HV257
32-Channel High Voltage
Sample and Hold Amplifier Array
Features
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32 independent high voltage amplifiers
300V operating voltage
295V output voltage
2.2V/µs typical output slew rate
Adjustable output current source limit
Adjustable output current sink limit
Internal closed loop gain of 72V/V
12MΩ feedback impedance
Layout ideal for die applications
General Description
The Supertex HV257 is a 32 channel high voltage sample and
hold amplifier array integrated circuit. It operates on a single
high voltage supply, up to 300V, and two low voltage supplies,
V
DD
and V
NN
.
All 32 sample and hold circuits share a common analog input,
V
SIG
. The individual sample and hold circuits are selected by
a 5 to 32 logic decoder. The sampled voltage on the holding
capacitor is buffered by a low voltage amplifier and amplified
by a high voltage amplifier with a closed loop gain of 72V/V.
The internal closed loop gain is set for an input voltage range
of 0V to 4.096V. The input voltage can be up to 5.0V but
the output will saturate. The maximum output voltage swing is
5V below the V
PP
high voltage supply. The outputs can drive
capacitive loads of up to 3000pF.
The maximum output source and sink current can be adjusted
by using two external resistors. An external R
SOURCE
resistor
controls the maximum sourcing current, and an external R
SINK
resistor controls the maximum sinking current. The current
limit is approximated 12.5V divided by the external resistor
value. The setting is common for all 32 outputs. A low voltage
silicon junction diode is made available to help monitor the die
temperature.
Applications
► MEMS (microelectromechanical systems) driver
► Piezoelectric transducer driver
► Optical crosspoint switches (using MEMS technology)
Typical Application Circuit
Supertex HV257
DAC
V
SIG
Low Voltage
Power Supply
High Voltage
Power Supply
HV
OUT
0
HV
OUT
1
HV
OUT
2
HV
OUT
3
x
y
y
x
Micro
Processor
A
0
A
1
A
2
A
3
A
4
EN
D
GND
32
Low Voltage
Channel
Select
Sample
and Hold
High Voltage
OpAmp Array
MEMS
Array
HV
OUT
30
HV
OUT
31
R
SOURCE
R
SINK
A
GND
V
NN
SUPERTEX [ Supertex, Inc ]
