preliminary

preliminary

iC-DX

UNIVERSAL DIGITAL SENSOR OUTPUT DRIVER

Rev A3, Page 8/10

OUT

IN

NEP

tpio

ttrig()

EN

Figure 7: Timing diagram in push-pull operation

mode

36V

High Side Switch

DIGITAL INPUT

VREF

REG

&

<150 C

&

CVB

NEP

EN

1μF

CVOUT

100nF..

iC-DX

36V

Low Side Switch

+

-

OUT

5V

IN

GND

VB

GND

VOUT

OE

..30V

VB

Figure 8: Block diagram with EN and NEP internal

signals

CIRCUIT PROTECTION

The iC-DX is reverse polarity protected via internal

circutry. As far as the maximum voltage ratings are not

exceeded, no possible supply combination at the line

side pins (VB, GND and OUT) can damage the chip.

Since the chip current consumption is relatively low,

discharging of the backup capacitor C1 can be very

slow, and injected charge through disturbances may

in general result in capacitor voltage exceeding maxi-

mum ratings, leading to malfunction or destruction of

circuitry and associated parts.

Thus EMC require-

ments will afford more external circuitry.

Figure 9

shows the iC-DX with the additional protective device

D1, D2 and D3.

Figure 9: Circuit schematic showing protective de-

vices

For over-voltage protection, the suppressor diodes

D1,D2 and D3 absorbs transients on supply line in-

jected externally on the cable. Clamp voltage of the

diodes should be rated slightly above maximum speci-

fied supply voltage.

These currents can be passed to ground or to VB

by the internal ESD diodes of the iC-DX. Whereas

negative current injection will simply be drained off to

ground, positive current injection will charge capacitor

C1 further to higher voltages. If not suppressor diodes

nor any other over-voltage protection is implemented,

the backup capacitor C1 should be kept small. A typi-

cal 100nF value is normally OK.

Suggested protective devices

voltage from 36V has to be chosen in order to minimize

the energie in iC-DX for higer Voltages. For example

Diode type like Vishay GSOT36C or PJSD36W from

Pan Jit should be enouch as protection.