JPS63175909A - One-chip microcomputer - Google Patents

Abstract

PURPOSE:To make a current flowing when in a stand-by state much smaller, by stopping a clock supplied to an internal unit of a microcomputer, and also, lowering a power supply voltage supplied to the internal unit, when in the stand-by state. CONSTITUTION:When a stand-by instruction is executed, a control signal STOP becomes 'L', and 'L' is inputted to a transistor 14, an inverter 13, and a clock controlling circuit 12. In such a case, when the control signal STOP of the clock controlling circuit is 'L', a level of an output 18 of the clock controlling circuit is fixed to 'L' or 'H'. Therefore, since a clock signal is not supplied to a microcomputer internal unit 11, the internal unit stops its operation. In this case, at the time of stand-by, a voltage V3 becomes a power supply voltage of the unit 11. Accordingly, a leak current of the junction of a transistor in the internal unit 11 becomes much smaller, since a voltage applied to each gate of the transistor drops.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a one-chip microcomputer with a standby function.

[Conventional technology]

A conventional one-chip microcomputer with a standby function will be explained with reference to FIG. In FIG. 3, 11 is an internal unit of a one-chip microcomputer. 12 is a clock control circuit; 618 is an output of the clock control circuit 12; CLK is a clock signal input to the clock control circuit 12. 5TOP is a control signal input to the clock control circuit 12.

The operation of the standby function of a conventional one-chip microcomputer will be explained with reference to FIG. In this one-chip microcomputer, when a standby command is executed, the control signal "D" is "°L" level (hereinafter "
(abbreviated as “L”).

When the control signal -ys, TOP is "L", the output 18 of the clock control circuit 12 is at the "H" level (hereinafter abbreviated as "H").
Or it is fixed at "L" and the internal unit 11 stops operating.

Generally, in the CMO3, current flows through the circuit only when the gate input signal changes. Therefore, if the clock is stopped during standby and the change in the gate input signal of the internal unit 31 formed by the CMO 8'''C' FM is stopped, only the junction leak current flows through the internal unit 11.

[Problem that the invention seeks to solve]

In the conventional microcomputer described above, most of the current flowing during standby is junction leakage current. Therefore, an ultra-LSI with a large number of transistors has the disadvantage that the current flowing during standby increases.

[Means for solving problems]

The one-chip microcomputer of the present invention includes an internal unit of the microcomputer, a first control means for suppressing a clock signal supplied to the internal unit by a control signal that becomes active during standby, and a first control means for suppressing a clock signal supplied to the internal unit by a control signal that becomes active during standby; and a second control means for lowering the supplied power supply voltage.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention. In FIG. 1, reference numeral 11 indicates internal units 1 to 1 of the microcomputer. 12 is a tarok control circuit. 13 is an inverter. 14 is a P channel I transistor, connect the power supply (cc) to the train terminal, and connect the gate I transistor.
A control signal ST○p- is input to the terminal, and the drain/in terminal and gate terminal of the transistor 15 are connected to the source terminal. Reference numeral 15 denotes an n-channel l-transistor, the train terminal of which is connected to the source terminals of transistors 1 to 14, and the source terminal connected to the drain terminal and gate terminal of I-transistor 16. 16 is an n-channel I transistor, and the train terminal and gate I terminal are connected to transistor 15.
and connects the source terminal to the source terminal of the transistor 17, and also connects the source terminal of the internal unit I to
917 connected to 11 is a P-channel transistor, whose in terminal is connected to a power supply, whose gate terminal is connected to the output of inverter 13, and whose source terminal is connected to the source terminal of 1-transistor 16. 18 is the output of the clock control circuit 12. 5TOP is “L” in standby
′ is the control signal. CLK is a clock signal input to the clock control circuit.

Next, the operation of the microcomputer shown in FIG. 1 during standby will be explained. In the microcomputer shown in Fig. 1, when a standby instruction is executed, 5TOP goes “L”.
Thus, transistor 14, inverter 13 . "L" is input to the clock control circuit 12.Here, when the control signal 5TOP of the clock control circuit is "L", the level of the output 18 of the tarock control circuit is fixed at "L" or "H". Therefore, since no clock signal is supplied to the internal unit 11, the internal unit stops operating. The output level of the inverter 13 becomes "H" since the input level is "L", and this level is input to the transistor 17. Since the transistor 14 and the transistor 17 are P-channel transistors, 5TOP is "°". L°
”, the transistor 14 is turned on, and the transistor 1
7 is off. Now, assume that the voltage at the source terminal of the transistor 14 is Vl. The voltage V1 of this source terminal is 1 to
It is input to the drain terminal and gate terminal of the transistor 15. Here, the source terminal voltage (2) of the transistor 15 is shown in equation (1).

V 2 = V 1 (V T15+ΔV71+;)
...(+) Here, VTI5 is the threshold voltage of transistor 15.

ΔV 715 is the increase in V 715 due to the effect on pack game 1. Further, the source terminal voltage V2 of the 1-transistor 15 is input to the drain terminal and the gate terminal of the transistor 16. The source terminal voltage 3 of the I transistor 16 becomes the voltage shown by equation (2).

V3=V2 (VT16+AVT16) −(2>
In equation (2), V 7 ! 6 is the threshold voltage of transistor 16.

ΔVTI6 is the increase in ■7□6 due to the back gate effect. Substituting equation (1) into equation (2), VB=V1
(VT15+VT16+ΔV715+ΔV716)
...(3) Currently, the operation of the internal unit is stopped during standby, and the transistor 14.1 - range meta 15,1 is connected from the power supply.
- The current flowing into the internal unit 11 through the transistor 16 is minute. Therefore, the voltage drop caused by the transistor 14 can be almost ignored, and therefore V1'=Vcc. Also, generally the threshold voltage of a transistor is about 0.7
V, so V t15”: 0.7V, V H6
' = 0.7V. Jutte formula (3)% formula%) becomes. Here, if V cc" = 5 V, ■3 is approximately 3 V. During standby, this ■3 is the internal unit voltage.
The power supply voltage is y l·11. Therefore, internal unit 1
The leakage current at the junction of the I-transistor located within -11 becomes much smaller because the voltage applied to each gate 1 of the -1- transistor decreases.

Further, when not in the standby state, 5TOP becomes "°H", transistor 14 is turned off, and transistor 17 is turned on. Therefore, the internal unit 11 is supplied with the power supply voltage level VCC, and is also supplied with the tarok signal from the clock control circuit 12.

A second embodiment of the invention is shown in FIG. In FIG. 2, 11 is an internal unit 1- of the microcomputer. 12 is a clock control circuit.

13 is an inverter. 14.17 is a P-channel transistor. 21. ．． 22 and 23 are diodes. 18 is the output of the clock control circuit.

The operation of this second embodiment is similar to that of the first embodiment, but a diode is used as a means for lowering the power supply voltage. Here, the forward voltage drop of one diode is V
d, the voltage drop due to the three diodes is 3V
d, and the voltage on the n-channel side of diode 23 is ■
4 becomes V4'; Vcc-3Vd. Now V cc = 5
At V(1), V4 delivery is 3.2V (Vd”==0
．． 6V). The internal unit 11 of the microcomputer is supplied with this voltage (4) as a power supply voltage.

Further, the operation in cases other than the standby state is the same as that in the first embodiment.

Although the first embodiment of the present invention is realized by voltage drop using two 1-transistors, the number of transistors may be other than two. Further, although the second embodiment is realized by voltage drop using three diodes, the number of diodes may be other than three.

[Effects of the Invention, 1] As explained above, the present invention stops the clock supplied to the internal unit of the microcomputer during standby, and lowers the power supply voltage supplied to the internal unit. Compared to the standby method, which stops the system, the current flowing during standby can be made much smaller.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2 is a block diagram of a second embodiment of the present invention, and FIG. 3 is a block diagram of a conventional example. 11... Internal unit of microcomputer, 12
... Clock control circuit, 13 ... Inverter, 14
...P channel transistor, 15.16...n
Channel transistor, 18... Output of clock control circuit, 5TOP... Control signal that becomes "L" during standby, CLK... Clock signal input to clock control circuit, 21, 22.23... Diode . Agent: Susumu Uchihara, Patent Attorney: Figure 3

Claims (1)

[Claims] an internal unit of a microcomputer, a first control means for suppressing a clock signal supplied to the internal unit by a control signal that becomes active during standby, and a second control means for reducing a power supply voltage supplied to the internal unit by the control signal. A one-chip microcomputer characterized in that it has a control means.