of the power down circuit according to the third embodiment. This power supply dropping circuit receives a voltage dividing unit 21 for dividing a power supply voltage VDD supplied from the outside according to a ratio of the resistors R1 and R2, and a divided voltage level signal, and receives an instruction from a control unit (not shown). signal
The internal power supply voltage V output from the Pch transistor Tr1 which drops the voltage to the normal drive voltage by CTL1
Amplifier section 22 that feedback-controls the level of DDin
And a Pch transistor Tr2 that outputs a test power supply voltage Vtest having the same voltage value as the external power supply voltage VD as an internal power supply voltage VDDin according to an instruction signal CTL2 from a control unit (not shown).
And a P-channel transistor Tr3 functioning as a keeper circuit for generating the standby voltage Vstby while maintaining the always-on state.

The standby voltage Vstby by the Pch transistor Tr3 can be adjusted by further connecting the transistors in series as shown in FIG.

In this embodiment, the same operation and effect as those of the first embodiment can be obtained.

Referring to FIG. 5, the operation of the power down circuit configured as in the third embodiment will be described. In the present embodiment, for example, a normal drive power supply voltage (2.5 V), a test power supply voltage for performing burn-in, aging, or the like, an external power supply voltage VDD, and a standby state of a circuit element are generated as internal power supply voltage values to be generated. In this case, the description will be made assuming that the standby power supply voltage Vstby is relatively low.

First, when the instruction signal CTL1 is at the H level, the amplifier section 22 outputs the Pch
The transistor Tr1 outputs a normal drive power supply voltage.
At this time, the instruction signal CTL2 is at the H level, and the transistor Tr2 is off.

When the instruction signal CTL2 goes low, the transistor Tr2 is turned on and outputs the external power supply voltage VDD as the internal power supply voltage VDDin. At this time, since the normal drive power supply voltage VDDin output from the Pch transistor Tr1 is lower than the external power supply voltage VDD, the Pch transistor Tr1 may be in either ON or OFF state.

When the instruction signal CTL1 is at the L level, the amplifier 22 outputs the H level, and the Pch transistor Tr1 is off. When the instruction signal CTL2 is at the H level, the transistor Tr2 is off. Therefore, the standby voltage Vstby is output as the internal power supply voltage VDDin from the Pch transistor Tr3 which is always on.

In each of the embodiments described above, a Pch transistor is described as an example. However, the present invention is not limited to this, and another driving element may be used.

As described above, according to the embodiment, the logical operation of selecting one of the switches while maintaining the external power supply voltage of a constant voltage supplied from the outside,
It is set to a desired internal power supply voltage VDDin such as a drive power supply voltage VDD for performing normal driving, a test power supply voltage Vtest for burn-in or the like, or a standby power supply voltage Vstby at the time of standby which results in low current consumption. As a result, the change in the power supply voltage required when switching the internal power supply voltage as in the related art is eliminated, and the amplifier unit incorporated in the power supply drop circuit can be driven stably under a constant voltage environment. .

[0033]

As described above in detail, according to the present invention, the internal power supply voltage generated from the external power supply voltage can be switched to a plurality of three or more voltage values so that the circuit elements can be driven stably and in standby mode. And a power supply drop circuit that reduces DC current leakage.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a power down circuit according to a first embodiment.

FIG. 2 is a diagram illustrating a configuration example of a power down circuit according to a second embodiment;

FIG. 3 is a diagram illustrating a configuration example of a power down circuit according to a third embodiment;

FIG. 4 is a configuration example of a keeper circuit that generates a standby voltage Vstby.

FIG. 5 is a diagram for explaining an operation of a power down circuit according to a third embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Division part 2 ... Switch part 3 ... Low voltage (Pch) transistor 4 ... Amplifier part R1-R3 ... Resistance (column) 12CTL1, CTL2, CTL3 ... Instruction signal Tr1-Tr3 ... Pch transistor Vref1, Vref2, Vref3 ... Voltage level signal VDD: External power supply voltage VDDin: Internal power supply voltage Vstby: Standby power supply voltage

Claims (6)

[Claims] 1. A power supply drop circuit formed on a semiconductor substrate and stepping down an external power supply voltage supplied from the outside to supply a predetermined internal power supply voltage to a circuit element on the semiconductor substrate, comprising: Voltage dividing means for generating at least three or more different voltage dividing level signals; switching means for selectively outputting any one of the voltage dividing level signals; and a selected voltage dividing external power supply voltage Voltage drop means for stepping down to a desired internal power supply voltage level based on a level signal, wherein at least one of the circuit elements is supplied in a driving state, a standby state, or a burn-in (aging) state. A power supply dropping circuit for generating internal power supply voltages having different voltage values. 2. A power down circuit formed on a semiconductor substrate, which reduces an external power supply voltage supplied from the outside and supplies a predetermined internal power supply voltage to a circuit element on the semiconductor substrate. A plurality of resistor strings composed of resistors connected in parallel, and at least 3
A voltage dividing circuit for generating one or more different voltage dividing level signals; and applying the external power supply voltage to any one of the resistor strings according to a given instruction signal to selectively output the voltage dividing level signal. A switching transistor array, an amplifier unit that outputs the level of the internal power supply voltage to be supplied as a control signal by feedback control based on the selected divided voltage level signal, and a desired internal circuit based on the control signal. A voltage drop transistor for stepping down to a power supply voltage level, a first internal power supply voltage supplied at least when the circuit element is driven, a second internal power supply voltage supplied at the time of standby of the circuit element, Generate a third internal power supply voltage to be supplied at the time of burn-in or aging of the circuit element, and selectively supply either of them. A power down circuit characterized by: 3. A power supply dropping circuit formed on a semiconductor substrate and stepping down an external power supply voltage supplied from the outside and supplying a predetermined internal power supply voltage to a circuit element on the semiconductor substrate, wherein a plurality of resistors are provided. A voltage divider circuit for generating at least three or more different voltage division levels from the external power supply voltage by means of a resistor string connected in series based on the voltage division ratio of the external power supply voltage. A switching circuit comprising a plurality of transfer gates for outputting a divided voltage signal, and selectively outputting a divided voltage signal; and an internal power supply voltage to be supplied based on the selected divided voltage signal. An amplifier section for outputting a level as a control signal by feedback control; and a step-down voltage transformer for stepping down to a desired internal power supply voltage level based on the control signal. A first internal power supply voltage supplied at least when the circuit element is in a driving state, a second internal power supply voltage supplied at the time of standby of the circuit element, and when the circuit element is burned in or aged. A power supply drop circuit for generating a third internal power supply voltage to be supplied and selectively supplying any of the third internal power supply voltage. 4. A power supply drop circuit formed on a semiconductor substrate and stepping down an external power supply voltage supplied from the outside to supply a predetermined internal power supply voltage to a circuit element on the semiconductor substrate, wherein: Generating a predetermined partial pressure level signal,
A first internal power supply voltage output unit that receives the divided voltage level signal and is controlled by a first instruction signal to output a power supply voltage for normal driving of the circuit element; A second internal power supply voltage means for outputting a power supply voltage for performing burn-in or aging of the circuit element; and a power supply for both the first and second internal power supply voltage output means, which always maintains a power supply state. And a third internal power supply voltage output means for outputting a power supply for keeping the circuit element in a standby state when the circuit element is not in operation. Any one of the first, second, and third internal power supply voltage output means A power down circuit, wherein an internal power supply voltage is supplied to the circuit element from one of the first and second instruction signals. 5. A power supply dropping circuit formed on a semiconductor substrate and stepping down an external power supply voltage supplied from the outside and supplying a predetermined internal power supply voltage to a circuit element on the semiconductor substrate, wherein a desired voltage dividing ratio is obtained. A resistor string that is connected in series based on the external power supply voltage and generates a predetermined divided voltage level signal from the external power supply voltage, and that is controlled by an amplifier that receives the divided voltage level signal and operates according to a first instruction signal; A first transistor that outputs a power supply voltage for driving, a second transistor that outputs a power supply voltage for performing burn-in or aging of the circuit element according to a second instruction signal, A third transistor for outputting power for maintaining the circuit element in a standby state when the first and second transistors do not supply power. A power supply dropping circuit, comprising: driving one of the transistors in response to the first and second instruction signals to supply an internal power supply voltage to the circuit element. 6. The one or more multi-stage serial connection, wherein the third internal power supply voltage output means in the power supply drop circuit functions as a keeper circuit for preventing a power supply voltage applied to the circuit element from becoming zero. 5. The power down circuit according to claim 4, wherein said power down circuit comprises a transistor.