33661 datasheet(13/21 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33661

FUNCTIONAL DESCRIPTION

FUNCTIONAL PIN DESCRIPTION

WAKE INPUT PIN (WAKE)

The WAKE pin is a high-voltage input used to wake up the

device from the Sleep mode. WAKE is usually connected to

an external switch in the application. The typical wake

thresholds are VSUP/2.

The WAKE pin has a special design structure and allows

wake-up from both HIGH-to-LOW or LOW-to-HIGH

transitions. When entering into Sleep mode, the LIN monitors

the state of the WAKE pin and stores it as a reference state.

The opposite state of this reference state will be the wake-up

event used by the device to enter again into Normal mode.

An internal filter is implemented (40

µs typical filtering time

delay). WAKE pin input structure exhibits a high impedance,

with extremely low input current when voltage at this pin is

below 14 V. When voltage at the WAKE pin exceeds 14 V,

input current starts to sink into the device. A serial resistor

should be inserted in order to limit the input current mainly

during transient pulses. Recommended resistor value is

33 k

Ω.

Important The WAKE pin should not be left open. If the

wake-up function is not used, WAKE should be connected to

ground to avoid false wake-up.

33661 Datasheet(PDF) 13 Page - Freescale Semiconductor, Inc