JPH0426992A - Battery circuit for semiconductor memory device - Google Patents

Abstract

PURPOSE:To inform it to an external device that a counter charge prevention diode of a primary battery is destroyed or short-circuited by connecting a series connection comprising a counter charge prevention diode, a current limit resistor and a backup primary battery in parallel with a semiconductor memory element and providing a light emitting element and a resistor in parallel with the current limit resistor. CONSTITUTION:When counter charge prevention diode 4 is destroyed or short- circuited, a power supply from a terminal equipment is fed to a primary battery 2 via current limit resistors 3, 6 and a light emitting diode 7 to counter-charge the battery 2. That is, the primary battery 2 is counter-charged by a current being the sum of a current Ia flowing to the current limit resistor 3 and a current Ib flowing to the current limit resistor 6 and the light emitting diode 7. Since the current Ib is enough to light up the light emitting diode 7, the light emitting diode 7 is lighted. The current flowing thereat is limited by the resistor 6. Thus, the user recognizes it that the counter charge prevention diode 4 is destroyed resulting in short-circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a battery circuit of a semiconductor storage device, and particularly relates to a battery circuit of a portable semiconductor storage device having a protection function for the battery used. It is.

[Prior Art] FIG. 3 is a block diagram showing a battery circuit of a conventional semiconductor memory device. In FIG.
(2) is a primary battery such as a lithium battery that supplies power to the nonvolatile memory (1) when there is no input power from the terminal (not shown); (3) is a current limiting resistor;
4) is a reverse charge prevention diode, and these primary battery (2), resistor (3), and diode (4) are connected in series, and are provided in parallel with the nonvolatile memory (1). (5) is a backflow prevention diode.

Next, the operation of the battery circuit of the conventional semiconductor memory device shown in FIG. 3 will be explained. When input power is supplied from the terminal to the non-volatile memory (1), the terminal can perform read/write operations using the non-volatile memory (1) and interface signals.

Generally, the power supply voltage of the terminal is 5V, for example, and the primary battery (2
) is, for example, 3V. Therefore, at this time, no current flows through the primary battery (2) due to the action of the diode (4), so the primary battery (4) does not consume power.
If there is no power input from the terminal, use the primary battery (2)
Since the voltage is supplied to the nonvolatile memory (1) via the resistor (3) and the diode (4), the data stored in the nonvolatile memory (1) is retained.

Next, due to some reason, such as external noise, the diode (
4) Consider the case where is destroyed and short-circuited.

When power is input from the terminal in this state, the primary battery (2) is reversely charged via the resistor (3) because the diode (4) is short-circuited. If the primary battery (2) is reversely charged, it will be destroyed due to liquid leakage, etc., which may cause major problems depending on the case, so reverse charging must be avoided at all costs. Otherwise, the function of the primary battery (2) will be lost and the non-volatile memory (1) will no longer be able to function as a backup power source.

[Problems to be Solved by the Invention] As described above, in the battery circuit of a conventional semiconductor storage device, if the diode (4) breaks down and short-circuits, the power from the terminal device is transferred to the primary battery via the resistor (3). (2) is reversely charged, so if this state continues for a long period of time, there will be negative effects such as leakage of the primary battery (2), and the backup of the non-volatile memory (1) by the primary battery (2) will become permanent. It becomes possible, and
There was a problem in that it was not obvious that the diode (4) was short-circuited.

This invention has been made to solve the above-mentioned problems, and provides a battery circuit for a semiconductor storage device that displays a short-circuit in a reverse charge prevention diode and makes it visible from the outside of the semiconductor storage device. The purpose is to

[Means for Solving the Problems] A battery circuit for a semiconductor memory device according to the present invention includes a semiconductor memory element, a reverse charging prevention diode, a current limiting resistor, and a backup primary battery connected in series in parallel with the semiconductor memory element. A light emitting element and a resistor are provided in parallel with a current limiting resistor.

[Function] In the present invention, a light emitting element is provided in parallel with the current limiting resistor, and when the reverse charging prevention diode is broken or short-circuited, the light emitting element emits light to inform the outside.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention.
) to (5) are the same as described above.

In this embodiment, a current limiting resistor (6) and a light emitting element such as a light emitting diode (7) are connected in parallel with the current limiting resistor (3).
) to connect.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be explained. Now, when there is no power input from the terminal, the voltage of the primary battery (2) is supplied to the nonvolatile memory (1) via the current limiting resistor (3) and the reverse charge prevention diode (4). Ru. Since the light emitting diode (7) is inserted in the opposite direction to the current flow direction, no current flows. Therefore, the light emitting diode (7) does not emit light, and when power is supplied from the zero-order terminal that is turned off, the reverse charging prevention diode (4) functions as before when it is normal. conduct.

Now, the reverse charging prevention diode (4) is destroyed,
In the event of a short circuit, the power from the terminal device is connected to the current limiting resistor (3), the current limiting resistor (6), and the light emitting diode (
7) to the primary battery (2) to reverse charge it. That is, the primary battery (2) is connected to the current limiting resistor (3).
It is reversely charged by the sum of the current Ia flowing through the current limiting resistor (6) and the current Ib flowing through the current limiting resistor (6) and the light emitting diode (7). Since the current Ib has a value sufficient for the light emitting diode (7) to emit light, the light emitting diode (7) emits light.

The current flowing at this time is limited by the resistor (6). Therefore, when the light emitting diode (7) lights up, the user can know that the reverse charging prevention diode (4) has been destroyed and a short circuit has occurred. Therefore, the user immediately prohibits the use of this semiconductor storage device.

Fig. 2 shows an example of the mounting location of the light emitting diode (7), Fig. 2 (a) is its plan view, and Fig. 2 (b) is its side view. In Fig. 2 (a) , 8) is a semiconductor memory device, and (9) is a connector for a terminal.

The light emitting diode (7) is provided on the lower side opposite to the connector part (9) as shown in FIG. 2(b).

In the above embodiment, the light emitting diode (7) was mounted on the side surface, but it may be mounted on the front and back surfaces. Alternatively, a signal obtained from the anode side of the reverse charging prevention diode (4) may be sent from the semiconductor storage device to the terminal device, and a current limiting resistor (6) and a light emitting diode (7) may be provided on the terminal device side. In this case as well, the same effects as in the above embodiment can be achieved.

[Effects of the Invention] As described above, according to the present invention, a reverse charging prevention diode, a current limiting resistor, and a backup primary battery are connected in series to the semiconductor memory element and the main column, and the current limiting resistor is Since a light emitting element and a resistor are installed in parallel with the primary battery, it is possible to easily notify the outside that the reverse charging prevention diode of the primary battery has been destroyed and a short circuit has occurred, resulting in a highly safe and reliable semiconductor memory device. This has the effect of providing a battery circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a plan view and side view showing a mounting example of the present invention, and FIG. 3 is a block diagram showing a battery circuit of a conventional semiconductor memory device. . In the figure, (1) is a non-volatile memory, (2) is a primary battery, (3) and (6) are current limiting resistors, (4) is a reverse charge prevention diode, and (7) is a light emitting diode. be. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A reverse charging prevention diode, a current limiting resistor, and a backup primary battery are connected in series in parallel with a semiconductor memory element, and a light emitting element and a resistor are provided in parallel with the current limiting resistor. A battery circuit for a semiconductor storage device, characterized in that: