sg6901asz-f116 Fairchild Semiconductor, sg6901asz-f116 Datasheet - Page 3

• Manufacturer Part Number: sg6901asz-f116
• Description: Pfc/flyback-pwm Controller
• Manufacturer: Fairchild Semiconductor

PFC / Flyback PWM Controller
PIN DESCRIPTIONS
© System General Corp.
Version 1.0.1 (IAO33.0062.B0)
Name
VRMS
RI
OTP
IEA
IPFC
IMP
ISENS
E
FBPW
M
IPWM
AGND
SS
OPWM
GND
OPFC
VDD
RANGE
OVP
FBPFC
VEA
IAC
Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Type
Line-Voltage
Detection
Oscillator Setting
Over Temperature
Protection
Output for PFC
Current Amplifier
Inverting Input for
PFC Current
Amplifier
Non-inverting Input
for PFC Current
Amplifier
Peak Current Limit
Setting for PFC
PWM Feedback
Input
PWM Current
Sense
Ground
PWM Soft-Start
PWM Gate Drive
Ground
PFC Gate Drive
Supply
PFC Output
Voltage Control
PFC Over-Voltage
Input
Voltage Feedback
Input for PFC
Error Amplifier
Output for PFC
Voltage Feedback
Loop
Input AC Current
Function
Line voltage detection. The pin is used for PFC multiplier, RANGE control of PFC output
voltage, and brownout protection. For brownout protection, the controller is disabled
after a delay time when the VRMS voltage drops below a threshold.
Reference setting. One resistor connected between RI and ground determines the
switching frequency. The switching frequency is equal to [1560 / RI] KHz, where RI is
in KΩ. For example, if R
This pin supplies an over-temperature protection signal. A constant current is output from
this pin. An external NTC thermistor must be connected from this pin to ground. The
impedance of the NTC thermistor decreases whenever the temperature increases. Once
the voltage of the OTP pin drops below the OTP threshold, the SG6901A is disabled.
This is the output of the PFC current amplifier. The signal from this pin is compared with
an internal sawtooth and determines the pulse width for PFC gate drive.
The inverting input of the PFC current amplifier. Proper external compensation circuits
result in excellent input power factor via average-current-mode control.
The non-inverting input of the PFC current amplifier and the output of multiplier. Proper
external compensation circuits will result in excellent input power factor via
average-current-mode control.
The peak-current setting for PFC.
The control input for voltage-loop feedback of PWM stage. It is internally pulled high
through a 6.5kΩ resistance. Usually an external opto-coupler from secondary feedback
circuit is connected to this pin.
The current-sense input for the flyback PWM. Via a current sense resistor, this pin
provides the control input for peak-current-mode control and cycle-by-cycle current
limiting.
Signal ground.
During startup, the SS pin will charge an external capacitor with a 50µA (RI=24KΩ)
constant current source. The voltage on FBPWM will be clamped by SS during startup. In
the event of a protection condition occurring and/or PWM being disabled, the SS pin will
be quickly discharged.
The totem-pole output drive for the Flyback PWM MOSFET. This pin is internally
clamped under 17V to protect the
Power ground.
The totem-pole output drive for the PFC MOSFET. This pin is internally clamped under
17V to protect the
The power supply pin.
Two-level output voltage setting for PFC. The PFC output voltage at low line can be
reduced to improve efficiency. The RANGE pin has high impedance whenever the V
voltage is lower than a threshold.
The PFC stage over voltage input. The comparator disables the PFC output driver if the
voltage at this input exceeds a threshold. This pin can be connected to FBPFC or it can be
connected to the PFC boost output through a divider network.
The feedback input for PFC voltage loop. The inverting input of PFC error amplifier. This
pin is connected to the PFC output through a divider network.
The error amplifier output for PFC voltage feedback loop. A compensation network
(usually a capacitor) is connected between this pin and ground. A large capacitor value
results in a narrow bandwidth and improves the power factor.
This input is used to provide current reference for the multiplier.
- 3 -
MOSFET.
I
is equal to 24KΩ, the switching frequency is 65KHz.
MOSFET.
www.sg.com.tw • www.fairchildsemi.com
Product Specification
September 26, 2007
SG6901A
RMS