JPH03207091A - Internal power supply voltage drop circuit - Google Patents

Abstract

PURPOSE:To extend an operation power supply range to a memory without degradating a characteristic on a low voltage side by constituting an internal power supply voltage drop circuit so that a power supply voltage can be dropped when it is higher than a prescribed voltage and the power supply voltage can not be dropped when it is lower than the prescribed voltage. CONSTITUTION:In the circuit configuration that the threshold voltage of a transistor Q11 is defined as ¦VTP¦, the resistance values of resistors R11 and R12 are defined as R1 and R2 and the threshold voltage of a transistor Q13 is defined as VTN, the resistance values of the resistors R11 and R12 to a prescribed voltage V1 are set so as to satisfy the condition of ¦VTP¦=(R1/R1+ R2)XV1. As a result, a voltage to be expressed by VINT=Vcc in the case of Vcc<V1 and expressed by VINT=Vcc-V1 in the case of Vcc>=V1 can be obtained. Thus, since a power supply voltage Vcc is dropped when it is higher than the prescribed voltage V1 and the power supply voltage Vcc is not dropped when it is lower than the prescribed voltage V1, the operation power supply range can be extended without degrading the characteristic on the low voltage side.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an internal power supply voltage step-down circuit.

[Conventional technology]

A conventional circuit of this type will be explained with reference to FIGS. 3 and 4. P-channel MOS transistor Q shown in FIG.
) The threshold voltage of l is VT, then the gate and drain of the transistor are connected to VTNT, and the ground is the power supply voltage. . Since it is connected to VCC and v
Is the potential difference with 4A lV? It turns on when it is larger than Pl and turns off when it is smaller. For this reason, as shown in Figure 4, ■, always V. 0] ■, a voltage lower by 1 is obtained.

[Problem to be solved by the invention]

The conventional internal power supply voltage step-down circuit described above is always ■ regardless of the VCCo value. . -I Output Vtp l.

For example, when vcc" 3 (:V'), l VTp l
= 0. 8 [V], then V INT=2.
2 1:V:l and naru.

Let us consider the case where the conventional circuit is used in the memory circuit of the 5 [■] power supply system. Normally, the power range in which memory operates normally is ■
. . = about 3.5[:V] to 7[■]. When using the conventional circuit, VCC = 4.3 CvE ~ 7.8CV)
When V TNT = Vcc l VTp l, V INT = 3.5 [■] to 7 [■], and the voltage level on the high voltage side approaches the operating range on the high voltage side of the memory, but conversely, the voltage level on the low voltage side As the voltage level on the side drops further, the operating range of the memory becomes narrower. Therefore, there is a drawback that the operating margin for the guaranteed range of memory power supply voltage of 4.4 (:V) to 5.5 [V:] becomes very small.

Also, in the case of static RAM, in data retention mode, VCC = 3 [vl] and VIN? = 2. 2
[V], which has the disadvantage that memory cell data is likely to be destroyed due to the influence of minute leaks in the memory, causing redness and deterioration of characteristics.

SUMMARY OF THE INVENTION An object of the present invention is to provide an internal power supply voltage step-down circuit that can extend the operating power supply range for a memory or the like.

[Means to solve the problem]

The internal power supply voltage step-down circuit of the present invention includes first and second resistors connected in series between a first power supply and a second power supply, and a connection point between the first and second resistors connected to a gate. and a source-drain path connected to the first power source and the node.
one conductivity type MOS transistor, the node and the second conductivity type MOS transistor;
a second one-conductivity type MOS transistor having a gate connected to the node and a source-drain path connected between the first power source and the output terminal; The device is characterized in that it includes an opposite conductivity type MOS transistor connected to the first power source and having a source-drain path connected between the first power source and the output terminal.

? Example〕 The present invention will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a circuit diagram for explaining one embodiment of the present invention, and FIG. 2 is a voltage characteristic of the circuit shown in FIG. R 1+
+ R l 2 and R 1s are high resistance elements, Q. ，，
Q and ■ are P-channel MOS transistors, and Q1 is an N-channel MOS transistor.

In such a circuit configuration, the transistor Q l 3
Let the threshold voltage of VAN be VAN, the threshold voltage of resistor R, , R, t {tlu+, R2, transistor Q1, IVtpl, and for a predetermined voltage vI, V
Set so that TPI:V+-lVtpl=R+:Rz.

? First, when V cc < V 1, the potential of the first node N+ is V due to the resistance values of resistors R + + and R1■. .

×R + +Rx Next ■. The difference potential between 0 and node N11 is V. . −■. .

×Transistor Ql+ is turned off, and the second node Nut! Since it is connected to GND through the resistor Rl3, GND
level. Since the second node N12 is at the GND level, the transistor Q+2 is turned on and v1NT becomes the power supply level, that is, v , N, = v cc.

Next, ■. . When ≧V1, VCC and the first node N11
and? Transistor Ql1 turns on. If the resistance value of the resistor Rl1 is made sufficiently higher than the on-resistance of the transistor Ql+, the second node N1■ becomes the power supply level and the transistor q
+i is turned off.

The potential of VINT decreases to V due to the current flowing through the circuit to which VINY is supplied. . The potential difference between and VrNa is V
Transistor QB turns on when it becomes larger than TN, and turns off when it becomes smaller than VTN, so the potential of VINT is always ■. C maintained in VTN.

As explained above, if the resistor R1 is set for a predetermined voltage 1, then when V c < V +, V I
NT = V cc *V IN when Vcc≧■1
A voltage expressed as T''VCCVTN can be obtained.

? Effects of the Invention As explained above, the internal power supply voltage step-down circuit of the present invention has the following effects:
If the resistors R, , R, ■ are applied to the predetermined voltage V1, when Voo<V, VINT”VCe+ vcc≧v
When 1, VJN a = V ec V IN? A voltage expressed as is obtained.

In other words, the power supply voltage■. . When the voltage is higher than the predetermined voltage ■1, the voltage is stepped down by vTN, and when the voltage is lower than v1, the voltage is not stepped down. For this reason, for example, VTN” 0.8
V, V+ = 4. 3 V, the memory operating power supply range V cc ”3.5 V to 7.
OV can be expanded from 3.5V to 7.8V without deteriorating the characteristics on the low voltage side. Also, static R
Even in AM data retention mode, V cc = V rNt
= 3. Since it is OV, the characteristics will not be deteriorated.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining one embodiment of the present invention, and FIG. 2 is a diagram showing the power supply voltage of the circuit shown in FIG. 1. FIG. 3 is a circuit diagram showing a conventional internal power supply voltage step-down circuit, and FIG. 4 is a diagram showing internal power supply voltage characteristics with respect to the power supply voltage of the circuit shown in FIG. 3. R + + , R l 2 r R + g...
・・High resistance element, Qll, Ql2IQ3l・・・・
・P channel MOS transistor, Qts...
・・N channel MOS transistor s N++, N, ■
...Contact, VINT...Internal power supply voltage, VCC...Power supply voltage, GND...Grounding.

Claims (1)

[Scope of Claims] 1. In an internal power supply voltage step-down circuit that receives a power supply voltage as input and generates an output voltage at a voltage level corresponding to the power supply voltage level, the circuit operates when the power supply voltage is below a predetermined voltage to increase the output voltage. 1. An internal power supply voltage step-down circuit comprising: a first voltage generation means for generating an output voltage; and a second voltage generation means for supplying an output voltage when the first voltage generation is not operating. 2. The first power supply connected in series between the first power supply and the second power supply
and a second resistor, a first one-conductivity type MOS transistor having a gate connected to a connection point of the first and second resistances and a source/drain path connected to the first power source and the node; a third resistor connected between the node and the second power source; and a second one-conductivity type MOS having a gate connected to the node and a source/drain path connected between the first power source and an output terminal. An internal power supply voltage step-down circuit comprising: a transistor; and a reverse conductivity type MOS transistor whose gate is connected to the first power supply and whose source-drain path is connected between the first power supply and the output terminal. .