AS1720B 查看數據表（PDF） - austriamicrosystems AG

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AS1720B

Solenoid / Valve Driver with Current Limitation

austriamicrosystems AG 

AS1720

Datasheet - Application Information

9 Application Information

In order to drive relays, which need more than 100mA current, an external circuitry (see Figure 11) can be used. This application shows how to

drive 5W @12V relays.

This circuit is only applicable for AS1720A.

For this example with R1 = 100Ω and RS = 2.5Ω the current Is is calculated as follows:

IS

=

I1

×

R----1- =

RS

0, 01A × 12---,-0---50-=

400mA

(EQ 3)

Figure 11. AS1720A - Typical Application

Vsupply: +12V

VDDHV

100nF

VDDA

DUTY

AS1720A

10mA

IS

R1

100Ω 1V

RS

I1

OUT

-

+

LM741

BC161

VSS

Relay

Free-

Wheeling

Diode

ENN

IE

RIE

120kΩ

Energising Current adjust

IH

RIH

240kΩ

Hold Current adjust

www.austriamicrosystems.com/Solenoid-Relay-Driver/AS1720 Revision 1.04

8 - 12

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