SG6846 查看數據表（PDF） - Unspecified
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SG6846 Datasheet PDF : 14 Pages
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Highly-Integrated Green-Mode PWM Controller
Product Specification
SG6846
PIN DESCRIPTIONS
Pin No. Symbol Function Description
1
GND
Ground
Ground.
The signal from the external compensation circuit is fed into this pin. This FB pin and the
2
FB
Feedback
current-sense signal from Pin 6 determine the PWM duty cycle.
Line-voltage detection. The line-voltage detection is used for brownout protection with
Line-voltage
3
VIN
hysteresis. Constant output power limit over universal AC input range is also achieved using
Detection
this VIN signal. It is suggested to add low pass filter to filter out line ripple on bulk capacitor.
A resistor from the RI pin to ground will generate a reference current source inside SG6846.
Reference
4
RI
This determines the switching frequency. Increasing the resistance will reduce the switching
Setting
frequency. Using a 26kΩ resistor Ri results in a 65kHz switching frequency.
For over-temperature protection. An external NTC thermistor is connected from this pin to
Temperature
5
RT
GND pin. The impedance of the NTC will decrease at high temperatures. Once the voltage
Detection
of the RT pin drops below a threshold, PWM output will be disabled.
Current sense. The sensed voltage is used for peak-current-mode control and
cycle-by-cycle current limiting. If the switching current is higher than 2/3 of the peak-current
6
SENSE Current Sense
threshold for longer than 96ms, over-current protection will be activated. This two-level OCP
feature is especially suitable for SMPS with surge current output.
Power Supply. The internal protection circuit will disable PWM output when VDD over
7
VDD
Power Supply
voltage.
The totem-pole output driver for the power MOSFET. A soft driving waveform is
8
GATE
Driver Output
implemented for improved EMI.
BLOCK DIAGRAM (OTP LATCH VERSION)
© System General Corp.
-3-
Version 1.0(IAO33.0008.B0)
www.sg.com.tw
Sep. 30, 2004
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