HV257DB2
High Voltage Sample and Hold Array
General Description
The Supertex HV257DB2 is a 32-Channel, 295V, sample
and hold amplifier array with a nominal gain of 72V/V. The
purpose of the HV257DB2 is to provide a means to easily
evaluate the Supertex HV257FG device. A high voltage
supply, V
PP
, and four low voltage supplies, AV
DD
and DV
DD
,
AV
NN
and DV
NN
, are required. Referring to the demo board
drawing shown below, the logic and V
SIG
connections are on
the left, the high voltage outputs are on the bottom, and the
supplies are on the right. Please follow the power up/down
sequence to avoid damaging the device.
Specifications
Parameter
V
PP
, High voltage supply:
AV
DD
/ DV
DD
, Low voltage positive supply:
AV
NN
/ DV
NN
, Low voltage negative supply:
V
SIG
, Input signal range:
HV
OUT
, Output voltage swing
A
V
, Closed loop gain
SR, Output slew rate into 100pF load
Value
300V
6.0V to 7.5V
-4.5V to -6.5V
0V to 5.0V
0V to 295V
72V/V ±5%
2.0V/µs
Board Layout
EN
A0
A1
A2
A3
A4
V
SIG
V
SGND
HV257DB2
C10
R3
C4
C5
C9
C7
U1
HV257
DGND
DV
DD
DV
NN
AGND
No Connect
AV
DD
AV
NN
AV
PP
C2
C8
C6
R1 R2
D2
C3
D1
C1
pin1
HV
OUT
31
HV
OUT
0
Power Up/Down Sequence
The device can be damaged due to improper power up/down
sequence. To prevent damage, please follow the acceptable
power up/down sequences. Two external diodes, D1 and
D2, are added in the demo board to prevent damage dur-
ing power Up/Down. The first diode is a high voltage diode
across V
PP
and V
DD
. Any low current high voltage diode can
be used. The second diode can be any low voltage schottky
diode across V
NN
and GND.
Acceptable Power Up Sequences
1) V
PP
2) V
NN
3) V
DD
4) Inputs & Anode
or
1) V
NN
2) V
DD
3) V
PP
4) Inputs & Anode
Acceptable Power Down Sequences
1) Inputs & Anode
2) V
DD
3) V
NN
4) V
PP
or
1) Inputs & Anode
2) V
PP
3) V
DD
4) V
NN
SUPERTEX [ Supertex, Inc ]
