MAX13362ATL/V+ [MAXIM]
24-Channel Automotive Switch Monitor; 24通道汽车开关监测
| 型号： | MAX13362ATL/V+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 24-Channel Automotive Switch Monitor |
| 文件： | 总14页 (文件大小：204K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4464; Rev 0; 2/09
24-Channel Automotive Switch Monitor
MAX1362
General Description
Features
♦ 9V to 18V Operating Voltage Range with Full
The MAX13362 is a 24-channel automotive contact mon-
itor designed as an interface between mechanical
switches and low-voltage processors or other logic cir-
cuits. The IC operates over a voltage range of 5.5V to
28V, and withstands voltages up to 40V. It protects low-
voltage circuitry from high voltages and reverse battery
conditions. The MAX13362’s low-current operation under
all operating conditions makes it suitable for use in elec-
tronic control units (ECUs) that are connected directly to
the automotive battery. It has an adjustable scan mode
that significantly reduces the current drawn in key-off.
Performance
♦ Fully Functional Range of 5.5V to 28V
♦ Switch Inputs Withstand 27V
♦ Switch Inputs Withstand Reverse Battery
♦ Ultra-Low Operating Current 100µA (typ) in Scan
Mode
♦ Built-In Switching Hysteresis
♦ Built-In Switch Deglitching
The MAX13362 features an SPI™ interface to monitor
the switch status and set the device configuration.
Multiple MAX13362s can be cascaded to support any
multiple of 24 switches.
♦ CMOS-Compatible Logic Outputs Down to 3.0V
♦ Interrupt Output to Processor
♦ Configurable Wetting Current (0mA, 5mA, 10mA,
The MAX13362 is available in a 6mm x 6mm, 40-pin
thin QFN package and operates over the -40°C to
+125°C temperature range.
or 15mA) for Each Switch Input
♦ AEC-Q100 Qualified
Ordering Information
Applications
Automotive Body Controllers
Automotive Door Modules
PART
TEMP RANGE
PIN-PACKAGE
40 Thin QFN-EP*
(6mm x 6mm)
MAX13362ATL/V+
-40°C to +125°C
Automotive Smart Junction Boxes
*EP = Exposed pad.
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V Denotes an automotive qualified part.
Typical Application Circuit
Pin Configuration
TOP VIEW
BATTERY
9V TO 18V
24 SWITCHES, 1 BATTERY-CONNECTED
ECU CONNECTOR
IN7 31
IN8 32
20 VS
19 VS
18 GND
0.047μF
IN9 33
0.047μF
IN10 34
IN11 35
IN12 36
IN13 37
IN14 38
IN15 39
IN16 40
17
V
DD
100Ω
MAX13362
16 GND
15 SDI
14 CS
VS
IN
REGULATOR
13 SDO
12 CLK
11 N.C.
MAX13362
OUT
V
DD
SD
GND
SDI
SDO
CLK
CS
INT
+
MICROCONTROLLER
/LOGIC CIRCUIT
THIN QFN
(6mm x 6mm)
SPI is a trademark of Motorola, Inc.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
24-Channel Automotive Switch Monitor
ABSOLUTE MAXIMUM RATING
Current Into Any Pin.......................................................... 20mA
V
, CLK, SDI, CS to GND ......................................-0.3V to +6V
VS, SD, INT to GND................................................-0.3V to +40V
DD
Continuous Power Dissipation (T = +70°C)
A
(derate 37mW/°C above +70°C)(multilayer board)....2963mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature........................................-40°C to +150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
IN0–IN23 to GND.....................................................-15V to +27V
SDO to GND...............................................-0.3V to (V
+ 0.3V)
DD
ESD Protection, All Pins (HBM)............................................ 2kV
ESD Protection on Pins IN0–IN23 to IEC61000-4-2 Specification
(with added 0.047µF capacitor, and/or 100Ω resistor).... 8kV
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.
MAX1362
ELECTRICAL CHARACTERISTICS
(V = 5V, V = 14V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T =+25°C.)
DD
VS
A
A
PARAMETER
POWER SUPPLY
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
V
Operating Supply Range
Supply Current
V
3
5.5
10
V
µA
V
DD
DD
DD
I
0.1
DD
VS Supply Range
V
(Note 1)
= 64ms, t
5.5
3
28
VS
VS Undervoltage Lockout
V
5.5
V
UVLO
t
= 1ms; LP bit in
POLL_ACT
POLL
internal register = 0, 24 channels active, all
switches open, T = +25°C
100
100
170
200
A
t
= 64ms, t
= 1ms; LP bit in
Total Supply Current (Flowing
POLL
POLL_ACT
I
µA
SUP
internal register = 0, 24 channels active, all
switches open
into VS and V
)
DD
Continuous polling mode, wetting current
set to 5mA
1000
6
VS Supply Current in Shutdown
Mode
V
= 0, V = 14V, all switches open, T =
SD VS A
I
10
5
µA
µA
SDVS
+25°C
V
Supply Current in Shutdown
DD
I
V
= 0, V = 14V, T = +25°C
0.1
SDVDD
SD
VS
A
Mode
SWITCH INPUTS
V
= 5.5V to 28V, measured with 100Ω
VS
Input Voltage Threshold
V
2.5
3.7
V
TH
series resistor for high-side switches
V
= 5.5V to 28V, measured with 100Ω
VS
Input Hysteresis
V
0.2
5
V
H
series resistor for high-side switches
Wetting Current Rise/Fall Time
t
µs
IWETT
Wetting current set to 15mA,
9V < V < 18V
VS
12.7
10.5
15
17.25
19.5
Wetting Current
I
mA
µA
WETT
Wetting current set to 15mA,
15
16
(5.5V < V < 9V) or (18V < V < 28V)
VS
VS
V
V
= 0, T = +25°C
2
IN_
IN_
A
IN0–IN23 Input Current
I
IN_
= 14V, T = +25°C (Note 2)
30
A
IN0–IN23 Input Leakage Current
in Shutdown
I
V
= 0 or 14V, V = 0, T = +25°C
2
µA
V
LEAKSD
VS
SD
A
IN4–IN23 Dropout Voltage
V
I
= 15mA (Note 3)
2.8
4.0
DO15
WETT
2
_______________________________________________________________________________________
24-Channel Automotive Switch Monitor
MAX1362
ELECTRICAL CHARACTERISTICS (continued)
(V = 5V, V = 14V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T =+25°C.)
DD
VS
A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC LEVELS
INT Output-Voltage Low
SDO Output-Voltage Low
SDO Output-Voltage High
V
Sinking 1mA
Sinking 1mA
Sourcing 1mA
0.4
V
V
V
OLINT
V
0.2 x V
DD
OLSDO
OHSDO
V
0.8 x V
-1
DD
SDO Leakage Current in High-
Impedance Mode
I
V
= 5V
CS
+1
0.33 x V
µA
LSDO
SDI, CLK, CS Input-Voltage Low
SDI, CLK, CS Input-Voltage High
SD Input Low Voltage
SD Input High Voltage
SDI Internal Pulldown Resistor
CLK Pin Leakage
V
V
V
IL
DD
V
0.66 x V
0.8
IH
DD
V
V
ILSD
IHSD
V
2.4
120
1
V
R
30
50
kΩ
µA
µA
µA
µA
PD
LEAKCLK
I
V
V
V
V
= 5V, T = +25°C
CLK A
CS Pin Leakage
I
I
= 5V, T = +25°C
1
LEAKCS
CS
SD
INT
A
SD Pin Leakage
= 5V, T = +25°C
1
LEAKSD
A
INT Pin Leakage
I
= high impedance, T = +25°C
1
LEAKINT
A
THERMAL SHUTDOWN
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
TIMING
T
Temperature rising (Note 4)
+150
+165
15
°C
°C
SHDN
T
HYST
Switch Inputs Deglitching Time
CLK Frequency Range
t
37
50
63
4
µs
GT
f
(Note 4)
0.01
MHz
CLK
Falling Edge of CS to Rising
Edge of CLK Setup Time
Polling mode, input rise/fall time
< 10ns (Note 4)
t
100
100
30
ns
ns
ns
ns
ns
ns
ns
LEAD
Falling Edge of CLK to Rising
Edge of CS Setup Time
Input rise/fall time < 10ns
(Note 4)
t
LAG
SDI-to-CLK Falling Edge Setup
Time
t
(Note 4)
(Note 4)
SI(SU)
SDI Hold Time After Falling Edge
of CLK
t
20
SI(HOLD)
Time from Rising Edge of CLK to
SDO Data Valid
t
C
= 50pF (Note 3)
SDO
70
55
55
VALID
Time from Falling Edge of CS to
SDO Low Impedance
t
(Note 4)
(Note 4)
SO(EN)
Time from Rising Edge of CS to
SDO High Impedance
t
SDO(DIS)
_______________________________________________________________________________________
3
24-Channel Automotive Switch Monitor
ELECTRICAL CHARACTERISTICS (continued)
(V = 5V, V = 14V, T = -40°C to +125°C, unless otherwise noted. Typical values are at T =+25°C.)
DD
VS
A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
-20
-20
TYP
MAX
+20
+20
UNITS
%
Polling Active Time Accuracy
Polling Time Accuracy
t
POLL_ACT
t
%
POLL
Time from Shutdown to Normal
Operation
t
0.1
1
ms
START
Note 1: When V is above 28V, the wetting current is disabled to limit power dissipation, and the switch inputs are not monitored.
VS
MAX1362
When V returns, there is a 1ms blanking time before the external switches are polled.
VS
Note 2: This current only flows during the polling active time thus the average value is much lower. For example with a polling time
of 64ms and a polling active time of 1ms the average current on an input when connected to 14V is typically 16µA x 1/64 =
0.25µA.
Note 3: Difference between VS and IN_ voltage when wetting current has dropped to 90% of its nominal value.
Note 4: Guaranteed by design.
CS
t
t
LAG
LEAD
CLK
SDI
t
t
SI(HOLD)
SI(SU)
MSB IN
t
t
t
SDO(DIS)
SO(EN)
VALID
SDO
MSB OUT
LSB OUT
Figure 1. SPI Timing Characteristics
4
_______________________________________________________________________________________
24-Channel Automotive Switch Monitor
MAX1362
Typical Operating Characteristics
(V = V = 5V, V = 14V, T = +25°C, unless otherwise noted.)
DD
SD
VS
A
SWITCH STATUS CHANGE
(CONTINUOUS MODE)
WETTING CURRENT vs. VS VOLTAGE
WETTING CURRENT vs. TEMPERATURE
MAX13362 toc03
20
20
15
10
5
V
10V/div
5mA/div
10V
0V
IN0
15
10
5
I
I
= 15mA
= 10mA
I
WETT
WETT
I
I
= 15mA
= 10mA
0mA
5mA
WETT
WETT
V
2V/div
2V/div
INT
WETT
I
= 5mA
WETT
V
CS
I
= 5mA
WETT
0
0
5
6
7
8
9
10 11 12 13 14 15 16 17 18
VS VOLTAGE (V)
-40 -20
0
20 40 60 80 100 120 140
10ms/div
TEMPERATURE (°C)
VS SUPPLY CURRENT vs. TEMPERATURE
(POLLING MODE)
VS SUPPLY CURRENT vs. TEMPERATURE
(CONTINUOUS MODE)
WETTING CURRENT
(POLLING MODE)
MAX13362 toc04
130
120
110
100
90
2600
2200
1800
1400
1000
600
I
= 15mA FOR ALL CHANNELS
POLLING TIME = 65.536ms
POLLING ACTIVE TIME = 1.024ms
ALL CHANNELS OPEN
WETT
I
= 5mA
WETT
I
= 10mA FOR ALL CHANNELS
5mA
WETT
I
I
= 5mA FOR ALL CHANNELS
WETT
ALL CHANNELS OPEN
= 0mA FOR ALL CHANNELS
4.096ms POLLING TIME
512μs POLLING ACTIVE TIME
WETT
200
-40 -20
0
20 40 60 80 100 120 140
-40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
1ms/div
TEMPERATURE (°C)
SWITCH THRESHOLD vs. TEMPERATURE
(HIGH SIDE SWITCH)
VS SUPPLY CURRENT vs. TEMPERATURE
(SHUTDOWN MODE)
SWITCH THRESHOLD vs. TEMPERATURE
(LOW-SIDE SWITCH)
3.4
3.3
3.2
3.1
3.0
6.5
6.2
5.9
5.6
5.3
5.0
3.4
3.3
3.2
3.1
3.0
SWITCH OPEN TO CLOSE
SWITCH CLOSE TO OPEN
SWITCH OPEN TO CLOSE
SWITCH CLOSE TO OPEN
HIGH SIDE SWITCH
15mA WETTING CURRENT
100Ω INCLUDED
LOW-SIDE SWITCH
15mA WETTING CURRENT
-40 -20
0
20 40 60 80 100 120 140
-40 -20
0
20 40 60 80 100 120 140
-40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
24-Channel Automotive Switch Monitor
Typical Operating Characteristics (continued)
(V = V = 5V, V = 14V, T = +25°C, unless otherwise noted.)
DD
SD
VS
A
SWITCH THRESHOLD vs. VS VOLTAGE
(LOW-SIDE SWITCH)
SWITCH STATUS CHANGE
(POLLING MODE)
MAX13362 toc11
3.5
10V
3.4
3.3
3.2
3.1
SWITCH OPEN TO CLOSE
SWITCH CLOSE TO OPEN
5V/div
2V/div
V
IN
MAX1362
0V
0V
V
INT
3.0
9
10 11 12 13 14 15 16 17 18
VS VOLTAGE (V)
2ms/div
Pin Description
PIN
NAME
FUNCTION
1, 2, 11,
29, 30
N.C.
No Connection. Not internally connected.
3
4
5
6
7
8
IN17
IN18
IN19
IN20
IN21
IN22
Switch Monitor Input Channel 17. Connect IN17 to a ground-connected switch.
Switch Monitor Input Channel 18. Connect IN18 to a ground-connected switch.
Switch Monitor Input Channel 19. Connect IN19 to a ground-connected switch.
Switch Monitor Input Channel 20. Connect IN20 to a ground-connected switch.
Switch Monitor Input Channel 21. Connect IN21 to a ground-connected switch.
Switch Monitor Input Channel 22. Connect IN22 to a ground-connected switch.
Switch Monitor Input Channel 23. Connect IN23 to a battery-connected or ground-connected switch.
When used for a battery-connected switch, add a 100Ω series protection resistor to the input.
9
IN23
Interrupt Output. INT is an open-drain output that asserts low when one or more of the inputs (IN0–IN23)
change state and are enabled for interrupts, or when the overtemperature threshold is exceeded.
10
12
INT
CLK
SPI Serial Clock Input
SPI Serial Data Output. SPI data is output on SDO on the rising edges of CLK while CS is held low.
SDO is high impedance when CS is high. Connect SDO to a microcontroller data input or to a
succeeding device in a daisy chain.
13
14
15
SDO
SPI Chip-Select Input. Drive CS low to enable clocking of data into and out of the IC. SPI data is
latched into the device on the rising edge of CS.
CS
SPI Serial Data Input. SPI data is latched into the internal shift register on the falling edges of CLK
while CS is held low. SDI has an internal 50kΩ pulldown resistor. Connect SDI to the SDO of a
preceding device in a daisy chain or to the microcontroller data output.
SDI
16, 18
17
GND
Ground. Pins 16 and 18 must be connected to ground.
Logic Supply Voltage. Connect V
to a 3.3V or 5V logic supply. Bypass V
to GND with at least a
DD
DD
V
DD
0.1µF capacitor placed as close as possible to V
.
DD
6
_______________________________________________________________________________________
24-Channel Automotive Switch Monitor
MAX1362
Pin Description (continued)
PIN
NAME
FUNCTION
Supply Voltage Input. VS should be protected from reverse battery using a series diode. Bypass VS to
GND with a 0.1µF ceramic capacitor placed as close as possible to VS. In addition, bypass VS with a
47µF or greater capacitor.
19, 20
VS
Shutdown Input. Drive SD low to place the IC into shutdown mode. Drive SD high for normal operation.
SD is battery-voltage compatible.
21
22
23
24
25
SD
IN0
IN1
IN2
IN3
Switch Monitor Input Channel 0. Connect IN0 to a battery-connected or ground-connected switch.
When used for a battery-connected switch, add a 100Ω series protection resistor to the input.
Switch Monitor Input Channel 1. Connect IN1 to a battery-connected or ground-connected switch.
When used for a battery-connected switch, add a 100Ω series protection resistor to the input.
Switch Monitor Input Channel 2. Connect IN2 to a battery-connected or ground-connected switch.
When used for a battery-connected switch, add a 100Ω series protection resistor to the input.
Switch Monitor Input Channel 3. Connect IN3 to a battery-connected or ground-connected switch.
When used for a battery-connected switch, add a 100Ω series protection resistor to the input.
26
27
28
31
32
33
34
35
36
37
38
39
40
—
IN4
IN5
Switch Monitor Input Channel 4. Connect IN4 to a ground-connected switch.
Switch Monitor Input Channel 5. Connect IN5 to a ground-connected switch.
Switch Monitor Input Channel 6. Connect IN6 to a ground-connected switch.
Switch Monitor Input Channel 7. Connect IN7 to a ground-connected switch.
Switch Monitor Input Channel 8. Connect IN8 to a ground-connected switch.
Switch Monitor Input Channel 9. Connect IN9 to a ground-connected switch.
Switch Monitor Input Channel 10. Connect IN10 to a ground-connected switch.
Switch Monitor Input Channel 11. Connect IN11 to a ground-connected switch.
Switch Monitor Input Channel 12. Connect IN12 to a ground-connected switch.
Switch Monitor Input Channel 13. Connect IN13 to a ground-connected switch.
Switch Monitor Input Channel 14. Connect IN14 to a ground-connected switch.
Switch Monitor Input Channel 15. Connect IN15 to a ground-connected switch.
Switch Monitor Input Channel 16. Connect IN16 to a ground-connected switch.
Exposed Pad. Connect EP to GND for enhanced thermal performance.
IN6
IN7
IN8
IN9
IN10
IN11
IN12
IN13
IN14
IN15
IN16
EP
_______________________________________________________________________________________
7
24-Channel Automotive Switch Monitor
Functional Diagram
VS
V
DD
MAX13362
SDO
CS
MAX1362
IN0
1 OF 24
IN1
IN2
IN3
IN4
IN5
IN6
IN7
IN8
IN9
CLK
INT
SHIFT
REGISTER
+
IN10
IN11
WETTING
CURRENT
CONTROL
IN12
IN13
IN14
IN15
IN16
IN17
IN18
IN19
CONTROL
SD
IN20
IN21
IN22
IN23
24 OF 24
SDI
REF
GENERATOR
GND
8
_______________________________________________________________________________________
24-Channel Automotive Switch Monitor
MAX1362
battery-connected switches by writing to the LH0–LH3
Detailed Description
and LH23 bits (see Table 2). The default configuration
The MAX13362 is a 24-channel automotive contact
of the IN0–IN3 and IN23 inputs after power-up is for
ground-connected switches.
monitor designed as an interface between mechanical
switches and low-voltage microcontrollers or other logic
circuits. It features an SPI interface to monitor individual
switch inputs and to configure interrupt capability, wet-
ting current, switch configuration (battery-connected or
ground-connected), polling time and polling active
time. Any switch status change will cause an interrupt
signal if the switch is interrupt enabled. The MAX13362
has three modes of operation: continuous mode, polling
mode, and shutdown mode.
Wetting Current
The MAX13362 applies a programmable wetting current
to any closed switch to clean switch contacts that are
exposed to adverse conditions. The wetting current for
each switch can be set to 0mA, 5mA, 10mA, or 15mA
by the W_.0 and W_.1 data bits in the command regis-
ters (see Table 5) by means of an SPI data transaction.
When using wetting current, special care must be
taken to avoid exceeding the maximum power dissipa-
tion of the MAX13362 (see the Applications Information
section). Disabling the wetting current or limiting the
active-wetting current time reduces power consump-
tion. The default state upon power-up is with wetting
current disabled.
V
DD
and VS
V
is the power-supply input for the logic input/
DD
output circuitry. Connect V
to a 3V to 5.5V logic-level
DD
supply. Bypass V
to GND with at least a 0.1µF
DD
capacitor placed as close as possible to V
.
DD
VS is the main power-supply input. Bypass VS to GND
with a 0.1µF ceramic capacitor placed as close as pos-
sible to VS. In addition, bypass VS with a 47µF or
greater capacitor.
Interrupt Output (INT)
INT is an active-low, open-drain output that asserts low
when any of the switch inputs change state and is
enabled for interrupts, or when the overtemperature
threshold is exceeded. An external pullup resistor to
Mechanical Switch Inputs (IN0–IN23)
IN0–IN23 are the inputs for remote mechanical switch-
es. The switch status is indicated by the S0–S23 bits in
the status register, and each switch input can be pro-
grammed to assert an interrupt (INT) by writing to the
IE0–IE23 bits in the command register. All switch inputs
are interrupt disabled upon power-up.
V
is needed on INT. INT is cleared when CS is driven
DD
low for a read/write operation. However, in polling mode,
any switch state change or overtemperature change
which occurs during an SPI transaction is stored and
causes an additional interrupt after the SPI transaction is
over and CS goes high (shown in Figure 2).
The IN4–IN22 inputs are intended for ground-connect-
ed switches. The IN0–IN3 and IN23 inputs can be pro-
grammed for either ground-connected switches or
If V
is absent, the INT output is functional provided
DD
that it is pulled up to a different supply voltage.
CS
SWITCH STATUS CHANGE
CLK
INT
NEW INTERRUPT
Figure 2. Switch State Change During the SPI transaction
_______________________________________________________________________________________
9
24-Channel Automotive Switch Monitor
daisy chaining is possible) and enables data latching
only if exactly 32 bits (or an integer multiple thereof)
have been clocked in.
Serial Peripheral Interface
(CS, SDO, SDI, CLK)
The MAX13362 operates as a serial peripheral interface
(SPI) slave device. An SPI master accesses and pro-
grams the MAX13362 by reading/writing the control
registers. The control registers are 32 bits wide, have 2
command bits (or register addresses) and 30 data bits
(see Table 1). Figure 3 shows the read/write sequence
through SPI. The SPI logic counts the number of bits
clocked into the IC (using a modulo-32 counter so that
Status Register
The status register contains the status of the switches
connected to IN0–IN23. The status register also con-
tains an overtemperature warning bit, a power-on-reset
bit and a device type bit (see Table 1). The status reg-
ister is accessed by the SPI-compatible interface.
MAX1362
CS
CLK
SDI
CB0 CB1 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18 D19 D20 D21 D22 D23 D24 D25 D26 D27 D28 D29
Z
DT RST
T
S0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19 S20 S21 S22 S23
x
x
x
x
x
Z
SDO
NOTE: X = UNUSED, Z = HIGH IMPEDANCE.
Figure 3. SPI Read/Write Sequence
Table 1. Bit Description
BIT NAME
BIT DESCRIPTION
CB0, CB1
D0–D29
S0–S23
T
Command bits. Select the internal register to which data bits D0–D29 are to be written.
Data bits.
Switch state bit. 0 = switch open, 1 = switch closed.
Overtemperature bit. When overtemperature occurs, this bit is set to 1. It is reset on the rising edge of CS.
Power-on-reset bit. It indicates whether the IC has had a power-on-reset since the last SPI read. 0 = device has
been reset. RST is set to 1 on the rising edge of CS.
RST
DT
Device type. 0 = reserved for future use, 1 = MAX13362.
10 ______________________________________________________________________________________
24-Channel Automotive Switch Monitor
MAX1362
Command Register
Three 32-bit command registers are used to configure
the MAX13362 for various modes of operation and are
accessed by the SPI-compatible interface (see Table 2).
The default configuration after power-on is LH_ = 0,
ground connected.
Table 2. Command Register Map
D29 D28 D27 D26 D25 D24 D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12 D11 D10 D9 D8
D7 D6 D5
D4 D3 D2 D1
D0 CB1 CB0
W23. W22. W21 W20 W19 W18 W17 W16. W15 W14 W13 W12 W11 W10 W9. W8. W7. W6. W5. W4. W3. W2. W1. W0.
X
X
PA2 PA1 PA0
X
X
X
0
0
0
1
LP
P3 P2
0
0
.0
.0
.1
.0
.1
.0
.1
.0
.1
0
.0
.1
.0
.1
.0
.1
.0
.1
.0
.1
.0
.1
0
0
0
0
0
0
0
0
0
0
W23. W22. W21 W20 W19 W18 W17 W16. W15 W14 W13 W12 W11 W10 W9. W8. W7. W6. W5. W4. W3. W2. W1. W0.
P1
P0
1
1
.1
1
1
1
1
1
1
1
1
1
1
1
LH2
3
LH3 LH2 LH1 LH0 IE23 IE22 IE21 IE20 IE19 IE18 IE17 IE16 IE15 IE14 IE13 IE12 IE11 IE10 IE9 IE8 IE7 IE6 IE5 IE4 IE3 IE2 IE1 IE0
NO OPERATION (NO DATA WRITTEN)
1
1
0
1
P0–P3: Polling Time
LH_: Switch Configuration for IN0–IN3 and IN23
P0–P3 are used to set the polling time as shown in Table 3.
The LH0–LH3 and LH23 bits set the switch configuration
for IN0–IN3 and IN23, respectively. Set LH_ to 0 to con-
figure the input channel to ground connected. Set LH_
to1 to configure the input channel to battery connected.
PA0–PA2: Polling Active Time
PA0–PA2 are used to set the polling active time as
shown in Table 4.
Table 3. Polling Time Setting
Table 4. Polling-Active Time Setting
P3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
P2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
P1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
P0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
POLLING TIME (ms)
Continuous*
4.096
PA2
PA1
PA0
POLLING ACTIVE TIME (µs)
0
0
0
64
0
0
1
128
4.096
0
1
0
256
4.096
0
1
1
512*
1024
2048
4096
4096
4.096
1
0
0
4.096
1
0
1
8.192
1
1
0
16.384
32.768
65.536
131
1
1
1
*Default POR Value.
262.1
524.3
1049
2097
4194
*Default POR value.
______________________________________________________________________________________ 11
24-Channel Automotive Switch Monitor
IE_: Interrupt Enable
The IE_ bit programs the switch input channel, IN_, to
be interrupt-enabled or interrupt-disabled (0 = interrupt
disabled, 1 = interrupt enabled). The default value after
power-on is 0.
switches for a preset duration to reduce the power con-
sumption. In shutdown mode, all switch inputs are high
impedance and all circuitry is shutdown.
Continuous Mode Operation (P0–P3 = 0)
In continuous mode, reading of the switch status is initi-
ated by a falling edge on CS. The microcontroller initi-
ates a low pulse on CS to update the MAX13362 switch
status register. If INT remains high, no action needs be
taken by the microcontroller. If INT goes low, the micro-
controller may perform a read operation to read the
updated switch status. On the rising edge of CS, INT is
updated. To get correct data, the microcontroller must
wait 10µs before initiating a switch status read opera-
tion. (See Figure 4.)
W_.0 and W_.1: Wetting Current
W_.0 and W_.1 bits set the corresponding switch
channel-wetting current as shown in Table 5.
Table 5. Wetting Current Setting
MAX1362
W_.1
W_.0
WETTING CURRENT (mA)
0
0
1
1
0
1
0
1
0*
5
10
15
*Default POR value.
CS
SWITCH
STATUS
LP: Low Quiescent Current Bit
INT UPDATED, PERFORM READ OPERATION
In polling mode, when LP is set to 0, the IC is operating
with the lowest quiescent current. The channels that are
not enabled to interrupt have their wetting current dis-
abled and are not monitored. The first pulse of wetting
current after the switch is closed and sampled is 5mA
unless the wetting current for that channel is set to
0mA. The default value of LP after power-on is 0. When
LP is 1, all channels are monitored and the wetting cur-
rent for each channel is set to the value determined by
W_.0 and W_.1. If the MAX13362 is in continuous
mode, LP is ignored.
CHANGE
INT
Figure 4. Continuous Mode Operation
Polling-Mode Operation
In polling mode (see Figure 5), each switch input is
sampled for a programmable polling active time set by
the PA0–PA2 bits between 64µs and 4ms (see Table 4).
Sampling is repeated at a period set by the P0–P3 bits
(from 4ms to continuous, see Table 3). All switch inputs
are sampled simultaneously at the end of the polling
active time. Wetting currents (if enabled) are applied to
closed switches during the polling active time.
Therefore, the polling mode reduces the current con-
sumption from the VS power supply to some value
dependent on the polling time chosen.
Operating Modes
The MAX13362 features three modes of operation: con-
tinuous mode, polling mode, and shutdown mode. In
continuous mode, the wetting currents (if enabled) are
continuously applied to the closed switches. In polling
mode, the wetting currents are applied to the closed
POLLING ACTIVE TIME
POLLING TIME
SWITCH
POSITION
SAMPLED
SWITCH
POLLING
POSITION
SAMPLED
ACTIVE TIME
GROUND-CONNECTED
SWITCH-INPUT
INT
SWITCH OPEN
Figure 5. Switch Sampling in Polling Mode
12 ______________________________________________________________________________________
24-Channel Automotive Switch Monitor
MAX1362
Any switch position change (if the switch is interrupt-
tery-level source but should be protected against
reverse battery in the application.
enabled) is signaled through the active-low open-drain
INT output. The INT output is cleared when CS goes
low.
Wetting Current and Power Dissipation
The maximum power dissipation happens when all
switch inputs configured with 15mA continuous wetting
current are all closed. Assuming the battery voltage is
14V, the corresponding power dissipated by the IC is
24 x 14V x 15mA = 5040mW. This exceeds the
absolute maximum power dissipation of 2963mW. In
polling mode, the wetting currents are pulsed at the
programmed polling time to reduce the total power dis-
sipated in the IC.
Shutdown Mode
In shutdown mode, all switch inputs are high imped-
ance and the external switches are no longer moni-
tored, reducing current consumption on VS to 6µA
(typ). The IC resets upon entering shutdown mode and
the contents of the command registers are lost.
Therefore, any setting other than power-on-reset
defaults needs to be reprogrammed after exiting from
the shutdown mode.
ISO 7637 Pulse Immunity
VS, SD, and IN0–IN23 are potentially exposed to ISO
7637 pulses. Bypass VS with a 0.1µF and a 47µF
capacitor. The VS and SD voltage must be limited
below 40V during load dump. Bypass IN0–IN23 with at
least 0.047µF capacitors at the ECU connector. When
IN0–IN3 or IN23 inputs are used with battery-connected
switches, a 100Ω series resistor is needed. These
external components allow VS, SD, and IN0–IN23 to
withstand ISO 7637 pulses in the application circuit.
Applications Information
Overtemperature Protection
If the IC junction temperature exceeds +165°C, an
interrupt signal is generated and the wetting currents
are disabled to reduce the on-chip power dissipation.
During an overtemperature event, the last switch status
is retained in internal memory and the switch status is
not updated. The interrupt output is cleared when CS
goes high, but the overtemperature bit T in the output
word remains for as long as the overtemperature condi-
tion persists. When the junction temperature drops by
15°C, the wetting currents are re-enabled and there is a
1ms blanking time before the switches can be polled.
Mechanical Switch Characteristics
The MAX13362 is designed to operate with switches
that have the following characteristics:
1) Minimum resistance value with switch open (due to
leakage): 10kΩ.
Reverse-Battery Tolerance
The IN0–IN23 switch inputs withstand up to -15V DC
voltage without damage. A reverse-battery diode is
needed to protect VS as shown in the Typical
Application Circuit. SD can be controlled from a bat-
2) Maximum resistance value with switch closed:
100Ω.
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________ 13
24-Channel Automotive Switch Monitor
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
21-0141
40 TQFN-EP
T4066+5
MAX1362
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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