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