19-0808; Rev 0; 4/07 KIT ATION EVALU E L B AVAILA Automotive Contact Monitor and Level Shifter 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 SPI™ 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 -40°C to +125°C temperature range. Applications Body Computers Electric Sunroofs Window Lifters Other Control ECUs 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 17µA (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 Seat Movers Ordering Information CLK SDI SDO CS 16 15 VL 19 17 N.C. 20 PART 18 DO1 TOP VIEW 21 Pin Configuration MAX13036ATI+ -40°C to +125°C 14 INT 23 13 OT DO0 22 SD *EP GND 24 12 GND BATREF 25 11 TDEB BAT 26 10 WET N.C. 27 9 HYST INO 28 8 N.C. MAX13036 4 5 6 7 IN6 IN7 3 IN3 IN4 2 IN2 IN5 1 IN1 + TQFN TEMP RANGE PINPACKAGE PKG CODE 28 TQFN-EP* (5mm x 5mm) T2855-8 + Denotes lead-free package. *EP = Exposed paddle. Typical Application Circuit appears at end of data sheet. SPI is a trademark of Motorola, Inc. *CONNECT EXPOSED PADDLE TO GROUND ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX13036 General Description MAX13036 Automotive Contact Monitor and Level Shifter 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 = +70°C, multilayer board) 28-Pin TQFN (derate 34.5mW/°C above +70°C) .......2759mW Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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 = -40°C to +125°C, unless otherwise noted. Typical values are at VL = +3.3V, BAT = +14V, TA = +25°C) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS POWER SUPPLY VL Supply Range VL VL Supply Current IL BAT Supply Range VBAT Total Supply Current Total Supply Current in Scan Mode 2.7 VL = +5.5V, VBAT = +14V 0 6 5.5 V 1 µA 26 V ISUP VL = +5V, VBAT = +14V, continuous scan, programmable hysteresis off, M0 = M1 =1, WEND = 1, IN0–IN7 = unconnected, CS = VL, SDI = CLK = GND (Note 2) 46 80 µA ISUP_SCAN VBAT = +14V, scan mode (SC0 = 0, SC1= 0, SC2 = 0), CS = VL, SDI = CLK = GND (Note 2) 17 36 µA 2 3.2 VSD = 0V, TA = +25°C VBAT = +14V, VBATREF = +14V TA = -40°C to +125°C (Note 2) Total Supply Current in Shutdown Mode ISHDN BATREF Input Leakage Current in Shutdown IL_BATREF VSD = 0V, VBATREF = +14V BATREF Input Resistance RBATREF VBATREF = +14V µA 2 4.0 1 1 µA MΩ SWITCH INPUTS (IN0–IN7) Input-Voltage Threshold Center (Note 3) Input-Voltage Threshold Hysteresis (Note 4) VTH_C RHYST = ∞ or programmable hysteresis disabled 0.575 x VBATREF 0.4 x 0.5 x VBATREF VBATREF RHYST = ∞ or programmable hysteresis disabled 0.133 x VBATREF 0.166 x VBATREF 0.22 x VBATREF RHYST = 90kΩ 0.26 x VBATREF 0.361 x VBATREF 0.48 x VBATREF RHYST = 0Ω 2 0.5 x VBATREF 0.63 x VBATREF RHYST = 90kΩ VTH_HYS 0.425 x VBATREF 0.5 x VBATREF _______________________________________________________________________________________ V V Automotive Contact Monitor and Level Shifter (VL = +2.7V to +5.5V, BAT = +6V to +26V, SD = VL, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VL = +3.3V, BAT = +14V, TA = +25°C) (Note 1) PARAMETER Switch-State Sense Resistor Wetting Current Rise/Fall Time SYMBOL CONDITIONS RSENSE IWET_RISE_ FALL RWET = 61kΩ (Note 5) MIN TYP MAX UNITS 11 16 22 kΩ Rise 6 Fall 1 RWET = 61kΩ Wetting Current IWET RWET = 30kΩ, VBAT = 14V 22 28 RWET = 330kΩ IN0–IN7 Input Impedance in Shutdown µs 40 51 mA 7.5 VSD = 0V, VIN_ = +14V 5.5 0.8 x VL 8.5 MΩ LOGIC-LEVELS SDO, DO0, DO1 Output Voltage High VOH Source current = 2mA SDO, DO0, DO1 Output Voltage Low VOL Sink current = 4mA INT, OT Output Voltage Low VINTL Sink current = 4mA SD Input Leakage Current IL_SD VSD = VBAT = +12V SD Input-Voltage Low VIL_SD SD Input-Voltage High VIH_SD V 0.2 x VL 15 V 0.4 V 30 µA 0.8 V 2.4 V 0.33 x VL CS, CLK, SDI Input-Voltage Low VIL CS, CLK, SDI Input-Voltage High VIH 0.66 x VL CS, CLK Input Leakage Current IIL -1 +1 µA INT, OT Leakage Current IOL -1 +1 µA RSDI 65 145 kΩ SDI Input Impedance V V 100 THERMAL SHUTDOWN Thermal Shutdown Temperature TSHDN +170 °C Thermal Shutdown Hysteresis THYST 15 °C _______________________________________________________________________________________ 3 MAX13036 ELECTRICAL CHARACTERISTICS (continued) MAX13036 Automotive Contact Monitor and Level Shifter TIMING CHARACTERISTICS (VL = +2.7V to +5.5V, BAT = +6V to +26V, SD = VL, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VL = +3.3V, BAT = +14V, TA = +25°C) (Note 1) PARAMETER IN0 to DO0 Propagation Delay IN1 to DO1 Propagation Delay SYMBOL tPROP TYP MAX VBAT = 6V CONDITIONS MIN 22 35 VBAT = +14V 22 UNITS µs CLK Frequency fCLK Input rise/fall time < 2ns, VL = +3.0V to +5.5V Falling Edge of CS to Rising Edge of CLK Required Setup Time tLEAD Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 110 ns Falling Edge of CLK to Rising Edge of CS Required Setup Time tLAG Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 50 ns SDI Valid to Falling Edge of CLK Required Setup Time tSI(SU) Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 30 ns tSI(HOLD) Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 20 ns Time From Falling Edge of CS to SDO Low Impedance tSO(EN) Input rise/fall time < 2ns, VL = +3.0V to +5.5V, Figure 1 55 ns Time From Rising Edge of CS to SDO High Impedance tSO(DIS) VL = +3.0V to +5.5V, Figures 1 and 2 55 ns Time from Rising Edge of CLK to SDO Data Valid tVALID CSDO =15pF, VL = +3.0V to +5.5V, Figure 1 70 ns Falling Edge of CLK to SDI Required Hold Time Debounce time tDEB Scanning Time Pulse tSCAN Scanning Time Period tSCAN_P Wetting Time Pulse Time from Shutdown To Normal Operation tWET CTDEB = 500pF CTDEB = 10nF (Note 6) 5 3.18 5.9 9.42 63 120 188 ms 130 250 400 µs SC2 = 0, SC1 = 1, SC0 = 1 4 8 14 ms WTOFF = 0 10 21 35 ms SD low-to-high transition to input monitoring enabled 200 Note 1: All units are 100% production tested at TA = +125°C. Limits over the operating temperature range are guaranteed by correlation to the +125°C 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 MHz _______________________________________________________________________________________ µs Automotive Contact Monitor and Level Shifter CS tLEAD tLAG CLK tSI(SU) SDI tSI(HOLD) MSB IN tSO(EN) SDO tSO(DIS) tVALID MSB OUT LSB OUT Figure 1. SPI Timing Characteristics VL CS 1kΩ tSO(EN) MAX13036 CS tSO(DIS) SDO 15pF SDO 1/3VL VOL + 0.1VL Figure 2. SDO Enable/Disable Test Circuit and Timing Diagram _______________________________________________________________________________________ 5 MAX13036 Test Circuits/Timing Diagrams Typical Operating Characteristics (VL = +3.3V, BAT = +14V, SD = VL, RWET = 61kΩ, RHYST = 90kΩ, CTDEB = 4700pF, TA = +25°C, unless otherwise noted.) WETTING CURRENT (mA) 20 GND-CONNECTED SWITCH 0 BAT-CONNECTED SWITCH -10 -20 -30 10 14 18 VBAT (V) 22 ADJUSTABLE HYSTERESIS ON MAX13036 toc02 BAT-CONNECTED SWITCH 30 80 130 180 230 RWET (kΩ) 280 20ms/div 330 BAT CURRENT vs. TEMPERATURE (SHUTDOWN MODE) 5 MAX13036 toc04 80 IIN_ 20mA/div -30 -40 -50 -60 BAT CURRENT vs. TEMPERATURE (NORMAL MODE) 90 INT 2V/div -10 -20 26 100 GND-CONNECTED SWITCH BAT CURRENT vs. TEMPERATURE (SCAN MODE) SD = LOW 30 4 25 SCANNING PERIOD = 2ms 70 20 50 ADJUSTABLE HYSTERESIS OFF 3 IBAT (μA) IBAT (μA) 60 40 MAX13036 toc06 6 MAX13036 toc03 VIN_ 10V/div MAX13036 toc05 30 WETTING CURRENT (mA) 60 50 40 30 20 10 0 MAX13036 toc01 40 10 WETTING CURRENT PULSE (NORMAL MODE, WTOFF = 0, WEN = WEND = 1) WETTING CURRENT vs. RWET WETTING CURRENT vs. VBAT IBAT (μA) 2 15 SCANNING PERIOD = 64ms 10 30 1 20 5 10 0 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) TYPICAL IN0 DRIVING (NORMAL MODE, WTOFF = WEN = WEND = 0) TYPICAL IN0 DRIVING (NORMAL MODE, WTOFF = WEN = WEND = 0) MAX13036 toc07 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) HYSTERESIS vs. RHYST MAX13036 toc08 8 f = 100Hz ADJUSTABLE HYSTERESIS OFF f = 5kHz ADJUSTABLE HYSTERESIS ON 7 VIN0 5V/div VIN0 5V/div VDO0 2V/div MAX13036 toc09 0 6 HYSTERESIS (V) MAX13036 Automotive Contact Monitor and Level Shifter VDO0 2V/div 5 4 3 2 1 0 40μs/div 6 2ms/div 0 200k 400k 600k RHYST (Ω) _______________________________________________________________________________________ 800k 1M Automotive Contact Monitor and Level Shifter SWITCHING THRESHOLD vs. TEMPERATURE 9 8 VIN_ RISING 7 VIN_ FALLING 6 MAX13036 toc11 SWITCHING THRESHOLD (V) ADJUSTABLE HYSTERESIS OFF SWITCHING THRESHOLD vs. VBAT 25 ADJUSTABLE HYSTERESIS OFF SWITCHING THRESHOLD (V) MAX13036 toc10 10 20 15 VIN_ RISING 10 5 VIN_ FALLING 5 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 6 INPUT WAVEFORM IN SCAN MODE (SCAN MODE, WTOFF = WEN = 0, WEND = 1) 22 26 DEBOUNCE TIME (ms) 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 400μs/div MAX13036 toc13 SCANNING PERIOD = 2ms INPUT SWITCH OPEN -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) DEBOUNCE TIME vs. CTDEB DEBOUNCE TIME vs. BAT VOLTAGE MAX13036 toc15 120 MAX13036 toc14 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 100 DEBOUNCE TIME (ms) DEBOUNCE TIME (ms) 14 18 VBAT (V) DEBOUNCE TIME vs. TEMPERATURE MAX13036 toc12 VIN_ 5V/div 10 80 60 40 20 0 6 10 14 18 VBAT (V) 22 26 0 2000 4000 6000 CTDEB (pF) 8000 10000 _______________________________________________________________________________________ 7 MAX13036 Typical Operating Characteristics (continued) (VL = +3.3V, BAT = +14V, SD = VL, RWET = 61kΩ, RHYST = 90kΩ, CTDEB = 4700pF, TA = +25°C, unless otherwise noted.) Automotive Contact Monitor and Level Shifter MAX13036 Pin Description 8 PIN NAME FUNCTION 1 IN1 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). 2 IN2 Switch Input Channel 2. Connect IN2 to a switch connected to GND. 3 IN3 Switch Input Channel 3. Connect IN3 to a switch connected to GND. 4 IN4 Switch Input Channel 4. Connect IN4 to a switch connected to GND or BAT. 5 IN5 Switch Input Channel 5. Connect IN5 to a switch connected to GND or BAT. 6 IN6 Switch Input Channel 6. Connect IN6 to a switch connected to GND or BAT. 7 IN7 Switch Input Channel 7. Connect IN7 to a switch connected to GND or BAT. 8, 20, 27 N.C. No Connection. Not internally connected. 9 HYST Hysteresis Input. Connect HYST to GND with a 0 to 900kΩ resistor to set the input voltage hysteresis on IN0–IN7. 10 WET Wetting Current Input. Connect a 30kΩ to 330kΩ resistor from WET to GND to set the wetting current on IN0–IN7. 11 TDEB Switch Debounce Time Input. Connect a 500pF to 10nF capacitor from TDEB to GND to set the switch debounce time. 12, 24 GND Ground 13 OT Overtemperature Warning Output. OT is an open-drain output that asserts low when the thermal warning threshold is exceeded. 14 INT 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. 15 CS 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. 16 SDO 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. 17 SDI 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 100kΩ pulldown resistor. 18 CLK 19 VL 21 DO1 22 DO0 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 0.1µF 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). 23 SD 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. 25 BATREF Battery Reference Input. Switch thresholds are set to 50% of the voltage applied to BATREF. Connect BATREF to the system’s battery supply voltage. 26 BAT Battery Supply Input. Connect BAT to a positive 6V to 26V battery supply voltage. Bypass BAT to ground with a 0.1µF ceramic capacitor placed as close as possible to BAT. In addition, bypass BAT with a 10µF or greater capacitor. 28 IN0 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). — EP Exposed Paddle. Connect EP to GND. _______________________________________________________________________________________ Automotive Contact Monitor and Level Shifter SD BAT VL DO0 MAX13036 DO1 BATREF DIGITAL INTERFACE IN0 CS SPI INTERFACE IN1 IN3 IN4 CLK SDI IN2 WETTING CURRENT CONTROL LEVEL TRANSLATORS SDO SHIFT REGISTER INT IN5 INTERRUPT LOGIC IN6 OT IN7 WET HYST TDEB 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. GND 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 0.1µF capacitor placed as close as possible to the device. BAT BAT is the main power-supply input. Bypass BAT to ground with a 0.1µF ceramic capacitor placed as close as possible to BAT. In addition, bypass BAT with a 10µF 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. _______________________________________________________________________________________ 9 MAX13036 Functional Diagram MAX13036 Automotive Contact Monitor and Level Shifter 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 16kΩ 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. 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 16kΩ* IN0, IN1 NOTES: * WETTING CURRENT AND PULLUP/DOWN RESISTORS ARE CONTROLLED BY THE WEN AND WEND BITS IN THE COMMAND REGISTER (SEE TABLE 4) reverse-battery protection diode. The MAX13036 features adjustable hysteresis on the switch inputs by connecting an external 0 to 900kΩ 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(kΩ) ) ⎥⎦ ⎢⎣ 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 20µs in duration are automatically rejected by the MAX13036. 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. Figure 3. Input Structure of IN0 and IN1 10 ______________________________________________________________________________________ Automotive Contact Monitor and Level Shifter 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. 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 +170°C (typ), all wetting currents are disabled. The MAX13036 returns to normal operation after the internal temperature decreases below +155°C (typ). The thermal shutdown does not activate below +150°C. 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 (µP) 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 µP GPIO in a wired-OR configuration to save a µP pin. The OT output still asserts when VL is absent provided that it is pulled up to a different supply voltage. Serial Peripheral Interface (CS, SD0, SDI, CLK) 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. 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. 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 OT CS OT BIT Figure 4. Example Timing Diagram of the Overtemperature Alerts ______________________________________________________________________________________ 11 MAX13036 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 30kΩ to 330kΩ resistor from WET to ground. A 30kΩ resistor corresponds to a wetting current of 40mA (typ) and a 330kΩ 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. MAX13036 Automotive Contact Monitor and Level Shifter STATUS REGISTER IS COPIED TO SHIFT REGISTER SHIFT REGISTER IS COPIED TO COMMAND REGISTER CS 15 CLK SDI 14 WTOFF SC2 SW7 SDO 13 12 SC1 SC0 SW6 SW5 11 10 WEN WEND SW4 SW3 SW2 9 8 7 6 5 4 3 2 1 0 M1 M0 P7 P6 P5 P4 P3 P2 P1 P0 SW1 SW0 OT * * * * * * * * = UNUSED. 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 +170°C (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. 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. 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. Table 1. Status Register BIT 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 NAME SW7 SW6 SW5 SW4 SW3 SW2 SW1 SW0 OT — — — — — — — Table 2. Command Register BIT 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 NAME WTOFF SC2 SC1 SC0 WEN WEND M1 M0 P7 P6 P5 P4 P3 P2 P1 P0 POR 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 ______________________________________________________________________________________ Automotive Contact Monitor and Level Shifter Table 3. Programmable Scanning Period SC2 SC1 SC0 SCANNING PERIOD (ms) 0 0 0 64 0 0 1 32 0 1 0 16 0 1 1 8 1 0 0 4 1 0 1 2 ning 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 SWITCHES ARE POLLED FOR 250μs GND-CONNECTED SWITCH INPUT tSCAN-P SWITCH DEBOUNCE STARTS tDEB INT 1 1 0 Continuous / Adjustable Hysteresis Off 1 1 1 Continuous 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 WEND WETTING CURRENT (IN0, IN1) Ω SENSE RESISTOR 16kΩ (IN0, IN1) 0 0 Off Off Off On 0 1 Off On Off On 1 0 Off Off On On 1 1 On On On On WETTING CURRENT (IN2–IN7) Ω SENSE RESISTOR 16kΩ (IN2–IN7) ______________________________________________________________________________________ 13 MAX13036 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 250µs (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 250µs (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 scan- MAX13036 Automotive Contact Monitor and Level Shifter Table 5. Switch Configuration Controlled by M1 and M0 M0 IN7 AND IN6 SWITCH CONFIGURATION IN5 AND IN4 SWITCH CONFIGURATION IN3–IN0 SWITCH CONFIGURATION 0 0 Ground Ground Ground 0 1 Ground Battery Ground 1 0 Battery Ground Ground 1 1 Battery Battery Ground M1 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). 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. 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 command register to ([SC2:SC1:SC0] = [1:1:0]). The hysteresis is set to 0.166 x VBATREF when adjustable hysteresis is disabled. Scan Mode In scan mode, each sense resistor is connected for a finite duration of 250µs (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 17µA (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 250µs (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(μA) = 16 × ⎜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. 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 2µA (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 200µs (typ) to exit shutdown, at which point the command register is restored to its power-up ______________________________________________________________________________________ Automotive Contact Monitor and Level Shifter 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 1.5kΩ resistor. Applications Information RC 1MΩ 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. 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 1Ω and the battery voltage is 16V. If all switches are simultaneously closed, the corresponding power dissipated by the MAX13036 is (16V - (25mA x 1Ω)) x 25mA x 8 = 3.12W; this is higher than the absolute maximum power dissipation of 2759mW at TA = +70°C. 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. CHARGE-CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF RD 1500Ω DISCHARGE RESISTANCE DEVICE UNDER TEST STORAGE CAPACITOR Figure 7a. Human Body ESD Test Model IP 100% 90% Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) AMPERES 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Figure 7b. Human Body Model Current Waveform Chip Information PROCESS: BiCMOS ______________________________________________________________________________________ 15 MAX13036 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 470kΩ resistor. Having SD compatible with VL has the advantage of reducing input leakage current into SD when SD = VL. Automotive Contact Monitor and Level Shifter MAX13036 Typical Application Circuit BATTERY +6V TO +26V, +42V LOAD DUMP ECU CONNECTOR 0.01μF 4700pF IN0 IN1 IN2 IN3 IN4 IN5 IN6 IN7 BATREF TDEB BAT 47μF WET 0.1μF MAX13036 HYST 61kΩ 90kΩ IN +3.3V REGULATOR OUT GND DO0 VL DO1 SD SDO SDI CLK CS INT OT 0.1μF 20kΩ 20kΩ μP 16 ______________________________________________________________________________________ Automotive Contact Monitor and Level Shifter QFN THIN.EPS PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm 21-0140 K 1 2 ______________________________________________________________________________________ 17 MAX13036 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 Automotive Contact Monitor and Level Shifter 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 © 2007 Maxim Integrated Products Springer is a registered trademark of Maxim Integrated Products. Inc.