Holtek Semiconductor Inc HT7660 Datasheet
CMOS Switched-Capacitor Voltage Converter
Features
Simple conversion of VDDto -V
·
Cascade connection (two devices are
·
connected, V
Boost pin for higher switching frequency
·
Easy to use
·
-
Requires only two external capacitors
= -2VDD)
OUT
Applications
RS-232 power supply
·
On board negative supply for dynamic
·
RAMS
Supply voltage splitter, VO= ± VDD/2
·
General Description
HT7660 is a monolithic CMOS switched-capacitor voltage converter. HT7660 is designed to
complete a voltage conversion from positive to
negative. The only required external compo
nents aretwo low cost electrolytic capacitors.
HT7660 includes a voltage regulator, an RC oscillator and four output power MOS switches.
DD
HT7660
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
·
Operation amplifier supply
·
Data acquisition systems
·
Positive voltage doubler
·
The frequency of an RC oscillator can be low
ered by adding an external capacitor between
V
and the OSC pin, or an external clock can
DD
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
OSC
BOOST
LV
RC
Oscillator
Voltage
Regulator
VSS
Voltage
Level Shifter
Logic
Network
1 November 30, 1999
VDD
CAP+
CAP
VOUT
Pin Assignment
HT7660
BOOST
CAP+
VSS
CAP
1
2
3
-
4
VDD
8
OSC
7
LV
6
VOUT
5
H T 7 6 6 0
8 DIP/SOP
Pin Description
Pin No. Pin Name I/O
1 BOOST I
2 CAP+ O CMOS
3 VSS
4
CAP-
5 VOUT O NMOS
6LV I
7 OSC I/O
8 VDD
¾¾
O NMOS
¾¾
Internal
Connection
CMOS
Pull-low
¾
Transmission
Gate
Description
Higher switching frequency selection input
This pin is connected to the positive terminal of Ca
pacitor C1 for a charge pump
Negative power supply, ground
This pin is connected to the negative terminal of Ca
pacitor C1 for a charge pump
This pin is connected to the negative terminal of Ca
pacitor C2 for charge reservoir. Output voltage pass
through this pin
Floating this pin enables the voltage regulator. Connect this pin to VSS (Ground) to bypass voltage regulator and improve low voltage operation
External clock input pin. This pin can be connected
with an external capacitor to reduce switching frequency
Positive power supply
-
-
-
2 November 30, 1999
Absolute Maximum Ratings
HT7660
Supply Voltage ..............................-0.3V to 13V
Operating Temperature ..............-40°Cto85°C
Storage Temperature.................-50°Cto125°C
Note: These are stress ratings only. Stresses exceeding the range specified under ²Absolute Maxi
mum Ratings² may cause substantial damage to the device. Functional operation of this device
at other conditions beyond those listed in the specification is not implied and prolonged expo
sure to extreme conditions may affect device reliability.
Electrical Characteristics
Ta=25°C
Test Conditions
Symbol Parameter
V
DD
I
STB
f
OSC
R
OUT
V
CON-EFF
P
EFF
Operating Voltage
Standby Current
System Frequency
Output Source Resistance
Voltage Conversion Efficiency
Power Efficiency
DD
Conditions
V
¾¾
3V
No load
5V
3V
¾
5V 5 10
I
OUT
I
OUT
=10mA
=20mA
3V
5V
3V
No load
5V 99 99.9
3V
5V 96 98
5kW
R
L=
Min. Typ. Max. Unit
3
¾
12 V
¾
26 100
mA
80 160
¾
2.5 4
¾
kHz
¾
97 150
¾
W
60 100
¾
99
¾¾
%
¾
96
¾¾
%
¾
-
-
3 November 30, 1999
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