IBM 9493-AW1 Service Manual page 30

LM2674 Simple Switcher® Power Converter High Efficiency 500mA Step-Down Voltage Regulator
Pin Configuration
Block Diagram
FEEDBACK
4
R2
3.3V, R2 =4.32k
5V, R2 = 7.83k
12V, R2 = 22.3k
ADJ,R2 = 0Ω
R1
R1 is OPEN
= 2.5k
1.21V
Top View
V
IN
7
Gain Bias
Compensation Generator
Bias
V
RAMP
3.2V
0.6V
+
–
GM 1
GM 2
–
2k
+
10k
15k
+
10nF
20mH*
5V Internal
1.21V
Regulator
Referance
1.21V 5V
Freq. Shift
260kHz
Oscillator
Thermal
Shutdown
Reset
+
Control
–
Logic
PWM
Comparator
Enable
6
GND
Start
5 ON/OFF
UP
7V
Enable
Current
R
SENSE
Limit
C
1
BOOTSTRAP
500mA
Switch
Driver
V SWITCH
8