sg6980 Fairchild Semiconductor, sg6980 Datasheet - Page 3

• Manufacturer Part Number: sg6980
• Description: Single Stage Pfc Controller
• Manufacturer: Fairchild Semiconductor

Single-Stage PFC Controller
PIN DESCRIPTIONS
© System General Corp.
Version 1.0.1 (IAO33.0064.B0)
Name Pin
VRMS
OTP
RI
IEA
IPFC
IMP
IPK
SYNC
ON/OFF 9
GND
OUT
VDD
RDY
FB
VEA
IAC
1
2
3
4
5
6
7
8
10
11
12
13
14
15
16
Type
Line-Voltage Detection
Over-Temperature
Protection
Oscillator Setting
Current Amplifier Output
Inverting Input for PFC
Current Amplifier
Non-inverting Input for
PFC Current Amplifier
and Output of Multiplier
Peak Current Limit
Synchronous Signal
Remote On/Off
Ground
Gate Drive
Supply
Ready Signal Output
Feedback Input
Error Amplifier Output
Input AC Current
Function
Line voltage detection. The pin is used for PFC multiplier and brownout protection. For
brownout protection, the controller is disabled with a 195ms delay time when the VRMS
voltage drops below 0.8V. There is a 200mV hysteresis for brownout protection.
This pin supplies an over-temperature protection signal. A constant current is output from
this pin. If RI is equal to 24kΩ, the magnitude of the constant current is 50µA. 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 1.2V, the SG6980 is off, and auto restarts when the voltage is back to 1.4V.
The resistance of a resistor connected between RI and ground determines the switching
frequency. A resistance between 15kΩ and 40KΩ is recommended. The switching
frequency is equal to [1560 / RI] kHz, where RI is in kΩ. For example, if RI is equal to 24kΩ,
then the switching frequency is 65kHz.
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 will
result in excellent input power factor via average-current-mode control.
The non-inverting input of the PFC current amplifier and also the output of the multiplier.
Proper external compensation circuits result in excellent input power factor via
average-current-mode control.
The peak current setting for PFC.
This pin receives the external switching signal. The PFC switching can be synchronized by
SYNC with 1:1 ratio.
Active high. The SG6980 is disabled whenever the voltage at this pin is lower than 1V or the
pin is open. When SG6980 is disabled by ON/OFF, the I
The ground.
The totem pole output drive for the PFC MOSFET. This pin is internally clamped under 18V
to protect the
The power supply pin. The threshold voltages for start-up and turn-off are 12.5V and 10V,
respectively. The operating current is lower than 5mA.
This pin outputs a ready signal to control the power on sequence. Once the SG6980 is
turned on and the FB (PFC feedback input) voltage is higher than 2.7V, this pin locks high
impedance. Disabling the SG6980 resets this pin to the low.
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. The suggested maximum
I
AC
is 350µA.
MOSFET.
- 3 -
www.sg.com.tw • www.fairchildsemi.com
DD
current is lower than 35µA.
Product Specification
September 17, 2007
SG6980