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19-0808; Rev 0; 4/07
KIT ATION EVALU BLE AVAILA
Automotive Contact Monitor and Level Shifter
General Description Features
o +6V to +26V Operating Voltage Range o +42V Compatibility on BAT o Inputs Withstand Reverse Battery o Withstands Dynamic Battery Voltage Drop While VL is Present o Ultra-Low Operating Current 17A (typ) in Scan Mode o Resistor-Adjustable Switching Hysteresis o CMOS-Compatible Logic Outputs (+2.7V min) o Built-In Switch Debouncing o Interrupt Output o Immunity to Transients o High Modularity o Thermal Protection o 8kV HBM ESD Protection on IN0-IN7 Without External Components o Two Inputs (IN0, IN1) Programmable as Direct Outputs o Four Inputs (IN4-IN7) Programmable for BAT or GND Related Switches
MAX13036
The MAX13036 automotive contact monitor and level shifter monitors and debounces eight remote mechanical switches and asserts an interrupt (INT) if a switch changes state. The state of each switch is sampled through an SPITM interface by reading the status register and any switch can be prohibited from asserting an interrupt by writing to the command register. Four of the switch inputs are intended for ground-connected switches (IN0-IN3), and the other four inputs (IN4-IN7), are programmable in groups of two for either ground-connected or battery-connected switches. Two switch inputs (IN0, IN1) have direct level-shifted outputs (DO0, DO1) to be used for PWM or other timing-based signals. Switch input thresholds are set to 50% of the voltage applied to BATREF. The threshold hysteresis is set by connecting an external resistor from HYST to ground. The MAX13036 supplies an adjustable wetting current to each closed switch to clean mechanical switch contacts that are exposed to adverse conditions. The MAX13036 operates with a +6V to +26V battery voltage applied to BAT. A separate +2.7V to +5.5V logic supply input (VL) sets the interface voltage. The MAX13036 is available in a 5mm x 5mm 28-pin TQFN package and operates over the -40C to +125C temperature range.
Applications
Body Computers Window Lifters Seat Movers Electric Sunroofs Other Control ECUs
Pin Configuration
SDO DO1 N.C. CLK SDI
Ordering Information
PART TEMP RANGE PINPACKAGE 28 TQFN-EP* (5mm x 5mm) PKG CODE T2855-8
TOP VIEW
21
20
19
18
17
16
15
CS
VL
MAX13036ATI+ -40C to +125C
14
INT OT GND TDEB WET HYST N.C.
DO0 SD GND BATREF BAT N.C. INO
22
*EP
23 24 25 26 27 28
+
13 12
+ Denotes lead-free package. *EP = Exposed paddle.
MAX13036
11 10 9 8
Typical Application Circuit appears at end of data sheet.
1
2
3
4
5
6
IN6
IN3
IN5
IN7
IN1
IN2
IN4
7
TQFN
*CONNECT EXPOSED PADDLE TO GROUND
SPI is a trademark of Motorola, Inc.
________________________________________________________________ Maxim Integrated Products
1
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Automotive Contact Monitor and Level Shifter MAX13036
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND, unless otherwise noted.) VL ...........................................................................-0.3V to +6.0V BAT.........................................................................-0.3V to +42V BATREF, IN_ to BAT ................................................-45V to +45V BATREF, IN_ to GND...............................................-45V to +45V SD...........................................................................-0.3V to +45V HYST, WET, TDEB, OT, INT .....................................-0.3V to 6.0V CS, CLK, SDI, SDO, DO0, DO1 ....................-0.3V to (VL + 0.3V) Continuous Current (CS, CLK, SDI, SDO, DO0, DO1) .....20mA HBM ESD Protection (IN0-IN7)............................................8kV Continuous Power Dissipation (TA = +70C, multilayer board) 28-Pin TQFN (derate 34.5mW/C above +70C) .......2759mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+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
(VL = +2.7V to +5.5V, BAT = +6V to +26V, SD = VL, TA = -40C to +125C, unless otherwise noted. Typical values are at VL = +3.3V, BAT = +14V, TA = +25C) (Note 1)
PARAMETER POWER SUPPLY VL Supply Range VL Supply Current BAT Supply Range VL IL VBAT VL = +5V, VBAT = +14V, continuous scan, programmable hysteresis off, M0 = M1 =1, WEND = 1, IN0-IN7 = unconnected, CS = VL, SDI = CLK = GND (Note 2) VBAT = +14V, scan mode (SC0 = 0, SC1= 0, SC2 = 0), CS = VL, SDI = CLK = GND (Note 2) VSD = 0V, TA = +25C VBAT = +14V, VBATREF = +14V TA = -40C to +125C (Note 2) VSD = 0V, VBATREF = +14V VBATREF = +14V RHYST = or programmable hysteresis disabled RHYST = 90k RHYST = or programmable hysteresis disabled Input-Voltage Threshold Hysteresis (Note 4) VTH_HYS RHYST = 90k RHYST = 0 1 0.425 x VBATREF 0.4 x VBATREF 0.133 x VBATREF 0.26 x VBATREF 0.5 x VBATREF 0.5 x VBATREF 0.166 x VBATREF 0.361 x VBATREF 0.5 x VBATREF 0.575 x VBATREF 0.63 x VBATREF 0.22 x VBATREF 0.48 x VBATREF V VL = +5.5V, VBAT = +14V 6 2.7 0 5.5 1 26 V A V SYMBOL CONDITIONS MIN TYP MAX UNITS
Total Supply Current
ISUP
46
80
A
Total Supply Current in Scan Mode
ISUP_SCAN
17
36
A
Total Supply Current in Shutdown Mode BATREF Input Leakage Current in Shutdown BATREF Input Resistance SWITCH INPUTS (IN0-IN7) Input-Voltage Threshold Center (Note 3)
2 2
3.2 A 4.0 1 A M
ISHDN
IL_BATREF RBATREF
VTH_C
V
2
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Automotive Contact Monitor and Level Shifter
ELECTRICAL CHARACTERISTICS (continued)
(VL = +2.7V to +5.5V, BAT = +6V to +26V, SD = VL, TA = -40C to +125C, unless otherwise noted. Typical values are at VL = +3.3V, BAT = +14V, TA = +25C) (Note 1)
PARAMETER Switch-State Sense Resistor Wetting Current Rise/Fall Time SYMBOL RSENSE IWET_RISE_
FALL
MAX13036
CONDITIONS RWET = 61k (Note 5) RWET = 61k Rise Fall
MIN 11
TYP 16 6 1 22
MAX 22
UNITS k s
Wetting Current IN0-IN7 Input Impedance in Shutdown LOGIC-LEVELS SDO, DO0, DO1 Output Voltage High SDO, DO0, DO1 Output Voltage Low INT, OT Output Voltage Low SD Input Leakage Current SD Input-Voltage Low SD Input-Voltage High CS, CLK, SDI Input-Voltage Low CS, CLK, SDI Input-Voltage High CS, CLK Input Leakage Current INT, OT Leakage Current SDI Input Impedance THERMAL SHUTDOWN Thermal Shutdown Temperature Thermal Shutdown Hysteresis
IWET
RWET = 30k, VBAT = 14V RWET = 330k VSD = 0V, VIN_ = +14V
28
40 7.5
51
mA
5.5
8.5
M
VOH VOL VINTL IL_SD VIL_SD VIH_SD VIL VIH IIL IOL RSDI TSHDN THYST
Source current = 2mA Sink current = 4mA Sink current = 4mA VSD = VBAT = +12V
0.8 x VL 0.2 x VL 0.4 15 2.4 0.33 x VL 0.66 x VL -1 -1 65 100 +170 15 +1 +1 145 30 0.8
V V V A V V V V A A k C C
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Automotive Contact Monitor and Level Shifter MAX13036
TIMING CHARACTERISTICS
(VL = +2.7V to +5.5V, BAT = +6V to +26V, SD = VL, TA = -40C to +125C, unless otherwise noted. Typical values are at VL = +3.3V, BAT = +14V, TA = +25C) (Note 1)
PARAMETER IN0 to DO0 Propagation Delay IN1 to DO1 Propagation Delay CLK Frequency Falling Edge of CS to Rising Edge of CLK Required Setup Time Falling Edge of CLK to Rising Edge of CS Required Setup Time SDI Valid to Falling Edge of CLK Required Setup Time Falling Edge of CLK to SDI Required Hold Time Time From Falling Edge of CS to SDO Low Impedance Time From Rising Edge of CS to SDO High Impedance Time from Rising Edge of CLK to SDO Data Valid Debounce time Scanning Time Pulse Scanning Time Period Wetting Time Pulse Time from Shutdown To Normal Operation SYMBOL tPROP fCLK tLEAD tLAG tSI(SU) tSI(HOLD) tSO(EN) tSO(DIS) tVALID tDEB tSCAN tSCAN_P tWET SC2 = 0, SC1 = 1, SC0 = 1 WTOFF = 0 SD low-to-high transition to input monitoring enabled VBAT = 6V VBAT = +14V Input rise/fall time < 2ns, VL = +3.0V to +5.5V Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 VL = +3.0V to +5.5V, Figures 1 and 2 CSDO =15pF, VL = +3.0V to +5.5V, Figure 1 CTDEB = 500pF CTDEB = 10nF (Note 6) 3.18 63 130 4 10 5.9 120 250 8 21 200 110 50 30 20 55 55 70 9.42 188 400 14 35 CONDITIONS MIN TYP 22 22 5 MAX 35 UNITS s MHz ns ns ns ns ns ns ns ms s ms ms s
Note 1: All units are 100% production tested at TA = +125C. Limits over the operating temperature range are guaranteed by correlation to the +125C tests. Note 2: The total supply current is the sum of the current flowing into VL, BAT, and BATREF. Note 3: VTH_C = (VTH_HIGH + VTH_LOW)/2. Note 4: VTH_HYS = (VTH_HIGH - VTH_LOW). Note 5: Wetting current rise/fall time is measured as the time from 10% to 90% of the maximum wetting current. Note 6: Guaranteed by design.
4
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Automotive Contact Monitor and Level Shifter
Test Circuits/Timing Diagrams
MAX13036
CS tLEAD CLK tSI(SU) tSI(HOLD) tLAG
SDI tSO(EN)
MSB IN tVALID tSO(DIS)
SDO
MSB OUT
LSB OUT
Figure 1. SPI Timing Characteristics
VL CS 1k
MAX13036
CS SDO 15pF SDO
tSO(EN)
tSO(DIS)
1/3VL
VOL + 0.1VL
Figure 2. SDO Enable/Disable Test Circuit and Timing Diagram
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Automotive Contact Monitor and Level Shifter MAX13036
Typical Operating Characteristics
(VL = +3.3V, BAT = +14V, SD = VL, RWET = 61k, RHYST = 90k, CTDEB = 4700pF, TA = +25C, unless otherwise noted.)
WETTING CURRENT PULSE (NORMAL MODE, WTOFF = 0, WEN = WEND = 1)
MAX13036 toc03 MAX13036 toc02
WETTING CURRENT vs. VBAT
MAX13036 toc01
WETTING CURRENT vs. RWET
60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 30 80 BAT-CONNECTED SWITCH
40 30 WETTING CURRENT (mA) 20 10 0 BAT-CONNECTED SWITCH -10 -20 -30 6 10 14 18 VBAT (V) 22 GND-CONNECTED SWITCH
GND-CONNECTED SWITCH
VIN_ 10V/div INT 2V/div
WETTING CURRENT (mA)
IIN_ 20mA/div
26
130
180 230 RWET (k)
280
330
20ms/div
BAT CURRENT vs. TEMPERATURE (NORMAL MODE)
MAX13036 toc04
BAT CURRENT vs. TEMPERATURE (SHUTDOWN MODE)
MAX13036 toc05
BAT CURRENT vs. TEMPERATURE (SCAN MODE)
MAX13036 toc06
100 90 80 70 IBAT (A) ADJUSTABLE HYSTERESIS ON
5 SD = LOW 4
30 25 SCANNING PERIOD = 2ms 20
IBAT (A)
IBAT (A)
60 50 40 30 20 10 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) ADJUSTABLE HYSTERESIS OFF
3
15 SCANNING PERIOD = 64ms 10
2
1
5 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
0
TYPICAL IN0 DRIVING (NORMAL MODE, WTOFF = WEN = WEND = 0)
MAX13036 toc07
TYPICAL IN0 DRIVING (NORMAL MODE, WTOFF = WEN = WEND = 0)
MAX13036 toc08
HYSTERESIS vs. RHYST
ADJUSTABLE HYSTERESIS ON 7 6 HYSTERESIS (V) 5 4 3 2 1 0
MAX13036 toc09
f = 5kHz VIN0 5V/div VIN0 5V/div
f = 100Hz ADJUSTABLE HYSTERESIS OFF
8
VDO0 2V/div
VDO0 2V/div
40s/div
2ms/div
0
200k
400k 600k RHYST ()
800k
1M
6
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Automotive Contact Monitor and Level Shifter
Typical Operating Characteristics (continued)
(VL = +3.3V, BAT = +14V, SD = VL, RWET = 61k, RHYST = 90k, CTDEB = 4700pF, TA = +25C, unless otherwise noted.)
MAX13036
SWITCHING THRESHOLD vs. TEMPERATURE
MAX13036 toc10
SWITCHING THRESHOLD vs. VBAT
ADJUSTABLE HYSTERESIS OFF SWITCHING THRESHOLD (V) 20
MAX13036 toc11
10 ADJUSTABLE HYSTERESIS OFF SWITCHING THRESHOLD (V) 9
25
8 VIN_ RISING 7 VIN_ FALLING 6
15 VIN_ RISING 10
5 VIN_ FALLING
5 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
0 6 10 14 18 VBAT (V) 22 26
INPUT WAVEFORM IN SCAN MODE (SCAN MODE, WTOFF = WEN = 0, WEND = 1)
MAX13036 toc12
DEBOUNCE TIME vs. TEMPERATURE
55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40
MAX13036 toc13
SCANNING PERIOD = 2ms INPUT SWITCH OPEN DEBOUNCE TIME (ms) 400s/div VIN_ 5V/div
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
DEBOUNCE TIME vs. BAT VOLTAGE
55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 6 10 14 18 VBAT (V) 22
MAX13036 toc14
DEBOUNCE TIME vs. CTDEB
MAX13036 toc15
120 100 DEBOUNCE TIME (ms) 80 60 40 20 0
DEBOUNCE TIME (ms)
26
0
2000
4000 6000 CTDEB (pF)
8000
10000
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Automotive Contact Monitor and Level Shifter MAX13036
Pin Description
PIN 1 2 3 4 5 6 7 8, 20, 27 9 10 11 12, 24 13 14 15 16 17 18 19 21 22 23 25 NAME IN1 IN2 IN3 IN4 IN5 IN6 IN7 N.C. HYST WET TDEB GND OT INT CS SDO SDI CLK VL DO1 DO0 SD BATREF FUNCTION Switch Input Channel 1. Connect IN1 to a switch connected to GND. IN1 can be programmed as a direct input with a level-shifted output on DO1 (see the Mechanical Switch Inputs (IN0-IN7) section). Switch Input Channel 2. Connect IN2 to a switch connected to GND. Switch Input Channel 3. Connect IN3 to a switch connected to GND. Switch Input Channel 4. Connect IN4 to a switch connected to GND or BAT. Switch Input Channel 5. Connect IN5 to a switch connected to GND or BAT. Switch Input Channel 6. Connect IN6 to a switch connected to GND or BAT. Switch Input Channel 7. Connect IN7 to a switch connected to GND or BAT. No Connection. Not internally connected. Hysteresis Input. Connect HYST to GND with a 0 to 900k resistor to set the input voltage hysteresis on IN0-IN7. Wetting Current Input. Connect a 30k to 330k resistor from WET to GND to set the wetting current on IN0-IN7. Switch Debounce Time Input. Connect a 500pF to 10nF capacitor from TDEB to GND to set the switch debounce time. Ground Overtemperature Warning Output. OT is an open-drain output that asserts low when the thermal warning threshold is exceeded. Interrupt Output. INT is an open-drain output that asserts low when one or more of the IN0-IN7 inputs change state and is enabled for interrupts. SPI Chip-Select Input. Drive CS low to enable clocking of data into and out of the MAX13036. SPI data is latched into the MAX13036 on the rising edge of CS. SPI Serial Data Output. SPI data is output on SDO on the rising edges of CLK while CS is held low. SDO is tri-stated when CS is high. 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 100k pulldown resistor. SPI Serial Clock Input Logic Power-Supply Input. Connect VL to a positive 2.7V to 5.5V power supply. Bypass VL to ground with a 0.1F capacitor placed as close as possible to VL. Data Output Channel 1. DO1 is the level-shifted output of IN1 when WEND = 0 (normal mode only). Data Output Channel 0. DO0 is the level-shifted output of IN0 when WEND = 0 (normal mode only). Shutdown Input. Drive SD low to place the MAX13036 into shutdown mode. Drive SD high for normal operation. SD is compatible with voltages up to +45V. Battery Reference Input. Switch thresholds are set to 50% of the voltage applied to BATREF. Connect BATREF to the system's battery supply voltage. Battery Supply Input. Connect BAT to a positive 6V to 26V battery supply voltage. Bypass BAT to ground with a 0.1F ceramic capacitor placed as close as possible to BAT. In addition, bypass BAT with a 10F or greater capacitor. Switch Input Channel 0. Connect IN0 to a switch connected to GND. IN0 can be programmed as a direct input with a level-shifted output on DO0 (see Mechanical Switch Inputs (IN0-IN7) section). Exposed Paddle. Connect EP to GND.
26
BAT
28 --
IN0 EP
8
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Automotive Contact Monitor and Level Shifter
Functional Diagram
SD BAT VL
MAX13036
MAX13036
BATREF DIGITAL INTERFACE IN0 IN1 IN2 IN3 IN4 IN5 IN6 IN7 INTERRUPT LOGIC WETTING CURRENT CONTROL LEVEL TRANSLATORS SHIFT REGISTER SPI INTERFACE
DO0 DO1
CS CLK SDI SDO
INT
OT
WET
HYST
TDEB
GND
Detailed Description
The MAX13036 automotive contact monitor and level shifter monitors and debounces eight remote mechanical switches and asserts an interrupt (INT) if a switch changes state. Any of the switch inputs can be prohibited from asserting an interrupt. The switch threshold levels are set to 50% of the voltage applied to BATREF. All switch inputs feature a common adjustable hysteresis, debounce time and wetting current. Two switch inputs (IN0, IN1) are programmable to have direct outputs (DO0, DO1) useable for PWM or other timing based signals. The MAX13036 features an SPI interface to monitor individual switch inputs and to configure interrupt masking, hysteresis and wetting current enable/disable, switch configuration (battery connected or ground connected), and scanning period. The MAX13036 features three modes of operation: normal mode, scan mode, and shutdown mode. In normal mode, the part is fully functional and sensing resistors are connected to all switch inputs. In scan mode, the sensing resistors are connected for a finite duration to reduce power consumption. In shutdown mode, all switch inputs are high impedance to further reduce power consumption.
VL
VL is the power-supply input for the digital input/output buffers. The SPI interface (CS, CLK, SDI, SDO), and digital outputs (DO0, DO1) are referenced to the voltage on VL. Connect VL to the system's +2.7V to +5.5V logic-level supply. Bypass VL to ground with a 0.1F capacitor placed as close as possible to the device.
BAT
BAT is the main power-supply input. Bypass BAT to ground with a 0.1F ceramic capacitor placed as close as possible to BAT. In addition, bypass BAT with a 10F or greater capacitor. BAT can withstand DC voltages up to +42V.
Mechanical Switch Inputs (IN0-IN7)
IN0 through IN7 are the inputs for remote mechanical switches. The status of each switch input is indicated by the SW0 through SW7 bits in the status register, and each switch input can be programmed to not assert an interrupt (INT) by writing to the P0 through P7 bits in the command register. All switch inputs are configured to assert an interrupt upon power-up.
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9
Automotive Contact Monitor and Level Shifter MAX13036
The first four inputs (IN0-IN3) are intended for groundconnected switches. The remaining four inputs (IN4-IN7) can be programmed in sets of two for either ground-connected or battery-connected switches by writing to the M0 and M1 bits (see Table 5). The default state after power-up is IN2-IN7 configured for ground-connected switches, and IN0/IN1 configured for direct inputs. All switch inputs have internal 16k sense resistors to detect switch transitions. Inputs configured for groundconnected switches are pulled up to BAT and inputs configured for battery-connected switches are pulled down to GND. Figure 3 shows the switch input structure for IN0 and IN1. IN0 and IN1 can be programmed as direct inputs with level-shifted outputs (DO0 and DO1) by clearing the WEND bit in the command register (normal mode only). When programmed as direct inputs, IN0 and IN1 can be used for PWM or other signaling. Clearing the WEND bit disables the sense resistors and wetting currents on IN0 and IN1. When programmed as direct inputs, the status of IN0 and IN1 is not reflected in the status register, and interrupts are not allowed on these inputs. reverse-battery protection diode. The MAX13036 features adjustable hysteresis on the switch inputs by connecting an external 0 to 900k resistor from HYST to ground (normal mode only). Short HYST to ground to obtain the maximum hysteresis of (0.5 x VBATREF). The approximate formula for hysteresis is given below: 43 VHYST = 0.166 + (VBATREF ) (123 + (RHYST(k) ) To reduce power consumption, the adjustable hysteresis can be disabled by setting [SC2:SC1:SC0 = 1:1:0] in the command register. When the adjustable hysteresis is disabled, the hysteresis is set to 0.166 x VBATREF.
Switch Debounce and Deglitch
The switch inputs IN0-IN7 share a common programmable debounce timer to increase the noise immunity of the system in normal and scan mode. The switch debounce time is set by connecting a capacitor between the t DEB input and ground. The minimum value of this capacitor is 500pF and the maximum value is 10nF, corresponding to a debounce time of 5ms to 100ms respectively. To calculate other debounce times the following formula should be used: C(nF) = tDEB(ms)/10 All switch input glitches of less than 20s in duration are automatically rejected by the MAX13036.
Switch Threshold Levels and Hysteresis (BATREF, HYST)
Input thresholds for the remote switches are 50% of the voltage applied to BATREF. The BATREF input is typically connected to the battery voltage before the
VBAT
MAX13036
CONTROL LOGIC WETTING* CURRENT 16k*
Debounce in Normal Mode When a change of state occurs at the switch input the debounce timer starts. If the new state is stable for at least tDEB, the status register is updated and an interrupt is generated (if enabled). If the input returns to its previous state before the debounce time has elapsed, an interrupt is not generated and the status register is not updated. Debounce in Scan Mode A change of state at the switch input causes the device to automatically enter normal mode and the debounce timing to start. The device remains in normal mode as long as the input state differs from the previous state. As soon as the debounce time ends, the status register is updated, an interrupt is generated, and the device re-enters scan mode.
If the input returns to its previous state before the end of the debounce time, the device re-enters scan mode, an interrupt is not generated, and the status register is not updated.
IN0, IN1
NOTES: * WETTING CURRENT AND PULLUP/DOWN RESISTORS ARE CONTROLLED BY THE WEN AND WEND BITS IN THE COMMAND REGISTER (SEE TABLE 4)
Figure 3. Input Structure of IN0 and IN1
10 ______________________________________________________________________________________
Automotive Contact Monitor and Level Shifter
Wetting Current (WET)
The MAX13036 features adjustable wetting current to any closed switch to clean switch contacts that are exposed to adverse conditions. The wetting current is set by connecting a 30k to 330k resistor from WET to ground. A 30k resistor corresponds to a wetting current of 40mA (typ) and a 330k resistor corresponds to a 7.5mA (typ) wetting current. See the Typical Operating Characteristics section for the relationship between the wetting current and RWET. The WEN and WEND bits in the command register enable and disable the wetting currents and the WTOFF bit allows the wetting current to be activated for a duration of 20ms (typ) (see the Command Register section). Disabling wetting currents, or limiting the active wetting current time reduces power consumption. The default state upon power-up is all wetting currents disabled. Wetting current is activated on closed switches just after the debounce time. The wetting current pulse starts after the debounce time. A wetting current pulse is provided to all closed switches when a valid input change is detected. Wetting current rise and fall times are controlled to enhance EMC performance. There is one wetting current timer for all switch inputs. Therefore, it is possible to observe wetting pulses longer than expected whenever two switches turn on in sequence and are spaced out less than tWET. In scan mode, the wetting current is enabled during the polling pulse only. When using wetting currents, special care must be taken to avoid exceeding the maximum power dissipation of the MAX13036 (see the Applications Information section). The INT output will still assert when VL is absent provided that it is pulled up to a different supply voltage.
MAX13036
Thermal Protection (OT)
The MAX13036 features thermal protection that prevents the device from being damaged by overheating. When the internal temperature of the device exceeds the thermal warning threshold of +170C (typ), all wetting currents are disabled. The MAX13036 returns to normal operation after the internal temperature decreases below +155C (typ). The thermal shutdown does not activate below +150C. The thermal protection feature is disabled when WEN = 0 or when all inputs are open. An open-drain, active-low output (OT) asserts low when the internal temperature of the device rises above the thermal warning threshold. OT is immediately cleared when the CS input is driven low for write/read operations, regardless of whether the temperature is above the threshold or not. The overtemperature status of the MAX13036 can also be monitored by reading the OT bit in the status register. The OT bit is set when the internal temperature rises above the temperature threshold and it is cleared when the temperature falls below the temperature hysteresis level. This allows a microprocessor (P) to monitor the overtemperature status, even if the OT output has been cleared. See Figure 4 for an example timing diagram of the overtemperature alerts. If desired, the OT and INT outputs can be connected to the same P GPIO in a wired-OR configuration to save a P pin. The OT output still asserts when VL is absent provided that it is pulled up to a different supply voltage.
Switch Outputs (DO0, DO1)
DO0 and DO1 are direct level-shifted outputs of the switch inputs IN0 and IN1 when the WEND bit of the command register is cleared and when operating in normal mode. When configured as direct inputs, the wetting currents and sensing resistors are disabled on IN0 and IN1. DO0 and DO1 are tri-stated when the WEND bit is set or when operating in scan mode. When programmed as direct inputs, the status of IN0 and IN1 are not reflected in the status register and interrupts are not allowed on these inputs.
Serial Peripheral Interface (CS, SD0, SDI, CLK)
The MAX13036 operates as a Serial Peripheral Interface (SPI) slave device. An SPI master accesses the MAX13036 by reading from a status register and writing to a command register. Both registers are 16 bits long and are accessed most significant bit (MSB) first.
TEMPERATURE
Interrupt Output (INT)
INT is an active-low, open-drain output that asserts when any of the switch inputs changes state, as long as the particular input is enabled for interrupts (set by clearing P7-P0 in the command register). A pullup resistor to VL is needed on INT. INT is cleared when CS is driven low for a read/write operation.
OT CS OT BIT
Figure 4. Example Timing Diagram of the Overtemperature Alerts
11
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Automotive Contact Monitor and Level Shifter MAX13036
STATUS REGISTER IS COPIED TO SHIFT REGISTER CS CLK SDI SDO * = UNUSED. 15 14 13 SC1 SW5 12 SC0 SW4 11 10 9 M1 SW1 8 M0 SW0 7 P7 OT 6 P6 * 5 P5 * 4 P4 * 3 P3 * 2 P2 * 1 P1 * 0 P0 * SHIFT REGISTER IS COPIED TO COMMAND REGISTER
WTOFF SC2 SW7 SW6
WEN WEND SW3 SW2
Figure 5. SPI Read/Write Example
On the falling edge of CS, the status register is immediately loaded to an internal shift register and the contents are transferred out of the SDO output on the rising edge of CLK. Serial data on the SDI input is latched into the shift register on the falling edge of CLK. On the rising edge of CS, the contents of the shift register are copied to the command register (see Figure 5). The status and command registers are 16 bits wide, so it is essential to clock a total of 16 bits while CS is low for the input and output data to be valid. When CS is high, the SDO output is high-impedance and any transitions on CLK and SDI are ignored. The INT and OT flags are cleared on the CS falling edge. Input status changes occurring during the CS reading/writing operation are allowed. If a switch status changes when CS is low, the interrupt is asserted as usual. This allows the part to be used even if VL is absent provided that the INT output is pulled up to another supply voltage.
Notes: Bits 15-8: Switch 7 Through 0 Status (SW7-SW0) SW7 through SW0 reflect the status of the switches connected to inputs IN7 through IN0, respectively. Open switches are returned as a [0] and closed switches are returned as a [1]. Bit 7: Overtemperature Warning (OT) The OT bit returns a [1] when the internal temperature of the MAX13036 is above the temperature warning threshold of +170C (typ). The OT bit returns a [0] when the MAX13036 is either below the temperature threshold, or it has fallen below the temperature hysteresis level following an overtemperature event. Bits 6-0: Unused Bits 6 through 0 are unused and should be ignored.
Status Register The status register contains the status of the switches connected to IN7 through IN0 and it also contains an overtemperature warning bit (see Table 1). The status register is accessed through an SPI-compatible master.
Command Register The command register is used to configure the MAX13036 for various modes of operation and is accessed by an SPI-compatible master (see Table 2). The power-on reset (POR) value of the command register is 0x00.
Table 1. Status Register
BIT NAME 15 SW7 14 SW6 13 SW5 12 SW4 11 SW3 10 SW2 9 SW1 8 SW0 7 OT 6 -- 5 -- 4 -- 3 -- 2 -- 1 -- 0 --
Table 2. Command Register
BIT NAME POR 15 WTOFF 0 14 SC2 0 13 SC1 0 12 SC0 0 11 WEN 0 10 WEND 0 9 M1 0 8 M0 0 7 P7 0 6 P6 0 5 P5 0 4 P4 0 3 P3 0 2 P2 0 1 P1 0 0 P0 0
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Automotive Contact Monitor and Level Shifter
Notes: Bit 15: Wetting Current Mode (WTOFF) Set the WTOFF bit to configure the wetting currents as continuous on closed switches. Clear the WTOFF bit to configure the wetting current as a pulse where the wetting current is turned on for a set duration of 20ms after a switch closes (and the debounce is timed out). After 20ms elapses, the wetting current is turned off. Either wetting current mode is only applicable to switches that have wetting currents enabled (see WEN and WEND bits). In scan mode, the wetting currents are on for the polling time of 250s (typ) and are pulsed at the programmed scanning period. When WTOFF is set, the wetting current continuously pulses at the programmed scanning period. When WTOFF is cleared, the wetting current pulses at the programmed scanning period, but turns off after 20ms elapses. Bits 14, 13, 12: Scanning Period (SC2, SC1, SC0) The SC2, SC1, and SC0 bits are used to program the scanning period as depicted in Table 3. Switch inputs are simultaneously polled for a finite duration of 250s (typ) and polling occurs at a period selected through the SC2, SC1, and SC0 inputs. Figure 6 shows a timing diagram of switch scanning and sampling. When the inputs are not being polled, the sense resistors are discon-nected, reducing the current consumption caused from polling closed switches. For a continuous scanning period ([SC2:SC1:SC0] = [1:1:1] or [1:1:0]), the switch inputs are constantly being monitored and the sense resistors are always connected. The state [SC2:SC1:SC0] = [1:1:0] also disables adjustable hysteresis (normally set by RHYST) and fixes hysteresis at 0.166 x VBATREF. When adjustable hysteresis is not needed, it is recommended to disable this feature to reduce power consumption. Bit 11: Global Wetting Current Enable (WEN) The WEN bit is a global enable for the wetting currents on all the channels. Set the WEN bit to enable wetting currents on all channels and clear the WEN bit to disable wetting currents. Even with wetting currents globally enabled, the wetting currents and sense resistors on IN0 and IN1 can still be turned off with the WEND bit (see Table 4). Bit 10: IN0 and IN1 Wetting Current Enable (WEND) The WEND bit is used to turn on wetting currents and sense resistors on inputs IN0 and IN1. Set the WEND bit to enable wetting currents on IN0 and IN1 and clear the WEND bit to turn off the wetting current and sense resistors on IN0 and IN1. When the wetting currents and sense resistors are disabled (WEND = 0), IN0 and IN1 are configured as direct inputs with level-shifted outputs on DO0 and D01. DO0 and DO1 can only be used as level-shifted outputs in normal mode and are tri-stated in scan mode (see the Scan Mode section). Note that both the WEN and WEND bits need to be set for wetting currents to be enabled on IN0 and IN1 (see
tSCAN
MAX13036
Table 3. Programmable Scanning Period
SC2 0 0 0 0 1 1 1 1 SC1 0 0 1 1 0 0 1 1 SC0 0 1 0 1 0 1 0 1 SCANNING PERIOD (ms) 64 32 16 8 4 2 Continuous / Adjustable Hysteresis Off Continuous
SWITCHES ARE POLLED FOR 250s
GND-CONNECTED SWITCH INPUT tSCAN-P INT
SWITCH DEBOUNCE STARTS
tDEB
SWITCH CLOSES
STATUS REGISTERS AND INT ARE UPDATED AFTER tDEB
Figure 6. Switch Sampling in Scan Mode
Table 4. Truth Table for WEN and WEND
WEN 0 0 1 1 WEND 0 1 0 1 WETTING CURRENT (IN0, IN1) Off Off Off On 16k SENSE RESISTOR (IN0, IN1) Off On Off On WETTING CURRENT (IN2-IN7) Off Off On On 16k SENSE RESISTOR (IN2-IN7) On On On On
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Automotive Contact Monitor and Level Shifter MAX13036
Table 5. Switch Configuration Controlled by M1 and M0
M1 0 0 1 1 M0 0 1 0 1 IN7 AND IN6 SWITCH CONFIGURATION Ground Ground Battery Battery IN5 AND IN4 SWITCH CONFIGURATION Ground Battery Ground Battery IN3-IN0 SWITCH CONFIGURATION Ground Ground Ground Ground
Table 4). The DO0 and DO1 outputs are tri-stated when WEND = 1. When programmed as direct inputs (WEND = 0), any input changes on IN0 and IN1 are not reflected by the status register. Bits 9 and 8: Switch Configuration for IN7-IN4 (M1, M0) The M1 and M0 bits set the switch configuration in groups of two for IN7 through IN4 (see Table 5). Set M1 to configure IN7 and IN6 for battery-connected switches and clear M1 for ground-connected switches. Set M0 to configure IN5 and IN4 for battery-connected switches and clear M0 for ground-connected switches. Bits 7-0: Interrupt Enable for IN7-IN0 (P7-P0) The P7 through P0 bits allow independent control of whether inputs IN7 through IN0 generate an interrupt (INT). Set any bit to disable interrupts on the corresponding input and clear the bit to enable interrupts on the corresponding channel. An interrupt is asserted when any input configured for interrupts changes state. IN0 and IN1 do not generate an interrupt when configured as direct inputs (WEND = 0).
command register to ([SC2:SC1:SC0] = [1:1:0]). The hysteresis is set to 0.166 x VBATREF when adjustable hysteresis is disabled.
Operating Modes
The MAX13036 features three modes of operation: normal mode, scan mode, and shutdown mode. Normal mode is entered when the scanning period bits in the command register are configured for continuous scanning ([SC2:SC1:SC0] = [1:1:1] or [1:1:0]). Scan mode is entered when the scanning period bits are set for a periodic scanning time as shown in Table 3. Shutdown mode is entered by driving the shutdown input (SD) low. The default mode after power-up is scan mode (when SD = high) with a scan period of 64ms.
Scan Mode In scan mode, each sense resistor is connected for a finite duration of 250s (typ) and is repeated at a period according to the scanning period bits SC2, SC1, and SC0 (see Table 3). All input resistors are connected simultaneously and the inputs are polled at the same time. Scan mode reduces the current consumption from BAT to 17A (typ) when all external switches are open and the scanning period is 64ms. Wetting currents (if enabled) are applied to closed switches during the polling time of 250s (typ) and are pulsed at the programmed scanning period. When WTOFF is set, the wetting current continuously pulses at the programmed scanning period. When WTOFF is cleared, the wetting current pulses at the programmed scanning period, but turns off after 20ms elapses. Inputs IN0 and IN1 cannot be used as direct inputs (WEND = 0) in scan mode. When configured as direct inputs in scan mode, the outputs DO0 and DO1 are high impedance. The quiescent current for a given scan mode can be calculated by the following formula:
1 IBAT(A) = 16 x 1 + t SCAN _ P(ms) Where SD = 3.3V, IBAT is the BAT current expressed in microamps and t SCAN_P is the scanning period expressed in miliseconds.
Normal Mode (Continuous Scanning) In normal mode, the input sense resistors are always connected to the switch inputs to detect any input status change (except IN0 and IN1 when WEND = [0]). Wetting currents are enabled according to the WEN, WEND and WTOFF bits in the command register. If adjustable hysteresis is not required, this feature can be disabled to reduce power consumption (see the Typical Operating Characteristics) by setting the scanning period bits in the
14
Shutdown Mode In shutdown mode, all switch inputs are high impedance and the external switches are no longer monitored, reducing current consumption on BAT to 2A (typ). The MAX13036 resets upon entering shutdown mode and the contents of the command register are lost. Exit shutdown mode by bringing the voltage on SD above +2.4V. The SD input is compatible with voltages up to VBAT. The MAX13036 takes 200s (typ) to exit shutdown, at which point the command register is restored to its power-up
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Automotive Contact Monitor and Level Shifter
default (0x00) and the MAX13036 enters scan mode. Note that SD is compatible with both VL and BAT voltage levels. Having SD compatible to V BAT allows the MAX13036 to retain the settings in the command register as well as input monitoring even when VL is missing, provided that SD = VBAT. To reduce current consumption, connect SD to BAT through a 470k resistor. Having SD compatible with VL has the advantage of reducing input leakage current into SD when SD = VL.
Human Body Model The MAX13036 IN7-IN0 pins are characterized for 8kV ESD protection using the Human Body Model. Figure 7a shows the Human Body Model and Figure 7b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the device through a 1.5k resistor.
RC 1M CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 1500 DISCHARGE RESISTANCE DEVICE UNDER TEST
MAX13036
Applications Information
Automotive Considerations
Reverse-Battery Tolerance The BATREF and IN0-IN7 inputs withstand voltages down to -45V without damage so that reverse battery is not an issue. The BAT pin should be protected with a reverse-battery diode as shown in the Typical Application Circuit. The shutdown input (SD) can be controlled from a battery-level source but should be protected against reverse battery in the application.
Cs 100pF
STORAGE CAPACITOR
Wetting Currents and Power Dissipation
It is important to consider the effects of wetting currents on the power dissipated by the MAX13036. For example, assume all inputs are configured for a continuous wetting current of 25mA, all external switches have an on-resistance of 1 and the battery voltage is 16V. If all switches are simultaneously closed, the corresponding power dissipated by the MAX13036 is (16V - (25mA x 1)) x 25mA x 8 = 3.12W; this is higher than the absolute maximum power dissipation of 2759mW at TA = +70C.
Figure 7a. Human Body ESD Test Model
IP 100% 90% AMPERES 36.8% 10% 0 0 tRL TIME
Ir
PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE)
ESD Protection
As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The IN7-IN0 inputs have extra protection against static electricity. Maxim's engineers have developed state-ofthe-art structures to protect these pins against ESD of 8kV without damage.
tDL CURRENT WAVEFORM
Figure 7b. Human Body Model Current Waveform
Chip Information
PROCESS: BiCMOS
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15
Automotive Contact Monitor and Level Shifter MAX13036
Typical Application Circuit
ECU CONNECTOR 0.01F
BATTERY +6V TO +26V, +42V LOAD DUMP
4700pF
IN0 TDEB
IN1
IN2
IN3
IN4
IN5
IN6
IN7 BATREF BAT
WET HYST 61k 90k GND DO0 DO1 SD SDO SDI CLK CS INT OT VL 0.1F 20k
47F 0.1F IN +3.3V REGULATOR OUT
MAX13036
20k
P
16
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Automotive Contact Monitor and Level Shifter
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
MAX13036
PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
21-0140
K
1
2
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QFN THIN.EPS
17
Automotive Contact Monitor and Level Shifter MAX13036
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
21-0140
K
2
2
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.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2007 Maxim Integrated Products
Springer
is a registered trademark of Maxim Integrated Products. Inc.

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