JPS5884453A - Integrated circuit - Google Patents

Abstract

PURPOSE:To lengthen the battery life time, by providing a circuit detecting the voltage drop of a power source element in an IC and allowing it to be charged before the discharge in 100%. CONSTITUTION:When the output voltage of the power source element 203 becomes V1 or less resulting in a state that a charging is required, a flip-flop 214 is set, and the power source element 203 is charged by an external power source 202 via a charge control circuit 205. Next, when the charge is finished, i.e. the output voltage of the power source element 203 becomes V0, the flip-flop 214 is reset, and the charging control circuit 205 breaks the connection between the external power source 202 and the power source element 203 and finishes the charging. Thereby, since the power source element 203 is not charged to V0 or more, overcharging is simultaneously prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an integrated circuit with a built-in power supply element, and more particularly to a configuration of an integrated circuit suitable for extending the life of the built-in power supply element.

Conventionally, when using a volatile memory whose contents are erased when power is not applied, a backup power source such as a battery is required to prevent the contents from being erased even when the power is turned off. Additionally, systems with low power consumption, such as calculators, are designed to operate on both an external power source and a dry cell battery. Therefore, there is a strong desire to realize an integrated circuit with a built-in power supply element, and this demand has become possible with the miniaturization of power supply elements. Here, CM
An integrated circuit with a built-in power supply element will be described as an example of an OS static RAM. FIG. 1 is a diagram showing the cross-sectional structure of this integrated circuit with a built-in power supply element.

In FIG. 1, a CMOS static RAM consists of an n-type silicon substrate 1, a p-type well 2, an n-region 3, a p
''' area 4, insulating film 5, wiring metal 6゜61, 6//
, 6111 and gate 7.7'. The power supply element consists of Si and N applied to the surface of this RAM chip.
, etc. is formed on the passivation film 8. That is, the positive or negative electrode material film 9 of the power supply element, the solid electrolyte 1
0. It is made by sequentially forming the negative or positive electrode material films 11 of the power supply element. % as a positive electrode material for power supply elements
As a negative electrode material such as T'81svse, te f1% L
i-AtiLt-Bt gold alloy or the like is used. Moreover, as a solid electrolyte membrane, Li4s io, -Li, PO,
A compound thin film, Li, Nt, tx compound thin film, etc. is used. The power supply element and the RAM chip are connected by connecting the connection terminal Vgs6 and the power supply terminal Vcc6' of the RAM chip to the positive and negative electrodes of the power supply element via current collectors 12 and 12', respectively. Finally, a passivation film 13 is formed, bonded, and then packaged. Although FIG. 1 shows the case where the power supply element is formed on the RAM chip, it is of course possible to make the RAM chip and the power supply element separately and connect them with wiring inside the package. be.

However, the lifespan of a hole integrated circuit with a built-in power supply element depends on the lifespan of the power supply element, for example, the lifespan of the integrated circuit chip itself is more than 10 years, whereas the lifespan of the power supply element is less than 5 years. In most cases, the lifespan of a power supply element is determined by determining the lifespan of a power supply element, especially when the power supply element is a rechargeable secondary battery. Determined by the number of repetitions.

An object of the present invention is to provide an integrated circuit with a long life by extending the life of the power supply element in an integrated circuit incorporating such a power supply element.

In general, in the case of rechargeable secondary batteries, if you charge the battery before it is 100% discharged, the battery life will be longer than if you charge it after 100% discharge. It has a long lifespan. Further, the amount of discharge can be detected by sensing the output voltage of the battery. The present invention takes advantage of the characteristics of such secondary batteries, provides an integrated circuit with a circuit that detects the voltage drop of the power supply element, and charges the battery before it is 100% discharged, thereby extending the life of the battery. It is meant to be long. Furthermore, the present invention enables the integrated circuit to operate on external power when the external power is applied, thereby reducing the amount of battery discharge, thereby reducing the number of charging/discharging cycles and extending the battery life. It is something to do.

Hereinafter, the present invention will be explained in detail using Examples.

FIG. 2 is a diagram showing the configuration of an embodiment of the present invention.

The integrated circuit 201 is operated by the power supply 202 when the power supply 202 external to the integrated circuit is applied, and is operated by the built-in power supply element 203 when the power supply 202 is not applied. Voltage is supplied. 203 is a secondary battery. 204 is power supply element 2
This is a detection circuit that detects the voltage drop of 03. 205 is
A charging control circuit is configured to charge the power supply element 203 using the external power supply 202 according to instructions from the detection circuit 204 . As time passes, the output voltage of the power supply element 203 drops as shown in FIG. In Figure 3, the voltage Vo
, Vx is 100% charged by the power supply element 203,
This is the output voltage when the battery is 100% discharged. vl is the voltage at which charging should be started when the lifespan of the power supply element 203 is approximately equal to the lifespan of the integrated circuit element; This is the voltage at which charging should start. Detection circuit 20 in FIG.
214 in 4 is a 7 lip-flop for storing that the output voltage of the power supply element 203 is below V and requires charging, or that charging is in progress. Resistors 211, 212, and 213 are power supply element 2.
The resistance value is set so that the signal 215 at the output voltage viO of 03 and the signal 216 at the output voltage Vo become the threshold voltage for setting and resetting the flip-flop 214t, respectively. When charging the power supply element 203t, it is charged at a voltage V (1+V, (V, for example, around 0.5V) higher than 1 dVa. In this case, the output voltage of the external power supply 202 is V, +
V, and a voltage conversion circuit is provided in the power supply switching circuit 206 so that the output 217 of the power supply switching circuit 206 has the same voltage both when operating with the power supply element 203 and when operating with the external power supply 202. As is clear from FIG. 2, the power supply element 20
When the output voltage of 3 becomes below V, the flip-flop 21
4 is set, and the power source element 203 is charged by the external power source 202 via the charging control circuit 205. Next, when charging ends, that is, when the output voltage of the power supply element 203 becomes vo, the flip-flop 214 is reset, and the charging control circuit 205 ends the connection IRt-disconnection charging between the external power supply 202 and the power supply element 203. For this reason, the power supply element 20
Since the battery 3 is not charged to more than We, overcharging is also prevented at the same time. If the resistance values of the resistors 211, 212, and 213 are made as large as possible,
3, the power consumption is small. As is clear from the above description, when the present invention is used, when an external power supply is connected, the integrated circuit operates on the external power supply, so the amount of discharge of the internal power supply element is almost zero, The number of repetitions of charging and discharging of the internal power supply element is small, and the number of times the internal power supply element is charged and discharged is small.
Since charging starts before 00% discharge, it is possible to realize an integrated circuit with a built-in power supply element that has a long life.

In addition, in FIG. 2, the signal 215 is a voltage V.

Although it was stated that the flip-flop 214 should be set when the voltage v1 is reached, there are various setting values for the voltage v1.

For example, if the output 218 of the flip-flop 214 is used to light up a display element such as a liquid crystal mounted outside the integrated circuit, and a human detects this and immediately applies the external power supply 202, the voltage v1 becomes the voltage Vs. Can be set approximately equal. If the maximum time during which no external power is applied is known, Vs t- may be set in consideration of the maximum time t1.

In FIG. 2, if there is a possibility that the external power source 202 will not be continuously applied for a long enough time to sufficiently charge the power source element 203, the output 218 of the flip-flop 214 is used to light up the display element. If the external power supply 202 is applied while the element is lit, the power supply element 2
03 can be charged with V(lt).

In addition, since the voltage drop time of the power supply element 203 in FIG. If there is a possibility of malfunction, a Schmitt trigger circuit may be provided at the input of the flip-flop 214.

Further, in FIG. 2, a resistor and a flip 70 tube are used as the detection circuit 204, but other circuits such as a differential circuit can also be used.

As explained above, according to the present invention, the discharge time of the power supply element incorporated in the integrated circuit can be reduced, and the number of repeated charging and discharging operations can be reduced. Furthermore, since the power supply element can be charged before it is 100% discharged, there is a great effect that the life of the power supply element can be extended, and the life of the integrated circuit containing the power supply element can be extended.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the cross-sectional structure of an integrated circuit incorporating a power supply element, Fig. 2 is a diagram showing an embodiment of the present invention, and Fig. 3 is a diagram showing a power supply used in the integrated circuit of Fig. 2. FIG. 3 is a diagram showing an example of discharge characteristics of an element. Agent Patent Attorney Toshiyuki Usuda￥I 1 Country'''fJ2 Figure'! fj3 Figure R Ginma

Claims (1)

[Claims] 1. An integrated circuit configured to supply power supply voltage from a built-in power supply element, comprising a detection circuit for detecting a voltage drop in the power supply element, and controlling charging of the power supply element by the output of the detection circuit. integrated circuit.