Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsLinear ICsMAX9926UAEE+T

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

MAX9924–MAX9927

Variable Reluctance Sensor Interfaces with

Differential Input and Adaptive Peak Threshold

________________________________________________________________

Maxim Integrated Products

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.

PART TEMP RANGE PIN-PACKAGE

MAX9924UAUB+

-40°C to +125°C

10 µMAX

MAX9924UAUB/V+

-40°C to +125°C

10 µMAX

MAX9925AUB+

-40°C to +125°C

10 µMAX

MAX9926UAEE+

-40°C to +125°C

16 QSOP

MAX9926UAEE/V+

-40°C to +125°C

16 QSOP

MAX9927

AEE+ -40°C to +125°C 16 QSOP

MAX9927AEE/V+ -40°C to +125°C 16 QSOP

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

μC

DIFFERENTIAL

AMPLIFIER

ADAPTIVE/MINIMUM

AND

ZERO-CROSSING

THRESHOLDS

INTERNAL/EXTERNAL

BIAS VOLTAGE

VR SENSOR

ENGINE BLOCK

MAX9924

Summary of content (23 pages)

PAGE 1
9-4283; Rev 4; 3/12 Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold 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.
PAGE 2
MAX9924–MAX9927 Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold ABSOLUTE MAXIMUM RATINGS VCC to GND .............................................................-0.3V to + 6V All Other Pins..............................................-0.3V to (VCC + 0.3V) Current into IN+, IN-, IN_+, IN_-.......................................±40mA Current into All Other Pins ................................................±20mA Output Short-Circuit (OUT_, OUT) to GND.............
PAGE 3
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold (VCC = 5V, VGND = 0V, MAX9925/MAX9927 gain setting = 1V/V, Mode A1, VBIAS = 2.5V, VPULLUP = 5V, RPULLUP = 1kΩ, CCOUT = 50pF. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS VCC + 0.
PAGE 4
MAX9924–MAX9927 Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold ELECTRICAL CHARACTERISTICS (continued) (VCC = 5V, VGND = 0V, MAX9925/MAX9927 gain setting = 1V/V, Mode A1, VBIAS = 2.5V, VPULLUP = 5V, RPULLUP = 1kΩ, CCOUT = 50pF. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS EXT EXT Voltage Range Input Current to EXT Mode B, TA = +125°C 1.5 VCC - 1.
PAGE 5
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold INPUT OFFSET VOLTAGE vs. INPUT COMMON-MODE VOLTAGE 10 5 120 0.4 100 80 0.3 CMRR (dB) 15 0.5 MAX9924 toc02 0.2 40 0.1 0 -0.5 3.5 4.5 0 5.5 1 100 100 -80 -90 10k 100k VOL AND VOH vs. TEMPERATURE MAX9924 toc06 VCC = 5V VBIAS = 2.
PAGE 6
Typical Operating Characteristics (continued) (VCC = 5V, VGND = 0V, MAX9925/MAX9927 gain setting = 1V/V. All values are at TA = +25°C, unless otherwise noted.) MINIMUM AND ZERO-CROSSING THRESHOLD vs. TEMPERATURE MINIMUM THRESHOLD MAX9924 toc11 25 MAX9924 toc12 100 MAX9924 toc10 VCM = 2.5V fIN = 5Hz INPUT SIGNAL vs. COUT WITH WATCHDOG TIMER EXPIRED CMRR vs.
PAGE 7
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold PIN NAME FUNCTION 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 Input Bias. Connect to an external resistor-divider and bypass to ground with a 0.1µF and 10µF capacitor.
PAGE 8
MAX9924–MAX9927 Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold Functional Diagrams 100kΩ VCC VCC 100kΩ IN- VCC MAX9924 GND OP AMP 100kΩ IN+ 100kΩ COMPARATOR 65ms WATCHDOG COUT INTERNAL REFERENCE 2.
PAGE 9
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold OUT VCC IN- VCC VCC MAX9925 GND OP AMP IN+ COMPARATOR BIAS 85ms WATCHDOG COUT BUFFER 30% VCC PEAK DETECTOR 10kΩ VMIN THRESHOLD MODE LOGIC ZERO_EN INT_THRS EXT _______________________________________________________________________________________ 9 MAX9924–MAX9927 Functional Diagrams (continued)
PAGE 10
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold MAX9924–MAX9927 Functional Diagrams (continued) 100kΩ VCC VCC 100kΩ IN1- VCC MAX9926 GND OP AMP 100kΩ IN1+ 100kΩ 85ms WATCHDOG COMPARATOR COUT1 INTERNAL REFERENCE 2.
PAGE 11
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold OUT1 VCC IN1- VCC VCC MAX9927 GND OP AMP IN1+ COMPARATOR BIAS1 85ms WATCHDOG COUT1 BUFFER 30% PEAK DETECTOR VMIN THRESHOLD EXT1 VCC IN2- VCC OUT1 OP AMP IN2+ COMPARATOR BIAS2 85ms WATCHDOG COUT2 BUFFER 30% MODE LOGIC PEAK DETECTOR INT_THRS1 INT_THRS2 VMIN THRESHOLD EXT2 ______________________________________________________________________________________ 11 MAX9924–MAX9927 Functional Diagra
PAGE 12
MAX9924–MAX9927 Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold Detailed Description ing the output of the input differential amplifier with a threshold voltage that is set depending on the mode that the device is in (see the Mode Selection section). The MAX9924–MAX9927 interface with variable reluctance (VR) or magnetic coil sensors.
PAGE 13
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold Adaptive Peak Threshold Modes A1 and A2 in the MAX9924–MAX9927 use an internal adaptive peak threshold voltage to trigger the output comparator. This adaptive peak threshold voltage scheme provides robust noise immunity to the input VR signal, preventing false triggers from occurring due to broken tooth or off-centered gear-tooth wheel. See Figure 1.
PAGE 14
MAX9924–MAX9927 Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold Zero Crossing The zero-crossing signal provides true timing information for engine-control applications. The zero-voltage level in the VR sensor signal corresponds to the center of the gear-tooth and is the most reliable marker for position/angle-sensing applications. Since the output of the differential amplifier is level-shifted to the BIAS voltage, the zero of the input VR signal is simply BIAS.
PAGE 15
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold VPULLUP 10kΩ IN+ RPULLUP VR SENSOR μC 1nF COUT 10kΩ TPU INBIAS 10μF || 0.1μF 1kΩ MAX9924 MAX9926 1kΩ EXT VCC +5V ZERO_EN INT_THRS GND Figure 2. MAX9924/MAX9926 Operating Mode A1 VPULLUP 10kΩ IN+ RPULLUP VR SENSOR μC 1nF COUT 10kΩ TPU INBIAS MAX9924 MAX9926 EXT +5V VCC ZERO_EN INT_THRS GND Figure 3.
PAGE 16
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold MAX9924–MAX9927 Application Circuits (continued) VPULLUP 10kΩ IN+ RPULLUP VR SENSOR μC 1nF TPU COUT 10kΩ INBIAS 1kΩ 10μF || 0.1μF 1kΩ +5V PWM MAX9924 MAX9926 EXT FILTER VCC ZERO_EN INT_THRS GND Figure 4. MAX9924/MAX9926 Operating Mode B VPULLUP 10kΩ IN+ RPULLUP VR SENSOR μC 1nF COUT 10kΩ TPU INBIAS 10μF || 0.1μF 1kΩ MAX9924 MAX9926 1kΩ +5V R2 EXT VCC INT_THRS ZERO_EN GND R1 Figure 5.
PAGE 17
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold 10kΩ INVR SENSOR VPULLUP OUT RPULLUP 1nF μC 10kΩ COUT IN+ TPU MAX9925 MAX9927 BIAS 1kΩ 10μF || 0.1μF EXT 1kΩ VCC +5V ZERO_EN INT_THRS GND Figure 6. MAX9925/MAX9927 Operating Mode A 10kΩ INVR SENSOR VPULLUP OUT RPULLUP 1nF μC 10kΩ COUT IN+ TPU PWM MAX9925 MAX9927 BIAS 10μF || 0.1μF 1kΩ EXT 1kΩ +5V FILTER VCC ZERO_EN INT_THRS GND Figure 7.
PAGE 18
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold MAX9924–MAX9927 Application Circuits (continued) 10kΩ INVR SENSOR VPULLUP OUT RPULLUP 1nF μC 10kΩ COUT IN+ MAX9925 TPU R2 BIAS 10μF || 0.1μF 1kΩ EXT 1kΩ +5V VCC INT_THRS ZERO_EN GND R1 Figure 8.
PAGE 19
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold 4.5V TO 5.5V VCC 100kΩ VCC 100kΩ INVCC MAX9924 VR SENSOR VPULLUP OP AMP IN+ 100kΩ μC RPULLUP 100kΩ COMPARATOR 85ms WATCHDOG COUT TPU BANDGAP REFERENCE VOLTAGE = 2 x VBG BUFFER 30% BIAS VCC PEAK DETECTOR 10kΩ VMIN THRESHOLD *THE MAX9924 IS CONFIGURED IN MODE A2.
PAGE 20
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold MAX9924–MAX9927 Pin Configurations TOP VIEW IN_THRS1 1 + 16 IN1+ IN_THRS1 1 + 16 IN1+ EXT1 2 15 IN1- EXT1 2 15 IN1- BIAS1 3 14 VCC BIAS1 3 14 VCC MAX9926 COUT1 4 MAX9927 13 ZERO_EN COUT1 4 COUT2 5 12 DIRN COUT2 5 12 OUT2 BIAS2 6 11 GND BIAS2 6 11 GND EXT2 7 10 IN2- EXT2 7 10 IN2- IN2+ INT_THRS2 8 9 INT_THRS2 8 13 OUT1 9 QSOP IN2+ QSOP TOP VIEW IN+ 1 IN- 2 N.C.
PAGE 21
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 10 µMAX U10+2 21-0061 90-0330 16 QSOP E16+1 21-0055 90-0167 10LUMAX.EPS PACKAGE TYPE α α ______________________________________________________________________________________ 21 MAX9924–MAX9927 Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages.
PAGE 22
MAX9924–MAX9927 Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
PAGE 23
Variable Reluctance Sensor Interfaces with Differential Input and Adaptive Peak Threshold REVISION NUMBER REVISION DATE 0 10/08 Initial release 1 2/09 Removed future product references for the MAX9926 and MAX9927, updated EC table DESCRIPTION PAGES CHANGED — 2 3/09 Corrected various errors 3 3/11 Updated Figures 6, 7, and 8 4 3/12 Added automotive qualifies parts 1–4 2, 3, 4, 6, 13 17, 18 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied