MAXIM MAX9924, MAX9927 Technical data

General Description

The MAX9924–MAX9927 variable reluctance (VR or mag­netic coil) sensor interface devices are ideal for position
and speed sensing for automotive crankshafts,
camshafts, transmission shafts, etc. These devices inte­grate a precision amplifier and comparator with selectable
adaptive peak threshold and zero-crossing circuit blocks
that generate robust output pulses even in the presence
of substantial system noise or extremely weak VR signals.

The MAX9926/MAX9927 are dual versions of the
MAX9924/MAX9925, respectively. The MAX9924/
MAX9926 combine matched resistors with a CMOS input
precision operational amplifier to give high CMRR over a
wide range of input frequencies and temperatures. The
MAX9924/MAX9926 differential amplifiers provide a fixed
gain of 1V/V. The MAX9925/MAX9927 make all three ter­minals of the internal operational amplifier available,
allowing greater flexibility for gain. The MAX9926 also
provides a direction output that is useful for quadrature­connected VR sensors that are used in certain high-per­formance engines. These devices interface with both
new-generation differential VR sensors as well as legacy
single-ended VR sensors.

The MAX9924/MAX9925 are available in the 10-pin
µMAX®package, while the MAX9926/MAX9927 are
available in the 16-pin QSOP package. All devices are
specified over the -40°C to +125°C automotive temper­ature range.

Applications

Camshaft VRS Interfaces

Crankshaft VRS Interfaces

Vehicle Speed VRS Interfaces

Features

o Differential Input Stage Provides Enhanced Noise

Immunity

o Precision Amplifier and Comparator Allows

Small-Signal Detection

o User-Enabled Internal Adaptive Peak Threshold or

Flexible External Threshold

o Zero-Crossing Detection Provides Accurate

Phase Information

MAX9924–MAX9927

Variable Reluctance Sensor Interfaces with

Differential Input and Adaptive Peak Threshold

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

19-4283; Rev 4; 3/12

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.

/V denotes an automotive qualified part.

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

Simplified Block Diagram

PART TEMP RANGE PIN-PACKAGE

MAX9924UAUB+

MAX9924UAUB/V+

MAX9925AUB+

MAX9926UAEE+

MAX9926UAEE/V+

MAX9927

MAX9927AEE/V+ -40°C to +125°C 16 QSOP

+

AEE+ -40°C to +125°C 16 QSOP

-40°C to +125°C

-40°C to +125°C

-40°C to +125°C

-40°C to +125°C

-40°C to +125°C

10 µMAX

10 µMAX

10 µMAX

16 QSOP

16 QSOP

ENGINE BLOCK

MAX9924

VR SENSOR

DIFFERENTIAL
AMPLIFIER

ADAPTIVE/MINIMUM

AND

ZERO-CROSSING

THRESHOLDS

INTERNAL/EXTERNAL

BIAS VOLTAGE

μC

MAX9924–MAX9927

Variable Reluctance Sensor Interfaces with
Differential Input and Adaptive Peak Threshold

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= 5V, V

GND

= 0V, MAX9925/MAX9927 gain setting = 1V/V, Mode A1, V

BIAS

= 2.5V, V

PULLUP

= 5V, R

PULLUP

= 1kΩ, C

COUT

=

50pF. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)

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.

VCCto GND.............................................................-0.3V to + 6V

All Other Pins..............................................-0.3V to (V

CC

+ 0.3V)

Current into IN+, IN-, IN_+, IN_-.......................................±40mA

Current into All Other Pins ................................................±20mA

Output Short-Circuit (OUT_, OUT) to GND.............................10s

Continuous Power Dissipation (T

A

= +70°C) (Note 1)

10-Pin µMAX (derate 8.8mW/°C above +70°C) ........707.3mW

16-Pin QSOP (derate 9.6mW/°C above +70°C)........771.5mW

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

Soldering Temperature (reflow) .......................................+260°C

Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer

board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial

.

µMAX

Junction-to-Ambient Thermal Resistance (θ

JA

) ......113.1°C/W

Junction-to-Case Thermal Resistance (θ

JC

) ................42°C/W

QSOP

Junction-to-Ambient Thermal Resistance (θ

JA

) ......103.7°C/W

Junction-to-Case Thermal Resistance (θ

JC

) ................37°C/W

PACKAGE THERMAL CHARACTERISTICS (Note 1)

POWER SUPPLY

Operating Supply Range V

Supply Current I

Power-On Time P

INPUT OPERATIONAL AMPLIFIER (MAX9925/MAX9927)

Input Voltage Range IN+, IN- Guaranteed by CMRR 0 V

Input Offset Voltage V

Input Bias Current I

Input Offset Current I

Common-Mode Rejection Ratio CMRR From VCM = 0 to V

Power-Supply Rejection Ratio PSRR

Output Voltage Low V

Output Voltage High V

Recovery Time from Saturation t

Gain-Bandwidth Product GBW 1.4 MHz

Slew Rate SR 2.3 V/µs

Charge-Pump Frequency f

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CC

CC

ON

OS-OA

BIAS

OFFSET

OL

OH

SAT

CP

(Note 3) 4.5 5.5 V

MAX9924/MAX9925 2.6 5

MAX9926/MAX9927 4.7 10

VCC > V
~ 1µs

Temperature drift 5 µV/° C

(Note 4) 0.1 6 nA

(Note 4) 0.05 2 nA

MAX9925 88 105

MAX9927 77 94

IOL = 1mA 0.050 V

IOH = -1mA

To 1% of the actual V
saturates

= 4.1V, step time for V

UVLO

CC

after output

OUT

CC

75 102 dB

V

CC

0.050

30 150 µs

0.5 3 mV

-

1.2 µs

1.3 MHz

CC

mA

V

dB

V

MAX9924–MAX9927

Variable Reluctance Sensor Interfaces with

Differential Input and Adaptive Peak Threshold

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= 5V, V

GND

= 0V, MAX9925/MAX9927 gain setting = 1V/V, Mode A1, V

BIAS

= 2.5V, V

PULLUP

= 5V, R

PULLUP

= 1kΩ, C

COUT

=

50pF. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)

INPUT DIFFERENTIAL AMPLIFIER (MAX9924/MAX9926)

Input Voltage Range IN+, IN- Guaranteed by CMRR -0.3

Differential Amplifier
Common-Mode Rejection Ratio

Input Resistance R

ADAPTIVE PEAK DETECTION

Zero-Crossing Threshold V

Fixed and Adaptive Peak
Threshold

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CMRR

IN

ZERO_THRESH

V

ADAPTIVE

V

MIN-THRESH

MAX9924 (Note 5) 60 87

MAX9926 (Note 5) 55 78

(Note 5) 65 100 135 kΩ

Mode B
operation
(Notes 5, 6) MAX9926/MAX9927 -6.5 0 +10

Adaptive peak threshold 33 %PK

Minimum threshold of hysteresis
comparator MAX9924/MAX9926
(Notes 5, 6)

Minimum threshold of hysteresis
comparator MAX9925/MAX9927
(Notes 5, 6)

V

MIN-THRESH

MAX9924 (Notes 5, 6)

V

MIN-THRESH

MAX9926 (Notes 5, 6)

V

MIN-THRESH

MAX9925/MAX9927 (Notes 5, 6)

MAX9924/MAX9925 -6.5 0 +6.5

- V

ZERO-THRESH

- V

ZERO-THRESH

- V

ZERO-THRESH

for

for

for

41530

20 30 50

71526

21530

19 30 50

V

+

CC

0.3

V

dB

mV

mV

Watchdog Timeout for Adaptive
Peak Threshold

ENTIRE SYSTEM

Comparator Output Low Voltage V

Propagation Delay

COUT Transition Time t

Propagation Delay Jitter t

t

WD

COUT_OL

t

PDZ

t

PDA

HL-LH

PD-JITTER

Timing window to reset the adaptive
peak threshold if not triggered (input
level below threshold)

Overdrive = 2V to 3V, zero-crossing

Overdrive = 2V to 3V, adaptive peak

Includes noise of differential amplifier
and comparator, f = 10kHz,
V

IN

= 1V

sine wave

P-P

45 85 140 ms

0.2 V

50

150

2ns

20 ns

ns

MAX9924–MAX9927

Variable Reluctance Sensor Interfaces with
Differential Input and Adaptive Peak Threshold

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VCC= 5V, V

GND

= 0V, MAX9925/MAX9927 gain setting = 1V/V, Mode A1, V

BIAS

= 2.5V, V

PULLUP

= 5V, R

PULLUP

= 1kΩ, C

COUT

=

50pF. T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)

Note 2: Specifications are 100% tested at T

A

= +125°C, unless otherwise noted. All temperature limits are guaranteed by design.

Note 3: Inferred from functional PSRR.
Note 4: CMOS inputs.
Note 5: Guaranteed by design.
Note 6: Includes effect of V

OS

of internal op amp and comparator.

EXT

EXT Voltage Range V

Input Current to EXT I

DIRN (MAX9926 Only)

Output Low Voltage 0.2 V

INT_THRS, ZERO_EN

Low Input V

High Input V

Input Leakage I

Input Current ZERO_EN I

Switching Time Between Modes
A1, A2, and Modes B, C

BIAS

Input Current to BIAS I

BIAS Voltage Range V

Internal BIAS Reference Voltage V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Mode B, TA = +125°C 1.5

EXT

Mode C, TA = +125°C 0.14

EXT

IL

IH

LEAK

SINK

t

SW

BIAS

BIAS

INT_BIAS

Mode B, V

Pullup resistor = 10kΩ,
V

ZERO_EN

With INT_THRS = GND, auto peak­detect is disabled, and EXT_THRS is
active

Modes A1, A2, B, C 1 µA

Modes A1, B, TA = +125°C 1.5

Mode C, TA = +125°C 0.2

Mode A2 (MAX9924/MAX9926) 2.46 V

EXT

= V

> V

GND

BIAS

; and Mode C 10 µA

0.7 x
V

CC

V

CC

- 1.1

V

CC

- 1.1

0.3 x
V

CC

1µA

500 800 µA

3µs

V

CC

- 1.1

V

CC

- 1.1

V

V

V

V

MAX9924–MAX9927

Variable Reluctance Sensor Interfaces with

Differential Input and Adaptive Peak Threshold

_______________________________________________________________________________________ 5

Typical Operating Characteristics

(VCC= 5V, V

GND

= 0V, MAX9925/MAX9927 gain setting = 1V/V. All values are at TA= +25°C, unless otherwise noted.)

INPUT OFFSET VOLTAGE DISTRIBUTION

20

VCM = 0
BIN SIZE = 250

15

10

PERCENTAGE OF UNITS (%)

5

0

-2000

-1500

-1000

0

500

1000

-500

INPUT OFFSET VOLTAGE (μV)

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

0

V

= 100mV

RIPPLE

-10

V

BIAS

-20

INPUTS COUPLED TO GND

-30

-40

-50

-60

PSSR (dB)

-70

-80

-90

-100

-110

-120
1 100k

= V

OUT

P-P

= 2.5V

FREQUENCY (Hz)

INPUT OFFSET VOLTAGE

vs. TEMPERATURE

0.6

0.5

0.4

0.3

0.2

INPUT OFFSET VOLTAGE (mV)

0.1

VCM = 2.5V

0

-50 25 50-25 0 75 100 125

TEMPERATURE (°C)

1500

V
MAX9925

VCM = 0

2000

10k1k10010

OUT

2500

= 2.5V

3000

vs. INPUT COMMON-MODE VOLTAGE

0.5

MAX9924 toc01

0.4

0.3

0.2

INPUT OFFSET VOLTAGE (mV)

0.1

0

-0.5 1.50.5 2.5 3.5 4.5 5.5

125

MAX9924 toc04

100

75

GAIN (dB)

50

25

0

0.001 10

900

MAX9924 toc07

800

700

600

500

400

300

200

ADAPTIVE THRESHOLD LEVEL (mV)

100

0

02.5

INPUT OFFSET VOLTAGE

V

= 2.5V

OUT

MAX9925

INPUT COMMON-MODE VOLTAGE (V)

OPEN LOOP FREQUENCY

RESPONSE

VCC = 5V

= 2.5V

V

BIAS

= 2V

V

OUT

P-P

MAX9925

0.1

FREQUENCY (kHz)

ADAPTIVE THRESHOLD AND RATIO

vs. SIGNAL LEVEL

fIN = 1kHz
MAX9924

1.5 2.01.00.5

SIGNAL LEVEL (VP)

MAX9924 toc02

MAX9924 toc05

MAX9924 toc08

COMMON-MODE REJECTION RATIO

120

100

80

60

CMRR (dB)

40

V

20

V
CMRR = 20log(ADM/ACM)

0

1100k

40

35

30

25

(mV)

OH

20

AND V

15

OL

V

10

5

0

-50 125

400

350

300

250

200

150

THRESHOLD (mV)

100

50

0

-50 125

vs. FREQUENCY

= V

= 2.5V

BIAS

OUT

= 2V

CM

P-P

10k1k10010

FREQUENCY (Hz)

VOL AND VOH vs. TEMPERATURE

VCC - V

OH

VOL

50 75 100250-25

TEMPERATURE (°C)

ADAPTIVE THRESHOLD

vs. TEMPERATURE

VIN = 2V

fIN = 1kHz
MAX9924

25 50 75 1000-25

TEMPERATURE (°C)

MAX9924 toc03

MAX9924 toc06

MAX9924 toc09

P-P

MAX9924–MAX9927

Variable Reluctance Sensor Interfaces with
Differential Input and Adaptive Peak Threshold

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC= 5V, V

GND

= 0V, MAX9925/MAX9927 gain setting = 1V/V. All values are at TA= +25°C, unless otherwise noted.)

-5

5

0

15

10

25

20

30

-50 0 25-25 50 75 100 125

MINIMUM AND ZERO-CROSSING

THRESHOLD vs. TEMPERATURE

MAX9924 toc10

TEMPERATURE (°C)

THRESHOLD (mV)

VCM = 2.5V
f

IN

= 5Hz

ZERO CROSSING
AT 5Hz

MINIMUM THRESHOLD

ZERO CROSSING
AT 1Hz

0

25

50

75

100

CMRR vs. TEMPERATURE

MAX9924 toc11

TEMPERATURE (°C)

CMRR (dB)

-50 25 50-25 0 75 100 125

MAX9924
V

CM

= 0 TO 5V

INPUT SIGNAL vs. COUT WITH

WATCHDOG TIMER EXPIRED

MAX9924 toc12

20ms/div

V

BIAS

5V

fIN = 5Hz

COUT

INPUT SIGNAL

INPUT SIGNAL vs. COUT WITH

WATCHDOG TIMER EXPIRED

MAX9924 toc13

100μs/div

V

BIAS

5V

fIN = 1kHz

COUT

INPUT SIGNAL

833mV

MAX9924 toc14

100μs/div

OVERDRIVEN INPUT VOLTAGES

(MAX9924)

MAX9924 toc15

200μs/div

DIRN OPERATION

(MAX9924)

INPUT REFERRED NOISE DENSITY

vs. FREQUENCY

100

80

60

40

INPUT VOLTAGE NOISE (nV/ Hz)

20

10

10 1k100 10k 100k 1M

FREQUENCY (Hz)

MAX9924 toc16

MAX9924–MAX9927

Variable Reluctance Sensor Interfaces with

Differential Input and Adaptive Peak Threshold

_______________________________________________________________________________________ 7

Pin Description

PIN

MAX9924 MAX9925 MAX9926 MAX9927

1 1 — — IN+ Noninverting Input

2 2 — — IN- Inverting Input

— 3 — — OUT Amplifier Output

3 — — — N.C. No Connection. Not internally connected.

4 4 — — BIAS

5 5 11 11 GND Ground

6 6 13 — ZERO_EN

7 7 — — COUT

8 8 — — EXT

9 9 — — INT_THRS Internal Adaptive Threshold. Mode configuration pin.

10 10 14 14 V

— — 1 1 INT_THRS1 Internal Adaptive Threshold 1. Mode configuration pin.

— — 2 2 EXT1

— — 3 3 BIAS1

— — 4 4 COUT1

— — 5 5 COUT2

— — 6 6 BIAS2

— — 7 7 EXT2

— — 8 8 INT_THRS2 Internal Adaptive Threshold 2. Mode configuration pin.

— — 9 9 IN2+ Noninverting Input 2

— — 10 10 IN2- Inverting Input 2

— — 12 — DIRN

— — — 12 OUT2 Amplifier Output 2

— — — 13 OUT1 Amplifier Output 1

— — 15 15 IN1- Noninverting Input 1

— — 16 16 IN1+ Inverting Input 1

NAME FUNCTION

Input Bias. Connect to an external resistor-divider and bypass
to ground with a 0.1µF and 10µF capacitor.

Zero-Crossing Enable. Mode configuration pin, internally

with 10kΩ resistor.

CC

PULLUP

.

PULLUP

PULLUP

PULLUP

CC

pulled up to V

Comparator Output. Open-drain output, connect a 10kΩ pullup
resistor from COUT to V

External Reference Input. Leave EXT unconnected in Modes
A1, A2. Apply an external voltage in Modes B, C.

Power Supply

External Reference Input 1. Leave EXT unconnected in Modes
A1, A2. Apply an external voltage in Modes B, C.

Input Bias 1. Connect to an external resistor-divider and
bypass to ground with a 0.1µF and 10µF capacitor.

Comparator Output 1. Open-drain output, connect a 10kΩ
pullup resistor from COUT1 to V

Comparator Output 2. Open-drain output, connect a 10kΩ
pullup resistor from COUT2 to V

Input Bias 2. Connect to an external resistor-divider and
bypass to ground with a 0.1µF and 10µF capacitor.

External Reference Input 2. Leave EXT unconnected in Modes
A1, A2. Apply an external voltage in Modes B, C.

Rotational Direction Output. Open-drain output, connect a
pullup resistor from DIRN to V

.

.

.