HV57009PG Ver la hoja de datos (PDF) - Supertex Inc
Número de pieza
componentes Descripción
Fabricante
HV57009PG Datasheet PDF : 7 Pages
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Typical Current
Programming Circuits
0.1µF
VDD
HV570
VBP
Logic
-+
+IN -IN
VSS
REXT
IREF
VREF
RD*
10K
CD*
390pF
Figure 8a: Negative Control
To other
outputs
IOUT
HVOUT
0.1µF
VDD
HV570
VBP
Logic
-+
+IN -IN
VREF
REXT
IREF
RD*
10K
CD*
390pF
To other
outputs
VSS
IOUT
HVOUT
Figure 8b: Positive Control
*Required if REXT > 10K or REXT is replaced by a constant
current source.
HV57009
Since I = I =
OUT
REF
VREF
REXT
Therefore, if IOUT = 2mA and VREF = -5V → REXT = 2.5KΩ.
If IOUT = 1mA and REXT = 1KΩ → VREF = -1V.
If
R
EXT
>10KΩ,
add series network R and C to ground for
D
D
stability as shown.
This control method behaves linearly as long as the operational
amplifier is not saturated. However, it requires a negative power
source and needs to provide a current IREF = IOUT for each HV570
chip being controlled.
If
HV
OUT
≥
+1V,
the
HV
OUT
cascode
may
no
longer
operate
as
a
perfect current source, and the output current will diminish. This
effect depends on the magnitude of the output current.
Given IOUT and VREF, the REXT can be calculated by using:
REXT = VREF = VREF
IREF
IOUT
The intersection of a set of IOUT and VREF values can be located
in the graph shown below. The value picked for R must always
EXT
be in the shaded area for linear operation. This control method
has the advantage that VREF is positive, and draws only leakage
current. If R > 10K, add series network R and C to ground
EXT
D
D
for stability as shown.
Note: Lower reference current IREF, results in higher distortion,
∆ICS, on the output.
8
7
6
100
5
4
250
500
3
REXT = 1K
2
2K
1
5K
0
1
2
3
4
5
VREF (V)
©2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
7
03/12/02
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 744-0100 • FAX: (408) 222-4895
www.supertex.com
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