F72815
6. Block Diagram
VDDA
V3VAA
0.4V
0.1V
OC
SD
40uA
Reference
Voltage
Bias & Regulator
(VDD & V3VAA)
Power On
Reset
Comp
Comp
OCSET
0.8V
VREF
TRAP_SEL
0.6V
UV
UVP
1.5V
Control
Logic
PH_M
Comp
VDD
BOOT
GM
Comp
FB
UGATE
PHASE
VDDA
LGATE
300KHz Tri-OSC
GND
Figure 1: Block Diagram
7. Function Description
The F72815 is a single PWM DC-DC converter controller for application which requires high current such as
motherboard, graphic card etc. The F72815 uses voltage mode PWM controller with fast transient response (driving
two external N-channel MOSFETs in a synchronous rectified buck converter topology) and integrates some functions
such as adjustable reference voltage input for overclock, soft-start, over current and short circuit protections etc. Over
current protection is achieved by monitoring the PHASE negative voltage when heavy loading without the need of a
current sensing resistor and short circuit condition is detected through FB pin. If over current condition occurs, the
F72815 will initiate the soft start cycle. After two cycles and the fault condition persist, the controller will go into shut
down status. In shut down status, both gate drive signals will be low. To restart the controller, either recycling VCC
supply or momentarily pulling the OCSET pin below 0.15V. If under voltage condition occurs, it will keep hiccup mode in
F72815
-5-
Aug, 2007
V0.14
FINTEK [ FEATURE INTEGRATION TECHNOLOGY INC. ]
