hv57009 Supertex, Inc., hv57009 Datasheet - Page 6

• Manufacturer Part Number: hv57009
• Description: 64-channel Serial To Parallel Converter With P-channel Open Drain Controllable Output Current
• Manufacturer: Supertex, Inc.

Typical Current Programing Circuits
Since I
Therefore:
If R
stability as shown.
This control method behaves linearly as long as the opera-
tional amplifi er is not saturated. However, it requires a nega-
tive power source and needs to provide a current I
for each HV570 chip being controlled.
If HV
ate as a perfect current source, and the output current will
diminish. This effect depends on the magnitude of the output
current.
EXT
VBP
OUT
>10KΩ, add series network R
OUT
If I
If I
≥ +1.0V, the HV
= I
OUT
OUT
0.1µF
VREF
+IN
HV57009
REF
Figure 1a: Negative Control
= 2.0mA and V
= 1.0mA and R
- +
=
-IN
REXT
IREF
‌ V
R
REF
EXT
VDD
‌
OUT
R
D
C
*10KΩ
D
REF
EXT
cascode may no longer oper-
*390pF
Logic
4
3
2
1
0
0
= -5.0V → R
= 1.0KΩ → V
D
0.1K
VSS
and C
1
0.2K
D
EXT
to ground for
REF
To other
outputs
= 2.5KΩ.
= -1.0V.
REF
0.5K
= I
IOUT
2
HVOUT
HV570 I
OUT
V
REF
OUT
6
(Volts)
*Required if R
vs. V
VBP
Given I
R
The intersection of a set of I
cated in the graph shown below. The value picked for R
must always be in the shaded area for linear operation. This
control method has the advantage that V
draws only leakage current. If R
work R
Note:
EXT
Lower reference current I
∆I
REF
1K
CS
3
=
VREF
, on the output.
D
OUT
V
I
0.1µF
+IN
REF
and C
HV57009
REF
and V
EXT
- +
Figure 1b: Positive Control
=
> 10KΩ or R
-IN
2K
REXT
D
IREF
V
I
4
to ground for stability as shown.
REF
OUT
REF
3K
, the R
VDD
R
5K
EXT
D
C
*10KΩ
D
EXT
Logic
is replaced by a constant current source.
* 390pF
REF
5
can be calculated by using:
OUT
, results in higher distortion,
EXT
and V
VSS
> 10KΩ, add series net-
REF
REF
To other
values can be lo-
outputs
is positive, and
HV57009
IOUT
HVOUT
EXT