preliminary

preliminary

iC-DX3

UNIVERSAL DIGITAL SENSOR OUTPUT DRIVER

Rev A1, Page 9/11

TIMING DESCRIPTION

The iC-DX3 has a built-in spurious pulse suppression

that prevents short (undesired) pulses at the input pins

from reaching the output. Every pulse at OE or IN

pins shorter than 1.6 µs (cf. Electrical Characteristics

No. 306) will be ignored and the output will not re-

act. The minimum required pulse length to be sure

that the output reacts is 4 µs (cf. Electrical Characteris-

tics No. 307). That means that every pulse longer than

4 µs will be propagated to the output but with an addi-

tional propagation delay of 1.2 µs maximum. The re-

sulting maximum propagation delay is 5.2 µs (cf. Elec-

trical Characteristics No. 305).

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-DX3

36V

Low Side Switch

+

-

OUT

3.3V

IN

GND

VB

GND

VOUT

OE

..30V

VB

Figure 8: Block diagram with EN and NEP internal

signals

CIRCUIT PROTECTION

The iC-DX3 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-DX3 with the additional protective device

D1, D2 and D3.

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-DX3. 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 sufficient.

Suggested protective devices

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

the energie in iC-DX3 for higher voltages. For example

diode type like Vishay GSOT36C or PJSD36W from

Pan Jit should be enouch as protection.