Sharp ZQ-5000 Service Manual page 9

Terminal No. Signal name
12 VDD
15
14 v s 2
9
13
C l
11
7 o s c 2
16
2
4
ALARM
4. Regulator (SC1771 1 Y DA)
This is used to produce power for RTC (SMC6115F). (6V + 3V)
1
2
GND
3
VOUT
The SC1771 1YDA is a voltage regulator developed with C-MOS SI
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
[Power terminal] (OV)
[Power terminal, Booster/voltage falling power terminal VSl (-1 .S/), VS2 (-3.0V)]
Across VDD - VS2: -3V power, Across VDD - VS3: Failing capacitor
[Booster power terminal (4.5V)] Capacitor is inserted between VDD and VS3.
[Constant voltage output terminal] Output terminal of IC internal power.
Capacitor is inserted between VDD and VST for stabilization of constant voltage output.
[Booster capacitor connection terminal] Capacitor is inserted between Cl and C2.
[System reset input] After oscillation frequency is stabilized,
Input
the system can be reset by high level input (6.25 msec or above).
Input
[Oscillation terminal] Oscillation input/output terminal
output
Input [Data input terminal] Normally pulled down to LOW.
[Data output terminal] Output amplitude is between VDD and VS2.
output
[Alarm output] Alarm buzzer drive output terminal
output
Output frequency is 4,096KHz, output amplitude is between VDD and VS2.
5. Low battery detection circuits
The ZQ-5000/5200 is equipped with the following two circuits for low
battery detection:
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 4.8V), the LCD battery lamp lights up. When the
voltage falls to the fatal level (about 3.9 to 4.2V), the power is compul-
sority turned off. This operation is common with the OZ/IQ-7000.
All detection circuit a>, Q 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 battery level is below the fatal level, the power cannot be
turned on.)
of low battery, the display will be as Fig. 1.
of low battery, the display will be as Fig. 2.
Fig. 1
Display remains for about 5 set,
and the power is turned off.
ZQ-5000
Fig. 2
Display remains for about 2 set,
and the normal operation mode
is restored. (The battery lamp
lights up.)