preliminary

preliminary

iC-DX

UNIVERSAL DIGITAL SENSOR OUTPUT DRIVER

Rev A3, Page 6/10

DESCRIPTION OF FUNCTIONS

iC-DX is a current limited switching channel which

enables digital sensors to drive peripheral elements.

They are designed to cope with high driver currents.

The switches are reverse-polarity protected, feature a

free-wheeling circuit for inductive loads, and a current

limited output.

Reverse polarity protection

The pins VB, OUT an GND on the line side of the chip

are reverse polarity protected. As far as the maximum

voltage ratings are not exceeded, no possible supply

combination at the line side pins can damage the chip.

Isc()lo

36V

A

B

V(OUT)

I(OUT)

3V

GND

C

VB

Figure 1: OUT characteristic when Low side active

B

C

VB-36V

36V

A

VB

GND

I(OUT)

Isc()hi

V(OUT)

Figure 2: OUT characteristic when high side active

Output characteristics of OUT

The switching channel is current limited to a value be-

tween 150mA and 450mA. (cf. Electrical Characteris-

tics Nos. 103, 104). The current limitation works only

for voltages higher than 3 V at OUT resp. lower than

VBO − 3 V. For smaller output voltages the current lim-

itation is reduced in order to minimise the saturation

voltages without increasing the power dissipation. Fig-

ures 1 and 2 show the characteristic of the switching

channels when activated. Region "A" is the saturation

range, where the current limitation is not fully active yet

and region "B" is the current limited range. Region "C"

corresponds to the free-wheeling circuit activated. The

switching channel is designed so that the low side can

only sink current and high side can only source current

(no reverse current).

Free-wheeling circuit for inductive loads

The free-wheeling circuit is always present and does

not depend on the current output status. It is acti-

vated by voltages higher than 36 V at OUT referenced

to GND or lower than -36 V at OUT referenced to VB.

In that case the correspondent channel will switch on

without current limitation (see Figure 3).

VB

VB-36V

36V

I(OUT)

36V

V(OUT)

GND

GND+36V

Figure 3: Free-wheeling characteristic