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19-5024; Rev 0; 11/09
TION KIT EVALUA BLE AILA AV
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
General Description
The MAX9621 is a continuation of the Maxim family of Hall-effect sensor interfaces that already includes the MAX9921. The MAX9621 provides a single-chip solution to interface two 2-wire Hall-effect sensors to low-voltage microprocessors (FP) through either a digital output for Hall-effect switches or an analog output for linear information or both. The MAX9621 protects the Hall sensors from supply transients up to 60V at the BAT supply. Normal operating supply voltage ranges from 5.5V to 18V. If the BAT supply rises above 18V, the MAX9621 shuts off the current to the Hall sensors. When a short-to-ground fault condition is detected, the current to the Hall input is shut off and the condition is indicated at the analog output by a zerocurrent level and a high digital output. The MAX9621 provides a minimum of 50Fs blanking time following Hall sensor power-up or restart. The opendrain digital outputs are compatible with logic levels up to 5.5V. The MAX9621 is available in a 3mm x 5mm, 10-pin FMAXM package and is rated for operation in the -40NC to +125NC temperature range. 2-Wire Hall-Effect Sensors
S 5.5V to 18V Operating Voltage Range S Protects Hall Sensors Against Up to 60V Supply
Features
S Provides Supply Current and Interfaces to Two
MAX9621
Transients
S Low-Power Shutdown for Power Saving S Filtered Digital Outputs S Analog Output Mirrors the Hall Sensor Current S Hall Inputs Protected from Short to Ground S Hall Sensor Blanking Following Power-Up and
Restart from Shutdown and Short to Ground
S Operates with 3V Ground Shift Between the Hall
Sensor and the MAX9621
S 2kV Human Body Model ESD and 200V Machine
Model ESD at All Pins
S 3mm x 5mm, 10-Pin MAX Package
Ordering Information
PART MAX9621AUB+T TEMP RANGE -40NC to +125NC PIN-PACKAGE 10 FMAX
Applications
Window Lifters Seat Movers Electric Sunroofs Seatbelt Buckles Door Power Locks Ignition Key Steering Column Speed Sensing
+Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel.
Functional Diagram
BAT REF BAT SLEEP-MODE CONTROL 10kI SLEEP
ISET
REFERENCE
AOUT1 DOUT1 IN1 REF FILTER
BAT INPUT SHORT DETECTION
MAX9621
AOUT2 DOUT2
Typical Application Circuit appears at end of data sheet.
IN2 REF FILTER
MAX is a registered trademark of Maxim Integrated Products, Inc.
GND
_______________________________________________________________ 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.
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621
ABSOLUTE MAXIMUM RATINGS
BAT to GND...........................................................-0.3V to +60V ISET to BAT ..........................................................-2.0V to +0.3V IN1, IN2 to GND ................ -3V to lower of +60V or (VBAT + 1V) AOUT1, DOUT1, AOUT2, DOUT2, SLEEP to GND .....................................................-0.3V to +6V Short-Circuit Duration AOUT1, DOUT1, AOUT2, DOUT2 to GND or to 5.5V (individually) .......................................Continuous Current In to IN1, IN2 .................................................... 100mA Current In to Any Other Pin ............................................. 20mA Continuous Power Dissipation for a Single-Layer Board (TA = +70NC) 10-Pin MAX (derate 5.6mW/NC) above +70NC........444.4mW Continuous Power Dissipation for a Multilayer Board (TA = +70NC) 10-Pin MAX (derate 8.8mW/NC) above +70NC........707.3mW Operating Temperature Range ........................ -40NC to +125NC Junction Temperature .....................................................+150NC Storage Temperature Range............................ -65NC to +160NC Lead Temperature (soldering, 10s) ................................+300NC
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.
DC ELECTRICAL CHARACTERISTICS
(VBAT = 13.6V, VSLEEP = 5V, IN1 = IN2 = no connection, RSET = 61.9kI to BAT, RPU = 10kI at DOUT1 and DOUT2, RL = 5kI to GND at AOUT1 and AOUT2, unless otherwise noted, TA = -40NC to +125NC. Typical values are at TA = +25NC.) (Note 1) PARAMETER GENERAL BAT Supply Range BAT Supply Current VBAT IBAT ISD Guaranteed by functional test of IIH, IIL, and GEI Normal mode VSLEEP = 0V VBAT = 5.5V, at IN1 and IN2, IIN = -14mA VBAT = 5.5V, at IN1 and IN2, IIN = -20mA Machine Model Human Body Model RSET = 95.3kI RSET = 52.3kI RSET = 95.3kI RSET = 52.3kI Peak-to-peak as percent of average high/ low threshold (Note 2) High threshold Low threshold ISC A short to GND is not a sustained condition, Hall input reverts to -50FA when detected (Note 2) -20 -5 -9 8 0.02 0.02 1 0.59 0.86 200 2000 -7.7 -14 5.5 18 1 10 1.26 V 1.86 V V mA FA SYMBOL CONDITIONS MIN TYP MAX UNITS
Hall Input Voltage Dropout
VDO
ESD Protection
INPUT THRESHOLDS FOR DOUT1, DOUT2 SWITCHING Input Current for Output High (Note 2) Input Current for Output Low (Note 2) Input Current Hysteresis for High/Low Detection Channel-to-Channel Input Threshold Variation Short-Circuit Current Limit AOUT1, AOUT2 ANALOG OUTPUTS Current Gain for AOUT1 and AOUT2 Outputs Current Gain Error for AOUT1 and AOUT2 Outputs 2 GI GEI -18mA P IIN P -2mA IIN = -5mA, -14mA 0.05 0.2 1.7 mA/mA % IIH IIL IIN_HYS mA mA % mA
mA
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
DC ELECTRICAL CHARACTERISTICS (continued)
(VBAT = 13.6V, VSLEEP = 5V, IN1 = IN2 = no connection, RSET = 61.9kI to BAT, RPU = 10kI at DOUT1 and DOUT2, RL = 5kI to GND at AOUT1 and AOUT2, unless otherwise noted, TA = -40NC to +125NC. Typical values are at TA = +25NC.) (Note 1) PARAMETER Input Referred Current Offset AOUT_ Dropout Voltage AOUT_ Output Impedance LOGIC I/O (DOUT1, DOUT2) Output-Voltage Low DOUT1, DOUT2 Three-State Output Current DOUT1, DOUT2 SLEEP Input-Voltage High Input-Voltage Low Input Resistance to GND AC TIMING CHARACTERISTICS Shutdown Delay from SLEEP Low to IN_ Shutoff IN_, Blanking Time at Hall Sensor Power-Up IN_, Current Ramp Rate After Turn-On Delay from IN_ to DOUT_ (Filter Delay) Delay Difference Between Rising and Falling Edges of Both Channels Delay Difference Between Channels Maximum Frequency on Hall Inputs Maximum Analog Output Current During Short-to-GND Fault IN_ Pulse Length Rejected by Filter to DOUT_ tSHDN tBL tRAMP tDEL IIH = -14mA to GND, time from SLEEP low to IN_ drop 500mV, CL = 20pF IIH = -14mA to GND, time from VIN_ = 500mV until DOUT_ high, CL = 20pF (Notes 2, 3) IN_ = GND (Note 2) From IIH to IIL or from IIL to IIH, CL = 20pF, Figure 1 (Note 2) CHALL-BYPASS = 0.01FF, IIH = -11.5mA and IIL = -7.5mA, CL = 20pF CHALL-BYPASS = 0.01FF, IIH = -11.5mA and IIL = -7.5mA, CL = 20pF CHALL-BYPASS = 0.01FF, IIH = -11.5mA and IIL = -7.5mA, CL = 20pF (Note 2) 34 33 40 46 Fs VOL IOZ Sink current = 1mA VSLEEP = 0V, 0V P VDOUT_ P 5V 2.0 0.8 50 100 0.4 1 V FA SYMBOL IOS CONDITIONS Inferred from measurements at IIN = -5mA, -14mA VBAT = 5.5V, for 5% current reduction IIN = -14mA IIN = -20mA MIN -120 0.85 1.09 500 TYP MAX +120 1.6 1.75 MI UNITS FA V
MAX9621
VIH VIL RIN
V V kI
76
89
103
Fs
3.6 10.8
5 13.5
6.7 16
mA/Fs Fs
tDM
1
Fs
tCC fMAX IMAO PR
500 39 -1.4
ns kHz mA 14.6
Figure 2 (Note 2)
7.8
11.5
Fs
Note 1: All DC specifications are 100% production tested at TA = +25C. AC specifications are guaranteed by design at TA = +25C. Note 2: Parameters that change with the value of the RSET resistor: IIH, IIL, IIN_HYS, ISC, tBL, tRAMP, tDEL, fMAX, and PR. Note 3: Following power-up or startup from sleep mode, the start of the blanking period is delayed 20Fs.
3
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621
Timing Diagrams
APPROXIMATELY 100mA HALL SENSOR OPEN 14mA IN1 7mA 0mA HALL SENSOR OPEN AOUT1 0.7mA 0.35mA 0mA DOUT1 5V 0V tDEL tDEL APPROXIMATELY 1.4mA RESTART 5mA/s SHORT CIRCUIT APPROXIMATELY 100mA 5mA/s
Figure 1. Timing Diagram
PR 14mA IN_ 7mA 0mA
PR
tDEL DOUT_ 5V 0V
tDEL
Figure 2. Hall Input Pulse Rejection
4
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
Typical Operating Characteristics
(VBAT = 13.6V, RSET = 61.9kI, RL = 5kI to GND at AOUT_, VSLEEP = 5V, TA = +25NC, unless otherwise noted.)
BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE
MAX9621 toc01
MAX9621
BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE
MAX9621 toc02
BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE
TA = +125NC
MAX9621 toc03
0.9 0.8 BAT CURRENT (mA) 0.7 0.6 0.5 0.4 19.0
TA = -40NC
0.9 0.8 BAT CURRENT (mA) 0.7 0.6 0.5 0.4
TA = +25NC
0.9 0.8 BAT CURRENT (mA) 0.7 0.6 0.5 0.4
19.5
20.0 BAT VOLTAGE (V)
20.5
21.0
19.0
19.5
20.0 BAT VOLTAGE (V)
20.5
21.0
19.0
19.5
20.0 BAT VOLTAGE (V)
20.5
21.0
BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE
MAX9621 toc04
BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE
MAX9621 toc05
BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE
TA = +125NC
MAX9621 toc06
1.0
TA = -40NC
1.0
TA = +25NC
1.0
0.8
BAT CURRENT (mA) BAT CURRENT (mA)
0.8
BAT CURRENT (mA)
0.8
0.6
0.6
0.6
0.4
0.4
0.4
0.2 0 10 20 30 40 50 60 BAT VOLTAGE (V)
0.2 0 10 20 30 40 50 60 BAT VOLTAGE (V)
0.2 0 10 20 30 40 50 60 BAT VOLTAGE (V)
BAT SUPPLY CURRENT vs. VBAT IN SHUTDOWN MODE
MAX9621 toc07
HALL INPUT CURRENT THRESHOLDS FOR HIGH/LOW vs. TEMPERATURE
MAX9621 toc08
180 160 BAT CURRENT (nA) 140 120 100 80 60 40 20 0 0
TA = +125C
10.2 HALL INPUT CURRENT (mA) 10.0 9.8 9.6 9.4 9.2 9.0 HIGH TO LOW LOW TO HIGH
10.25 HALL INPUT CURRENT (mA) 10.00 9.75 9.50 9.25 9.00 8.75 8.50 5.5 8.0 10.5 13.0 15.5 HIGH TO LOW LOW TO HIGH
TA = +25C AND -40C
20
40 60 BAT VOLTAGE (V)
80
8.8 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
18.0
BAT VOLTAGE (V)
MAX9621 toc09
200
HALL INPUT CURRENT THRESHOLDS vs. VBAT
10.50
10.4
5
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621
Typical Operating Characteristics (continued)
(VBAT = 13.6V, RSET = 61.9kI, RL = 5kI to GND at AOUT_, VSLEEP = 5V, TA = +25NC, unless otherwise noted.)
INPUT BLANKING TIME AT RESTART FROM SLEEP MODE (OR POWER-UP) vs. TEMPERATURE
MAX9621 toc10 MAX9621 toc11
HALL INPUT CURRENT THRESHOLDS vs. ISET RESISTOR
16 14 HALL INPUT CURRENT (mA) 12 10 8 HIGH TO LOW 6 4 50 60 70 80 90 100 RESISTANCE (kI) LOW TO HIGH 100 95 IN_ BLANKING TIME (s) 90 85 80 75 70 65 60
IN-CURRENT RAMP RATE AFTER TURN-ON vs. TEMPERATURE
9 CURRENT RATE (mA/us) 8 7 6 5 4 3
MAX9621 toc12
10
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
2 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
DELAY FROM IN_ TO DOUT_ (FILTER DELAY) vs. TEMPERATURE
MAX9621 toc13
DELAY DIFFERENCE BETWEEN CHANNELS vs. TEMPERATURE
MAX9621 toc14
MAXIMUM FREQUENCY ON HALL INPUTS vs. TEMPERATURE
MAX9621 toc15
20
900 700 DELAY DIFFERENCE (ns) 500 300 100
60 50 FREQUENCY (kHz) 40 30 20 10 -50 -25 0 25 50 75 100 IN2
15 DELAY (s)
IN1
10
5
0 -50 -25 0 25 50 75 100 125 TEMPERATURE (NC)
-100 -50 -25 0 25 50 75 100 125 TEMPERATURE (NC)
125
TEMPERATURE (NC)
IN_ PULSE LENGTH REJECTED BY FILTER TO DOUT_ vs. TEMPERATURE
MAX9621 toc16
INPUT DROPOUT VOLTAGE vs. TEMPERATURE
MAX9621 toc17
INPUT DROPOUT VOLTAGE vs. VBAT
1.05 INPUT DROPOUT VOLTAGE (V) 0.95 0.85 0.75 0.65 0.55 0.45 0.35 0.25 TA = -40C TA = +25C IIN1 = -14mA TA = +125C
MAX9621 toc18
20 18 16 PULSE LENGTH (s) 14 12 10 8 6 4 2 0 -50 -25 0 25 50 75 100 POSITIVE PULSE NEGATIVE PULSE
1.15 1.05 DROPOUT VOLTAGE (V) 0.95 0.85 0.75 0.65 0.55 0.45 0.35 0.25 VBAT = 5.5V IIN1 = -14mA
1.15
125
-45 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
5.50
8.00
10.50
13.00
15.50
18.00
TEMPERATURE (NC)
VBAT (V)
6
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
Typical Operating Characteristics (continued)
(VBAT = 13.6V, RSET = 61.9kI, RL = 5kI to GND at AOUT_, VSLEEP = 5V, TA = +25NC, unless otherwise noted.)
MAX9621
CURRENT GAIN vs. SUPPLY VOLTAGE
MAX9621 toc19
CURRENT GAIN vs. TEMPERATURE
MAX9621 toc20
0.07
0.07
CURRENT GAIN (mA/mA)
0.05
CURRENT GAIN (mA/mA)
0.06
0.06
0.05
0.04
0.04
0.03
5.50
8.00
10.50
13.00
15.50
18.00
0.03 -50 -25 0 25 50 75 100 125 TEMPERATURE (NC)
SUPPLY VOLTAGE (V)
RESPONSE TO SHORT TO GROUND
MAX9621 toc21
REENERGIZING OF THE HALL INPUT FROM OPEN-CIRCUIT CONDITION
MAX9621 toc22
VIN1 VAOUT1 VIN1 VDOUT1 IIN1
IIN1
VAOUT1 400ns/div 100s/div
STARTUP OF IN_/AOUT_ FROM SHUTDOWN
MAX9621 toc23
STARTUP OF IN_/DOUT_ FROM SHUTDOWN
MAX9621 toc24
VSLEEP VIN1
VSLEEP VIN1
IIN1 VAOUT1
IIN1
VDOUT1
10s/div
20s/div
7
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621
Pin Configuration
TOP VIEW +
BAT ISET IN1 IN2 GND
1 2 3 4 5
10 9 8 7 6
SLEEP AOUT1 DOUT1 AOUT2 DOUT2
MAX9621
MAX
Pin Description
PIN 1 NAME BAT FUNCTION Battery Power Supply. Connect to the positive supply through an external reverse-polarity diode. Bypassed to GND with a 0.1FF capacitor. Current Setting Input. Place a 1% resistor (RSET) between BAT and ISET to set the desired input current threshold range for the DOUT_ outputs. See the Typical Operating Characteristics section for the correct value of RSET for the desired range. Make no other connections to this pin. All routing must have low parasitic capacitance. See the Input Current Thresholds and Short to Ground section. Hall-Effect Sensor Input 1. Supplies current to the Hall sensor and monitors the current level drawn to determine the high/low state of the sensor. Bypass to GND with a 0.01FF capacitor. Connect an unused input to BAT pin. Hall-Effect Sensor Input 2. Supplies current to the Hall sensor and monitors the current level drawn to determine the high/low state of the sensor. Bypass to GND with a 0.01FF capacitor. Connect an unused input to BAT pin. Ground
2
ISET
3
IN1
4 5
IN2 GND
8
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
Pin Description (continued)
PIN 6 NAME DOUT2 FUNCTION Open-Drain Output. Signal translated from Hall sensor 2. DOUT2 is high when the current flowing out of IN2 exceeds the input current threshold high, and is low when less than the input current threshold low. See Table 1 for output response to operating conditions. Analog Current Output. Mirrors the current to the corresponding Hall sensor at IN2. When IN2 has been shut down due to a short to GND a current of zero is supplied to AOUT2. See Table 1 for output response to operating conditions. To obtain a voltage output, connect a resistor from AOUT_ to ground. Open-Drain Output. Signal translated from Hall sensor 1. DOUT1 is high when the current flowing out of IN1 exceeds the input current threshold high, and is low when less than the input current threshold low. See Table 1 for output response to operating conditions. Analog Current Output. Mirrors the current to the corresponding Hall sensor at IN1. When IN1 has been shut down due to a short to GND a current of zero is supplied to AOUT1. See Table 1 for output response to operating conditions. To obtain a voltage output, connect a resistor from AOUT_ to ground. Sleep Mode Input. The part is placed in sleep mode when the SLEEP input is low for more than 40Fs. If the SLEEP input is low for less than 20Fs and then goes high, the part restarts any Hall input that has been shut off due to a detected short to GND. Any Hall input that is operational is not affected when SLEEP is cycled low for less than 20Fs. There is an internal 100kI pulldown resistance to GND.
MAX9621
7
AOUT2
8
DOUT1
9
AOUT1
10
SLEEP
Detailed Description
The MAX9621, an interface between two 2-wire Halleffect sensors and a low-voltage microprocessor, supplies and monitors current through IN1 and IN2 to two Hall sensors. The MAX9621 complements Maxim's existing family of Hall-effect sensor interfaces that includes the MAX9921. The MAX9621 provides two independent channels with two outputs for each channel, a digital output, and an analog output. The digital outputs (DOUT1 and DOUT2) are open-drain and indicate a logic level that corresponds to the Hall sensor status. DOUT1 or DOUT2 outputs high when the current out of IN1 or IN2, respectively, exceeds the high-input current threshold. DOUT1 or DOUT2
outputs low when the current flowing out of IN1 or IN2, respectively, is lower than the low-input current threshold. DOUT1 and DOUT2 provide a time domain output filter for robust noise immunity. See Figure 2. The analog outputs (AOUT1 and AOUT2) mirror the current flowing out to the corresponding inputs IN1 and IN2 with a nominal gain of 0.05mA/mA.
The MAX9621 protects the hall sensors from supply transients by shutting off current at IN1 and IN2 when the BAT voltage is 18V. The digital outputs go low and analog outputs have zero output current. When VBAT returns to the proper operating range, both inputs restart following a blanking cycle.
Hall Sensor Protection from Supply Transients
9
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621
Table 1. AOUT_/DOUT_ Truth Table
CONDITION IN_ Short to GND IN_ Short to BAT or IN_ Open SLEEP Low VBAT > 18V AOUT_ 0 0 0 0 DOUT_ High-Z Low* High-Z Low*
tripping into a short-to-ground latched state. During the short-to-ground fault, DOUT1 and DOUT2 are high impedance (pulled high by the pullup resistors), while AOUT1 and AOUT2 are set to zero-output current.
*If IN_ is already shorted to BAT or open during power-up, DOUT_ goes to high-Z until IN_ is loaded.
The MAX9621 interprets a short to battery when the voltage at IN1 or IN2 is higher than VBAT - 100mV. The digital outputs go low and the analog outputs are set to zero output current. If IN1 or IN2 is more than 1V above VBAT, it back-drives current into BAT. The MAX9621 restarts the Hall inputs when the Hall input is loaded again. The Hall input short-to-ground fault is effectively a latched condition if the input remains loaded by the Hall switch. The current required to power the Hall switch is shut off and only a 50A pullup current remains. The Hall input can be manually reenergized or it can be reenergized by the P. A 10s to 20s negative pulse at SLEEP restarts with a blanking cycle any Hall input that has been shut down due to the short-to-ground condition. During startup or restart, it is possible for a Hall input to charge up an external capacitance of 0.02F without
Hall Input Short-to-Battery Condition
Figure 3 shows the behavior of the MAX9621 when a Hall input is open. Figure 4 shows the behavior of the MAX9621 when the open input is reconnected to a Hall sensor. Figures 3 and 4 demonstrate how a short-toground Hall input can be reset. Resetting a short-toground Hall input involves three steps: 1) Relieve the short to ground at the Hall sensor. 2) Disconnect the Hall input from the Hall sensor (openinput fault condition). 3) Reconnect the Hall input to the Hall sensor. The MAX9621 restarts the Hall input with a blanking cycle. If the Hall input is disconnected from the Hall sensor for 10ms, it allows the Hall input to be pulled up by the 50FA pullup current to register the open-input fault condition. Reconnecting the Hall input to the Hall sensor restarts the Hall input with a blanking cycle. This provides a manual means of reenergizing a Hall input without having to resort to the FP to restart it. This also demonstrates the behavior of an intermittent connection to a Hall sensor.
Manual Method for Reenergizing Hall Sensor and Means for Diagnosing an Intermittent Hall Sensor Connection
Hall Input Short to Ground
14V HALL INPUT SHORT-TOGROUND FAULT 0V HALL INPUT DISCONNECTED FROM SENSOR 50A IIN_ 0A TIME VBAT - 25mV 5mV/ms HALL INPUT OPEN-CIRCUIT FAULT TIME
VIN_
Figure 3. Hall Input Ramps to Open-Circuit Fault When a Short to Ground Is Relieved
10
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621
VBAT - 25mV 14V VIN_ 8V VBAT - 500mV
0V 11.5mA IIN_ 0A 5mA/s
TIME
HALL INPUT RECONNECTED TO HALL SENSOR TIME
Figure 4. Hall Input Reenergized When Open Input Is Reconnected to Hall Sensor
The MAX9621 features an active-low SLEEP input. Pull SLEEP low for more than 40Fs to put the device into sleep mode for power saving. In sleep mode, the DOUT1 and DOUT2 outputs are high impedance and are pulled high by pullup resistors. AOUT1 and AOUT2 are set to zero-output current. Hall Input Restart When an input has been shut down due to a short to ground, cycle SLEEP for 10Fs to 20Fs to restart the input. If the other input is operational it is not affected. The restart happens on the rising edge of SLEEP.
Sleep Mode Input (SLEEP)
I = I0 +
1 (I < 0) Rxm
I is the mean of the threshold current limits, R is the value of the RSET resistance in k, the constant I0 = 0.03717mA, and the constant m = -0.001668 (1/(k x mA)). The following equation is useful for finding the value of RSET resistance given a mean of the threshold current limits:
Y = Y0 + m x I (I < 0) R= 1 Y
The input current high and low thresholds that determine the logic level of the digital outputs are adjusted by changing the RSET value. When the RSET value changes, the following parameters change as well: IIN_HYS, ISC, tBL, tRAMP, tDEL, fMAX, and PR. IIH, IIL, IIN_HYS, ISC, tRAMP, and fMAX are inversely proportional to RSET and decrease as RSET increases. This inverse relationship is linear. For example, a 10% change in (1/RSET) results in a 10% change in current parameters. Conversely, time and delay parameters are linear and directly proportional to RSET, and a 10% change in RSET results in an 10% change in time parameters. The difference between the maximum and minimum threshold current limits is the min/max limit spread, which is greater than the threshold hysteresis. The min/max spread and the hysteresis both change by the same percentage as the mean of the threshold current limits. The following equation is useful for finding the mean of the threshold current limits given a value of RSET resistance:
Input Current Thresholds and Short to Ground
Y0 = 6.2013 x 10-5 units of (1/k) To compute the typical input current thresholds from the mean input current, it is necessary to obtain the hysteresis. The following equation finds the hysteresis given the mean threshold current, I: H = H0 + k x I (I < 0) where H0 = -0.033463 in mA, and k = -0.08414 in mA/mA. Input current threshold high = I - H/2, input current threshold low = I + H/2.
Application Information
The digital output can be used to provide the FP with an interrupt signal that can represent a Hall sensor change of status. DOUT1 and DOUT2 provide a time domain output filter for robust noise immunity. See Figure 2. The analog output can be connected to an ADC with an appropriate load resistor, and can be used to perform custom diagnostics.
11
Use of Digital and Analog Outputs
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621
R
MAX9621
X
VCC
IN_
Figure 5. 3-Wire Hall-Effect Switches Configured as 2-Wire
Table 2. A Partial List of Compatible Hall Switches
PART NO. HAL573-6 HAL556/560/566 HAL579/581/584 A1140/1/2/3 A3161 TLE4941/C MANUFACTURER Micronas Micronas Micronas Allegro Allegro Infineon WEBSITE www.micronas.com www.micronas.com www.micronas.com www.allegromicro.com www.allegromicro.com www.infineon.com COMMENTS 2-wire 2-wire 2-wire 2-wire 3-wire, optimized for 2-wire use without added resistor 2-wire
Sleep mode can be used in applications that do not continuously require the polling of the Hall sensors. In such cases, the FP can enable the MAX9621 for a short time, check the sensor status, and then put the MAX9621 back to sleep. A blanking period follows upon exiting sleep mode. The MAX9621 targets applications with 2-wire Hall-effect sensors. 2-wire sensors have connections for supply and ground. The output level is signaled by means of modulation of the current drawn by the Hall sensor from its supply. The two threshold currents for high/low are generally in the range of 5mA to 14mA. Thus, the interfacing of a 2-wire sensor is not simply a matter of detecting two voltage thresholds, but requires a coarse current-sense function. Because of the high-side current-sense structure of the MAX9621, the device is immune to shifts between the
Sleep Mode
sensor ground, the ground of the MAX9621 and FP. This ground-shift immunity eliminates the need for a groundconnection wire, allowing a single-wire interface to the Hall sensor. The MAX9621 is optimized for use with 2-wire Hall-effect switches or with 3-wire Hall-effect switches connected as 2-wire (Figure 5). When using a 3-wire Hall sensor the resistor R is chosen so that the current drawn by the Hall sensor crosses the MAX9621 current threshold when the magnetic threshold of the Hall sensor is exceeded. A partial list of Hall switches that can be used with the MAX9621 is given in Table 2. To get the best input current threshold precision, it is recommended that the RSET resistor be directly connected to the BAT pin. A true Kelvin type connection is best.
Hall-Effect Sensor Selection
Remote Ground
Input Current Threshold Precision
12
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
Typical Application Circuit
BATTERY: 5.5V TO 18V OPERATING, 60V WITHSTAND 0.1F
MAX9621
1.8V TO 5.5V RPU 10kI RPU 10kI
RSET
ISET REFERENCE REF
BAT
BAT
SLEEP-MODE CONTROL
SLEEP 100kI
AOUT1 5kI ADC
DOUT1
ECUCONNECTOR FILTER
IN1 0.01F
REF
N S
MICROPROCESSOR
BAT
REMOTE GROUND
INPUT SHORT DETECTION
MAX9621
AOUT2 5kI IN2
N S
ADC
0.01F
REF FILTER
DOUT2
REMOTE GROUND
GND
Chip Information
PROCESS: BiCMOS
13
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621
Package Information
For the latest package outline information and land patterns, 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.
PACKAGE TYPE 10 FMAX PACKAGE CODE U10+2 DOCUMENT NO. 21-0061
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
14
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Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
10LUMAX.EPS

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