Maxim MAX9921, MAX9921AUB+T Datasheet

General Description

The MAX9921 provides a single chip solution to interface two 2-wire Hall-effect sensors to a low-voltage microprocessor (µP). 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 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 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

♦ Withstands 60V at BAT Supply and Hall Inputs

♦ 6V to 18V Operating Voltage Range

♦ Provides Supply Current and Interfaces to Two

2-Wire Hall Sensors

♦ Error Output with Diagnostics of Hall Inputs and

BAT Voltage

♦ Protects Hall Sensors from Overvoltage by

Isolating them from Supply Transients

♦ Hall Inputs Protected from Short to Ground

♦ Ramps Current to Hall Sensors at 4mA/µs

♦ Output Enable Input Allows Multiplexing of

Outputs from Multiple MAX9921s

♦ Hall Output Filtering

♦ Hall Sensor Blanking Following Hall Sensor

Power-Up and Restart

♦ Low-Power Shutdown, Controlled with OE and

DIAG Inputs

♦ Operates with ±2V Ground Shifts Between Hall

Sensor and MAX9921

MAX9921

Dual, 2-Wire Hall-Effect Sensor Interface

with Diagnostics

________________________________________________________________

Maxim Integrated Products

Ordering Information

REMOTE

GROUND

ISET

BATTERY

ERR

DIAG

OUT1

OUT2

BAT

ISET

= 63.4kΩ, 1%

BAT

: 6V TO 18V OPERATING,

WITHSTANDS 60V

3.3V TO 5V

IN1

0.1μF

10kΩ

IN2

REF

GENERATION,

DIAGNOSTICS

AND

OVERVOLTAGE

DETECT

REMOTE

GROUND

0.01μF

CONTROL

FILTER

μP/LOGIC

CIRCUIT

GND

0.01μF

GND

MAX9921

E C U

C O N N E C T O R

Typical Application Circuit

19-4119; Rev 0; 6/08

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-free package.

T = Tape and reel.

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

Pin Configuration appears at end of data sheet.

Door Modules

Window Lifters

Seat Movers

Electric Sunroofs

Powered Lift Gate Controllers

Powered Running Boards

Seatbelt Buckles

PART TEMP RANGE PIN-PACKAGE

MAX9921AUB+T -40°C to +125°C 10 µMAX

MAX9921

Dual, 2-Wire Hall-Effect Sensor Interface with Diagnostics

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

BAT

= 13.6V, V

DIAG

= 0V, VOE= 5V, IN1 = IN2 = no connection, R

ISET

= 63.4kΩ, RPU= 10kΩ at ERR, OUT1 and OUT2, TA= -40°C

to +125°C, unless otherwise noted. Typical values are at T

= +25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

BAT to GND............................................................-0.3V to +60V

ISET to BAT ...........................................................-2.0V to +0.3V

IN1, IN2 to GND..........-5.0V to the lower of +60V or (V

BAT

+ 1V)

DIAG, OE to GND..................................................-0.3V to +6.0V

OUT1, OUT2, ERR to GND....................................-0.3V to +6.0V

Short-Circuit Duration of OUT1, OUT2, ERR to GND

or to 5.5V (individually)............................................Continuous

Current into Any Pin Except IN1, IN2 ...............................±20mA

Current into IN1, IN2.......................................................±100mA

Continuous Power Dissipation (T

= +70°C)

10-Pin µMAX (derate 5.6mW/°C above +70°C) .........444.4mW

Operating Temperature Range .........................-40°C to +125°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

GENERAL

BAT Supply Range V

Low for ERR Output Active V

BAT

High for ERR Output Active V

BAT

BAT Supply Current

HALL INPUTS (IN1 and IN2)

Input Current for Output High I

Input Current for Output Low I

Input Current Hysteresis for High/Low Detection

Input Pullup Impedance R

Input Voltage Interpreted as Shorted to Battery

Current Range Interpreted as Open Circuit

Current Level Interpreted as Shorted Sensor to Ground

BAT

IN,HYS

Normal mode 1 1.3 mA

Shutdown mode, VOE = V

BAT

= -14mA

Measured with respect to V

Not a sustained condition, reverts to -50µA when detected

= 6V, inputs IN1, IN2 with

= 0V 1 µA

DIAG

BAT

618V

5.2 V

22 V

-11.5 mA

-7.2 mA

0.76 mA

50 Ω

100 mV

-2 +0.02 mA

-23 mA

MAX9921

Dual, 2-Wire Hall-Effect Sensor Interface

with Diagnostics

_______________________________________________________________________________________ 3

Note 1: All DC specifications are 100% tested at TA= +25°C. AC specifications and specifications over -40°C to +125°C are guar-

anteed by design.

Note 2: C

is external load capacitance on the outputs for test only.

Note 3: These blanking times apply when the MAX9921 is operating in normal mode. Blanking times following power-up or startup

from shutdown mode are 20µs longer.

AC TIMING CHARACTERISTICS

BAT

= 13.6V, V

DIAG

= 0V, VOE= 5V, IN1 = IN2 = no connection, R

ISET

= 63.4kΩ, R

= 10kΩ at ERR, OUT1 and OUT2, TA= -40°C

to +125°C, unless otherwise noted. Typical values are at T

= +25°C.) (Notes 1 and 2)

DC ELECTRICAL CHARACTERISTICS (continued)

BAT

= 13.6V, V

DIAG

= 0V, VOE= 5V, IN1 = IN2 = no connection, R

ISET

= 63.4kΩ, RPU= 10kΩ at ERR, OUT1 and OUT2, TA= -40°C

to +125°C, unless otherwise noted. Typical values are at T

= +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LOGIC I/O (OUT1, OUT2, ERR, DIAG, and OE)

Output Voltage Low (ERR, OUT1, OUT2)

Three-State Output Current (ERR, OUT1, OUT2)

Input-Voltage High (DIAG, OE) V

Input-Voltage Low (DIAG, OE) V

Input Resistance to GND (DIAG, OE)

Sink current = 1mA 0.4 V

VOE = 0V, 0 ≤ V

≤ 5V ±1 µA

OUT_

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IN1, IN2 Blanking Time at Hall Switch Power-Up

IN1, IN2 Current Ramp Rate After Turn-On

Delay from IN_ to OUT_ (Filter Delay)

Delay from IN_ Fault to ERR t

Delay from DIAG High to OUT_ and ERR

Delay from DIAG Low to OUT_ and ERR

Delay Difference Between Rising and Falling Edges for Both Channels

RAMP

DEL

ERR

DLH

DHL

IIH = -11.5mA to GND, time from V 500mV until OUT_ high, C

VIN = GND 3.8 mA/µs

From IIH to IIL or from IIL to IIH, CL = 20pF, Figure 1

From IIL to ISC or from IIH to I only, C

Rising edge of DIAG to falling or rising edge of outputs, C

Falling edge of DIAG to falling or rising edge of outputs, C

HALL-BYPASS

= -7.2mA, CL = 20pF

= 20pF, Figure 1

= 0.01µF, IIH = -11.5mA and

IN_

= 20pF (Note 3)

falling edge

OC,

2.1 V

0.8 V

50 80 kΩ

50 140 µs

6.5 µs

31 ns

350 ns

1.6 µs

20 ns

Delay Difference Between Channels

Maximum Frequency on Hall Inputs

IN_ Pulse Length Rejected by Filter to OUT_

MAX

HALL-BYPASS

= -7.2mA, CL = 20pF

HALL-BYPASS

= -7.2mA, CL = 20pF

= 0.01µF, IIH = -11.5mA and

100 ns

50 kHz

Figure 2 5.5 µs

MAX9921

Dual, 2-Wire Hall-Effect Sensor Interface with Diagnostics

4 _______________________________________________________________________________________

Timing Diagrams

Figure 1. Timing Diagram

APPROX. 50 mA

SHORT CIRCUIT

14mA

IN 1

7mA

RETRY

4mA/μs

0mA

OUT1

OUT2

ERR

DIAG

HALL SENSOR OPEN CIRCUIT

DEL

ERR

MAX9921

Dual, 2-Wire Hall-Effect Sensor Interface

with Diagnostics

_______________________________________________________________________________________ 5

Timing Diagrams (continued)

Figure 2. Hall Input Pulse Rejection

14mA

IN_

7mA

0mA

OUT_

DEL

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