EL7531
Pin Descriptions
PIN NUMBER
1
2
3
4
5
6
7
8
9
10
PIN NAME
SGND
PGND
LX
VIN
VDD
SYNC
EN
PG
VO
FB
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 V
O
and SGND for variable
output
PIN FUNCTION
Block Diagram
100Ω
0.1µF
C4
470pF
V
DD
V
O
10pF
INDUCTOR SHORT
+
-
CURRENT
SENSE
PWM
COMPENSATION
+
-
PWM
COMPARATOR
PFM
ON-TIME
CONTROL
CONTROL
LOGIC
124K
FB
5M
-
+
V
IN
100K
SYNC
EN
10µF
SYNC
EN
SOFT-
START
CLOCK
RAMP
GENERATOR
P-DRIVER
LX
1.8µH
1.8V
0 TO 1A
+
-
PWM
COMPARATOR
UNDER-
VOLTAGE
LOCKOUT
TEMPERATURE
SENSE
N-DRIVER
10µF
3.3V
+
–
BANDGAP
REFERENCE
SGND
+
-
SYNCHRONOUS
RECTIFIER
PGND
100K
PG
PG
POWER
GOOD
3
FN7428.6
August 5, 2005
INTERSIL [ INTERSIL CORPORATION ]
