MAX9924_09 Datasheet, PDF (1/23 Pages) Maxim Integrated Products – Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold

19-4283; Rev 2; 3/09
Variable Reluctance Sensor Interfaces with
Differential Input and Adaptive Peak Threshold
General Description
The MAX9924–MAX9927 variable reluctance (VR or mag-
netic coil) sensor interface devices are ideal for position
and speed sensing for automotive crankshafts,
camshafts, transmission shafts, etc. These devices inte-
grate 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 ter-
minals of the internal operational amplifier available,
allowing greater flexibility for gain. The MAX9926 also
provides a direction output that is useful for quadrature-
connected VR sensors that are used in certain high-per-
formance 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 temper-
ature 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
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX9924UAUB+
-40°C to +125°C 10 µMAX
MAX9925AUB+
-40°C to +125°C 10 µMAX
MAX9926UAEE+
-40°C to +125°C 16 QSOP
MAX9927AEE+
-40°C to +125°C 16 QSOP
+Denotes a lead(Pb)-free/RoHS-compliant package.
Selector Guide
PART
MAX9924UAUB
MAX9925AUB
MAX9926UAEE
MAX9927AEE
AMPLIFIER
1 x Differential
1 x Operational
2 x Differential
2 x Operational
GAIN
1V/V
Externally Set
1V/V
Externally Set
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Simplified Block Diagram
ENGINE BLOCK
VR SENSOR
MAX9924
DIFFERENTIAL
AMPLIFIER
μC
ADAPTIVE/MINIMUM
AND
ZERO-CROSSING
THRESHOLDS
INTERNAL/EXTERNAL
BIAS VOLTAGE
________________________________________________________________ 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.