Circuit Description
5-8
Samsung Electronics
STATIC VOLTAGE CIRCUIT (4.1V OUTPUT)
The secondary (cathod of D23) output voltage Vo
is separated by R50, VR1, R55, R79 and applied to
the comparator U24-B pin 6. Q41 turns off
(10k~33k) or on (0~5.1k) according to the resistance
value in V/F (front/rear) terminal of R50,R79.
In accordance, when Q41 turns on, the parallel
linked resistance value of R50 and R79 become
smaller, so that 4.1V comes out. The voltage will be
compared with the reference input voltage of pin
5, and feedback to the primary by U2(OPT).
U24-B output voltage is linked to U24-A output. It
turns Q36 off. Consequently, if either one of these
static voltage or static current overflows, it will
automatically turn U1 off. R45 and C36 are used to
compensate the phase difference caused by the
time delay.
Since, the Vd is maintained to be the same level as
the reference voltage Vr is,
STATIC VOLTAGE CIRCUIT (4.2V OUTPUT)
The secondary (cathod of D23) output voltage Vo is
separated by R50, VR21, R55, R79 and applied to
the comparator U24-B pin 6. Q41 turns off
(10k~33k) or on (0~5.1k) according to the resistance
value in V/F (front/rear) terminal of R50, R79.
In accordance, when Q41 turns off, only the
parallel linked resistance value of R50 is selected,
so that 4.2V comes out. The voltage will be
compared with the reference input voltage of pin
5, and feedback to the primary by U2.
U24-B output voltage is linked to U24-A output. It
turns Q36 off. Consequently, if either one of these
static voltage or static current overflows, it will
automatically turn U2 off. R45 and C36 are used to
compensate the phase difference caused by the
time delay.
Since the Vd is maintained to be the same level as
the reference voltage Vr is,
CHARGE SWITCHING CIRCUITRY
The rapid charger has two charge ports; front port
and rear port.
When the battery is charged in the front port, Q35
turns on. It turns Q34-A (P-CHANNEL FET) on.
When the battery is charged in the rear port, Q33
turns on. It turns Q34-B (P-CHANNEL FET) on.
When the battery level becomes low, this circuitry
will charge the battery until it reaches 2.7V with
Q26 and Q39.
5-4-2 Controller
MICRO-CONTROLLER
U21 is a 4-bit micro-controller which controls the
whole charging system. It contains I/O port, timer,
and A/D converter. 4 MHz clock is used for the
controller.
DETECTION OF CHARGE VOLTAGE
The battery voltage in the front port is detected by
R60 and R61, and measured at the pin 13 of the
MPU.
The battery voltage in the rear port is detected by
R58 and R59, and measured at the pin 14 of the
MPU through the analog switch U25. measured at
the pin 14 of the MPU through U25.
Vd = Vo
(R50//R79 + VR21) + R55
R55
Vo = Vr
R55
(R50//R79 + VR21) +R55
Vd = Vo
(R50 + VR21) + R55
R55
Vo = Vr
R55
(R50 + VR21) +R55
Summary of Contents for SCH-470
Page 2: ... à Samsung Electronics Co Ltd APR 1998 Printed in Korea Code No GH68 60687A ...
Page 6: ...2 2 Samsung Electronics ...
Page 12: ...NAM Programming 3 6 Samsung Electronics ...
Page 24: ...Circuit Description 5 10 Samsung Electronics ...
Page 26: ...Exploded View and its Parts List 6 2 Samsung Electronics 6 1 Fixed Phone Exploded View ...
Page 30: ...6 6 Samsung Electronics Exploded View and its Parts List ...
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Page 43: ...Samsung Electronics 8 1 8 Troubleshoot ing 8 1 Logic Section 8 1 1 No Power ...
Page 45: ...Samsung Electronics 8 3 Troubleshooting 8 1 3 Abnormal Backlight Operation ...
Page 46: ...Troubleshooting 8 4 Samsung Electronics 8 1 4 Abnormal Key Data Input ...
Page 47: ...Samsung Electronics 8 5 Troubleshooting 8 1 5 Abnormal Keytone ...
Page 48: ...Troubleshooting 8 6 Samsung Electronics 8 1 6 Abnormal Alert Tone ...
Page 49: ...Samsung Electronics 8 7 Troubleshooting 8 2 RF Section 8 2 1 RF Secton Troubleshooting ...
Page 50: ...Troubleshooting 8 8 Samsung Electronics 8 2 2 Receiver Part ...
Page 51: ...Samsung Electronics 8 9 Troubleshooting 8 2 3 Transmitter Part ...
Page 52: ...Troubleshooting 8 4 Desk Top charger 8 4 1 Check 1 8 10 Samsung Electronics ...
Page 53: ...Troubleshooting Samsung Electronics 8 11 ...
Page 54: ...8 4 2 Check 2 Troubleshooting 8 12 Samsung Electronics ...
Page 55: ...8 4 3 Check 3 Troubleshooting Samsung Electronics 8 13 ...
Page 56: ...Troubleshooting 8 14 Samsung Electronics ...
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