HT7627 Datasheet, PDF (1/6 Pages) Holtek Semiconductor Inc – PFM Step-up DC/DC Converter & Voltage Detector

HT7627
PFM Step-up DC/DC Converter & Voltage Detector
Features
· High output voltage accuracy: ±5%
· Low ripple and low noise
· Low start-up voltage
(when the output current is 1mA): 0.95V
Applications
· Pager
· 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
· 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
TEST
LX
VSS
B u ffe r
O s c illa to r
E rro r A m p
B ia s V r e fe r e n c e
B ia s
VH
PW DET
R RW 1
VO UT
R RW 2
VL
R RW 3
VDET
CP
Pin Assignment
NC ₁
LX ₂
NC ₃
VSS ₄
8 ^{VO UT}
7 ^NC
6 ^VDET
5 ^CP
H T7627
8 S O P -A
Rev. 1.00
1
January 18, 2002