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MAX9621
Technical data
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MAXIM MAX9621 Technical data

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19-5024; Rev 1; 9/11
EVALUATION KIT
AVAILABLE
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.
Applications
Window Lifters
Seat Movers
Electric Sunroofs
Seatbelt Buckles
Door Power Locks
Ignition Key
Steering Column
Speed Sensing
Features
S Provides Supply Current and Interfaces to Two
2-Wire Hall-Effect Sensors
S 5.5V to 18V Operating Voltage Range S Protects Hall Sensors Against Up to 60V Supply
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 µMAX Package
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX9621AUB+T -40NC to +125NC 10 FMAX MAX9621AUB/V+ -40NC to +125NC 10 FMAX
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel. /V denotes an automotive qualified part.
Functional Diagram
BAT
ISET
REFERENCE
IN1
REF
BAT
SLEEP-MODE
CONTROL
REF
FILTER
10k
I
MAX9621
SLEEP
AOUT1 DOUT1
BAT
MAX9621
AOUT2 DOUT2
REF
FILTER
GND
Typical Application Circuit appears at end of data sheet.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
_______________________________________________________________ Maxim Integrated Products 1
INPUT
SHORT
DETECTION
IN2
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
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 (V
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
MAX9621
Current In to IN1, IN2 .................................................... ±100mA
Current In to Any Other Pin ............................................. ±20mA
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
+ 1V)
DC ELECTRICAL CHARACTERISTICS
(V
= 13.6V, V
BAT
GND at AOUT1 and AOUT2, unless otherwise noted, TA = -40NC to +125NC. Typical values are at TA = +25NC.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
GENERAL
BAT Supply Range V
BAT Supply Current
Hall Input Voltage Dropout V
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 I
AOUT1, AOUT2 ANALOG OUTPUTS
Current Gain for AOUT1 and AOUT2 Outputs
Current Gain Error for AOUT1 and AOUT2 Outputs
= 5V, IN1 = IN2 = no connection, R
SLEEP
BAT
I
BAT
I
SD
DO
I
IH
I
IL
I
IN_HYS
SC
G
I
G
EI
SET
Guaranteed by functional test of IIH, IIL, and G
EI
Normal mode 1 mA V
= 0V
SLEEP
V
= 5.5V, at IN1 and IN2,
BAT
IIN = -14mA
V
= 5.5V, at IN1 and IN2,
BAT
IIN = -20mA
Machine Model
Human Body Model
R
= 95.3kI
SET
R
= 52.3kI
SET
R
= 95.3kI
SET
R
= 52.3kI
SET
Peak-to-peak as percent of average high/ low threshold (Note 2)
High threshold 0.02 Low threshold 0.02
A short to GND is not a sustained condition, Hall input reverts to -50FA when detected (Note 2)
-18mA P IIN P -2mA
IIN = -5mA, -14mA 0.2
Continuous Power Dissipation for a Single-Layer Board (TA = +70NC)
10-Pin µMAX (derate 5.6mW/NC) above +70NC........ 444.4mW
Continuous Power Dissipation for a Multilayer Board (TA = +70NC)
10-Pin µMAX (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
Soldering Temperature (reflow) ......................................+260NC
= 61.9kI to BAT, RPU = 10kI at DOUT1 and DOUT2, RL = 5kI to
5.5 18 V
1 10
0.59 1.26
0.86 1.86
±200
±2000
-7.7
-14
-5
-9
8 %
-20 mA
0.05 mA/mA
±1.7
mA
mA
mA
FA
V
V
%
2
Dual, 2-Wire Hall-Effect Sensor Interface with
Analog and Digital Outputs
DC ELECTRICAL CHARACTERISTICS (continued)
(V
= 13.6V, V
BAT
GND at AOUT1 and AOUT2, unless otherwise noted, TA = -40NC to +125NC. Typical values are at TA = +25NC.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Referred Current Offset I
AOUT_ Dropout Voltage
AOUT_ Output Impedance 500
LOGIC I/O (DOUT1, DOUT2)
Output-Voltage Low DOUT1, DOUT2
Three-State Output Current DOUT1, DOUT2
SLEEP
Input-Voltage High V Input-Voltage Low V Input Resistance to GND R
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_
= 5V, IN1 = IN2 = no connection, R
SLEEP
OS
V
OL
I
OZ
IH
IL
IN
t
SHDN
t
BL
t
RAMP
t
DEL
t
DM
t
CC
f
MAX
I
MAO
P
R
= 61.9kI to BAT, RPU = 10kI at DOUT1 and DOUT2, RL = 5kI to
SET
Inferred from measurements at IIN = -5mA, -14mA
V
= 5.5V,
BAT
for 5% current reduction
Sink current = 1mA 0.4 V
V
= 0V, 0V P V
SLEEP
IIH = -14mA to GND, time from SLEEP low to IN_ drop 500mV, CL = 20pF
IIH = -14mA to GND, time from V
= 500mV until DOUT_ high, CL =
IN_
20pF (Notes 2, 3)
IN_ = GND (Note 2) 3.6 5 6.7
From IIH to IIL or from IIL to IIH, CL = 20pF, Figure 1 (Note 2)
C
HALL-BYPASS
and IIL = -7.5mA, CL = 20pF
C
HALL-BYPASS
and IIL = -7.5mA, CL = 20pF
C
HALL-BYPASS
and IIL = -7.5mA, CL = 20pF (Note 2)
Figure 2 (Note 2) 7.8 11.5 14.6
= 0.01FF, IIH = -11.5mA
= 0.01FF, IIH = -11.5mA
= 0.01FF, IIH = -11.5mA
IIN = -14mA 0.85 1.6
IIN = -20mA 1.09 1.75
P 5V
DOUT_
-120 +120
±1
2.0 V
0.8 V
50 100
33 40 46
76 89 103
10.8 13.5 16
1
500 ns
34 39 kHz
-1.4 mA
MAX9621
FA
V
MI
FA
kI
Fs
Fs
mA/Fs
Fs
Fs
Fs
Note 1: All DC specifications are 100% production tested at TA = +25°C. AC specifications are guaranteed by design at TA =
+25°C.
Note 2: Parameters that change with the value of the R Note 3: Following power-up or startup from sleep mode, the start of the blanking period is delayed 20Fs.
resistor: IIH, IIL, I
SET
IN_HYS
, ISC, tBL, t
RAMP
, t
, f
MAX
, and PR.
DEL
3
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
Timing Diagrams
APPROXIMATELY 100mA
MAX9621
Figure 1. Timing Diagram
IN1
AOUT1
DOUT1
14mA
7mA
0mA
0.7mA
0.35mA
0mA
HALL SENSOR
OPEN
HALL SENSOR OPEN
t
5V
0V
DEL
SHORT CIRCUIT APPROXIMATELY 100mA
5mA/µs
APPROXIMATELY 1.4mA
RESTART
5mA/µs
t
DEL
IN_
DOUT_
Figure 2. Hall Input Pulse Rejection
14mA
7mA
0mA
P
R
t
DEL
5V
0V
P
R
t
DEL
4
Dual, 2-Wire Hall-Effect Sensor Interface with
Analog and Digital Outputs
Typical Operating Characteristics
(V
= 13.6V, R
BAT
= 61.9kI, RL = 5kI to GND at AOUT_, V
SET
= 5V, TA = +25NC, unless otherwise noted.)
SLEEP
MAX9621
BAT SUPPLY CURRENT
vs. V
IN OPERATING MODE
0.9
0.8
0.7
0.6
BAT CURRENT (mA)
0.5
0.4
19.0 21.0
BAT
TA = -40NC
BAT VOLTAGE (V)
BAT SUPPLY CURRENT
vs. V
IN OPERATING MODE
1.0
0.8
0.6
BAT CURRENT (mA)
0.4
BAT
TA = -40NC
BAT SUPPLY CURRENT
vs. V
IN OPERATING MODE
0.9
MAX9621 toc01
0.8
0.7
0.6
BAT CURRENT (mA)
0.5
0.4
20.520.019.5
19.0 21.0
BAT
TA = +25NC
20.520.019.5
BAT VOLTAGE (V)
MAX9621 toc02
BAT CURRENT (mA)
0.9
0.8
0.7
0.6
0.5
0.4
19.0 21.0
BAT SUPPLY CURRENT
vs. V
IN OPERATING MODE
TA = +25NC
BAT
1.0
MAX9621 toc05
0.8
0.6
BAT CURRENT (mA)
0.4
1.0
MAX9621 toc04
0.8
0.6
BAT CURRENT (mA)
0.4
BAT SUPPLY CURRENT
vs. V
IN OPERATING MODE
BAT
TA = +125NC
BAT VOLTAGE (V)
BAT SUPPLY CURRENT
vs. V
IN OPERATING MODE
BAT
TA = +125NC
MAX9621 toc03
20.520.019.5
MAX9621 toc06
0.2 0 60
BAT VOLTAGE (V)
BAT SUPPLY CURRENT
vs. V
IN SHUTDOWN MODE
200
180
160
140
120
100
80
BAT CURRENT (nA)
60
40
20
0
0 80
BAT
TA = +125°C
= +25°C AND -40°C
T
A
BAT VOLTAGE (V)
5040302010
0.2 0 60
BAT VOLTAGE (V)
5040302010
HALL INPUT CURRENT THRESHOLDS
FOR HIGH/LOW vs. TEMPERATURE
10.4
10.2
MAX9621 toc07
10.0
9.8
9.6
9.4
HALL INPUT CURRENT (mA)
9.2
9.0
604020
8.8
LOW TO HIGH
HIGH TO LOW
-40 125 TEMPERATURE (°C)
11095-25 -10 5 35 50 6520 80
0.2 0 60
10.50
10.25
MAX9621 toc08
10.00
9.75
9.50
9.25
HALL INPUT CURRENT (mA)
9.00
8.75
8.50
5.5 18.0
BAT VOLTAGE (V)
HALL INPUT CURRENT
THRESHOLDS vs. V
LOW TO HIGH
HIGH TO LOW
BAT VOLTAGE (V)
5040302010
BAT
MAX9621 toc09
15.513.08.0 10.5
5
Dual, 2-Wire Hall-Effect Sensor Interface with
BAT
Analog and Digital Outputs
Typical Operating Characteristics (continued)
(V
= 13.6V, R
BAT
HALL INPUT CURRENT THRESHOLDS
16
MAX9621
14
12
10
8
HALL INPUT CURRENT (mA)
6
4
50 100
= 61.9kI, RL = 5kI to GND at AOUT_, V
SET
vs. ISET RESISTOR
100
95
MAX9621 toc10
90
LOW TO HIGH
HIGH TO LOW
90807060
RESISTANCE (kI)
85
80
75
IN_ BLANKING TIME (µs)
70
65
60
-40 125
= 5V, TA = +25NC, unless otherwise noted.)
SLEEP
INPUT BLANKING TIME AT RESTART FROM SLEEP MODE (OR POWER-UP)
vs. TEMPERATURE
11095-25 -10 5 35 50 6520 80
TEMPERATURE (°C)
10
MAX9621 toc11
9
8
7
6
5
CURRENT RATE (mA/us)
4
3
2
IN-CURRENT RAMP RATE AFTER
TURN-ON vs. TEMPERATURE
-40 125 TEMPERATURE (°C)
MAX9621 toc12
11095-25 -10 5 35 50 6520 80
DELAY FROM IN_ TO DOUT_ (FILTER DELAY)
vs. TEMPERATURE
20
15
10
DELAY (µs)
5
0
-50 125 TEMPERATURE (NC)
IN_ PULSE LENGTH REJECTED BY FILTER
TO DOUT_ vs. TEMPERATURE
20
18
16
14
12
10
8
PULSE LENGTH (µs)
6
4
2
0
NEGATIVE PULSE
POSITIVE PULSE
-50 125 TEMPERATURE (NC)
DELAY DIFFERENCE BETWEEN CHANNELS
vs. TEMPERATURE
900
MAX9621 toc13
700
500
300
DELAY DIFFERENCE (ns)
100
1007550250-25
-100
-50 125 TEMPERATURE (NC)
1007550250-25
MAX9621 toc14
FREQUENCY (kHz)
60
50
40
30
20
10
INPUT DROPOUT VOLTAGE
vs. TEMPERATURE
1.15 V
= 5.5V
BAT
1.05 I
= -14mA
MAX9621 toc16
1007525 500-25
IN1
0.95
0.85
0.75
0.65
0.55
DROPOUT VOLTAGE (V)
0.45
0.35
0.25
-45 125 TEMPERATURE (°C)
1109565 80-10 5 20 35 50-25
1.15
1.05
MAX9621 toc17
0.95
0.85
0.75
0.65
0.55
INPUT DROPOUT VOLTAGE (V)
0.45
0.35
0.25
MAXIMUM FREQUENCY ON
HALL INPUTS vs. TEMPERATURE
IN1
IN2
-50 125 TEMPERATURE (NC)
1007550250-25
INPUT DROPOUT VOLTAGE
vs. V
BAT
I
= -14mA
IN1
TA = +125°C
TA = +25°C
TA = -40°C
5.50 8.00 10.50 13.00 15.50
V
(V)
18.00
MAX9621 toc15
MAX9621 toc18
6
Dual, 2-Wire Hall-Effect Sensor Interface with
Analog and Digital Outputs
Typical Operating Characteristics (continued)
(V
= 13.6V, R
BAT
= 61.9kI, RL = 5kI to GND at AOUT_, V
SET
= 5V, TA = +25NC, unless otherwise noted.)
SLEEP
MAX9621
CURRENT GAIN vs. SUPPLY VOLTAGE
0.07
0.06
0.05
CURRENT GAIN (mA/mA)
0.04
0.03
5.50
8.00
10.50
SUPPLY VOLTAGE (V)
RESPONSE TO SHORT TO GROUND
13.00
15.50
MAX9621 toc21
18.00
MAX9621 toc19
V
IN1
I
IN1
CURRENT GAIN vs. TEMPERATURE
0.07
0.06
0.05
CURRENT GAIN (mA/mA)
0.04
0.03
-50 125 TEMPERATURE (NC)
REENERGIZING OF THE HALL INPUT
FROM OPEN-CIRCUIT CONDITION
1007550250-25
MAX9621 toc22
MAX9621 toc20
V
IN1
V
AOUT1
V
DOUT1
I
IN1
400ns/div
STARTUP OF IN_/AOUT_
FROM SHUTDOWN
10µs/div
MAX9621 toc23
V
V V
I
IN1
V
AOUT1
SLEEP IN1
AOUT1
100µs/div
STARTUP OF IN_/DOUT_
FROM SHUTDOWN
20µs/div
MAX9621 toc24
V
SLEEP
V
IN1
I
IN1
V
DOUT1
7
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
Pin Configuration
TOP VIEW
+
MAX9621
1
BAT SLEEP
2
ISET
IN1
3
MAX9621
10
9
AOUT1
8
DOUT1
IN2
GND
4
5
µMAX
7
AOUT2
6
DOUT2
Pin Description
PIN NAME FUNCTION
1 BAT
2 ISET
3 IN1
4 IN2
5 GND Ground
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 (R threshold range for the DOUT_ outputs. See the Typical Operating Characteristics section for the correct value of R 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.
for the desired range. Make no other connections to this pin. All routing must have low
SET
) between BAT and ISET to set the desired input current
SET
8
Dual, 2-Wire Hall-Effect Sensor Interface with
Analog and Digital Outputs
Pin Description (continued)
PIN NAME FUNCTION
Open-Drain Output. Signal translated from Hall sensor 2. DOUT2 is high when the current flowing out of
6 DOUT2
7 AOUT2
8 DOUT1
9 AOUT1
10
SLEEP
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
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.
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.
Hall Sensor Protection
from Supply Transients
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 V returns to the proper operating range, both inputs restart following a blanking cycle.
BAT
9
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
Table 1. AOUT_/DOUT_ Truth Table
CONDITION AOUT_ DOUT_
IN_ Short to GND 0 High-Z IN_ Short to BAT or IN_ Open 0 Low* SLEEP Low 0 High-Z V
> 18V 0 Low*
BAT
*If IN_ is already shorted to BAT or open during power-up,
MAX9621
DOUT_ goes to high-Z until IN_ is loaded.
Hall Input Short-to-Battery Condition
The MAX9621 interprets a short to battery when the volt­age at IN1 or IN2 is higher than V tal outputs go low and the analog outputs are set to zero output current. If IN1 or IN2 is more than 1V above V it back-drives current into BAT. The MAX9621 restarts the Hall inputs when the Hall input is loaded again.
Hall Input Short to Ground
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 50µA pullup current remains. The Hall input can be manually reenergized or it can be reener­gized by the µP. A 10µs to 20µs 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 0.02µF without
- 100mV. The digi-
BAT
BAT
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.
Manual Method for Reenergizing Hall
Sensor and Means for Diagnosing an
Intermittent Hall Sensor Connection
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.
14V
V
IN_
0V
50µA
I
IN_
0A TIME
Figure 3. Hall Input Ramps to Open-Circuit Fault When a Short to Ground Is Relieved
10
HALL INPUT
SHORT-TO-
GROUND FAULT
HALL INPUT
DISCONNECTED
FROM SENSOR
5mV/ms
HALL INPUT
OPEN-CIRCUIT
FAULT
V
- 25mV
BAT
TIME
Dual, 2-Wire Hall-Effect Sensor Interface with
( )
= + × <
Analog and Digital Outputs
- 25mV
V
14V
BAT
MAX9621
V
IN_
0V
11.5mA
I
IN_
0A
Figure 4. Hall Input Reenergized When Open Input Is Reconnected to Hall Sensor
8V
5mA/µs
HALL INPUT RECONNECTED TO HALL SENSOR
Sleep Mode Input (SLEEP)
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.
I is the mean of the threshold current limits, R is the value of the R I0 = 0.03717mA, and the constant m = -0.001668 (1/(kΩ x mA)).
The following equation is useful for finding the value of R
resistance given a mean of the threshold current
SET
limits:
If the other input is operational it is not affected. The restart happens on the rising edge of SLEEP.
Input Current Thresholds and
Short to Ground
IIH, IIL, I
RAMP
IN_HYS
, t
portional to R
value. When the R
SET
, f
DEL
, ISC, t
SET
and PR.
MAX,
, and f
RAMP
and decrease as R
value changes,
SET
IN_HYS
are inversely pro-
MAX
increases. This
SET
, ISC,
inverse relationship is linear. For example, a 10% change in (1/R
) results in a 10% change in current parameters.
SET
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:
where H0 = -0.033463 in mA, and k = -0.08414 in mA/mA.
threshold low = I + H/2. Conversely, time and delay parameters are linear and directly proportional to R
, and a 10% change in R
SET
SET
Application Information
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 R
resistance:
SET
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
The analog output can be connected to an ADC with an
appropriate load resistor, and can be used to perform
custom diagnostics.
V
- 500mV
BAT
TIME
TIME
I I I 0
= + <
SET
Y Y m I I 0
1
R m
×
( )
0
resistance in kΩ, the constant
0
1
=
R
Y0 = 6.2013 x 10-5 units of (1/kΩ)
H = H0 + k x I (I < 0)
Use of Digital and Analog Outputs
11
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
R
MAX9621
V
X
CC
IN_
MAX9621
Figure 5. 3-Wire Hall-Effect Switches Configured as 2-Wire
Table 2. A Partial List of Compatible Hall Switches
PART NO. MANUFACTURER WEBSITE COMMENTS
HAL573-6 Micronas www.micronas.com 2-wire HAL556/560/566 Micronas www.micronas.com 2-wire HAL579/581/584 Micronas www.micronas.com 2-wire A1140/1/2/3 Allegro www.allegromicro.com 2-wire
A3161 Allegro www.allegromicro.com
TLE4941/C Infineon www.infineon.com 2-wire
Sleep Mode
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.
Remote Ground
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
sensor ground, the ground of the MAX9621 and FP. This
ground-shift immunity eliminates the need for a ground-
connection wire, allowing a single-wire interface to the
Hall sensor.
Hall-Effect Sensor Selection
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.
Input Current Threshold Precision
To get the best input current threshold precision, it is rec-
ommended that the R
to the BAT pin. A true Kelvin type connection is best.
SET
3-wire, optimized for 2-wire
use without added resistor
resistor be directly connected
12
Dual, 2-Wire Hall-Effect Sensor Interface with
Typical Application Circuit
Analog and Digital Outputs
MAX9621
BATTERY: 5.5V TO 18V
OPERATING,
60V WITHSTAND
N S
REMOTE GROUND
R
SET
0.01µF
ECUCONNECTOR
ISET REF
IN1
DETECTION
REFERENCE
INPUT
SHORT
BAT
BAT
0.1µF
R
PU
10kI
BAT
SLEEP-MODE
CONTROL
REF
FILTER
SLEEP
100kI
AOUT1
DOUT1
1.8V TO 5.5V
R
PU
10kI
5kI
ADC
MICROPROCESSOR
MAX9621
N S
REMOTE
GROUND
0.01µF
IN2
AOUT2
DOUT2
REF
GND
FILTER
ADC
5kI
Chip Information
PROCESS: BiCMOS
13
Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs
Package Information
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.
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
10 FMAX
U10+2
21-0061 90-0330
MAX9621
10LUMAX.EPS
α
α
14
Dual, 2-Wire Hall-Effect Sensor Interface with
Analog and Digital Outputs
Revision History
MAX9621
REVISION
NUMBER
0 11/09 Initial release — 1 9/11 Added automotive qualified part 1
REVISION
DATE
DESCRIPTION
PAGES
CHANGED
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 15
©
2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
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