SG6841SZ Fairchild Semiconductor, SG6841SZ Datasheet - Page 2

• Manufacturer Part Number: SG6841SZ
• Description: IC CTLR PWM HI INTEGRATED 8-SOIC
• Manufacturer: Fairchild Semiconductor

Specifications of SG6841SZ

• Frequency - Max: 70kHz
• Pwm Type: Controller
• Number Of Outputs: 1
• Duty Cycle: 90%
• Voltage - Supply: 10 V ~ 20 V
• Buck: No
• Boost: No
• Flyback: Yes
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -20°C ~ 85°C
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

High-integrated Green-mode PWM Controller
MARKING DIAGRAMS
ORDERING INFORMATION
Part Number
SG6841S
SG6841D
SG6841SZ
SG6841DZ
PIN DESCRIPTIONS
©System General Corp.
Version 2.1 (IRO33.0001.B5)
Pin No.
1
2
3
4
5
6
7
8
SG6841TP
XXXXXXXYYWWV
Symbol Function
GND
FB
VIN
Ri
RT
SENSE
VDD
GATE
Ground
Feedback
Start-Up
Reference Setting
Temperature
Protection
Current Sense
Power supply
Driver Output
Package
8-Pin SOP
8-Pin DIP
8-Pin SOP(Lead Free)
8-Pin DIP(Lead Free)
Input
T: D = DIP, S = SOP
P: Z = Lead Free
XXXXXXX: Wafer Lot
YY: Year; WW: Week
V: Assembly Location
Null=regular package
Description
Ground.
The signal from external compensation circuit is feed into this pin. The PWM duty cycle is
determined by this FB pin and current sense signal from Pin 6.
This pin is pulled high to the rectified line input through a resistor for start-up. Since the
start-up current requirement for SG6841 is very small, a large start-up resistance can be
used to minimize power loss. Under normal operation, this pin is also used to detect line
voltage to compensate for constant output power limit for universal AC input.
A resistor from RI pin to ground will generate a constant current source forSG6841. This
current is used to charge an internal capacitor and hence the switching frequency are
determined. Increasing the resistance will decrease the current source and reduce the
switching frequency. A 26kΩ resistor R
65kHz switching frequency.
For over-temperature protection. An external NTC thermistor is connected from this pin
to ground. The impedance of the NTC will decrease under high temperature. Once the
voltage on RT pin drops below a fixed limit, the PWM output will be disabled.
Current sense. The sensed voltage is used for current mode control and pulse-by-pulse
current limiting.
Power Supply.
The totem-pole output driver for the power MOSFET. A soft driving waveform is
implemented to improve EMI.
- 2 -
PIN CONFIGURATION
GND
VIN
FB
i
RI
creates a 50uA constant current I
Product Specification
www.sg.com.tw
GATE
VDD
SENSE
RT
i
and generates
Jun.15,2006
SG6841