FAN50FC3 Datasheet, PDF (3/21 Pages) Fairchild Semiconductor – 8-Bit Programmable, 2- to 3-Phase FastvCore™ Buck Controller

Pin Assignments
VID6 25
VID5 26
VID4 27
VID3 28
VID2 29
VID1 30
VID0 31
VIDSEL 32
Exposed Paddle on
Bottom of Package
FAN50FC3
16 _VOSADJ
15 OD#
14 GND
13 CSCOMP
12 CSSUM
11 CSREF
10 RAMPADJ
9 RT
Figure 2. Pin Assignments
Pin Definitions
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
Name
EN
PWRGD
FBRTN
FB
COMP
SS
DELAY
ILIMIT
RT
RAMPADJ
CSREF
CSSUM
CSCOMP
Description
Power Supply Enable Input. Analog comparator input with hysteresis. If the input
voltage is higher than the internal threshold, the controller is enabled; if lower, the
controller is disabled.
Power Good Output. Open-drain output that pulls to GND when the output voltage is
outside the proper operating range.
Feedback Return. VID DAC and error amplifier reference for remote sensing output
voltage.
Feedback Input. Error amplifier input for remote sensing output voltage. A positive
internal current source is connected to this pin to allow the output voltage to be offset
lower than the DAC voltage.
Error Amplifier Output. For loop compensation.
Soft-Start Input. An external capacitor connected between this pin and GND sets the
soft-start ramp-up time.
Delay Timer Input. An external capacitor connected between this pin and GND sets
the over-current latch-off delay time, BOOT voltage hold time, EN delay time, and
PWRGD delay time.
Current Limit Set. An external resistor from this pin to GND sets the current limit
threshold of the converter.
Frequency Set Input. An external resistor connected between this pin and GND sets
the oscillator frequency of the device.
PWM Ramp Set Input. An external resistor connected between this pin and the
converter input voltage sets the internal PWM ramp.
Current-Sense Amplifier Positive Input. The voltage on this pin is used as the
reference for the current-sense amplifier. The Power Good and Crowbar functions are
internally connected to this pin.
Current-Sense Amplifier Negative Input.
Current-Sense Amplifier Compensation Output.
© 2007 Fairchild Semiconductor Corporation
FAN50FC3 Rev. 1.0.0
3 of 21
www.fairchildsemi.com