33972_09 Datasheet, PDF (11/32 Pages) Freescale Semiconductor, Inc – Multiple Switch Detection Interface with Suppressed Wake-up

FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
WAKE-UP (WAKE)
The WAKE pin is an open-drain output and a wake-up
input. The pin is designed to control a power supply Enable
pin. In the Normal mode, the WAKE pin is LOW. In the Sleep
mode, the WAKE pin is HIGH. The WAKE pin has a pull-up to
the internal + 5.0 V supply.
In Sleep mode with the WAKE pin HIGH, the falling edge
of WAKE will place the 33972 in Normal mode. In Sleep mode
with V_DD applied, the INT pin must be HIGH for negative edge
of WAKE to wake up the device. If V_DD is not applied to the
device in Sleep mode, INT does not affect WAKE operation.
BATTERY INPUT (VPWR)
The VPWR pin is battery input and Power-ON Reset to the
33972 IC. The VPWR pin requires external reverse battery
and transient protection. Maximum input voltage on VPWR is
50 V. All wetting, sustain, and internal logic current is
provided from the VPWR pin.
VOLTAGE DRAIN SUPPLY (VDD)
The VDD input pin is used to determine logic levels on the
microprocessor interface (SPI) pins. Current from VDD is
used to drive SO output and the pull-up current for CS and
INT pins. VDD must be applied for wake-up from negative
edge of CS or INT.
GROUND (GND)
The GND pin provides ground for the IC as well as ground
for inputs programmed as switch-to-battery inputs.
PROGRAMMABLE SWITCHES (SP0 : SP7)
The 33972 device has 8 switch inputs capable of being
programmed to read switch-to-ground or switch-to-battery
contacts. The input is compared with a 4.0 V reference.
When programmed to be switch-to-battery, voltages greater
than 4.0 V are considered closed. Voltages less than 4.0 V
are considered open. The opposite holds true when inputs
are programmed as switch-to-ground. Programming features
are defined in Table 6 through Table 11 in the Functional
Device Operation section of this datasheet beginning on
page 13. Voltages greater than the VPWR supply voltage will
source current through the SP inputs to the VPWR pin.
Transient battery voltages greater than 38/40 V must be
clamped by an external device.
SWITCH-TO-GROUND INPUTS (SG0 : SG13)
The SGn pins are switch-to-ground inputs only. The input
is compared with a 4.0 V reference. Voltages greater than
4.0 V are considered open. Voltages less than 4.0 V are
considered closed. Programming features are defined in
Table 6 through Table 11 in the Functional Device Operation
section of this datasheet beginning on page 13. Voltages
greater than the VPWR supply voltage will source current
through the SG inputs to the VPWR pin. Transient battery
voltages greater than 40 V must be clamped by an external
device.
Analog Integrated Circuit Device Data
Freescale Semiconductor
33972
11