JPH05158813A - Backup device for semiconductor memory - Google Patents

Abstract

PURPOSE:To provide the backup device of a semiconductor memory capable of suppressing power consumption to the minimum and extending the holding time of data by backup battery power supply. CONSTITUTION:Plural DRAMs 4-1 to 4-N in which digital-coded data is recorded and switches 5-1 to 5-N which are provided in accordance with each DRAM and turn on/off backup power supply to each semiconductor memory at the time of the fall of the voltage of main power supply 6 are provided. Then, a host CPU 2 to on/off-control the switches 5-1 to 5-N in order to supply the backup power supply to only the DRAM in which the digital-coded data is recorded at the time of the fall of the voltage of the main power supply 6 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor memory backup device, and more particularly to a semiconductor memory backup device for recording digitally encoded data in a digital data recorder or the like.

[0002]

2. Description of the Related Art In a digital data recorder, for example, a digital voice recorder, voice data converted into digital data is recorded in a data recording semiconductor memory by a voice recording / reproducing IC. If the voltage supplied to the data recording semiconductor memory drops due to a power outage or the pulling out of the power cord, the power failure detection circuit detects this voltage drop and turns on the switch that supplies power from the backup battery power supply. To be done. As a result, backup power is supplied to all semiconductor memories, so that the audio data in the semiconductor memories is retained.

[0003]

The semiconductor memory for data recording of the above-mentioned digital voice recorder is usually a DRA.
M (Dynamic Random Access Memory) is used,
In the event of a power failure or the like, a large amount of backup power is required to retain the voice data recorded in it. For example, the commonly used ADPCM (Adaptive D
elta Pulse Code

When audio data is compressed at a bit rate of 16 kbps of a digital encoding method based on the Modulation method, about 1 minute of audio data can be recorded in a 1 Mbit DRAM. 1 Mbit DRAM is required. Here, 5V is generally used for holding 1Mbit DRAM data.
Since it consumes a voltage of several mA and a current of several mA,
If the voice data recorded in 10 1M bit DRAMs is held by 4 AAA batteries, it will take only about several hours. As a result, in order to prolong the holding time, a battery of a larger size may be used, but it is difficult to reduce the size, which is a feature of the digital audio recorder.

The backup device of the semiconductor memory of the present invention has been made in view of such a problem, and an object thereof is to save data when the voltage supplied to the semiconductor memory is lowered due to a power failure or the like. It is an object of the present invention to provide a semiconductor memory backup device that can minimize the power consumption by supplying the backup power only to the recorded semiconductor memory and can significantly extend the data retention time by the backup battery power supply. ..

[0006]

In order to achieve the above object, the present invention provides a plurality of semiconductor memories in which digitally encoded data is recorded, and a semiconductor memory provided corresponding to each semiconductor memory. A switch that turns on / off the backup power supply to each semiconductor memory when the voltage drops, and supplies the backup power only to the semiconductor memory in which the digitally encoded data is recorded when the main power supply voltage drops. In order to do so, a switch control means for on / off controlling the switch is provided.

[0007]

That is, according to the present invention, a semiconductor memory in which digitally encoded data is recorded by controlling a switch for turning on / off the supply of backup power to each semiconductor memory when the voltage of the main power source drops. Supply backup power only.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a semiconductor memory backup device according to the present invention will be described below.

In the present embodiment, among the ICs used in the digital voice recorder, the power consumption of the DRAM used as the semiconductor memory is extremely large as compared with other ICs for which low power consumption is measured. Focusing on the fact that the amount of voice data that is normally recorded is less than half of the total DRAM capacity in most cases, it is intended to improve the data retention time by the backup power supply.

In FIG. 1, a mode setting signal for recording, reproducing, erasing, etc. is input from the control key 1, and the host CPU 2 recognizes this and simultaneously controls each circuit.
For example, when the recording button is pressed with the control key 1 and a recording setting signal is input, a voice analog signal input from the microphone 10 is amplified by the microphone amplifier 9, converted into digital data by the AD / DA converter 8, and recorded. It is input to the IC3 again. Here, the message management unit 2 in the host CPU 2
In a, the encoded voice data is DRAMs 4-1 to 4-
The recording / reproducing IC 3 is controlled so that the recording / reproducing IC 3 is stored from the tip of the N empty area.

When the reproduction button is pressed with the control key 1 and the reproduction setting signal is input, the DRAM number and the memory address of the designated message are retrieved from the message management section 2a and the corresponding data is retrieved. Read, A
After being converted into an analog signal by the D / DA converter 8, it is amplified by the power amplifier 11 and output from the speaker 12.

By the way, it is necessary to supply electric power to each part in order to enable the above operation. In this embodiment, the voltage of the main power supply 6, for example, 9V, is regulated to the stabilized power supply circuit 1.
It is converted to 5V by 5 and supplied to the DRAMs 4-1 to 4-N and the like. Reference numeral 7 is a backup power supply for a power failure and is composed of a battery. Backup power supply 7
Backup power from the switch (5-1 to 5-
N) is turned on by a control signal from the host CPU 2 as a switch control means to selectively switch the DRAM 4-
1 to 4-N.

Here, if the power supply from the main power supply 6 is cut off due to a power failure or the like, the voltage of the main power supply 6 will decrease, but since the large capacitor 14 is connected, it will not decrease sharply. The data in the DRAMs 4-1 to 4-N will not be lost after the power failure occurs and before the power supply is switched to the backup power supply. And the main power supply voltage detection circuit
When the voltage 13 drops from 9V to 7V, for example, 13 detects this and outputs a detection signal to the host CPU 2. At this time,
The host CPU 2 searches the message address information in the message management unit 2a for the number of the DRAM in which the voice data is already recorded among the DRAMs 4-1 to 4-N. Then, a DRAM in which a message (voice data) is recorded, for example, DRAMs 4-1 and 4-in FIG.
Only the switch corresponding to 2 is turned on to switch the power supply to the backup power supply 7 side. Below, referring to FIG.
The operation at the time of recording voice data will be described.

First, in step S1, it is determined whether or not the recording button of the control key 1 has been pressed to input a recording setting signal. Step S1 is repeated while no input is made. When input, the AD / DA converter 8 is controlled to convert the audio analog signal input from the microphone 10 into digital data (step S2). Next, in step S3, empty areas of the DRAMs 4-1 to 4-N are searched and digital data is transferred to the searched empty areas (step S4). Next, the operations of battery backup and backup cancellation will be described with reference to FIG.

First, in step ST1, it is determined whether or not the voltage of the main power supply 6 has dropped, based on the output from the main power supply voltage detection circuit 13. Repeat this step as long as the voltage drop is not detected, and DR if the voltage drop is detected.
The DRAM in which the audio data is recorded is searched from AM4-1 to 4-N (step ST2), and the corresponding DR is searched.
The switch connected to the AM is switched to the backup power source 7 side (step ST3). After a predetermined time, it is determined whether the main power source 6 is turned on (step ST
4) Repeat this step while not ON, but ON
In this case, the switch is switched from the backup power source 7 side to the main power source 6 side to cancel the backup (step ST5). In this way, step ST1 and subsequent steps are repeated.

As described above, in this embodiment, the host CPU 2 controls the switches (5-1 to 5-N) to record the voice data when the voltage of the main power source 6 drops due to a power failure or the like. The backup power is supplied only to the existing DRAM. As a result, unnecessary battery current does not flow from the backup power supply 7 to the DRAM that does not contain voice data, so that power consumption is saved.

In most cases, the amount of normally recorded voice data is less than half the total DRAM capacity that can be recorded, so the effect of applying this embodiment to a digital voice recorder is great. ..

[0018]

As described above, according to the semiconductor memory backup device of the present invention, it is possible to minimize the power consumption when the voltage of the main power supply drops, so that the data retention time can be greatly extended. It will be possible.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a message is recorded in a part of DRAM.

FIG. 3 is a flowchart for explaining an operation when recording audio data.

FIG. 4 is a flowchart for explaining a battery backup operation and a backup cancellation operation.

[Explanation of symbols]

1 ... Control key, 2 ... Host CPU, 2a ... Message management section, 3 ... Recording / reproducing IC, 4-1 to 4-N ... DRA
M, 5-1 to 5-N ... Switch, 6 ... Main power supply, 7 ... Backup power supply, 8 ... AD / DA converter, 9 ... Microphone amplifier, 10 ... Microphone, 11 ... Power amplifier, 12 ... Speaker, 13 ... Main Power supply voltage detection circuit, 14 ... Capacitor, 15 ... Stabilized power supply circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H02J 1/00 307 C 7373-5G

Claims (1)

[Claims] 1. A plurality of semiconductor memories in which digitally encoded data are recorded and a semiconductor memory provided corresponding to each semiconductor memory, and supply of backup power to each semiconductor memory is turned on when the voltage of the main power supply drops. A switch for turning off, and a switch control means for controlling on / off of the switch in order to supply backup power only to the semiconductor memory in which the digitally encoded data is recorded when the voltage of the main power supply drops. A backup device for semiconductor memory, which is characterized by being provided.