33975A_14 데이터 시트보기 (PDF) - Freescale Semiconductor

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33975A_14

Multiple Switch Detection Interface with Suppressed Wake-up and 32 mA Wetting Current

Freescale Semiconductor 

FUNCTIONAL DESCRIPTIONS

FUNCTIONAL PIN DESCRIPTION

In Sleep mode with the WAKE pin high, the falling edge of

WAKE will place the 33975 in Normal mode. In Sleep mode

with VDD applied, the INT pin must be high for a negative

edge of WAKE to wake up the device. If VDD is not applied to

the device in Sleep mode, INT does not affect the WAKE

operation.

LOAD SUPPLY VOLTAGE (VPWR)

The VPWR pin is battery input and Power-ON Reset to the

33975 IC. The VPWR pin requires external reverse battery

and transient protection. The maximum input voltage on

VPWR is 50 V. All wetting, sustain, and internal logic current is

provided from the VPWR pin.

LOGIC VOLTAGE (VDD)

The VDD input pin is used to determine logic levels on the

microprocessor interface (SPI) pins. Current from VDD is

used to drive the SO output, and the pull-up current for CS

and INT pins. VDD must be applied for a wake-up from the

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 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 16. 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 (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 16. Voltages

greater than the VPWR supply voltage will source current

through the SG inputs to the VPWR pin. Transient battery

voltages greater than 38/40 V must be clamped by an

external device.

Analog Integrated Circuit Device Data

Freescale Semiconductor

33975

13

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