19-4119; Rev 1; 1/10
Dual, 2-Wire Hall-Effect Sensor Interface
The MAX9921 provides a single chip solution to interface
two 2-wire Hall-effect sensors to a low-voltage micro-
processor (µP). This device supplies and monitors the cur-
rent drawn by two Hall-effect sensors, filters the sensed
current level, and outputs the corresponding logic level.
The MAX9921 includes input diagnostics and fault pro-
tection. These features allow the device to determine fault
conditions such as open inputs, inputs shorted to the bat-
tery, 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 protects the Hall sensors from supply tran-
sients up to 60V at the BAT supply. Normal operating
supply voltage ranges from 6V to 18V. If the battery volt-
age is out of range, the MAX9921 shuts off the current to
the Hall sensors.
The MAX9921 provides an 80µs 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 µMAX®
package and is specified over the -40°C to +125°C
automotive temperature range.
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o Withstands 60V at BAT Supply and Hall Inputs
o 6V to 18V Operating Voltage Range
o Provides Supply Current and Interfaces to Two
2-Wire Hall Sensors
o Error Output with Diagnostics of Hall Inputs and
o Protects Hall Sensors from Overvoltage by
Isolating Them from Supply Transients
o Hall Inputs Protected from Short to Ground
o Ramps Current to Hall Sensors at 4mA/µs
o Output Enable Input Allows Multiplexing of
Outputs from Multiple MAX9921s
o Hall Output Filtering
o Hall Sensor Blanking Following Hall Sensor
Power-Up or Restart
o Low-Power Shutdown, Controlled with OE and
o Operates with ±2V Ground Shifts Between Hall
Sensor and MAX9921
-40°C to +125°C 10 µMAX
MAX9921AUB/V+T -40°C to +125°C 10 µMAX
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
/V denotes an automotive qualified part.
Pin Configuration appears at end of data sheet.
Typical Application Circuit
VBAT: 6V TO 18V OPERATING,
RISET = 63.4kΩ, 1%
3.3V TO 5V
µMAX is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.