SN65HVDA100-Q1

SLIS128

– NOVEMBER 2011

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Sleep Mode

Sleep mode is the power saving mode for the SN65HVDA100. Even with the extremely low current consumption

in this mode, the SN65HVDA100 can still wake up from LIN bus via a wake-up signal, a low on NWake, or if EN

is set high. The LIN bus and NWake are filtered to prevent false wake-up events. The wake-up events must be

The sleep mode is entered by setting EN low.

While the device is in sleep 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). However, the weak current pullup is active to prevent false wake-up events

in case an external connection to the LIN bus is lost.

•

The normal receiver is disabled.

•

INH is high impedance.

•

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

Wake-Up Events

There are three ways to wake up from sleep mode:

•

Remote wake-up via recessive (high) to dominant (low) state transition on LIN bus. The dominant state must

from disturbances on the LIN bus or if the bus is shorted to ground).

•

wake-ups from disturbances on NWake)

•

Local wake-up via EN being set high

Wake-Up Request (RXD)

When the device encounters a wake-up event from the LIN bus or NWake pin, RXD goes low, and the device

transitions to standby mode (until EN is reasserted high and the device enters normal mode). Once the device

enters normal mode, the RXD pin is releasing the wake-up request signal, and the RXD pin then reflects the

receiver output from the bus.

Wake-Up Source Recognition (TXD)

When the device encounters a wake-up event from the LIN bus or NWake pin, TXD indicates the source while

the device enters and remains in standby mode (until EN is reasserted high and the device enters normal mode).

In addition to the internal pullup resistor on TXD, typically an external pullup resistor (~5 k

Ω) is used in the

system

's I/O supply voltage. A high on TXD in standby mode indicates a remote wake-up via the LIN bus, and a

low (strong pulldown) on the TXD pin indicates a local wake-up via the NWAKE pin.

Standby Mode

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

mode. The LIN bus slave termination circuit and INH are turned on when standby mode is entered. The

application system powers up once INH is turned on, assuming the system is using a voltage regulator

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

When EN is set high while the device 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 enabled.

During power up if EN is low the device goes into Standby mode and if EN is high the device goes into Normal

mode. EN has an internal pull down resistor, so if the pin is floating in the system, the internal pull down will

ensure it is pulled low.

Application Hint: if the INH output of the HVDA100 is not used to control the system power management

(voltage regulators) and monitor wake up sources, but sleep mode is used to reduce system current the RXD pin

the RXD pin transitions low and would signal to the software that the HVDA100 is in standby mode and should

be returned to sleep mode to return to the lowest power state.

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© 2011, Texas Instruments Incorporated