JPH11340800A - Comparator circuit with on and off function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of terminals by constituting a comparator circuit having ON/OFF functions for using ON/OFF control terminals also as the input terminal of the comparator circuit. SOLUTION: In a comparator circuit having ON/OF F functions, the ON/OFF of the comparator circuit is controlled by the input terminal voltage of the comparator circuit. That is, ON/OFF control terminals are used also as the input terminal of the comparator circuit. For example, in this comparator circuit, invertors 200 and 201 for controlling ON/OFF are used. Then, when the input voltage of the comparator circuit is larger than the comparator voltage Vref of the comparator circuit, the comparator circuit can be stopped by using the characteristics of the invertors 200 and 201. That is, PchTr 202 and 203 are turned off when Vin>Vdd/2, and currents from the Vdd are cut so that the current consumption of the comparator circuit can be cut when the Vin> Vdd/2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a comparison circuit which requires ON / OFF control and which can reduce the number of ON / OFF control terminals.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a conventional comparison circuit having an ON / OFF control terminal. The operation of the comparison circuit 10 includes the voltage Vin at the plus terminal 11 and the voltage V at the minus terminal 12
ref, and as the value of the output terminal voltage Vout, Vin> Vref
Vdd (H) is output at the time, and Vss (L) is output at the time of Vin <Vref. When the voltage Vof of the ON / OFF control terminal 13 is low, the comparison circuit 10 is turned on (operating state), and when the voltage Vof is high, the comparison circuit 10 is turned off (stopped).

FIG. 4 shows an example of a circuit diagram of the comparison circuit shown in FIG. FIG. 4 shows a Pch transistor (hereinafter referred to as PchTr) differential input type comparison circuit. When the gate voltage Vin of PchTr M1 is higher than the gate voltage Vref of PchTr M2, Vou
t becomes Vdd (H), and if Vin is smaller than Vref, Vout becomes V
ss (L). If Vref = 1.0V in FIG. 3, Vin = 1.0
Vout switches Vout. FIG. 5 shows the Vin-Vout relationship. That is, when Vin <1.0, Vout is "L", Vin
At> 1.0, Vout becomes "H".

[0004] The meaning of the ON / OFF control terminal is to turn off the operation of the comparison circuit when it is not used in order to reduce the power consumption as much as possible. Conventionally, the comparison circuit is controlled to be ON or OFF by connecting the ON / OFF control terminal to Vdd or Vss.

[0005]

In a conventional comparison circuit including an ON / OFF control terminal, the number of terminals is increased by the number of ON / OFF control terminals, and at the same time, the space is taken up, and the package cost is high. There was a problem of becoming.

[0006]

In order to solve the above problems, the present invention uses an ON / OFF control terminal also as an input terminal of a comparison circuit to reduce the number of terminals.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, an ON / OFF control terminal is also used as an input terminal of a comparison circuit.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a comparison circuit in which an ON / OFF control terminal according to an embodiment of the present invention is also used as an input terminal of the comparison circuit. Also, input terminals 11 and 12, comparison circuit 10, ON / O
The FF control circuit 20 is the same as the conventional one. Conventionally, there are two ON / OFF control terminals and two input terminals in FIG. 3, but in FIG. 1 of the present invention, it can be seen that the control terminal and the input terminal of the ON / OFF circuit are common. FIG.
FIG. 1 shows an example of the circuit diagram of FIG. In FIG. 2, ON / O
Although the inverters 200 and 201 for FF control are used, the internal circuit diagram of the inverters 200 and 201 is shown in FIG. FIG.
, When the K value and Vth of the PchTr 601 and the NchTr 602 are equal, the PchTr 601 is turned off at Vin> Vdd / 2, and the NchTr 602 is turned off at Vin>
Turns on at Vdd / 2. Therefore, when Vin <Vdd / 2, V01 = Vd
When d and Vin> Vdd / 2, V01 = Vss. That is, when "H" is input, "L" is output, and when "L" is input, "L" is output.
H "is output.

By using the characteristics of the above-mentioned inverter, the input voltage of the comparison circuit becomes equal to the comparison voltage Vref of the comparison circuit.
The comparison circuit can be stopped at a voltage higher than (1.0 V in FIG. 5). That is, the PchT shown in FIG.
Since r 202 and 203 are turned off when Vin> Vdd / 2 and the current from Vdd is cut, the current consumption of the comparison circuit can be cut when Vin> Vdd / 2. For example, Vdd =
At 3.0V, the current consumption of the comparison circuit is cut when Vin> 1.5V. This is shown in FIG. NchTr 204, PchTr 2
05 turns on when Vin> Vdd / 2, the NchTr 204 drops the undefined voltage to Vss, and the PchTr 205 fixes the output voltage Vout to "H" when the comparison circuit stops.

In the above description, an example in which the output voltage Vout is fixed at "H" when the comparison circuit is stopped has been described.
It is also possible to fix to L ". What has been described above is that the PchTr601 and NchTr6 of the inverters 200 and 201 shown in FIG.
Assuming that the K value of 02 (see FIG. 6) is equal to Vth, Vin = Vd
The comparison circuit was switched ON / OFF at d / 2.
The voltage for controlling N / OFF can be freely changed. The following are three examples. FIG. 8 shows a first embodiment showing that the voltage for ON / OFF control can be freely changed.

FIG. 8 shows that the ON / OFF of the comparison circuit 801 is determined by comparing the input current Vin of the comparison circuit 801 with the voltage Vref of the minus terminal 81.
At this time, the comparator 802 causes the comparison circuit 8
Turns 01 off. The operation of the comparison circuit 801 is the same as that of the comparison circuit 10 shown in FIG. comparator
In 802, assuming that the voltage of the minus terminal 82 is Vref + α, the ON / OFF of the comparison circuit 801 can be switched by Vin = Vref + α. FIG. 9 shows the relationship between Vin and the current consumption of the comparison circuit at this time. Here, the value of α may be any value as long as it is a positive value. The comparator 802 described here corresponds to the ON / OFF control circuit 20 shown in FIG. 1, and therefore is the same as a block diagram in FIG.
The operation details for turning on / off the comparison circuit are shown in the figure.
1, as described in FIG.

In this case, a comparator requiring a high speed, that is, a comparator which consumes a large amount of current, is used.
By controlling ON / OFF of 801 with a comparator 802 that consumes less current, the current consumption can be reduced. FIG. 10 shows a second embodiment showing that the voltage for ON / OFF control can be freely changed.
Shown in

FIG. 10 shows ON / OFF of the comparison circuit 1001 when the input current Vin of the comparison circuit 1001 is the voltage of the minus terminal 101.
When the voltage is equal to or lower than Vref, the comparator 1002 turns off the comparison circuit 1001. The operation of the comparison circuit 1001 is the same as that of the comparison circuit 10 shown in FIG. In the comparator 1002, assuming that the voltage of the plus terminal 102 is Vref-β, ON / OFF of the comparison circuit 1001 can be switched by Vin = Vref-β. FIG. 11 shows the relationship between Vin and the current consumption of the comparison circuit at this time. Here, the value of β may be any value as long as it is a positive value. The comparator 1002 described here is the ON / OFF control circuit 2 shown in FIG.
Since this corresponds to 0, the block diagram is the same as FIG. The operation details for turning on / off the comparison circuit are shown in the figure.
1, as described in FIG.

FIG. 12 shows a third embodiment showing that the voltage for ON / OFF control can be freely changed. Figure
12 is a circuit for comparing ON / OFF of the comparison circuit 1201 with the comparator 120
2, 1203. Comparator 120
2 indicates that the input current Vin of the comparison circuit 1201 is
When the input current Vin of the comparison circuit 1201 is equal to or less than the voltage Vref of the minus terminal 121, the comparator 1203 turns off the comparison circuit 1201 when the voltage is equal to or higher than the voltage Vref of 1.
This is for turning off the comparison circuit 1201. Comparison circuit
The operation of 1001 is the same as that of the comparison circuit 10 shown in FIG. In the comparator 1202, assuming that the voltage of the minus terminal 122 is Vref + α, the ON / OFF of the comparison circuit 1201 is
It is possible to switch with Vin = Vref + α. Also,
In the comparator 1203, the voltage of the plus terminal 123 is
Assuming f−β, ON / OFF of the comparison circuit 1203 is Vin = Vref−
It is possible to switch with β. The comparison circuit 1201 sets the output to "H" based on the voltage Vref of the minus terminal 121.
Or "L", but here, the reference voltage Vref
The comparison circuit operates only in the vicinity of. FIG. 13 shows the relationship between Vin and the current consumption of the comparison circuit at this time. Here, the values of α and β may be any values as long as they are positive values. Comparators 1202 and 1203 described here
Corresponds to the ON / OFF control circuit 20 shown in FIG. 1, so that the block diagram is the same as FIG. The operation of turning on / off the comparison circuit is as described with reference to FIGS.

[0015]

The present invention is embodied in the form described above and has the following effects. 1
By eliminating the ON / OFF terminal, the number of pins can be reduced when a PKG is formed.

2 By eliminating the ON / OFF terminal, other elements can be arranged in the IC accordingly. 3 PKG
Cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a comparison circuit diagram with a built-in ON / OFF control terminal of the present invention.

FIG. 2 is an internal circuit diagram of FIG.

FIG. 3 is a comparison circuit diagram with a conventional ON / OFF control terminal.

FIG. 4 is an internal circuit diagram of FIG. 3;

FIG. 5 is a diagram showing Vin-Vout characteristics in FIG. 3;

FIG. 6 is an inverter circuit diagram.

FIG. 7 is a diagram showing the current consumption characteristics of the Vin-comparison circuit according to the present invention.

FIG. 8 is a block diagram of a first embodiment showing that a voltage for ON / OFF control can be freely changed.

FIG. 9 is a diagram of the Vin-comparison circuit current consumption characteristic of FIG.

FIG. 10 is a block diagram of a second embodiment showing that the voltage for ON / OFF control can be freely changed.

FIG. 11 is a graph showing the current consumption characteristics of the Vin-comparison circuit of FIG. 10;

FIG. 12 is a block diagram of a third embodiment showing that a voltage for ON / OFF control can be freely changed.

FIG. 13 is a diagram illustrating the current consumption characteristics of the Vin-comparative circuit in FIG. 12;

[Explanation of symbols]

 Reference Signs List 10 comparison circuit 11 plus input terminal 12 minus input terminal 13 ON / OFF terminal 20 ON / OFF control circuit 200, 201 inverter 202, 203, 205 PchTr 204 NchTr 601 PchTr 602 NchTr 81, 82 minus input terminal 801 comparison circuit 802 comparator 101 , 102 Negative input terminal 1001 Comparison circuit 1002 Comparator 121, 122, 123 Negative input terminal 1201 Comparison circuit 1202, 1203 Comparator

Claims (1)

[Claims] 1. A comparison circuit having an ON / OFF function, wherein ON / OFF of the comparison circuit is controlled by an input terminal voltage of the comparison circuit.