AD5758 datasheet(71/72 Pages) AD

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Data Sheet

AD5758

Rev. 0 | Page 71 of 72

DRIVING INDUCTIVE LOADS

Driving pure inductive loads while the AD5758 is in a current

output mode requires additional external components. Due to

the operation of the fault protection switch, connecting a pure

inductive load to the output causes a spike in voltage due to the

back electromagnetic force (EMF) from the inductor. This spike

can cause the fault protect switch to open and close indefinitely.

For example, if the load wire on the screw terminal disconnects,

a technician can reconnect the wire without disabling the AD5758

output. The reconnection of this wire onto a current output

introduces the voltage spike caused by the back EMF. To avoid

such issues, the inside of the fault protect switch on the AD5758

is available on the VIOUT_INT pin. Connecting a 300 Ω resistor from

VIOUT_INT to VIOUT bypasses the fault protection switch and avoids

the oscillations. The additional external components are required

to ensure that no oscillations occur when applying a current

step into the inductive load, for example, a full-scale step from

zero scale.

VIOUT

FPS_EN

VIOUT_INT

RESD

RSHUNT

CPIN

CSCREW

SCREW

TERMINAL

Figure 94. Required External Components for Driving an Inductive Load

The recommended external components are as follows:



RSHUNT = 300 Ω



CPIN = 20 nF



CSCREW = 10 nF



RESD = 50 Ω

AD5758 Datasheet(PDF) 71 Page - Analog Devices