19-5024; Rev 0; 11/09 TION KIT EVALUA BLE A IL A AV Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs Features 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. S Provides Supply Current and Interfaces to Two 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. S Filtered Digital Outputs 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. S ±2kV Human Body Model ESD and ±200V Machine 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 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 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 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 +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. Functional Diagram Seat Movers Electric Sunroofs BAT Seatbelt Buckles Door Power Locks ISET REFERENCE REF BAT SLEEP-MODE CONTROL Ignition Key SLEEP 10kI Steering Column Speed Sensing AOUT1 DOUT1 IN1 FILTER REF BAT INPUT SHORT DETECTION MAX9621 Typical Application Circuit appears at end of data sheet. AOUT2 DOUT2 IN2 µMAX is a registered trademark of Maxim Integrated Products, Inc. FILTER REF 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. MAX9621 General Description MAX9621 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 (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 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 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 SYMBOL CONDITIONS MIN TYP MAX UNITS 18 V GENERAL BAT Supply Range VBAT Guaranteed by functional test of IIH, IIL, and GEI IBAT Normal mode ISD VSLEEP = 0V BAT Supply Current Hall Input Voltage Dropout VDO ESD Protection 5.5 1 mA 1 10 FA VBAT = 5.5V, at IN1 and IN2, IIN = -14mA 0.59 1.26 VBAT = 5.5V, at IN1 and IN2, IIN = -20mA 0.86 1.86 Machine Model ±200 Human Body Model ±2000 V V INPUT THRESHOLDS FOR DOUT1, DOUT2 SWITCHING Input Current for Output High (Note 2) IIH Input Current for Output Low (Note 2) IIL Input Current Hysteresis for High/Low Detection IIN_HYS RSET = 95.3kI -7.7 RSET = 52.3kI -14 RSET = 95.3kI -5 RSET = 52.3kI -9 Peak-to-peak as percent of average high/ low threshold (Note 2) High threshold Low threshold Channel-to-Channel Input Threshold Variation mA 8 % 0.02 0.02 mA ISC A short to GND is not a sustained condition, Hall input reverts to -50FA when detected (Note 2) Current Gain for AOUT1 and AOUT2 Outputs GI -18mA P IIN P -2mA 0.05 Current Gain Error for AOUT1 and AOUT2 Outputs GEI IIN = -5mA, -14mA 0.2 Short-Circuit Current Limit mA -20 mA AOUT1, AOUT2 ANALOG OUTPUTS 2 mA/mA ±1.7 % Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs (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 SYMBOL IOS CONDITIONS Inferred from measurements at IIN = -5mA, -14mA VBAT = 5.5V, for 5% current reduction AOUT_ Dropout Voltage MIN TYP -120 MAX UNITS +120 FA IIN = -14mA 0.85 1.6 IIN = -20mA 1.09 1.75 AOUT_ Output Impedance 500 V MI LOGIC I/O (DOUT1, DOUT2) Output-Voltage Low DOUT1, DOUT2 VOL Sink current = 1mA 0.4 V Three-State Output Current DOUT1, DOUT2 IOZ VSLEEP = 0V, 0V P VDOUT_ P 5V ±1 FA SLEEP Input-Voltage High VIH Input-Voltage Low VIL Input Resistance to GND RIN 2.0 V 0.8 V 50 100 IIH = -14mA to GND, time from SLEEP low to IN_ drop 500mV, CL = 20pF 33 40 46 Fs IIH = -14mA to GND, time from VIN_ = 500mV until DOUT_ high, CL = 20pF (Notes 2, 3) 76 89 103 Fs IN_ = GND (Note 2) 3.6 5 6.7 mA/Fs 10.8 13.5 16 Fs kI 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 tSHDN tBL tRAMP Delay from IN_ to DOUT_ (Filter Delay) tDEL From IIH to IIL or from IIL to IIH, CL = 20pF, Figure 1 (Note 2) Delay Difference Between Rising and Falling Edges of Both Channels tDM CHALL-BYPASS = 0.01FF, IIH = -11.5mA and IIL = -7.5mA, CL = 20pF 1 Fs Delay Difference Between Channels tCC CHALL-BYPASS = 0.01FF, IIH = -11.5mA and IIL = -7.5mA, CL = 20pF 500 ns Maximum Frequency on Hall Inputs fMAX CHALL-BYPASS = 0.01FF, IIH = -11.5mA and IIL = -7.5mA, CL = 20pF (Note 2) 39 kHz Maximum Analog Output Current During Short-to-GND Fault IMAO -1.4 mA IN_ Pulse Length Rejected by Filter to DOUT_ PR Figure 2 (Note 2) 34 7.8 11.5 14.6 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 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 MAX9621 DC ELECTRICAL CHARACTERISTICS (continued) Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621 Timing Diagrams APPROXIMATELY 100mA HALL SENSOR OPEN SHORT CIRCUIT APPROXIMATELY 100mA 14mA IN1 5mA/µs 7mA 0mA APPROXIMATELY 1.4mA RESTART HALL SENSOR OPEN AOUT1 0.7mA 5mA/µs 0.35mA 0mA 5V DOUT1 tDEL tDEL 0V Figure 1. Timing Diagram PR PR 14mA IN_ 7mA 0mA tDEL DOUT_ 5V 0V Figure 2. Hall Input Pulse Rejection 4 tDEL Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs 0.6 0.5 0.7 0.6 20.0 20.5 21.0 20.0 20.5 21.0 20.5 21.0 BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE 1.0 MAX9621 toc05 1.0 TA = +25NC BAT CURRENT (mA) BAT CURRENT (mA) 0.6 20 30 40 50 60 0.6 0.4 0.2 10 TA = +125NC 0.8 0.4 0.2 MAX9621 toc06 BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE 0.4 0.2 0 10 20 30 40 50 60 0 10 20 30 40 50 BAT VOLTAGE (V) BAT VOLTAGE (V) BAT VOLTAGE (V) BAT SUPPLY CURRENT vs. VBAT IN SHUTDOWN MODE HALL INPUT CURRENT THRESHOLDS FOR HIGH/LOW vs. TEMPERATURE HALL INPUT CURRENT THRESHOLDS vs. VBAT 140 120 100 80 60 TA = +25°C AND -40°C 40 60 BAT VOLTAGE (V) 80 LOW TO HIGH 9.8 9.6 9.4 9.2 9.0 0 20 10.0 HIGH TO LOW 60 MAX9621 toc09 10.50 10.25 HALL INPUT CURRENT (mA) 10.2 HALL INPUT CURRENT (mA) 160 10.4 MAX9621 toc08 TA = +125°C MAX9621 toc07 200 0 20.0 BAT VOLTAGE (V) 0.6 20 19.5 19.0 0.8 40 MAX9621 toc03 0.4 19.5 BAT VOLTAGE (V) 0.8 180 0.6 BAT VOLTAGE (V) TA = -40NC 0 0.7 0.5 19.0 MAX9621 toc04 1.0 19.5 TA = +125NC 0.8 0.4 19.0 BAT CURRENT (mA) 0.9 0.5 0.4 BAT CURRENT (nA) TA = +25NC 0.8 BAT CURRENT (mA) 0.7 BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE BAT CURRENT (mA) TA = -40NC 0.8 BAT CURRENT (mA) 0.9 MAX9621 toc01 0.9 BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE MAX9621 toc02 BAT SUPPLY CURRENT vs. VBAT IN OPERATING MODE 10.00 LOW TO HIGH 9.75 9.50 9.25 9.00 HIGH TO LOW 8.75 8.50 8.8 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 5.5 8.0 10.5 13.0 15.5 18.0 BAT VOLTAGE (V) 5 MAX9621 Typical Operating Characteristics (VBAT = 13.6V, RSET = 61.9kI, RL = 5kI to GND at AOUT_, VSLEEP = 5V, TA = +25NC, unless otherwise noted.) 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 LOW TO HIGH 8 HIGH TO LOW 6 MAX9621 toc11 90 9 85 80 75 70 65 60 50 70 80 90 6 5 4 -40 -25 -10 5 20 35 50 65 80 95 110 125 RESISTANCE (kI) TEMPERATURE (°C) TEMPERATURE (°C) DELAY FROM IN_ TO DOUT_ (FILTER DELAY) vs. TEMPERATURE DELAY DIFFERENCE BETWEEN CHANNELS vs. TEMPERATURE MAXIMUM FREQUENCY ON HALL INPUTS vs. TEMPERATURE 5 500 300 100 0 0 25 50 75 100 -100 125 -50 TEMPERATURE (NC) IN_ PULSE LENGTH REJECTED BY FILTER TO DOUT_ vs. TEMPERATURE 18 16 12 10 8 1.05 DROPOUT VOLTAGE (V) NEGATIVE PULSE 14 POSITIVE PULSE 6 25 50 75 100 -25 0 25 50 75 TEMPERATURE (NC) 100 125 MAX9621 toc15 0 25 50 75 100 INPUT DROPOUT VOLTAGE vs. VBAT VBAT = 5.5V IIN1 = -14mA 0.55 1.15 1.05 IIN1 = -14mA TA = +125°C 0.95 125 0.85 0.75 TA = +25°C 0.65 0.55 TA = -40°C 0.45 0.35 0.25 0.25 -50 -25 INPUT DROPOUT VOLTAGE vs. TEMPERATURE 0.65 0.35 -50 TEMPERATURE (NC) 0.75 2 10 125 0.85 0.45 IN2 30 TEMPERATURE (NC) 0.95 4 0 0 1.15 MAX9621 toc16 20 -25 INPUT DROPOUT VOLTAGE (V) -25 40 20 MAX9621 toc17 -50 IN1 MAX9621 toc18 10 50 FREQUENCY (kHz) 700 DELAY DIFFERENCE (ns) 15 60 MAX9621 toc14 900 MAX9621 toc13 20 6 7 2 -40 -25 -10 5 20 35 50 65 80 95 110 125 100 8 3 60 4 DELAY (µs) 10 CURRENT RATE (mA/us) 12 10 95 IN_ BLANKING TIME (µs) 14 HALL INPUT CURRENT (mA) 100 MAX9621 toc10 16 IN-CURRENT RAMP RATE AFTER TURN-ON vs. TEMPERATURE MAX9621 toc12 HALL INPUT CURRENT THRESHOLDS vs. ISET RESISTOR PULSE LENGTH (µs) MAX9621 Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs -45 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 5.50 8.00 10.50 13.00 VBAT (V) 15.50 18.00 Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs CURRENT GAIN vs. SUPPLY VOLTAGE CURRENT GAIN vs. TEMPERATURE 0.06 0.05 0.04 0.03 5.50 8.00 10.50 13.00 15.50 18.00 MAX9621 toc20 MAX9621 toc19 0.07 CURRENT GAIN (mA/mA) CURRENT GAIN (mA/mA) 0.07 0.06 0.05 0.04 0.03 -50 -25 0 25 50 75 100 125 TEMPERATURE (NC) SUPPLY VOLTAGE (V) REENERGIZING OF THE HALL INPUT FROM OPEN-CIRCUIT CONDITION RESPONSE TO SHORT TO GROUND MAX9621 toc21 MAX9621 toc22 VIN1 VAOUT1 VIN1 VDOUT1 IIN1 IIN1 VAOUT1 400ns/div 100µs/div STARTUP OF IN_/AOUT_ FROM SHUTDOWN STARTUP OF IN_/DOUT_ FROM SHUTDOWN MAX9621 toc24 MAX9621 toc23 VSLEEP VIN1 VSLEEP VIN1 IIN1 IIN1 VAOUT1 VDOUT1 10µs/div 20µs/div 7 MAX9621 Typical Operating Characteristics (continued) (VBAT = 13.6V, RSET = 61.9kI, RL = 5kI to GND at AOUT_, VSLEEP = 5V, TA = +25NC, unless otherwise noted.) Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621 Pin Configuration TOP VIEW BAT 1 ISET 2 IN1 + 10 SLEEP 9 AOUT1 3 8 DOUT1 IN2 4 7 AOUT2 GND 5 6 DOUT2 MAX9621 µMAX Pin Description PIN FUNCTION BAT Battery Power Supply. Connect to the positive supply through an external reverse-polarity diode. Bypassed to GND with a 0.1FF capacitor. 2 ISET 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. 3 IN1 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. 4 IN2 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. 5 GND 1 8 NAME Ground Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs PIN NAME 6 DOUT2 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. 7 AOUT2 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. 8 DOUT1 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. 9 AOUT1 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 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. 10 FUNCTION 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. 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 VBAT returns to the proper operating range, both inputs restart following a blanking cycle. 9 MAX9621 Pin Description (continued) MAX9621 Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs 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. Table 1. AOUT_/DOUT_ Truth Table AOUT_ DOUT_ IN_ Short to GND CONDITION 0 High-Z IN_ Short to BAT or IN_ Open 0 Low* SLEEP Low 0 High-Z VBAT > 18V 0 Low* Manual Method for Reenergizing Hall Sensor and Means for Diagnosing an Intermittent Hall Sensor Connection *If IN_ is already shorted to BAT or open during power-up, 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 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. 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 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) D isconnect 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. 14V HALL INPUT SHORT-TOGROUND FAULT VIN_ VBAT - 25mV 5mV/ms HALL INPUT OPEN-CIRCUIT FAULT 0V TIME HALL INPUT DISCONNECTED FROM SENSOR 50µA IIN_ 0A Figure 3. Hall Input Ramps to Open-Circuit Fault When a Short to Ground Is Relieved 10 TIME Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs MAX9621 VBAT - 25mV 14V VIN_ 8V VBAT - 500mV 0V TIME 11.5mA IIN_ 5mA/µs HALL INPUT RECONNECTED TO HALL SENSOR 0A TIME Figure 4. Hall Input Reenergized When Open Input Is 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. 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 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: I = I0 + 1 (I < 0) R×m I is the mean of the threshold current limits, R is the value of the RSET resistance in kΩ, the constant I0 = 0.03717mA, and the constant m = -0.001668 (1/(kΩ 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 × I (I < 0) R= 1 Y Y0 = 6.2013 x 10-5 units of (1/kΩ) 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 Use of Digital and Analog Outputs 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 MAX9621 Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs 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. 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 3-wire, optimized for 2-wire use without added resistor 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 12 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. 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 recommended that the RSET resistor be directly connected to the BAT pin. A true Kelvin type connection is best. Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs 1.8V TO 5.5V 0.1µF BATTERY: 5.5V TO 18V OPERATING, 60V WITHSTAND RPU 10kI RSET ISET REFERENCE RPU 10kI BAT REF SLEEP-MODE CONTROL BAT SLEEP 100kI AOUT1 5kI ADC ECUCONNECTOR DOUT1 N S IN1 FILTER REF 0.01µF MICROPROCESSOR INPUT SHORT DETECTION REMOTE GROUND BAT MAX9621 AOUT2 ADC 5kI IN2 N S DOUT2 0.01µF FILTER REF REMOTE GROUND GND Chip Information PROCESS: BiCMOS 13 MAX9621 Typical Application Circuit 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 PACKAGE CODE DOCUMENT NO. 10 FMAX U10+2 21-0061 10LUMAX.EPS MAX9621 Dual, 2-Wire Hall-Effect Sensor Interface with Analog and Digital Outputs α α 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 © 2009 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.