EL7531
Pin Descriptions
PIN NUMBER
1
2
3
4
PIN NAME
SGND
PGND
LX
VIN
5
VDD
6
SYNC
7
EN
8
PG
9
VO
10
FB
Block Diagram
PIN FUNCTION
Negative supply for the controller stage
Negative supply for the power stage
Inductor drive pin; high current digital output with average voltage equal to the regulator output voltage
Positive supply for the power stage
Power supply for the controller stage
SYNC input pin; when connected to HI, regulator runs at forced PWM mode; when connected to Low, auto
PFM/PWM mode; when connected to external sync signal, at external PWM frequency up to 12MHz
Enable
Power-Good open drain output
Output voltage sense
Voltage feedback input; connected to an external resistor divider between VO and SGND for variable
output
100Ω
VDD
0.1µF
VO
C4
124K
470pF
FB 5M
10pF
-
+
SYNC
EN
100K
10µF
SYNC
EN
CLOCK
SOFT-
START
3.3V
+
–
BANDGAP
REFERENCE
SGND
INDUCTOR SHORT
PWM
COMPENSATION
RAMP
GENERATOR
+
-
CURRENT
SENSE
+
-
PWM
COMPARATOR
PFM
ON-TIME
CONTROL
P-DRIVER
CONTROL
LOGIC
VIN
LX 1.8µH
UNDER-
VOLTAGE
LOCKOUT
POWER
GOOD
+
-
PWM
COMPARATOR
TEMPERATURE
SENSE
N-DRIVER
10µF
+
-
SYNCHRONOUS
RECTIFIER
PGND
PG
1.8V
0 TO 1A
100K
PG
3
FN7428.9
July 13, 2006