Sharp ZQ-5000, Service Manual

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ZQ-5000
Terminal No. Signal name
12 VDD
[Power terminal] (OV)
15
[Power terminal, Booster/voltage falling power terminal (-1
14 v s 2
Across VDD -3V power, Across Failing capacitor
9
[Booster power terminal Capacitor is inserted between and
13
[Constant voltage output terminal] Output terminal of internal power.
Capacitor is inserted between and VST for stabilization of constant voltage output.
C l
11
[Booster capacitor connection terminal] Capacitor is inserted between and C2.
7
o s c 2
16
2
4
ALARM
Input
Input
output
Input
output
output
[System reset input] After oscillation frequency is stabilized,
the system can be reset by high level input (6.25
or above).
[Oscillation terminal] Oscillation input/output terminal
[Data input terminal] Normally pulled down to LOW.
[Data output terminal] Output amplitude is between and
[Alarm output] Alarm buzzer drive output terminal
Output frequency is
output amplitude is between and VS2.
4. Regulator 1 DA)
5. Low battery detection circuits
This is used to produce power for RTC (6V 3V)
1
2
GND
3
VOUT
The is equipped with the following two circuits for low
battery detection:
Main battery voltage detection circuit
Memory protection battery voltage detection circuit
The main battery voltage detection circuit detects the battery volt-
age during operation of the unit. When the voltage falls to the caution
level (about 4.4 to
the LCD battery lamp lights up. When the
voltage falls to the fatal level (about 3.9 to the power is
sority turned off. This operation is common with the
All detection circuit detect the battery voltage when the power
is turned on, and provide the message of low battery if required.
The detection procedures in that case are as follows:
The fatal level of the battery for operating the unit is checked. (If
The is a voltage regulator developed with C-MOS
gate process, and is composed of a high accuracy and low power
consumption reference voltage supplier, a differential amplifier control
transistor, and a voltage setting resistor. The output votage is inter-
nally fixed. It is a negative output voltage regulator.
The package is mini power mold plastic package.
VREF
the battery level is below the fatal level, the power cannot be
turned on.)
The level of the unit memory protection battery is checked. case
of low battery, the display will be as Fig.
The unit memory header is checked.
The caution level of the unit operation battery is checked. In case
of low battery, the display will be as Fig. 2.
Fig. 1
Fig. 2
Display remains for about 5
Display remains for about 2
and the power is turned off. and the normal operation mode
is restored. (The battery lamp
lights up.)