MAX9921

This device supplies and monitors the current drawn by two Hall-effect sensors, filters the sensed current level, and outputs the corresponding logic level. The MAX9921 includes input diagnostics and fault protection. These features allow the device to determine fault conditions such as open inputs, inputs shorted to the battery, and inputs shorted to ground. If the MAX9921 detects any of these conditions at either IN1 or IN2, the device shuts off the current to the corresponding input. The MAX9921 provides an 80s blanking time following Hall sensor power-up or restart. The open-drain logic outputs are compatible with logic levels up to 5.5V. The MAX9921 is available in a small 10-pin MAX package and is specified over the -40°C to +125°C automotive temperature range. The MAX9921 provides a single chip solution to interface two 2-wire Hall-effect sensors to a low-voltage microprocessor (P). The MAX9921 protects the Hall sensors from supply transients up to 60V at the BAT supply. Normal operating supply voltage ranges from 6V to 18V. If the battery voltage is out of range, the MAX9921 shuts off the current to the Hall sensors.

The features of MAX9921 can be summarized as (1)withstands 60V at BAT supply and hall inputs; (2)6V to 18V operating voltage range; (3)provides supply current and interfaces to two 2-wire hall sensors; (4)error output with diagnostics of hall inputs and BAT voltage; (5)protects hall sensors from overvoltage by isolating them from supply transients; (6)hall inputs protected from short to ground; (7)ramps current to hall sensors at 4mA/s; (8)output enable input allows multiplexing of outputs from multiple MAX9921s; (9)hall output filtering; (10)hall sensor blanking following hall sensor power-up or restart; (11)low-power shutdown, controlled with OE and DIAG inputs; (12)operates with ±2V ground shifts between hall sensor and MAX9921.

The absolute maximum ratings of MAX9921 are (1)BAT to GND: -0.3V to +60V; (2)ISET to BAT: -2.0V to +0.3V; (3)IN1, IN2 to GND: -5.0V to the lower of +60V or (VBAT + 1V); (4)DIAG, OE to GND: -0.3V to +6.0V; (5)OUT1, OUT2, ERR to GND: -0.3V to +6.0V; (6)short-circuit duration of OUT1, OUT2, ERR to GND or to 5.5V (individually): continuous; (7)current into any pin except IN1, IN2: ±20mA; (8)current into IN1, IN2: ±100mA; (9)continuous power dissipation (TA = +70°C) 10-Pin MAX (derate 5.6mW/°C above +70°C): 444.4mW; (10)operating temperature range: -40°C to +125°C; (11)junction temperature: +150°C; (12)storage temperature range: -65°C to +150°C; (13)lead temperature (soldering, 10s): +300°C.