Harman Kardon DVD 38, Service Manual

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Product Specification
Low Cost Green-Mode PWM Controller for Flyback Converters
SG6848
© System General Corp.
- 2 - www.sg.com.tw
Version 1.2(IRO33.0010.B0) May.06, 2003
MARKING DIAGRAMS PIN CONFIGURATION
ORDERING INFORMATION
Part Number PWM Frequency Package
SG6848T 70kHz 6-Pin SOT-26
SG6848D 70kHz 8-pin DIP-8
PIN DESCRIPTIONS
Pin No.
Name
DIP-8 / (SOT-26)
Type Function
GATE 1 / (6) Driver Output The totem-pole output driver for driving the power MOSFET.
VDD 2 / (5) Supply Power supply.
NC 3 NC pin.
SENSE 4 / (4) Analog Input
Current sense. This pin senses the voltage across a resistor. When the voltage reaches
the internal threshold, PWM output is disabled. This activates over-current protection.
This pin also provides current amplitude information for current-mode control.
RI 5 / (3)
Analog
Input/Output
A resistor connected from the RI pin to ground will generate a constant current source for
the SG6848. This current is used to charge an internal capacitor, to determine the
switching frequency. Increasing the resistance will reduce the amplitude of the current
source and reduce the switching frequency. A 95k
Ω resistor R
i
results in a 50uA constant
current I
i
and a 70kHz switching frequency.
NC 6 NC pin.
FB 7 / (2) Analog Input
Feedback. The FB pin provides the output voltage regulation signal. It provides feedback
to the internal PWM comparator, so that the PWM comparator can control the duty cycle.
GND 8 / (1) Supply Ground.
M : Mask Version
Y : Year; WW : Work Week
1
2
3
4
5
6
SOT-26
GND
FB
RI
GATE
VDD
SENSE
1
M A YWW
XXXXXXX : Wafer Lot
YY : Year; WW : Week
V : Assembly Location
8
1
SG6848D
XXXXXXXYYWWV
DIP-8
RI
NC
FB
GND
SENSE
NC
VDD
GATE
4
3
2
1
5
6
7
8
DVD38
harman/kardon
137