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Normal Mode

Low Power Mode

Wake-Up Events

Standby Mode

TPIC1021

LIN Physical Interface

SLIS113 – OCTOBER 2004

OPERATING STATES (continued)

Operating Modes

MODE

EN

RXD

LIN BUS

INH

TRANSMITTER

COMMENTS

TERMINATION

Low Power

0

Floating

High impedance

High impedance

Off

Standby

0

Low

30 k

Ω (typical)

High

Off

Wake-up event detected,

waiting on MCU to set EN

Normal

1

LIN bus data

30 k

Ω (typical)

High

On

This is the normal operational mode where the receiver and driver are active. The receiver detects the data

stream on the LIN bus and outputs it on the RXD pin for the LIN controller where recessive on the LIN bus is a

digital high and dominate on the LIN bus is digital low. The driver will transmit input data on the TXD pin to the

LIN bus.

The power saving mode for the TPIC1021 and the default state after power-up (assuming EN=0). Even with the

extremely low current consumption in this mode, the TPIC1021 can still wake-up from LIN bus activity, a falling

edge on the NWake pin or if EN is set high. The LIN bus and NWake pins are filtered to prevent false wake-up

The low power mode is entered by setting the EN pin low.

While the device is in low power mode the following conditions exist:

•

The LIN bus driver is disabled and the internal LIN bus termination is switched off (to minimize power loss if

LIN is short-circuited to ground).

•

The normal receiver is disabled.

•

The INH pin is high impedance.

•

EN input, NWake input and the LIN wake-up receiver are active.

There are three ways to wake-up the TPIC1021 from Low Power Mode.

•

Remote wake-up via recessive (high) to dominant (low) state transition on LIN Bus where dominant bus state

ups from disturbances on the LIN Bus).

•

ups from disturbances on NWake).

•

Local wake-up via EN being set high

This mode is entered whenever a wake-up event occurs via the LIN bus or NWake pin while the TPIC1021 is in

low power mode. The LIN bus slave termination circuit and the INH pin are turned on when standby mode is

entered. The application system will power up once the INH pin is turn assuming it is using a voltage regulator

connected via INH pin. Standby Mode is signaled via a low level on RXD pin.

When EN pin is set high while the TPIC1021 is in Standby Mode the device returns to Normal Mode and the

normal transmission paths from TXD to LIN bus and LIN bus to RXD are turned on.

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