33975 Datasheet, PDF (12/32 Pages) Freescale Semiconductor, Inc – Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current

FUNCTIONAL DESCRIPTIONS
FUNCTIONAL TERMINAL DESCRIPTION
WAKE INPUT (WAKE)
The WAKE terminal is an open-drain output and a wake-up
input. The terminal is designed to control a power supply
Enable terminal. In the Normal mode, the WAKE terminal is
low. In the Sleep mode, the WAKE terminal is high. The
WAKE terminal has a pull-up to the internal +5.0 V supply.
In Sleep mode with the WAKE terminal high, falling edge of
WAKE will place the 33975 in Normal mode. In Sleep mode
with VDD applied, the INT terminal must be high for negative
edge of WAKE to wake up the device. If VDD is not applied to
the device in Sleep mode, INT does not affect WAKE
operation.
LOAD SUPPLY VOLTAGE (VPWR)
The VPWR terminal is battery input and Power-ON Reset
to the 33975 IC. The VPWR terminal requires external
reverse battery and transient protection. Maximum input
voltage on V_PWR is 50 V. All wetting, sustain, and internal
logic current is provided from the V_PWR terminal.
LOGIC VOLTAGE (VDD)
The VDD input terminal is used to determine logic levels
on the microprocessor interface (SPI) terminals. Current from
VDD is used to drive SO output and the pull-up current for CS
and INT terminals. VDD must be applied for wake-up from
negative edge of CS or INT.
GROUND (GND)
The GND terminal provides ground for the IC as well as
ground for inputs programmed as switch-to-battery inputs.
PROGRAMMABLE SWITCHES (SP0–SP7)
The 33975 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 14. Voltages greater than the V_PWR supply voltage will
source current through the SP inputs to the VPWR terminal.
Transient battery voltages greater than 38/40 V must be
clamped by an external device.
SWITCH-TO-GROUND (SG0–SG13)
The SGn terminals 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 14. Voltages
greater than the V_PWR supply voltage will source current
through the SG inputs to the VPWR terminal. Transient
battery voltages greater than 38/40 V must be clamped by an
external device.
33975
12
Analog Integrated Circuit Device Data
Freescale Semiconductor