HT7627
PFM Step-up DC/DC Converter & Voltage Detector
Features
·
High output voltage accuracy:
±5%
·
Low ripple and low noise
·
Low start-up voltage
·
Low current consumption: 14mA with 1.5V input (typ.)
·
Fixed output voltage: 2.7V
·
Built-in 2.1V (typ.) voltage detector
·
8-pin SOP package
(when the output current is 1mA): 0.95V
Applications
·
Pager
·
RF Mouse/Keyboard
General Description
The HT7627 DC/DC converter with built in voltage de-
tector is a high performance CMOS IC, suitable for use
in battery-powered system application with low noise
and low supply current. The HT7627 consists of two ma-
jor parts, one is DC/DC converter and the other is volt-
age detector. The DC/DC converter part consists of
reference voltage source, error amplifier, control transis-
tor, oscillation circuit and output voltage setting resistor.
The voltage detector part consists of a high-precision
and low power consumption standard voltage source, a
comparator, hysteresis circuit and an output driver. As
external parts, a coil, a diode, and a capacitor are avail-
able for obtaining a constant output (2.7V) higher than
the input voltage for the DC/DC converter part.
Block Diagram
T E S T
L X
B u ffe r
R
O s c illa to r
B ia s
E rro r A m p
B ia s V r e fe r e n c e
V
L
V O U T
R
R W 1
R W 2
R
R W 3
V D E T
V S S
V
H
P W D E T
C P
Pin Assignment
N C
1
L X
2
N C
3
V S S
4
8
7
6
5
V O U T
N C
V D E T
C P
H T 7 6 2 7
8 S O P -A
Rev. 1.00
1
January 18, 2002
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
