Datasheet

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Normal Mode
Low Power Mode
Wake-Up Events
Standby Mode
TPIC1021
LIN Physical Interface
SLIS113C – OCTOBER 2004 – REVISED JULY 2005
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
events. The wake-up events must be active for their respective time periods: t
LINBUS
, t
NWake
.
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
of 50% threshold is detected. The dominant state must be held for t
LINBUS
filter time (to eliminate false wake
ups from disturbances on the LIN Bus).
• Local wake-up via falling edge on NWake pin which is held low for filter time t
NWake
(to eliminate false wake
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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