MAX13037 Datasheet, PDF (11/22 Pages) Maxim Integrated Products – Automotive Contact Monitor and Level Shifters with LDO Regulator

REGON
REGOFF
BATREF
IN0
IN1
IN2
IN3
IN4
IN5
IN6
IN7
Automotive Contact Monitor and
Level Shifters with LDO Regulator
Functional Diagram
SD
BAT
MAX13037
MAX13038
WAKE-UP
LOGIC
WETTING
CURRENT
CONTROL
LEVEL
TRANSLATORS
LINEAR
REGULATOR
RESET +
WATCHDOG
SPI
INTERFACE
SHIFT
REGISTER
INTERRUPT
LOGIC
DIGITAL
INTERFACE
V_LO
WDI
THRESH
TD
DO0
DO1
CS
CLK
SDI
SDO
INT
RST
OT
WET
HYST TDEB
GND
Detailed Description
The MAX13037/MAX13038 automotive contact monitor
and level shifters monitor and debounce eight remote
mechanical switches and assert 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 and all switch inputs feature a common
adjustable hysteresis, debounce time, and wetting cur-
rent. Two switch inputs (IN0, IN1) are programmable to
have direct outputs (DO0, DO1), useable for PWM or
other timing-based signals.
The MAX13037/MAX13038 feature an SPI interface to
monitor individual switch inputs and to configure inter-
rupt masking, hysteresis, and wetting current
enable/disable, switch configuration (battery-
connected or ground-connected), and scanning period.
The MAX13037/MAX13038 provide an internal low
dropout (LDO) linear regulator capable of supplying up
to 150mA. The LDO can be enabled or disabled
through two digital control inputs: REGON and REGOFF.
A watchdog timer and power-on reset circuitry is provid-
ed on the MAX13037/MAX13038 to supervise external
microcontrollers (µC).
The MAX13037/MAX13038 feature three modes of
operation: normal mode, scanning mode, and shut-
down mode. In normal mode, the part is fully functional
and internal sensing resistors are connected to all
switch inputs. In scanning mode, the sensing resistors
are connected for a finite duration to reduce power
consumption. In shutdown mode, all switch inputs are
high impedance and the internal LDO is switched off to
further reduce power consumption.
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