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iC-DXC3

DIGITAL SENSOR I/O DRIVER

Rev B2, Page 7/12

DESCRIPTION OF FUNCTIONS

iC-DXC3 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 Characteristics

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 limitation

is reduced in order to minimize the saturation voltages

without increasing the power dissipation. Figures 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" cor-

responds 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 activated

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