CMOS Switched-Capacitor Voltage Converter
Features
·
·
·
·
HT7660
Simple conversion of V
DD
to
-V
DD
Cascade connection (two devices are
connected, V
OUT
=
-2
V
DD
)
Boost pin for higher switching frequency
Easy to use
-
Requires only two external capacitors
·
·
·
·
No external diode required
Typically with no load voltage conversion,
99.9% efficiency
Typical power efficiency is 98%
Wide operating voltage range: 3V to 12V
Applications
·
·
·
RS-232 power supply
On board negative supply for dynamic
RAMS
Supply voltage splitter, V
O
=
±
V
DD
/2
·
·
·
Operation amplifier supply
Data acquisition systems
Positive voltage doubler
General Description
HT7660 is a monolithic CMOS switched-capaci-
tor voltage converter. HT7660 is designed to
complete a voltage conversion from positive to
negative. The only required external compo-
nents are two low cost electrolytic capacitors.
HT7660 includes a voltage regulator, an RC os-
cillator and four output power MOS switches.
The frequency of an RC oscillator can be low-
ered by adding an external capacitor between
V
DD
and the OSC pin, or an external clock can
be connected to the OSC pin to replace the origi-
nal oscillator. The LV terminal may be tied to
VSS to disable the voltage regulator. By doing
this, low voltage operation can be improved.
Block Diagram
VDD
OSC
BOOST
RC
Oscillator
Voltage
Level Shifter
CAP+
CAP
VOUT
LV
Voltage
Regulator
Logic
Network
VSS
1
November 30, 1999
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
