ą UCC29421, UCC29422, UCC39421, UCC39422 MULTIMODE HIGHĆFREQUENCY PWM CONTROLLER
SLUS246C − OCTOBER 1999 − REVISED FEBR...
ą UCC29421, UCC29422, UCC39421, UCC39422 MULTIMODE HIGHĆFREQUENCY PWM CONTROLLER
SLUS246C − OCTOBER 1999 − REVISED FEBRUARY 2005
D Operation Down to an Input
Voltage of 1.8 V
simplified schematic block diagram and application circuit
D High Efficiency Boost, SEPIC or
Flyback (Buck-Boost) Topologies
D Drives External FETs for
High-Current Applications
D Up to 2-MHz Oscillator D Synchronizable Fixed Frequency
Operation
D High-Efficiency Low-Power Mode D High-Efficiency at Very Low-Power
with Programmable Variable Frequency Mode
D Pulse-by-Pulse Current Limit D 5-µA Supply Current in Shutdown D 150-µA Supply Current in Sleep
Mode
D Selectable NMOS or PMOS
Rectification
D Built-In Power-On Reset
(UCC39422 Only)
D Built-In Low-
Voltage Detect
(UCC39422 Only)
description
SYNC/SD 13
RT 14
1.8 V(MIN)
1.24 V VREF
PWM OSC
VPUMP 7
VIN 9
CHARGE PUMP
VPUMP
8 CP
3 VOUT
2 RSEN RECT
4
ANTI− CROSS COND.
VGD
RSEL 19
CHRG 6
PWM CIRCUITRY
CURRENT LIMIT
LOW POWER MODE
SLOPE COMPENSATION
PFM MODE CONTROL
GND 15
+ X10
ERROR 1.24 V AMP +
ISENSE 12
PGND 5
FB 17
COMP 18
PFM 16
+
+ 2 CELL
ALKALINE/
+
NiCd OR 1 LI−ION
VOUT
50 mV TYP
The UCC39421 family of synchronous
RESET
PWM controllers is optimized to operate
1
from dual alkaline/NiCd cells or a single
Lithium-Ion (Li-Ion) cell, and convert to
LOWBAT
adjustable output
voltages from 2.5 V to
10
8 V. For applications where the input
voltage does not exceed the output, a
standard boost configuration is used.
200 mS RE...
