Current Consumption Check - Sharp PC-E500S Service Manual

7. Low battery detection circuit
This model is equipped with the low battery detection circuit, the
operations of which are described below. (Location Nos. of the parts
are different from the actual ones.)
The LBIC (RH5VA39A) detects two levels; the CAU level and the
STOP level. For that reason, a voltage applied to the input pin (2 pin)
is divided by R1 and R2, and R2 is turned on/off by the CAU signal of
G.A.
When the power voltage falls below the CAU level, as shown in Fig.
3, the BATT symbol lights up. When it falls further below the STOP
level, the BATT symbol goes off.
To detect the CAU level, the CPU E3 is turned on (LOW) and the
CPU IRQ pin state is checked. (If the IRQ pin is at LOW, the symbol
lights up.) :
VCC VCC [Fig. 1]
Ag no ePuL
i {
res LB A
CPU E3__ hoicel | IRQ
B
(V) TIN
oo
Power voltage (V)
\.
Voltage detection IC operation
Symbol! lights up.
[Fig. 2] [Fig. 3]
Low battery detection circuit check
CAU level VCC-GND: 4.2V - 4.6V
STOP level VCC-GND: 3.8V - 4.2V
8. Current consumption check
Power source: 11-pin connector, +5V - OV applied to VCC (2 pin) -
GND (3 pin)
Reference
PC-E500S5
[__[eseration | display |
DC-DC =
| converter 3
pvoo | 075m A
TC4S81F
| TC3WO1F
Ammeter
Turn on the main DC
| = _ power (+6.3V 40.1 V). a
Ee While pressing ON key,
press RESET key.
* Press Y key to initialize
the internal RAM.
Press PF1 key to go into
the BASIC mode.
+3.7V+ 0.1V. out
4
i
eee ne ewww we ee eee ew eee eee
the 11-pin connector with |
a 3.9KQ resistor for 6 |
sec. |