A S 1 7 2 0

S o l e n o i d / Va l v e D r i v e r w i t h C u r r e n t L i m i t a t i o n

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

Revision 1.04

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D a t a s h e e t

1 General Description

The AS1720A is a low side current source providing an optimized

DC Operation for power saving and ultra low electromagnetic

radiation.

The AS1720B is a low side switch providing a PWM output, which

frequency is defined by an internal RC oscillator. The adjustable

PWM allows a fine control of the power delivered to the load.

The AS1720A and AS1720B can be set to provide a strong initial

closure current and is automatically switching to hold mode for

power saving. The initial DC current, the hold current and the duty

cycle of the PWM can be adjusted by external resistors. An internal

thermal sensor prevents damage of the circuit due to excessive

heating up.

Both devices are optimized for driving electromechanical devices

such as valves, solenoids relays, actuators and positioners.

2 Key Features

Supply Range: +5V to +50V

Internal VDDA: 3.3V

Supply Current: 1 mA

Internal osc frequency: 30kHz

Fix delay: 136ms

Adjustable duty cycle: 20% – 90% (AS1720B only)

Adjustable energizing current: 10mA – 100mA

Adjustable hold current: 30% - 70% of energizing current

Current Limitation

Thermal shutdown: 150ºC

8-pin MLPD (2x2mm) Package

On request SOIC 8 Package (reduced temperature range -40°C

to +85°C)

3 Applications

The AS1720 is ideal for fluid and gas flow systems, industrial control,

electrical heaters, motor speed control.

Table 1. Standard Products

Model

Operation Mode

AS1720A

DC Current Source Operation

AS1720B

PWM Switching Operation

L

Energising Current adjust

Thermal

Shutdown

PWM &

Control

Free-

Wheeling

Diode

Vsupply: +5V to +50V

IH

ENN

IE

adjustable

Duty cycle

Hold Current adjust

Internal VDDA typ. 3.3V

Current

Adjust

LDO &

Ref Generator

R1

R2

100nF

On

Off

AS1720

Delay

30kHz

Oscillator

VDDA

3

DUTY

2

VDDA

1

VDDHV

4

OUT

5

VSS

7

6

8

Figure 1. AS1720 - Block Diagram

10nF