Chapter 5. Power Supply Circuit - Sharp PC-4741 Service Manual

CHAPTER 5. POWER SUPPLY CIRCUIT
(5) Output voltage
-
P C-4741
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5-1. Block diagram
Fig. 5-1 shows the block diagram.
[F ~~VAe
VLB
vaG
VR2 VA2
(veo)
(VGG)
INTER FACE
&
LCD
DRIVING CIRCUIT
Fig. 5-1 Block diagram
5·2.
Electric characteristics
(1)
Input voltage
veRT
vee
PVCRT
IPON
V-'
V+12(VBKL)
V·12
VLCD
This power supply unit CQuid be operated by using one of the
foUow~
ing input voltage and the combination of them.
a. AC adaptor (CE-452V) 9.0V±0.5V 2.5A
b. Lead battery (UBATZ1 003ACZZ) 5.0V-6.5V 4.2Ah
(2) Non-load current
Table 6-2 shows the input current from the battery connector when all
outputs are non-load with 6.3V input from battery connector without
using AC adaptor.
IPON CURRENT
Low less than 500IJA
High
less than 200mA
Table 5-1
(3)
Monitering output
The power supply unit outputs the following 2 monitering outputs.
a.
VLB
The VLB telis the battery voltage to the system.
The output connect the battery terminal through the diode.
b.VAC
The V AC tells whether the AC adaptor is connected or not.
The output should be more than 6.5V while the AC adaptor Is con-
nected.
(4) Battery voltage detection
When VLB voltage is changed according to the value in table 6-2
without connecting AC adaptor, the VGG output voltage satisfies the
value in the table 2.
(IPON is set to low. VGG load is adjusted to 1 mA.)
VLB voltage (V)
VGG voltage (V)
from 0 to 4.0 less than 0.3
fromOt05.1
4.75 -5.25
from 6.0 to 4.8 4.75 -5.25
from 6.0 to 4.0 less than 0.3
Table 5-2
-25-
inputs of AC adaptor or battery.
The converting efficiency should be more than 70% when using the
battery as the input.
a.
VGG (+5V±O.25V)
The VGG output is always supplied to the logic ICs on the Main PCB.
b. VCC (+5V±O.25V)
The VCC output is supplied to the logic ICs on the Main PCB. LCD
unit, FDD unit, and HDD unit while the control signallPON is high.
c.
V+12, VBKL (+12V±O.6V)
The V+12 and VSKL output is supplied to the lGs and Inverter for
CCFT Backlight while the IPON is high.
d. V-12 (-12V±1.0V)
The V-t 2 output is supplied to the ICs while the IPON is high.
e. V--5 (--5V±O.25V)
The V-5 output is supplied to the optional MODEM unit while the
IPON is high.
f. VLCD (-24V±1.2V)
The VLCD output is supplied to the LCD unit while the IPON is high.
g. VCRT (+5V±O.25V)
The VCRT output is supplied to the optional CRT adaptor while the
control signals IPON and PVCRT are high.
The following table is output characteristics of all outputs.
OUTPUT CONDITION VOLTAGE (V) CURRENT (mA) RIPPLE (mVp-p)
VGG 5.D±0.25 0.1 -15 less than 100
VCC
IPON = High
5.D±D.25
300 - 2800 less than 100
IPON=Low
less than 0.3
V+12 IPON = High 12.D±0.6
0-270 less than 150
VBKL
IPON = Low D±D.3
V-12
IPON = High -12.D±1.0
0--20
less than 150
IPON = Low D±D.3
V-5
IPON = High -5.D±0.25
0-20
less than 100
IPON=Low D±D.3
VCRT
PVCRT = High 5.D±D.25
0-120 less than 100
PVCRT=Low less than 0.3
VLCD
IPON = High
-24±1.2V
-10-25 less than 200
IPON=Low
0+0.3
Table 6-3
NOTES 1) The control signals are from the CMOS IC powered by
VGG, and the range of high is 4.0 to 5.25V, low is less
than 0.5V.
2) PVCRT
=
High means IPON
=
High too.
3) The currents of the VCC is the peak current.
It is continuously supplied less than 1.6A.
(6) Input current of IPON, PVCRT, PVBKL
When IPON, PVCRT, is high level (+4.0V) at on mode, the input
current of them satisfy the Table 6-4.
Input current
IPON
less than 1 rnA
PVCRT
less than 1 mA
Table 5-4
5·3. Battery recharge circuit
When the AC
adapt~r
or VEX is supplied, if IPON is at low (the set Is
OFF), the charging characteristic of the battery is as shown in Fig.
6-2. To check the operation, provide a dummy resistor to the battery
connector and check points A - D in Fig. 6-2 and Table 6-5.