JPH01129769A - semiconductor integrated circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor integrated circuit, and particularly to a voltage converter suitable for a static random access memory that can be backed up perfectly.

[Conventional technology]

Regarding the conventional voltage converter, FIG. 7(a) shows the conventional voltage converter.

IEE, International Solid State Circuit Conference, 1987 Technical Digest, p252 (I
EEE 15SCC1987, Tech, Dig, p
252), a differential amplifier was used to compare the external power supply potential ■cC and the set potential Vgv. In addition, in order to supply charge from the external power supply to the internal power supply, an N-type MO8
FET and P-type MO8FET 2-') (7) MOSFE
NMO8FET uses externally applied voltage VC.
When C is larger than v■, the amplifier is operated and driven, and when VCC is smaller than VBIF, the gate electrode of the PMOSFET is electrically grounded and turned on. In this conventional example, a TTL voltage of 5V is used as an external voltage.
This is a countermeasure against the deterioration of characteristics caused by hot carriers in MOSFETs when used in O3LSIs. When the power supply voltage vcC is large, the voltage converter works, and a predetermined voltage smaller than vcC is applied to the internal power supply voltage vDo to reduce MO by hot carriers.
To prevent deterioration of SFET. Furthermore, when VCC is small, internal power supply voltage VDD is made to match VCC.

[Problem that the invention seeks to solve]

The above conventional technology has two problems as described below.

The first problem is that since a differential amplifier is used for the VCC voltage detector and a bias current is passed regardless of the CC voltage, it is impossible to reduce current consumption. This type of method is suitable for battery backup applications.
With SI, the current is too large to be used. For example, it cannot be used in CMO8SRAM for battery backup purposes.

The second problem is that it is necessary to use a large-area MOSFET in the driver to allow a large current to flow, but in this conventional technology, the driver uses an NMO8FET when vcc is larger than vllw, and when Vcc is smaller than vBv. Since it uses a PMOSFET and two drivers, it requires a large occupied area.

The purpose of the present invention is to solve such conventional problems, reduce power consumption when the power supply potential VCC is lower than the set potential v0, enable battery backup in low voltage operation, and reduce the occupied area. An object of the present invention is to provide a semiconductor integrated circuit that functions as a voltage converter for a small LSI.

[Means for solving problems]

In order to solve the above problems, the semiconductor integrated circuit of the present invention has a wiring for supplying a first power supply potential vc0 and a wiring for supplying a second power supply potential VOO on a semiconductor substrate, and a predetermined set potential V□, and outputs the comparison result as a control signal, and if the potential VCC is smaller than vsW, the power consumption is reduced to 1.
A VCC voltage detector having a means for cutting the current so that the current becomes 0 μW or less, and an amplifier that consumes power only when the potential VCC is greater than VSV according to the control signal, and the amplifier causes the first power source to Potential V
The feature is that a driver for supplying charge from CC to the second power supply potential VDD is driven.

Further, the semiconductor integrated circuit uses a current mirror type differential amplifier using the first PMOSFET as a current source as the amplifier, and the control signal causes the first PMOSFET to
The feature is that the power consumed by the differential amplifier is controlled by controlling the power consumption of the differential amplifier.

Furthermore, the semiconductor integrated circuit has the second power supply potential v
n. A current flowing through a circuit that generates a reference potential vR11KF is controlled by the control signal, a second PMOSFET is used as the driver, and the second PMOSFET is used as the driver.
It has means for electrically bringing the gate electrode of the ET to a ground potential, and the first power supply potential vcc is equal to the set potential vf.
If it is smaller than 1v, the control signal causes the second P
The feature is that the gate electrode of the MOSFET is at ground potential.

[Effect]

In the present invention, when the power supply potential vcc is lower than the set potential vo, the comparison circuit between vcc and vBW has a circuit whose power consumption is extremely small.

The control signal generated from this causes the amplifier that controls the driver to be inactive to eliminate power consumption.

The reference voltage generation circuit also eliminates the current flowing through it.

At this time, the driver is kept in a conductive state by electrical means separate from the amplifier. Due to these things, VCC becomes vl
If it is smaller than lv, the power consumption can be made extremely small, and a voltage converter that can be applied to battery backup can be realized.

On the other hand, when VCC is greater than V8V, Vcc is
The same driver as that used when the voltage is smaller than 6V is used, and this is controlled by an amplifier to bring VDD to a predetermined potential. This makes it possible to reduce the area required for the driver.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a basic configuration diagram of a semiconductor integrated circuit showing a first embodiment of the present invention.

In FIG. 1, 1 is V c c which compares the first power supply potential VCC given from the node and the set potential v8v.
'! 2 is a differential amplifier having a reference voltage VR, 3 is a driver for supplying charge from the first power supply potential vC0 to the second power supply potential vDo, 4 is VCC.
This is a switch that turns on the differential amplifier 2 according to the control signal output from the voltage detector 1. Further, 5 is a current cut circuit built in the VCC voltage detector 1, and has potentials vcC and V. .

By comparing VCC with v8. If it is smaller, the current flowing to the voltage detector 1 is cut off to eliminate the current consumption. In other words, the power consumption should be 1oμW or less. The operation of this embodiment will be explained below.

The vcc voltage detector 1 outputs a control signal according to the result of comparing vcc and v8v, and when Voo is larger than vo, the switch 4 is turned on and the differential amplifier 2 is operated. In differential amplifier 2, the reference voltage ■R6F
The driver 3 is controlled in accordance with this to supply charge to the terminal that provides VOO. Here, the input of the differential amplifier 2 is vo
o potential feedback is applied, and V and f are V
If it is larger than SW, the driver 3 is controlled so that voo matches vR6F. Also,
When VC, is smaller than V, sv, the current cut circuit 5 turns off the switch 4 (inactive state) to eliminate the current flowing to the differential amplifier 2.

According to the above results, when VCC is smaller than V8%l, the vcc voltage detector 1. The power consumption by the differential amplifier 2 is eliminated, and it becomes possible to combine it with an LSI for battery backup use such as an SRAM.

FIG. 2 is a block diagram of a semiconductor integrated circuit showing a second embodiment of the present invention. This is a slightly more specific version of the basic configuration shown in FIG.

In this embodiment, the reference voltage generator 6. Differential amplifier 2
are connected to the power supply VC through PMOSFETs 7 and 8, respectively.
When VCC is greater than v9v, the control signal turns on PMOSFETs 7 and 8, operates reference voltage generator 6 and differential amplifier 2, and controls PMO3FET 9, which serves as a driver. On the other hand, v
If cC is less than Vf3W, PMOSFET7
and 8 are cut off by a control signal to suppress the current flowing to the reference voltage generator 6 and the differential amplifier 2.
MO8FETIO is made conductive and node 1°1, which provides gate potential of PMO3FET9, is set to ground potential and PM
OSFET9 is made conductive and VDD and vo. Match. By doing this.

Current will flow only through the circuit connected to the voo terminal. At this time, by connecting an LSI such as an SRAM capable of battery backup to the vDo terminal, it is possible to create a system capable of battery backup.

Moreover, in one embodiment, vo. Since the PMOSFET 9 is used as a means for supplying charge from to VDD both when vco is larger than VSW and when it is smaller than VSW, the occupied area can be made smaller than when separate drivers are used in both cases.

FIG. 3 is a specific circuit diagram of the VCC voltage detector 1 shown in FIG. 1 or 2. In FIG.

In Figure 3, 20, 21, 22, 23 are NMOSF
ET and is diode-connected.

24.27 is resistor, 25 is capacitor, 26 is NMOS
FET, 15 is NMOSFET28 and PMOSFE
CMOS inverter composed of T29, 16 is NM
This is a CMOS inverter composed of an OSFET 30 and a PMOSFET 31.

FIG. 4 is a diagram for explaining the circuit operation of the vC0 voltage detector 1 of FIG. 3. (a) shows the potential of terminals 32, 33 with respect to vcC, and (b) shows Ii, I of FIG. 3 with respect to vco. Hereinafter, the operation of the circuit shown in FIG. 3 will be explained with reference to FIG.

Since the MOSFETs 20 to 23 are diode-connected, the voltage-current equation for one MOSFET is given by the following equation.

ID” (! (ffiogVo) ' ” ' (
1) However, Vo≦vT8 I o= k (Va-V?+1)” ・” ・(
2) However, VD>VT□ knee, I is the drain current, VD is the drain voltage,
Due to diode connection, it matches Vc.

α is a constant, and V is the threshold voltage of the MOSFET. Equation (1) allows the current to be small in the so-called subthreshold region. Equation (2) indicates a large current region.

Now, let Vd = 0.9V. That is, VCC=
When set to 2.8V (Vcc<Vg, (7) state),
The VCC voltage will be divided by 20 to 23 MOSFETs, and the voltage applied to one MOSFET will be 0.7
It becomes v. In this case, MOSFET (7) current is (1)
In other words, it becomes a subthreshold region, and the current flowing here becomes extremely small as shown in FIG. 4(b). Therefore, the terminal 32 has almost the same potential as v8B. Then, MOSFET 26 becomes non-conductive, and terminal 33 becomes at the same potential as vcc. Since there are two stages of CMOS inverters as buffers in the latter stage, a signal having the same potential as VCC is outputted to the terminal 34. On the other hand, when VCC is larger than 78W, for example, when VCC is 5V, the voltage applied to MOSFETs 20 to 23 becomes 77 or more, so that the MOSFET operates in the large current region given by equation (2). Then, since a current flows through the resistor 24, the potential of the terminal 32 becomes such a potential as to make the MOSFET 26 conductive. Then, terminal 33 becomes VIiii
As a result, a signal having the same potential as V is output to the terminal 34.

In this way, this circuit outputs the determined signal 7 to the terminal 34 when vcC is smaller than v8W and when it is larger than v8W, but especially when vcC is v8W,
．． When it is smaller, almost no current flows steadily in the circuit, and low power consumption can be achieved.

FIG. 5(a) is a specific circuit configuration diagram of the amplifier and driver portion in FIG. 1 or FIG. 2, and FIG. 5(b) is a diagram showing an example of the configuration of a differential amplifier.

In FIG. 5, 51 is a terminal that provides a signal T; generated from the VCC voltage detector 1, 55 is a differential amplifier, 53 is a PMOSFET that serves as a driver, 52 is a PMOSFET that serves as a switch for the amplifier 55, and 54 is a driver. 56 is a reference voltage generator, 58 is a P MOSFET, and 59 is an NMOSFE.
It is T.

Next, the operation of this circuit will be explained.

■When the signal is "High", that is, when VCC is smaller than ■8W, the PMOSFET 52 becomes non-conductive and the amplifier 55 does not operate. Also, MOSFE
T54 becomes conductive and terminal 57 becomes Voslt! PMOSFET 53 becomes conductive and vo
Make the potentials of C and VDD the same.

On the other hand, if 4 is II L Ov II, that is, VC
When C is larger than vgl, the NMOSFET 54 becomes non-conductive, while the PMOSFET 52 becomes conductive, the amplifier 55 operates, and the reference voltage V□.

and V. The PMOSFET 52 becomes conductive so that f and have the same potential, the amplifier 55 operates, and the basic lightning voltage R
PMOSFET53 so that EF and voo have the same potential
The circuit is designed with negative feedback to control. Here, it is necessary to select a voltage as vREF such that the MOSFET of the internal circuit connected to the Vool) J terminal is not degraded by hot carriers. In this way, in the circuit of the embodiment.

If VCC is less than V8v, MOSFET53
It is a circuit that consumes no power other than that, making it possible to reduce power consumption.

Also, VCC is V. Since PMO3FET53 is used as a driver for both larger and smaller cases,
The area can be reduced. Further, the above-mentioned differential amplifier 55 may be of a current mirror type as shown in FIG. 5(b).

FIG. 6 shows the reference voltage VR1! , is a specific configuration diagram of a circuit for making . The reference voltage V R, , may be generated using a battery or the like, but it can also be created using a circuit as shown in Figure 6.
This circuit connects the VCC voltage to NMOSFETs 61 to 64 and P
It is created by dividing the pressure using MOSFETs 65 and 66. At this time, the PMOSFET 67 can be selected to be conductive or non-conductive by the I signal. That is, when the VCC voltage is lower than VSW, this PMOSFET6
7 becomes non-conductive, and it is possible to eliminate the power consumed here.

〔Effect of the invention〕

As explained above, according to the present invention, the power supply potential VCC
When V is smaller than the set potential vBv, almost no current flows through the VCC voltage detector, amplifier, and reference voltage generator, resulting in lower power consumption.Furthermore, the driver is made conductive to connect VCC and VDD. Can be made conductive. On the other hand, if VCC is greater than VSW,
Vcc? ? ! pressure detector.

The amplifier and reference voltage generator require current to flow, and the driver is controlled by the amplifier. can be the reference voltage generated from the reference voltage generator, so vccf
l! Even if the voltage is large, a highly reliable LSI that is free from deterioration due to hot carriers in the MOSFET in the LSI connected to the vDD terminal can be realized. Furthermore, since the same driver is used for both operations, the area occupied by the driver can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of a semiconductor integrated circuit showing a first embodiment of the invention, FIG. 2 is a configuration diagram of a semiconductor integrated circuit showing a second embodiment of the invention, and FIG. A specific circuit configuration diagram of the VCC voltage detector in the embodiment, FIG. 4 is a diagram for explaining the operation of the VCC voltage detector in FIG. 3, and FIG. 5 is a circuit diagram of the amplifier and driver portion in the embodiment of the present invention. FIG. 6 is a specific configuration diagram of a circuit for generating the reference voltage V□2 in an embodiment of the present invention, and FIG. 7 is a configuration diagram of a conventional semiconductor integrated circuit (voltage converter). 1: Vcc voltage detector, 2: Differential amplifier, 3: Driver, 4: Switch, 5: Current cut circuit, 6: Reference voltage generation circuit, 7, 8, 9: PMOSFET, 10
: NMOSFET, 11 : Node. Fig. 1 Fig. 2 VCC Fig. 3 cc 'S25 ""・No. 4
Figure (a) VCC (G) Figure 5 (a) CC

Claims (1)

[Claims] 1. A semiconductor substrate has a wiring for supplying a first power supply potential V_C_C and a wiring for supplying a second power supply potential V_D_D,
The first power supply potential V_C_C is compared with a predetermined set potential V_S_W, and the comparison result is output as a control signal, and when the potential V_C_C is smaller than V_S_W, the power consumption is set to 10 μW or less. A V_C_C voltage detector having means for cutting current; and the control signal causes the potential V_C_C to be set to V_S.
and an amplifier that consumes power only when the power is greater than _W, and the amplifier drives a driver for supplying charge from the first power supply potential V_C_C to the second power supply potential V_D_D. integrated circuit. 2. In the semiconductor integrated circuit according to claim 1, a differential amplifier having a first current source is used as the amplifier, and the first current source is controlled by the control signal to operate the differential amplifier. A semiconductor integrated circuit characterized by controlling power consumption. 3. In the semiconductor integrated circuit according to claim 2, a potential V serving as a reference for the second power supply potential V_D_D
A semiconductor integrated circuit characterized in that a current flowing through a circuit that generates _R_E_F is controlled by the control signal. 4. The semiconductor integrated circuit according to claim 3, wherein a second PMOSFET is used as the driver, and means for electrically bringing the gate electrode of the second PMOSFET to a ground potential; The first power supply potential V_C_
A semiconductor integrated circuit characterized in that when C is smaller than the set potential V_S_W, the gate electrode of the second PMOSFET is brought to a ground potential by the control signal.