SG6858 Fairchild Semiconductor, SG6858 Datasheet - Page 3

• Manufacturer Part Number: SG6858
• Description: This highly integrated PWM controller provides several special enhancements designed to meet the low standby power needs of low-power SMPS
• Manufacturer: Fairchild Semiconductor

© 2008 Fairchild Semiconductor Corporation
SG6858 • Rev. 1.2.4
Marking Information
Pin Configuration
Pin Definitions
DIP-8 SSOT-26
1
2
3
4
5
6
7
8
Pin #
GND
FB
RI
6
5
4
3
2
1
1
2
3
SENSE
Name Description
GATE
GND
VDD
NC
NC
FB
RI
SOT - 26
Totem-pole output driver for the power MOSFET.
Power supply.
No connection.
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 provides current amplitude information for current-mode control.
A resistor connected from the RI pin to ground generates a constant current source.
This current is used to charge an internal capacitor to determine the switching
frequency. Increasing the resistance reduces the amplitude of the current source
and reduces the switching frequency. A 95kΩ resistor, R
current, I
No connection.
Feedback. The FB pin provides the output voltage regulation signal, and feedback to
the internal PWM comparator, so the PWM comparator can control the duty cycle.
Ground.
I,
6
5
4
and a 70kHz switching frequency.
Figure 5. Pin Configurations
SENS E
GAT E
VDD
Figure 3. SSOT-26
Figure 4. DIP-8
3
XXX:AAI=SG6858
TT: Die run code
●: Year code
— : Week code
F: Fairchild Logo
Z: Assembly Plant Code
X: Year Code
Y: Week Code
TT: Die Run Code
T: N=DIP
P: Y=Green Package
M: Manufacture flow code
SE NSE
GATE
VDD
NC
1
2
3
4
I,
DIP-8
results in a 50µA constant
8
7
6
5
www.fairchildsemi.com
GND
FB
NC
RI