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19-4464; Rev 0; 2/09
KIT ATION EVALU ABLE AVAIL
24-Channel Automotive Switch Monitor
General Description Features
9V to 18V Operating Voltage Range with Full Performance Fully Functional Range of 5.5V to 28V Switch Inputs Withstand 27V Switch Inputs Withstand Reverse Battery Ultra-Low Operating Current 100A (typ) in Scan Mode Built-In Switching Hysteresis Built-In Switch Deglitching CMOS-Compatible Logic Outputs Down to 3.0V Interrupt Output to Processor Configurable Wetting Current (0mA, 5mA, 10mA, or 15mA) for Each Switch Input AEC-Q100 Qualified
MAX13362
The MAX13362 is a 24-channel automotive contact monitor designed as an interface between mechanical switches and low-voltage processors or other logic circuits. The IC operates over a voltage range of 5.5V to 28V, and withstands voltages up to 40V. It protects lowvoltage circuitry from high voltages and reverse battery conditions. The MAX13362's low-current operation under all operating conditions makes it suitable for use in electronic control units (ECUs) that are connected directly to the automotive battery. It has an adjustable scan mode that significantly reduces the current drawn in key-off. The MAX13362 features an SPITM interface to monitor the switch status and set the device configuration. Multiple MAX13362s can be cascaded to support any multiple of 24 switches. The MAX13362 is available in a 6mm x 6mm, 40-pin thin QFN package and operates over the -40C to +125C temperature range.
Applications
Automotive Body Controllers Automotive Door Modules Automotive Smart Junction Boxes
PART MAX13362ATL/V+
Ordering Information
TEMP RANGE -40C to +125C PIN-PACKAGE 40 Thin QFN-EP* (6mm x 6mm)
*EP = Exposed pad. +Denotes a lead(Pb)-free/RoHS-compliant package. /V Denotes an automotive qualified part.
Typical Application Circuit
TOP VIEW N.C. N.C. IN6 IN5
24 SWITCHES, 1 BATTERY-CONNECTED BATTERY 9V TO 18V
Pin Configuration
IN4 IN3 IN2 IN1 IN0 22 SD 21
30
29
28
27
26
25
24
ECU CONNECTOR
IN7 IN8
31 32 33 34 35 36 37 38 39 40
23
20 19 18 17
VS VS GND VDD GND SDI CS SDO CLK N.C.
0.047F 100
0.047F
IN9 IN10 IN11
MAX13362
16 15 14 13 12
IN23 IN22 IN21 IN20 IN19 IN18 IN17 IN16 IN15 IN14 IN13 IN12 IN11 IN10 IN9 IN8 IN7 IN6 IN5 IN4 IN3 IN2 IN1
IN0
IN12
VS IN REGULATOR
IN13 IN14 IN15 IN16
MAX13362
VDD GND SDI SDO CLK CS INT SD
OUT
+
10 1 2 3 4 5 6 7 8 9
11
IN17
IN18
IN19
IN20
IN21
IN22
SPI is a trademark of Motorola, Inc.
THIN QFN (6mm x 6mm)
________________________________________________________________ Maxim Integrated Products
IN23
N.C.
N.C.
INT
MICROCONTROLLER /LOGIC CIRCUIT
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.
24-Channel Automotive Switch Monitor MAX13362
ABSOLUTE MAXIMUM RATING
VDD, CLK, SDI, CS to GND ......................................-0.3V to +6V VS, SD, INT to GND................................................-0.3V to +40V IN0-IN23 to GND.....................................................-15V to +27V SDO to GND ...............................................-0.3V to (VDD + 0.3V) ESD Protection, All Pins (HBM)............................................2kV ESD Protection on Pins IN0-IN23 to IEC61000-4-2 Specification (with added 0.047F capacitor, and/or 100 resistor)....8kV Current Into Any Pin..........................................................20mA Continuous Power Dissipation (TA = +70C) (derate 37mW/C above +70C)(multilayer board)....2963mW Operating Temperature Range .........................-40C to +125C Junction Temperature........................................-40C to +150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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.
ELECTRICAL CHARACTERISTICS
(VDD = 5V, VVS = 14V, TA = -40C to +125C, unless otherwise noted. Typical values are at TA =+25C.)
PARAMETER POWER SUPPLY VDD Operating Supply Range VDD Supply Current VS Supply Range VS Undervoltage Lockout VDD IDD VVS VUVLO tPOLL = 64ms, tPOLL_ACT = 1ms; LP bit in internal register = 0, 24 channels active, all switches open, TA = +25C Total Supply Current (Flowing into VS and VDD) ISUP tPOLL = 64ms, tPOLL_ACT = 1ms; LP bit in internal register = 0, 24 channels active, all switches open Continuous polling mode, wetting current set to 5mA VS Supply Current in Shutdown Mode VDD Supply Current in Shutdown Mode SWITCH INPUTS Input Voltage Threshold Input Hysteresis Wetting Current Rise/Fall Time VTH VH tIWETT Wetting current set to 15mA, 9V < VVS < 18V Wetting current set to 15mA, (5.5V < VVS < 9V) or (18V < VVS < 28V) VIN_ = 0, TA = +25C VIN_ = 14V, TA = +25C (Note 2) VVS = 0 or 14V, VSD = 0, TA = +25C IWETT = 15mA (Note 3) 2.8 16 12.7 10.5 VVS = 5.5V to 28V, measured with 100 series resistor for high-side switches VVS = 5.5V to 28V, measured with 100 series resistor for high-side switches 2.5 0.2 5 15 15 17.25 mA 19.5 2 30 2 4.0 A A V 3.7 V V s ISDVS ISDVDD VSD = 0, VVS = 14V, all switches open, TA = +25C VSD = 0, VVS = 14V, TA = +25C (Note 1) 5.5 3 100 3 0.1 5.5 10 28 5.5 170 V A V V SYMBOL CONDITIONS MIN TYP MAX UNITS
100
200
A
1000 6 0.1 10 5 A A
Wetting Current
IWETT
IN0-IN23 Input Current IN0-IN23 Input Leakage Current in Shutdown IN4-IN23 Dropout Voltage
IIN_ ILEAKSD VDO15
2
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24-Channel Automotive Switch Monitor
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 5V, VVS = 14V, TA = -40C to +125C, unless otherwise noted. Typical values are at TA =+25C.)
PARAMETER LOGIC LEVELS INT Output-Voltage Low SDO Output-Voltage Low SDO Output-Voltage High SDO Leakage Current in HighImpedance Mode SDI, CLK, CS Input-Voltage Low SDI, CLK, CS Input-Voltage High SD Input Low Voltage SD Input High Voltage SDI Internal Pulldown Resistor CLK Pin Leakage CS Pin Leakage SD Pin Leakage INT Pin Leakage THERMAL SHUTDOWN Thermal Shutdown Threshold Thermal Shutdown Hysteresis TIMING Switch Inputs Deglitching Time CLK Frequency Range Falling Edge of CS to Rising Edge of CLK Setup Time Falling Edge of CLK to Rising Edge of CS Setup Time SDI-to-CLK Falling Edge Setup Time SDI Hold Time After Falling Edge of CLK Time from Rising Edge of CLK to SDO Data Valid Time from Falling Edge of CS to SDO Low Impedance Time from Rising Edge of CS to SDO High Impedance tGT fCLK tLEAD tLAG tSI(SU) tSI(HOLD) tVALID tSO(EN) tSDO(DIS) (Note 4) Polling mode, input rise/fall time < 10ns (Note 4) Input rise/fall time < 10ns (Note 4) (Note 4) (Note 4) CSDO = 50pF (Note 3) (Note 4) (Note 4) 37 0.01 100 100 30 20 70 55 55 50 63 4 s MHz ns ns ns ns ns ns ns TSHDN THYST Temperature rising (Note 4) +150 +165 15 C C VOLINT VOLSDO VOHSDO ILSDO VIL VIH VILSD VIHSD RPD ILEAKCLK ILEAKCS ILEAKSD ILEAKINT VCLK = 5V, TA = +25C VCS = 5V, TA = +25C VSD = 5V, TA = +25C VINT = high impedance, TA = +25C 30 50 0.66 x VDD 0.8 2.4 120 1 1 1 1 Sinking 1mA Sinking 1mA Sourcing 1mA VCS = 5V 0.8 x VDD -1 +1 0.33 x VDD 0.4 0.2 x VDD V V V A V V V V k A A A A SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX13362
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3
24-Channel Automotive Switch Monitor MAX13362
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 5V, VVS = 14V, TA = -40C to +125C, unless otherwise noted. Typical values are at TA =+25C.)
PARAMETER Polling Active Time Accuracy Polling Time Accuracy Time from Shutdown to Normal Operation SYMBOL tPOLL_ACT tPOLL tSTART CONDITIONS MIN -20 -20 0.1 TYP MAX +20 +20 1 UNITS % % ms
Note 1: When VVS is above 28V, the wetting current is disabled to limit power dissipation, and the switch inputs are not monitored. When VVS returns, there is a 1ms blanking time before the external switches are polled. Note 2: This current only flows during the polling active time thus the average value is much lower. For example with a polling time of 64ms and a polling active time of 1ms the average current on an input when connected to 14V is typically 16A x 1/64 = 0.25A. Note 3: Difference between VS and IN_ voltage when wetting current has dropped to 90% of its nominal value. Note 4: Guaranteed by design.
CS tLEAD CLK tSI(SU) tSI(HOLD) tLAG
SDI tSO(EN)
MSB IN tVALID tSDO(DIS)
SDO
MSB OUT
LSB OUT
Figure 1. SPI Timing Characteristics
4
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24-Channel Automotive Switch Monitor
Typical Operating Characteristics
(VDD = VSD = 5V, VVS = 14V, TA = +25C, unless otherwise noted.)
MAX13362
WETTING CURRENT vs. VS VOLTAGE
MAX13362 toc01
WETTING CURRENT vs. TEMPERATURE
MAX13362 toc02
SWITCH STATUS CHANGE (CONTINUOUS MODE)
MAX13362 toc03
20
20
VIN0 IWETT
10V 0mA
0V 5mA
10V/div 5mA/div
WETTING CURRENT (mA)
IWETT = 15mA
WETTING CURRENT (mA)
15
15
IWETT = 15mA
10
IWETT = 10mA
10
IWETT = 10mA
VINT
2V/div
5
IWETT = 5mA
5
IWETT = 5mA
VCS
2V/div
0 567 8 9 10 11 12 13 14 15 16 17 18 VS VOLTAGE (V)
0 -40 -20 0 20 40 60 80 100 120 140 10ms/div TEMPERATURE (C)
WETTING CURRENT (POLLING MODE)
MAX13362 toc04
VS SUPPLY CURRENT vs. TEMPERATURE (CONTINUOUS MODE)
IWETT = 15mA FOR ALL CHANNELS
MAX13362 toc05
VS SUPPLY CURRENT vs. TEMPERATURE (POLLING MODE)
POLLING TIME = 65.536ms POLLING ACTIVE TIME = 1.024ms ALL CHANNELS OPEN IWETT = 5mA
MAX13362 toc06 MAX13362 toc09
2600 2200
130
WETTING CURRENT (5mA/div)
SUPPLY CURRENT (A)
5mA
1800 1400
IWETT = 10mA FOR ALL CHANNELS
SUPPLY CURRENT (A)
120
110
IWETT = 5mA FOR ALL CHANNELS 1000 ALL CHANNELS OPEN 600 IWETT = 0mA FOR ALL CHANNELS 200
4.096ms POLLING TIME 512s POLLING ACTIVE TIME
100
90 -40 -20 0 20 40 60 80 100 120 140 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) TEMPERATURE (C)
1ms/div
VS SUPPLY CURRENT vs. TEMPERATURE (SHUTDOWN MODE)
MAX13362 toc07
SWITCH THRESHOLD vs. TEMPERATURE (HIGH SIDE SWITCH)
MAX13362 toc08
SWITCH THRESHOLD vs. TEMPERATURE (LOW-SIDE SWITCH)
3.4
6.5
3.4
6.2 SUPPLY CURRENT (A)
SWITCH THRESHOLD (V)
SWITCH THRESHOLD (V)
3.3 SWITCH OPEN TO CLOSE 3.2 SWITCH CLOSE TO OPEN
3.3
SWITCH OPEN TO CLOSE
5.9
3.2
5.6
SWITCH CLOSE TO OPEN
5.3
3.1
HIGH SIDE SWITCH 15mA WETTING CURRENT 100 INCLUDED -40 -20 0 20 40 60 80 100 120 140
3.1 LOW-SIDE SWITCH 15mA WETTING CURRENT 3.0 -40 -20 0 20 40 60 80 100 120 140
5.0 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C)
3.0 TEMPERATURE (C)
TEMPERATURE (C)
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5
24-Channel Automotive Switch Monitor MAX13362
Typical Operating Characteristics (continued)
(VDD = VSD = 5V, VVS = 14V, TA = +25C, unless otherwise noted.)
SWITCH THRESHOLD vs. VS VOLTAGE (LOW-SIDE SWITCH)
MAX13362 toc10
SWITCH STATUS CHANGE (POLLING MODE)
MAX13362 toc11
3.5
3.4 SWITCH THRESHOLD (V) SWITCH OPEN TO CLOSE
10V VIN 0V 5V/div
3.3
3.2 SWITCH CLOSE TO OPEN VINT 0V 2V/div
3.1
3.0 9 10 11 12 13 14 15 16 17 18 2ms/div VS VOLTAGE (V)
Pin Description
PIN 1, 2, 11, 29, 30 3 4 5 6 7 8 9 10 12 13 NAME N.C. IN17 IN18 IN19 IN20 IN21 IN22 IN23 INT CLK SDO No Connection. Not internally connected. Switch Monitor Input Channel 17. Connect IN17 to a ground-connected switch. Switch Monitor Input Channel 18. Connect IN18 to a ground-connected switch. Switch Monitor Input Channel 19. Connect IN19 to a ground-connected switch. Switch Monitor Input Channel 20. Connect IN20 to a ground-connected switch. Switch Monitor Input Channel 21. Connect IN21 to a ground-connected switch. Switch Monitor Input Channel 22. Connect IN22 to a ground-connected switch. Switch Monitor Input Channel 23. Connect IN23 to a battery-connected or ground-connected switch. When used for a battery-connected switch, add a 100 series protection resistor to the input. Interrupt Output. INT is an open-drain output that asserts low when one or more of the inputs (IN0-IN23) change state and are enabled for interrupts, or when the overtemperature threshold is exceeded. SPI Serial Clock Input SPI Serial Data Output. SPI data is output on SDO on the rising edges of CLK while CS is held low. SDO is high impedance when CS is high. Connect SDO to a microcontroller data input or to a succeeding device in a daisy chain. SPI Chip-Select Input. Drive CS low to enable clocking of data into and out of the IC. SPI data is latched into the device on the rising edge of CS. SPI Serial Data Input. SPI data is latched into the internal shift register on the falling edges of CLK while CS is held low. SDI has an internal 50k pulldown resistor. Connect SDI to the SDO of a preceding device in a daisy chain or to the microcontroller data output. Ground. Pins 16 and 18 must be connected to ground. Logic Supply Voltage. Connect VDD to a 3.3V or 5V logic supply. Bypass VDD to GND with at least a 0.1F capacitor placed as close as possible to VDD. FUNCTION
14
CS
15 16, 18 17
SDI GND VDD
6
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24-Channel Automotive Switch Monitor
Pin Description (continued)
PIN 19, 20 NAME VS FUNCTION Supply Voltage Input. VS should be protected from reverse battery using a series diode. Bypass VS to GND with a 0.1F ceramic capacitor placed as close as possible to VS. In addition, bypass VS with a 47F or greater capacitor. Shutdown Input. Drive SD low to place the IC into shutdown mode. Drive SD high for normal operation. SD is battery-voltage compatible. Switch Monitor Input Channel 0. Connect IN0 to a battery-connected or ground-connected switch. When used for a battery-connected switch, add a 100 series protection resistor to the input. Switch Monitor Input Channel 1. Connect IN1 to a battery-connected or ground-connected switch. When used for a battery-connected switch, add a 100 series protection resistor to the input. Switch Monitor Input Channel 2. Connect IN2 to a battery-connected or ground-connected switch. When used for a battery-connected switch, add a 100 series protection resistor to the input. Switch Monitor Input Channel 3. Connect IN3 to a battery-connected or ground-connected switch. When used for a battery-connected switch, add a 100 series protection resistor to the input. Switch Monitor Input Channel 4. Connect IN4 to a ground-connected switch. Switch Monitor Input Channel 5. Connect IN5 to a ground-connected switch. Switch Monitor Input Channel 6. Connect IN6 to a ground-connected switch. Switch Monitor Input Channel 7. Connect IN7 to a ground-connected switch. Switch Monitor Input Channel 8. Connect IN8 to a ground-connected switch. Switch Monitor Input Channel 9. Connect IN9 to a ground-connected switch. Switch Monitor Input Channel 10. Connect IN10 to a ground-connected switch. Switch Monitor Input Channel 11. Connect IN11 to a ground-connected switch. Switch Monitor Input Channel 12. Connect IN12 to a ground-connected switch. Switch Monitor Input Channel 13. Connect IN13 to a ground-connected switch. Switch Monitor Input Channel 14. Connect IN14 to a ground-connected switch. Switch Monitor Input Channel 15. Connect IN15 to a ground-connected switch. Switch Monitor Input Channel 16. Connect IN16 to a ground-connected switch. Exposed Pad. Connect EP to GND for enhanced thermal performance.
MAX13362
21 22 23 24 25 26 27 28 31 32 33 34 35 36 37 38 39 40 --
SD IN0 IN1 IN2 IN3 IN4 IN5 IN6 IN7 IN8 IN9 IN10 IN11 IN12 IN13 IN14 IN15 IN16 EP
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7
24-Channel Automotive Switch Monitor MAX13362
Functional Diagram
VS
VDD
MAX13362
SDO
IN0 IN1 IN2 IN3 IN4 IN5 IN6 IN7 IN8 IN9 IN10 IN11 IN12 IN13 IN14 IN15 IN16 IN17 IN18 IN19 IN20 IN21 IN22 IN23 1 OF 24 CS
CLK
WETTING CURRENT CONTROL
SHIFT REGISTER + CONTROL
INT
SD
24 OF 24
SDI REF GENERATOR
GND
8
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24-Channel Automotive Switch Monitor
Detailed Description
The MAX13362 is a 24-channel automotive contact monitor designed as an interface between mechanical switches and low-voltage microcontrollers or other logic circuits. It features an SPI interface to monitor individual switch inputs and to configure interrupt capability, wetting current, switch configuration (battery-connected or ground-connected), polling time and polling active time. Any switch status change will cause an interrupt signal if the switch is interrupt enabled. The MAX13362 has three modes of operation: continuous mode, polling mode, and shutdown mode. battery-connected switches by writing to the LH0-LH3 and LH23 bits (see Table 2). The default configuration of the IN0-IN3 and IN23 inputs after power-up is for ground-connected switches.
MAX13362
Wetting Current
The MAX13362 applies a programmable wetting current to any closed switch to clean switch contacts that are exposed to adverse conditions. The wetting current for each switch can be set to 0mA, 5mA, 10mA, or 15mA by the W_.0 and W_.1 data bits in the command registers (see Table 5) by means of an SPI data transaction. When using wetting current, special care must be taken to avoid exceeding the maximum power dissipation of the MAX13362 (see the Applications Information section). Disabling the wetting current or limiting the active-wetting current time reduces power consumption. The default state upon power-up is with wetting current disabled.
VDD and VS V DD is the power-supply input for the logic input/ output circuitry. Connect VDD to a 3V to 5.5V logic-level supply. Bypass V DD to GND with at least a 0.1F capacitor placed as close as possible to VDD. VS is the main power-supply input. Bypass VS to GND with a 0.1F ceramic capacitor placed as close as possible to VS. In addition, bypass VS with a 47F or greater capacitor. Mechanical Switch Inputs (IN0-IN23)
IN0-IN23 are the inputs for remote mechanical switches. The switch status is indicated by the S0-S23 bits in the status register, and each switch input can be programmed to assert an interrupt (INT) by writing to the IE0-IE23 bits in the command register. All switch inputs are interrupt disabled upon power-up. The IN4-IN22 inputs are intended for ground-connected switches. The IN0-IN3 and IN23 inputs can be programmed for either ground-connected switches or
Interrupt Output (INT)
INT is an active-low, open-drain output that asserts low when any of the switch inputs change state and is enabled for interrupts, or when the overtemperature threshold is exceeded. An external pullup resistor to VDD is needed on INT. INT is cleared when CS is driven low for a read/write operation. However, in polling mode, any switch state change or overtemperature change which occurs during an SPI transaction is stored and causes an additional interrupt after the SPI transaction is over and CS goes high (shown in Figure 2). If VDD is absent, the INT output is functional provided that it is pulled up to a different supply voltage.
CS
SWITCH STATUS CHANGE
CLK
INT NEW INTERRUPT
Figure 2. Switch State Change During the SPI transaction
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9
24-Channel Automotive Switch Monitor MAX13362
Serial Peripheral Interface (CS, SDO, SDI, CLK)
The MAX13362 operates as a serial peripheral interface (SPI) slave device. An SPI master accesses and programs the MAX13362 by reading/writing the control registers. The control registers are 32 bits wide, have 2 command bits (or register addresses) and 30 data bits (see Table 1). Figure 3 shows the read/write sequence through SPI. The SPI logic counts the number of bits clocked into the IC (using a modulo-32 counter so that daisy chaining is possible) and enables data latching only if exactly 32 bits (or an integer multiple thereof) have been clocked in.
Status Register The status register contains the status of the switches connected to IN0-IN23. The status register also contains an overtemperature warning bit, a power-on-reset bit and a device type bit (see Table 1). The status register is accessed by the SPI-compatible interface.
CS
CLK
SDI
CB0 CB1 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18 D19 D20 D21 D22 D23 D24 D25 D26 D27 D28 D29
SDO
Z DT RST T
S0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19 S20 S21 S22 S23 x
x
x
x
x
Z
NOTE: X = UNUSED, Z = HIGH IMPEDANCE.
Figure 3. SPI Read/Write Sequence
Table 1. Bit Description
BIT NAME CB0, CB1 D0-D29 S0-S23 T RST DT Data bits. Switch state bit. 0 = switch open, 1 = switch closed. Overtemperature bit. When overtemperature occurs, this bit is set to 1. It is reset on the rising edge of CS. Power-on-reset bit. It indicates whether the IC has had a power-on-reset since the last SPI read. 0 = device has been reset. RST is set to 1 on the rising edge of CS. Device type. 0 = reserved for future use, 1 = MAX13362. BIT DESCRIPTION Command bits. Select the internal register to which data bits D0-D29 are to be written.
10
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24-Channel Automotive Switch Monitor
Command Register Three 32-bit command registers are used to configure the MAX13362 for various modes of operation and are accessed by the SPI-compatible interface (see Table 2).
The default configuration after power-on is LH_ = 0, ground connected.
MAX13362
Table 2. Command Register Map
D29 D28 D27 D26 D25 D24 D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 X X LP P3 D10 D9 D8 D7 D6 D5 D4 W3. 0 W3. 1 IE3 D3 D2 D1 D0 X X X CB1 CB0 0 0 1 1 0 1 0 1 W23. W22. W21 W20 W19 W18 W17 W16. W15 W14 W13 W12 W11 W10 W9. W8. W7. PA2 PA1 PA0 0 0 .0 .0 .0 .0 .0 0 .0 .0 .0 .0 .0 .0 0 0 0 P2 P1 P0 W23. W22. W21 W20 W19 W18 W17 W16. W15 W14 W13 W12 W11 W10 W9. W8. W7. 1 1 .1 .1 .1 .1 .1 1 .1 .1 .1 .1 .1 .1 1 1 1 IE9 IE8 IE7 W6. W5. W4. 0 0 0 W6. W5. W4. 1 1 1 IE6 IE5 IE4 W2. W1. W0. 0 0 0 W2. W1. W0. 1 1 1 IE2 IE1 IE0
LH2 LH3 LH2 LH1 LH0 IE23 IE22 IE21 IE20 IE19 IE18 IE17 IE16 IE15 IE14 IE13 IE12 IE11 IE10 3 NO OPERATION (NO DATA WRITTEN)
LH_: Switch Configuration for IN0-IN3 and IN23 The LH0-LH3 and LH23 bits set the switch configuration for IN0-IN3 and IN23, respectively. Set LH_ to 0 to configure the input channel to ground connected. Set LH_ to1 to configure the input channel to battery connected.
P0-P3: Polling Time P0-P3 are used to set the polling time as shown in Table 3. PA0-PA2: Polling Active Time PA0-PA2 are used to set the polling active time as shown in Table 4.
Table 3. Polling Time Setting
P3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 P2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 P1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 P0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 POLLING TIME (ms) Continuous* 4.096 4.096 4.096 4.096 4.096 8.192 16.384 32.768 65.536 131 262.1 524.3 1049 2097 4194
Table 4. Polling-Active Time Setting
PA2 0 0 0 0 1 1 1 1 PA1 0 0 1 1 0 0 1 1 PA0 0 1 0 1 0 1 0 1 POLLING ACTIVE TIME (s) 64 128 256 512* 1024 2048 4096 4096
*Default POR Value.
*Default POR value.
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11
24-Channel Automotive Switch Monitor MAX13362
IE_: Interrupt Enable The IE_ bit programs the switch input channel, IN_, to be interrupt-enabled or interrupt-disabled (0 = interrupt disabled, 1 = interrupt enabled). The default value after power-on is 0. W_.0 and W_.1: Wetting Current W_.0 and W_.1 bits set the corresponding switch channel-wetting current as shown in Table 5.
switches for a preset duration to reduce the power consumption. In shutdown mode, all switch inputs are high impedance and all circuitry is shutdown.
Table 5. Wetting Current Setting
W_.1 0 0 1 1 W_.0 0 1 0 1 WETTING CURRENT (mA) 0* 5 10 15
Continuous Mode Operation (P0-P3 = 0) In continuous mode, reading of the switch status is initiated by a falling edge on CS. The microcontroller initiates a low pulse on CS to update the MAX13362 switch status register. If INT remains high, no action needs be taken by the microcontroller. If INT goes low, the microcontroller may perform a read operation to read the updated switch status. On the rising edge of CS, INT is updated. To get correct data, the microcontroller must wait 10s before initiating a switch status read operation. (See Figure 4.)
*Default POR value.
CS SWITCH STATUS CHANGE INT INT UPDATED, PERFORM READ OPERATION
LP: Low Quiescent Current Bit In polling mode, when LP is set to 0, the IC is operating with the lowest quiescent current. The channels that are not enabled to interrupt have their wetting current disabled and are not monitored. The first pulse of wetting current after the switch is closed and sampled is 5mA unless the wetting current for that channel is set to 0mA. The default value of LP after power-on is 0. When LP is 1, all channels are monitored and the wetting current for each channel is set to the value determined by W_.0 and W_.1. If the MAX13362 is in continuous mode, LP is ignored.
Figure 4. Continuous Mode Operation
Operating Modes
The MAX13362 features three modes of operation: continuous mode, polling mode, and shutdown mode. In continuous mode, the wetting currents (if enabled) are continuously applied to the closed switches. In polling mode, the wetting currents are applied to the closed
Polling-Mode Operation In polling mode (see Figure 5), each switch input is sampled for a programmable polling active time set by the PA0-PA2 bits between 64s and 4ms (see Table 4). Sampling is repeated at a period set by the P0-P3 bits (from 4ms to continuous, see Table 3). All switch inputs are sampled simultaneously at the end of the polling active time. Wetting currents (if enabled) are applied to closed switches during the polling active time. Therefore, the polling mode reduces the current consumption from the VS power supply to some value dependent on the polling time chosen.
POLLING ACTIVE TIME SWITCH POSITION SAMPLED
POLLING TIME
POLLING ACTIVE TIME GROUND-CONNECTED SWITCH-INPUT
SWITCH POSITION SAMPLED
INT SWITCH OPEN
Figure 5. Switch Sampling in Polling Mode
12 ______________________________________________________________________________________
24-Channel Automotive Switch Monitor
Any switch position change (if the switch is interruptenabled) is signaled through the active-low open-drain INT output. The INT output is cleared when CS goes low. tery-level source but should be protected against reverse battery in the application.
MAX13362
Wetting Current and Power Dissipation
The maximum power dissipation happens when all switch inputs configured with 15mA continuous wetting current are all closed. Assuming the battery voltage is 14V, the corresponding power dissipated by the IC is 24 x 14V x 15mA = 5040mW. This exceeds the absolute maximum power dissipation of 2963mW. In polling mode, the wetting currents are pulsed at the programmed polling time to reduce the total power dissipated in the IC.
Shutdown Mode In shutdown mode, all switch inputs are high impedance and the external switches are no longer monitored, reducing current consumption on VS to 6A (typ). The IC resets upon entering shutdown mode and the contents of the command registers are lost. Therefore, any setting other than power-on-reset defaults needs to be reprogrammed after exiting from the shutdown mode.
Applications Information
Overtemperature Protection
If the IC junction temperature exceeds +165C, an interrupt signal is generated and the wetting currents are disabled to reduce the on-chip power dissipation. During an overtemperature event, the last switch status is retained in internal memory and the switch status is not updated. The interrupt output is cleared when CS goes high, but the overtemperature bit T in the output word remains for as long as the overtemperature condition persists. When the junction temperature drops by 15C, the wetting currents are re-enabled and there is a 1ms blanking time before the switches can be polled.
ISO 7637 Pulse Immunity
VS, SD, and IN0-IN23 are potentially exposed to ISO 7637 pulses. Bypass VS with a 0.1F and a 47F capacitor. The VS and SD voltage must be limited below 40V during load dump. Bypass IN0-IN23 with at least 0.047F capacitors at the ECU connector. When IN0-IN3 or IN23 inputs are used with battery-connected switches, a 100 series resistor is needed. These external components allow VS, SD, and IN0-IN23 to withstand ISO 7637 pulses in the application circuit.
Mechanical Switch Characteristics
The MAX13362 is designed to operate with switches that have the following characteristics: 1) Minimum resistance value with switch open (due to leakage): 10k. 2) Maximum resistance value with switch closed: 100.
Reverse-Battery Tolerance
The IN0-IN23 switch inputs withstand up to -15V DC voltage without damage. A reverse-battery diode is needed to protect VS as shown in the Typical Application Circuit. SD can be controlled from a bat-
Chip Information
PROCESS: BiCMOS
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13
24-Channel Automotive Switch Monitor MAX13362
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 40 TQFN-EP PACKAGE CODE T4066+5 DOCUMENT NO. 21-0141
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 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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