HT77XXA Datasheet, PDF (1/18 Pages) Holtek Semiconductor Inc – PFM Step-up DC/DC Converter

HT77XXA
PFM Step-up DC/DC Converter
Features
· Low start-up voltage: 0.7V (Typ.)
· High efficiency: 85% (Typ.)
· High output voltage accuracy: ±2.5%
· Output voltage: 2.7V, 3.0V, 3.3V, 5.0V
· Ultra low supply current I_DD: 5mA (Typ.)
· Low ripple and low noise
· Low shutdown current: 0.5mA (Typ.)
· TO-92, SOT-89, SOT-23 and SOT-25 package
Applications
· Palmtops/PDAs
· Portable communicators/Smartphones
· Cameras/Camcorders
· Battery-powered equipment
General Description
The HT77XXA series is a set of PFM step-up DC/DC
converter with high efficiency and low ripple. The series
features extremely low start-up voltage and high output
voltage accuracy. They require only three external com-
ponents to provide a fixed output voltage of 2.7V, 3.0V,
3.3V or 5.0V. CMOS technology ensures ultra low sup-
ply current and makes them ideal for battery-operated
applications powered from one or more cells.
The HT77XXA consists of an oscillator, a PFM control
circuit, a driver transistor, a reference voltage unit, and a
high speed comparator. They employ pulse frequency
modulation (PFM) for minimum supply current and rip-
ple at light output loading. These devices are available
in space saving TO-92, SOT-89, SOT-23 and SOT-25
packages. For SOT-25 package, it also build-in a chip
enable function to reduce power consumption during
shutdown mode.
Selection Table
Part No.
HT7727A
HT7730A
HT7733A
HT7750A
Output Voltage
2.7V
3.0V
3.3V
5.0V
Package
TO-92
SOT-89
SOT-23
SOT-25
Marking
HT77XXA (for TO-92)
HT77XXA# (for SOT-89)
77XXA# (for SOT-23)
77XXA# (for SOT-25)
Note: ²XX² stands for output voltages.
Only lead free devices are available. ²#² stands for lead free devices. For the TO-92 package, there will be a
²#² mark at the end of the date code.
Block Diagram
LX
L X L im ite r O S C 2 0 0 k H z
VO UT
V re f
B u ffe r
P F M C o n tro l
GND
C h ip E n a b le
CE
Rev 1.10
1
September 26, 2007