2

4964B–AUTO–07/07

ATA6842

1.

Description

The ATA6842 is a monolithically-integrated multi-functional IC designed in Atmel

state-of-the-art 0.8 µm BCDMOS technology. With its built-in driver stages, voltage supplies and

monitoring functions, it is an ideal cost saving failsafe system IC.

The communication with an external microcontroller is provided by an 8-bit SPI interface.

Four protected and current limited driver stages are available to control relays and additionally

there is a gate driver including charge pump and bootstrap to control an external FET.

Three LEDs for status information can be controlled via three separate outputs: The high-side

driver at pin OUTP has monitoring functions for overcurrent and current threshold. The low-side

drivers at the pins WLN and OUTN also have monitoring functions for overcurrent, current

threshold, and voltage monitoring.

Two internal bandgap references control and monitor two independent 5V supply voltages. In

standby mode the internal IC-supply is provided by one of them; the other one is switched off, in

order to reduce the power consumption to a minimum. All internal blocks are supplied by a spe-

cific internal voltage regulator.

The system supply voltage and all internally-generated voltages are monitored and in case of

over or undervoltage all drivers are switched off. Via the SPI the system supply voltage can be

switched to provide power for external components.

The car battery voltage (KL 30) is monitored by an adjustable monitoring function.

An oscillator with an external RC circuitry and a fully-integrated auxiliary oscillator which can be

set via the pin RREF are the clock references for the watchdog and all other time constants.

Both oscillators monitor each other.

The independent watchdog circuitry monitors the microcontroller’s correct operation.

Two differential amplifiers support the use of external A/D converters for current measurement.

Two comparators are provided to monitor the 5V supply of external devices like sensors.

The ATA6842 is the improved version and successor of the ATA6814. Pin and function compat-

ible to it, the ATA6842 is the replacement in all applications. The ATA6842 offers a flawless

performance in reference to the requests of some automotive customers regarding very slow

supply voltage ramps ups and downs.