HV57009(2007) Ver la hoja de datos (PDF) - Supertex Inc

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Fabricante

HV57009
(Rev.:2007)

64-Channel Serial to Parallel Converter with P-Channel Open Drain Controllable Output Current

Supertex Inc 

HV57009

Typical Current Programing Circuits

0.1µF

VDD

0.1µF

VDD

HV57009

VBP

Logic

-+

+IN -IN

REXT

IREF

VREF

RD*10KΩ

VSS

CD* 390pF

HV57009

To other

outputs

VBP

IOUT

HVOUT

-+

+IN -IN

VREF

REXT

IREF

Logic

RD*10KΩ

VSS

CD* 390pF

To other

outputs

IOUT

HVOUT

Figure 1a: Negative Control

Figure 1b: Positive Control

*Required if REXT > 10KΩ or REXT is replaced by a constant current source.

Since IOUT = IREF =

‌ VREF ‌

REXT

Therefore:

If IOUT = 2.0mA and VREF = -5.0V → REXT = 2.5KΩ.

If IOUT = 1.0mA and REXT = 1.0KΩ → VREF = -1.0V.

Given IOUT and VREF, the REXT can be calculated by using:

REXT =

VREF

IREF

=

V

REF

IOUT

If REXT >10KΩ, add series network RD and CD to ground for

stability as shown.

The intersection of a set of IOUT and VREF values can be lo-

cated in the graph shown below. The value picked for REXT

must always be in the shaded area for linear operation. This

This control method behaves linearly as long as the opera-

tional amplifier is not saturated. However, it requires a nega-

tive power source and needs to provide a current IREF = IOUT

for each HV570 chip being controlled.

control method has the advantage that VREF is positive, and

draws only leakage current. If REXT > 10KΩ, add series net-

work RD and CD to ground for stability as shown.

Note:

If HVOUT ≥ +1.0V, the HVOUT cascode may no longer oper-

ate as a perfect current source, and the output current will

diminish. This effect depends on the magnitude of the output

Lower reference current IREF, results in higher distortion,

∆ICS, on the output.

current.

HV570 IOUT vs. VREF

4

0.1K

0.2K

0.5K

1K

2K 3K

3

2

5K

1

0

0

1

2

3

4

5

VREF (Volts)

6

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