Fairchild FAN7601B service manual
FAN7601B
Green Current Mode PWM Controller
FAN7601B — Green Current Mode PWM Controller
May 2012
Features
Green Current Mode PWM Control
Low Operating Current: Maximum 4mA
Burst Mode Operation
Internal High-Voltage Startup Switch
Under-Voltage Lockout (UVLO): 12V/8V
Latch Protection and Soft-Start Function
Over-Voltage Protection: 19V
Operating Frequency up to 300kHz
Maximum Duty Cycle: 95%
Applications
Offline Adapter Applications
Auxiliary Power Supplies
Related Resources
AN4129 — Green Current Mode PWM
Controller FAN7601
Description
The FAN7601B is a programmable frequency green
current mode PWM controller. It is specially designed for
the offline adapter applications and the auxiliary power
supplies that require high efficiency at light load and no
load. The internal high-voltage startup switch and burst
mode reduce the power loss.
FAN7601B includes protections, such as latch protection
and over-voltage protection. The latch protection can be
used for over-voltage protection, thermal protection, and
others. The soft-start prevents the output voltage
overshoot at startup.
Ordering Information
Operating
Part Number
FAN7601BM
FAN7601BMX 7601B 8-SOP Tape & Reel
FAN7601BGX 7601B 10-SSOP Tape & Reel
© 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN7601B • Rev. 1.0.3
Junction
Temperature
-40°C to +150°C
Top Mark Package Packing Method
7601B 8-SOP Rail
Block Diagram
R
t/Ct
(5)
V
REF
Latch/SS
(4)
3
OSC4
12µA
2.5V
FAN7601B — Green Current Mode PWM Controller
V
(10)
REF
5V Ref
1.5V
OVP
+
−
Enable
S
R
S
R
V
(1)
STR
18
V
CC
7
OVP
Startup
Circuit
UVLO
+
−
Q
Q
Delay
Circuit
+
−
12V/8V
+
−
19V
(8)
OUT
6
(7)
+
−
1V
GND
5
(6)
Note:
1. ( ) is 10-SSOP Pin Number.
Startup
Circuit
Reset
Circuit
Figure 1. Internal Block Diagram
0.97V/0.9V
+
−
Latch/SS
−
1V
2
CS/FB
(3)
© 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN7601B • Rev.1.0.3 2
Pin Configurations
FAN7601B — Green Current Mode PWM Controller
Figure 2. 8-Pin Configuration (Top View) Figure 3. 10-Pin Configuration (Top View)
Pin Definitions
Pin # (8-Pin) Pin # (10-Pin) Name Description
1 1 V
2 3 CS/FB Current Sense and Feedback
3 4 Latch/SS Latch Protection and Soft-Start
4 5 Rt/Ct Oscillator Timing
5 6 GND Ground
6 7 Out Gate Drive Output
7 8 VCC IC Power Supply
8 10 V
Startup
STR
Voltage Reference
REF
© 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com
FAN7601B • Rev.1.0.3 3
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