General Description

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.

Applications

Features

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

BAT Voltage

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

DIAG Inputs

o Operates with ±2V Ground Shifts Between Hall

Sensor and MAX9921

Dual, 2-Wire Hall-Effect Sensor Interface

with Diagnostics

________________________________________________________________

Maxim Integrated Products

1

PART

TEMP RANGE

PIN-PACKAGE

MAX9921AUB+T

-40°C to +125°C

10 µMAX

MAX9921AUB/V+T

-40°C to +125°C

10 µMAX

Ordering Information

N

REMOTE

GROUND

ISET

BATTERY

OE

ERR

DIAG

OUT1

OUT2

BAT

RISET = 63.4k

Ω, 1%

VBAT: 6V TO 18V OPERATING,

WITHSTANDS 60V

3.3V TO 5V

IN1

0.1

μF

10k

Ω

IN2

REF

GENERATION,

DIAGNOSTICS

AND

OVERVOLTAGE

DETECT

S

N

REMOTE

GROUND

S

0.01

μF

CONTROL

FILTER

FILTER

μP/LOGIC

CIRCUIT

GND

VCC

0.01

μF

GND

MAX9921

E

C

U

C

O

N

N

E

C

T

O

R

Typical Application Circuit

19-4119; Rev 1; 1/10

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.

+

Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

/V denotes an automotive qualified part.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

Pin Configuration appears at end of data sheet.

EVALUATION

KIT

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