iC-VRV

BIDIRECTIONAL µP INTERFACE TO 24V

Rev A2, Page 2/12

DESCRIPTION

iC-VRV is an 8-fold low-side driver with integrated control logic which is divided internally into two mutually

independent blocks (nibbles).

In the input mode, ports IO0 to IO7 can be used to record logical levels. In this process, a programmable

pull-down current (200 µA or 2 mA) sets a defined level and functions as the biasing current for switching

contacts. The stages programmed as outputs can drive any desired loads (e. g. lamps, long cables, relays)

at a continuous current of 100 mA or 500 mA in pulse operation. The free-wheeling currents created upon

each stage turn-off are discharged through the integrated free-wheeling diodes to a voltage applied externally

to the COM pin; a circuit with a Zener diode is also possible.

In the event of a short circuit, a protective circuit breaker ensures that the output stage affected does not just

simply switch off but is instead clocked as a function of the load. As a result, the current assumes a low

average value. The output stage is ready for operation immediately just as soon as the cause of the short

circuit has been eliminated.

The shutdown at overtemperature protects the IC against thermal destruction by causing the output stages

to turn off and the pull-down currents to be reduced from 2 mA to 200 µA. This shutdown is also triggered in

case of undervoltage at VCC.

Due to the microprocessor interface the iC-VRV can be operated directly on a bus system. The interface

consists of the data bits D0 to D7 and the associated control signals A0, A1, CSN, WRN and RDN. The signal

CLK clocks the implemented digital input filter and BLFQ clocks the programmed flashing function. In the

event of a signal change of the I/O pins programmed as inputs, an interrupt signal can be generated at output

INTN.

Activating the input RESN resets the initial condition.

Chip programming is conducted via four addresses at A0 and A1. During this programming, presettings for

flashing frequencies, filtering times, interrupt control, pull-down currents and input/output mode, etc. are stored

in two registers (CONTROL WORD1+2).

All inputs and outputs are protected with diodes against destruction due to ESD.