General Description
The MAX13036 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 tem-
perature range.
Applications
Control ECUs
Features
●+6V to +26V Operating Voltage Range
●+42V Compatibility on BAT
●Inputs Withstand Reverse Battery
●Withstands Dynamic Battery Voltage Drop While VL
is Present
● Ultra-Low Operating Current 17μA (typ) in Scan
Mode
●Resistor-Adjustable Switching Hysteresis
●CMOS-Compatible Logic Outputs (+2.7V min)
●Built-In Switch Debouncing
●Interrupt Output
●Immunity to Transients
●High Modularity
●Thermal Protection
●±8kV HBM ESD Protection on IN0–IN7 Without
External Components
●Two Inputs (IN0, IN1) Programmable as Direct
Outputs
●Four Inputs (IN4–IN7) Programmable for BAT or
GND Related Switches
Typical Application Circuit appears at end of data sheet.
19-0808; Rev 1; 2/15
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
PART TEMP RANGE PIN-PACKAGE
MAX13036ATI+ -40°C to +125°C 28 TQFN-EP*
(5mm x 5mm)
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
MAX13036
TQFN
TOP VIEW
SD
DO0
GND
BATREF
BAT
N.C.
INO
DO1
N.C.
V
L
CLK
SDI
SDO
CS
INT
OT
GND
TDEB
WET
HYST
N.C.
*EP
*CONNECT EXPOSED PADDLE TO GROUND
IN7
IN6
IN5
IN4
IN3
IN2
IN1
+
MAX13036 Contact Monitor and Level Shifter
Pin Conguration
Ordering Information
EVALUATION KIT AVAILABLE
(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
(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 VL2.7 5.5 V
VL Supply Current ILVL = +5.5V, VBAT = +14V 0 1 µA
BAT Supply Range VBAT 6 26 V
Total Supply Current 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
Total Supply Current in Scan
Mode ISUP_SCAN
VBAT = +14V, scan mode (SC0 = 0,
SC1= 0, SC2 = 0), CS = VL,
SDI = CLK = GND (Note 2)
17 36 µA
Total Supply Current in Shutdown
Mode ISHDN
VSD = 0V,
VBAT = +14V,
VBATREF =
+14V (Note 2)
TA = +25°C 2 3.2
µA
TA = -40°C to +125°C 2 4.0
BATREF Input Leakage Current in
Shutdown IL_BATREF VSD = 0V, VBATREF = +14V 1 µA
BATREF Input Resistance RBATREF VBATREF = +14V 1 MΩ
SWITCH INPUTS (IN0–IN7)
Input-Voltage Threshold Center
(Note 3) VTH_C
RHYST = ∞ or programmable hysteresis
disabled
0.425 x
VBATREF
0.5 x
VBATREF
0.575 x
VBATREF
V
RHYST = 90kΩ
0.4 x
VBATREF
0.5 x
VBATREF
0.63 x
VBATREF
Input-Voltage Threshold
Hysteresis (Note 4) VTH_HYS
RHYST = ∞ or programmable hysteresis
disabled
0.133 x
VBATREF
0.166 x
VBATREF
0.22 x
VBATREF
VRHYST = 90kΩ
0.26 x
VBATREF
0.361 x
VBATREF
0.48 x
VBATREF
RHYST = 0Ω
0.5 x
VBATREF
MAX13036 Contact Monitor and Level Shifter
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Absolute Maximum Ratings
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
Switch-State Sense Resistor RSENSE 11 16 22 kΩ
Wetting Current Rise/Fall Time IWET_RISE_
FALL
RWET = 61kΩ
(Note 5)
Rise 6 µs
Fall 1
Wetting Current IWET
RWET = 61kΩ 22
mARWET = 30kΩ, VBAT = 14V 28 40 51
RWET = 330kΩ 7.5
IN0–IN7 Input Impedance in
Shutdown VSD = 0V, VIN_ = +14V 5.5 8.5 MΩ
LOGIC-LEVELS
SDO, DO0, DO1 Output
Voltage High VOH Source current = 2mA 0.8 x VLV
SDO, DO0, DO1 Output
Voltage Low VOL Sink current = 4mA 0.2 x VLV
INT, OT Output Voltage Low VINTL Sink current = 4mA 0.4 V
SD Input Leakage Current IL_ SD VSD = VBAT = +12V 15 30 µA
SD Input-Voltage Low VIL_SD 0.8 V
SD Input-Voltage High VIH_ SD 2.4 V
CS, CLK, SDI Input-Voltage Low VIL 0.33 x VLV
CS, CLK, SDI Input-Voltage High VIH 0.66 x VLV
CS, CLK Input Leakage Current IIL -1 +1 µA
INT, OT Leakage Current IOL -1 +1 µA
SDI Input Impedance RSDI 65 100 145 kΩ
THERMAL SHUTDOWN
Thermal Shutdown Temperature TSHDN +170 °C
Thermal Shutdown Hysteresis THYST 15 °C
MAX13036 Contact Monitor and Level Shifter
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Electrical Characteristics (continued)
Note 1: All units are 100% production tested at TA = +125°C. Limits over the operating temperature range are guaranteed by cor-
relation 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.
(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
IN0 to DO0 Propagation Delay tPROP
VBAT = 6V 22 35 µs
IN1 to DO1 Propagation Delay VBAT = +14V 22
CLK Frequency fCLK
Input rise/fall time < 2ns,
VL = +3.0V to +5.5V 5 MHz
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
Falling Edge of CLK to SDI
Required Hold Time 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
Debounce time tDEB
CTDEB = 500pF 3.18 5.9 9.42 ms
CTDEB = 10nF (Note 6) 63 120 188
Scanning Time Pulse tSCAN 130 250 400 µs
Scanning Time Period tSCAN_P SC2 = 0, SC1 = 1, SC0 = 1 4 8 14 ms
Wetting Time Pulse tWET WTOFF = 0 10 21 35 ms
Time from Shutdown To Normal
Operation
SD low-to-high transition to input
monitoring enabled 200 µs
MAX13036 Contact Monitor and Level Shifter
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Timing Characteristics
Figure 1. SPI Timing Characteristics
Figure 2. SDO Enable/Disable Test Circuit and Timing Diagram
CS
CLK
SDI MSB IN
MSB OUT LSB OUT
tSO(DIS)
tVALID
tSO(EN)
tLEAD
SDO
tLAG
tSI(SU) tSI(HOLD)
MAX13036
CS
SDO
SDOCS
15pF 1/3VL
1kΩ
tSO(EN)
VL
tSO(DIS)
VOL + 0.1VL
MAX13036 Contact Monitor and Level Shifter
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Test Circuits/Timing Diagrams
(VL = +3.3V, BAT = +14V, SD = VL, RWET = 61kΩ, RHYST = 90kΩ, CTDEB = 4700pF, TA = +25°C, unless otherwise noted.)
WETTING CURRENT vs. RWET
RWET (kΩ)
WETTING CURRENT (mA)
MAX13036 toc02
30 80 130 180 230 280 330
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
GND-CONNECTED SWITCH
BAT-CONNECTED SWITCH
WETTING CURRENT PULSE
(NORMAL MODE, WTOFF = 0, WEN = WEND = 1)
MAX13036 toc03
20ms/div
VIN_
10V/div
IIN_
20mA/div
INT
2V/div
BAT CURRENT vs. TEMPERATURE
(NORMAL MODE)
TEMPERATURE (°C)
I
BAT
(µA)
MAX13036 toc04
-40 -25 -10 5 20 35 50 65 80 95 110 125
0
10
20
30
40
50
60
70
80
90
100
ADJUSTABLE HYSTERESIS OFF
ADJUSTABLE HYSTERESIS ON
BAT CURRENT vs. TEMPERATURE
(SHUTDOWN MODE)
TEMPERATURE (°C)
IBAT (µA)
MAX13036 toc05
-40 -25 -10 5 20 35 50 65 80 95 110 125
0
1
2
3
4
5
SD = LOW
BAT CURRENT vs. TEMPERATURE
(SCAN MODE)
TEMPERATURE (°C)
IBAT (µA)
MAX13036 toc06
-40 -25 -10 5 20 35 50 65 80 95 110 125
0
5
10
15
20
25
30
SCANNING PERIOD = 64ms
SCANNING PERIOD = 2ms
TYPICAL IN0 DRIVING
(NORMAL MODE, WTOFF = WEN = WEND = 0)
MAX13036 toc07
40µs/div
VIN0
5V/div
VDO0
2V/div
f = 5kHz
WETTING CURRENT vs. VBAT
VBAT (V)
WETTING CURRENT (mA)
MAX13036 toc01
6 10 14 18 22 26
-30
-20
-10
0
10
20
30
40
GND-CONNECTED SWITCH
BAT-CONNECTED SWITCH
TYPICAL IN0 DRIVING
(NORMAL MODE, WTOFF = WEN = WEND = 0)
MAX13036 toc08
2ms/div
VIN0
5V/div
VDO0
2V/div
f = 100Hz
ADJUSTABLE HYSTERESIS OFF
HYSTERESIS vs. RHYST
R
HYST
(Ω)
HYSTERESIS (V)
MAX13036 toc09
0 200k 400k 600k 800k 1M
0
1
2
3
4
5
6
7
8
ADJUSTABLE HYSTERESIS ON
MAX13036 Contact Monitor and Level Shifter
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Typical Operating Characteristics
(VL = +3.3V, BAT = +14V, SD = VL, RWET = 61kΩ, RHYST = 90kΩ, CTDEB = 4700pF, TA = +25°C, unless otherwise noted.)
INPUT WAVEFORM IN SCAN MODE
(SCAN MODE, WTOFF = WEN = 0, WEND = 1)
MAX13036 toc12
400µs/div
VIN_
5V/div
SCANNING PERIOD = 2ms
INPUT SWITCH OPEN
DEBOUNCE TIME vs. TEMPERATURE
TEMPERATURE (°C)
DEBOUNCE TIME (ms)
MAX13036 toc13
-40 -25 -10 5 20 35 50 65 80 95 110 125
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
DEBOUNCE TIME vs. BAT VOLTAGE
VBAT (V)
DEBOUNCE TIME (ms)
MAX13036 toc14
6 10 14 18 22 26
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
DEBOUNCE TIME vs. CTDEB
CTDEB (pF)
DEBOUNCE TIME (ms)
MAX13036 toc15
0 2000 4000 6000 8000 10000
0
20
40
60
80
100
120
SWITCHING THRESHOLD vs. TEMPERATURE
TEMPERATURE (°C)
SWITCHING THRESHOLD (V)
MAX13036 toc10
-40 -25 -10 5 20 35 50 65 80 95 110 125
5
6
7
8
9
10
ADJUSTABLE HYSTERESIS OFF
VIN_ RISING
VIN_ FALLING
SWITCHING THRESHOLD vs. VBAT
VBAT (V)
SWITCHING THRESHOLD (V)
MAX13036 toc11
6 10 14 18 22 26
0
5
10
15
20
25
VIN_ RISING
VIN_ FALLING
ADJUSTABLE HYSTERESIS OFF
MAX13036 Contact Monitor and Level Shifter
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Typical Operating Characteristics (continued)
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 SPI Serial Clock Input
19 VLLogic 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.
21 DO1 Data Output Channel 1. DO1 is the level-shifted output of IN1 when WEND = 0 (normal mode only).
22 DO0 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 Pad. Connect EP to GND.
MAX13036 Contact Monitor and Level Shifter
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Pin Description
Detailed Description
The MAX13036 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 program-
mable 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 mask-
ing, hysteresis and wetting current enable/disable, switch
configuration (battery connected or ground connected),
and scanning period.
The MAX13036 features three modes of operation: nor-
mal 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 sens-
ing 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 0.1μF 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 inter-
rupt upon power-up.
MAX13036
LEVEL
TRANSLATORS
WETTING
CURRENT
CONTROL
DIGITAL
INTERFACE
SHIFT
REGISTER
INTERRUPT
LOGIC
SPI
INTERFACE
IN0
BATREF
IN1
IN2
IN3
IN4
IN5
IN6
IN7
HYSTWET TDEB GND
BAT VL
SD
DO0
DO1
CS
CLK
SDI
SDO
INT
OT
MAX13036 Contact Monitor and Level Shifter
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Functional Diagram
The first four inputs (IN0–IN3) are intended for ground-
connected 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 ground-
connected switches are pulled up to BAT and inputs con-
figured 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
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 approxi-
mate formula for hysteresis is given below:
HYST BATREF
HYST(k )
43
V 0.166 (V )
(123 (R )
Ω

= +

+


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 dis-
abled, the hysteresis is set to 0.166 x VBATREF.
Switch Debounce and Deglitch
The switch inputs IN0–IN7 share a common programma-
ble 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 tDEB
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 calcu-
late 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 inter-
rupt is not generated, and the status register is not updated.
Figure 3. Input Structure of IN0 and IN1
MAX13036
16kΩ*
NOTES:
* WETTING CURRENT AND PULLUP/DOWN RESISTORS ARE
CONTROLLED BY THE WEN AND WEND BITS IN THE COMMAND
REGISTER (SEE TABLE 4)
WETTING*
CURRENT
IN0, IN1
VBAT
CONTROL
LOGIC
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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 connect-
ing 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.
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 detect-
ed. 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).
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 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 opera-
tions, 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 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)
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.
Figure 4. Example Timing Diagram of the Overtemperature Alerts
TEMPERATURE
OT
CS
OT BIT
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On the falling edge of CS, the status register is immedi-
ately 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.
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.
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 thresh-
old 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 follow-
ing 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.
Table 1. Status Register
Table 2. Command Register
Figure 5. SPI Read/Write Example
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 — — — — — — —
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
CLK
* = UNUSED.
SDI
CS
SDO
15
STATUS REGISTER
IS COPIED TO
SHIFT REGISTER
SHIFT REGISTER IS
COPIED TO COMMAND
REGISTER
14 13 12 11 109876543210
WTOFF
SC2 SC1 SC0 WEN WEND M1 M0 P7 P6 P5 P4 P3 P2 P1 P0
SW7 SW6 SW5 SW4 SW3 SW2 SW1 SW0 OT * * * * * * *
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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 wet-
ting 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 continu-
ously 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 disconnected,
reducing the current consumption caused from poll-
ing 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 wet-
ting 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
three-stated in scan mode (see the Scan Mode section).
Note that both the WEN and WEND bits need to be set
Table 4. Truth Table for WEN and WEND
Table 3. Programmable Scanning Period
Figure 6. Switch Sampling in Scan Mode
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
1 1 0 Continuous / Adjustable
Hysteresis Off
1 1 1 Continuous
WEN WEND WETTING CURRENT
(IN0, IN1)
16kΩ SENSE RESISTOR
(IN0, IN1)
WETTING CURRENT
(IN2–IN7)
16kΩ SENSE RESISTOR
(IN2–IN7)
0 0 Off Off Off On
0 1 Off On Off On
1 0 Off Off On On
1 1 On On On On
GND-CONNECTED
SWITCH INPUT
SWITCHES ARE
POLLED FOR 250s SWITCH
DEBOUNCE
STARTS
INT
tSCAN
tSCAN-P tDEB
SWITCH
CLOSES
STATUS REGISTERS AND
INT ARE UPDATED
AFTER tDEB
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for wetting currents to be enabled on IN0 and IN1 (see
Table 4). The DO0 and DO1 outputs are three-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 corre-
sponding 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 config-
ured 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 scan-
ning ([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
hystresis 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 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 simultane-
ously 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 continu-
ously 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:
BAT(µA) SCAN_P(ms)
1
I 16 1 t


= ×+


Where SD = 3.3V, IBAT is the BAT current expressed
in microamps and tSCAN_P is the scanning period
expressed in miliseconds.
Shutdown Mode
In shutdown mode, all switch inputs are high imped-
ance 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
Table 5. Switch Configuration Controlled by M1 and M0
M1 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
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point the command register is restored to its power-up
default (0x00) and the MAX13036 enters scan mode.
Note that SD is compatible with both VL and BAT volt-
age levels. Having SD compatible to VBAT 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.
Applications Information
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.
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 capaci-
tor charged to the ESD voltage of interest, which is then
discharged into the device through a 1.5kΩ resistor.
Figure 7a. Human Body ESD Test Model
Figure 7b. Human Body Model Current Waveform
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
Cs
100pF
RC 1MΩRD 1500Ω
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
IP 100%
90%
36.8%
tRL TIME
tDL
CURRENT WAVEFORM
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
10%
0
0
AMPERES
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PACKAGE
TYPE
PACKAGE e
CODE
OUTLINE
NO.
LAND
PATTERN NO.
28 TQFN-EP T2855+8 21-0140 90-0028
MAX13036
DO0
IN0
TDEB
BATTERY
+6V TO +26V,
+42V LOAD
DUMP
WET
HYST
GND
20kΩ
0.1F
0.1µF
47µF
4700pF
BATREF
0.01µF
90kΩ
61kΩ
DO1 SDO SDI
ECU CONNECTOR
IN
OUT
+3.3V
REGULATOR
CLK
IN1 IN2 IN3 IN4 IN5 IN6 IN7
VL
BAT
20kΩ
INT
CSSD OT
µP
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Typical Application Circuit
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
Chip Information
PROCESS: BiCMOS
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 4/07 Initial release —
1 5/14
No /V OPNs in Ordering Information; removed automotive references in
data sheet title, General Description, Detailed Description, and Applications
Information sections; added Package Information and Revision History tables
1–19
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX13036 Contact Monitor and Level Shifter
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17
Revision History
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