33399 datasheet(12/19 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33399

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

As described below and depicted in Figure 10 and Table 5

on page 13, the 33399 has two operational modes, normal

and sleep, and one transitional mode, Awake.

NORMAL MODE

This is the normal transmitting and receiving mode. All

features are available.

SLEEP MODE

In this mode the transmission path is disabled and the

device is in low power mode. Supply current from VSUP is

20 µA typical. Wake-up can occur from LIN bus activity, as

well as from node internal wake-up through the EN pin and

the WAKE input pin.

DEVICE POWER-UP (AWAKE TRANSITIONAL

MODE)

At system power-up (VSUP rises from zero), the 33399

automatically switches into the “Awake” mode (refer to

Figure 10 below and Table 5 on page 13. It switches the INH

pin in HIGH state to VSUP level. The microcontroller of the

application then confirms the Normal mode by setting the EN

pin HIGH.

DEVICE WAKE-UP EVENTS

The device can be awakened from Sleep mode by three

wake-up events:

• LIN bus activity

• Internal node wake-up (EN pin)

• Wake-up from WAKE pin

Figures 7, 8, and 9 on page 9 show device application

circuit and detail of wake-up operations.

Wake-Up from LIN Bus (Awake Transitional Mode)

A wake-up from the LIN pin switching from recessive to

dominant state (switch from VSUP to GND) can occur. This is

achieved by a node sending a wake-up frame on the bus.

This condition internally wakes up the interface, which

switches the INH pin to a HIGH level to enable the voltage

regulator. The device switches into the Awake mode. The

microcontroller and the complete application power up. The

microcontroller must switch the EN pin to a HIGH level to

allow the device to leave the Awake mode and turn it into

Normal mode in order to allow communication on the bus.

Wake-Up from Internal Node Activity (Normal Mode)

The application can internally wake up. In this case the

microcontroller of the application sets the EN pin in the HIGH

state. The device switches into Normal mode.

Wake-Up from WAKE Pin (Awake Transitional Mode)

The application can wake up with the activation of an

external switch. Refer to Table 1, 8-SOICN Pin Definitions on

page 3.

Figure 10. Operational and Transitional Modes State Diagram

Power-Up/

Sleep

Awake

Normal

EN LOW

LIN Bus or WAKE Pin

EN HIGH

Wake-Up

EN HIGH (Local Wake-Up Event)

1.0 to 20

kbps

VPWR > 7.0 V

Note Refer to Table 5 for explanation.

VPWR < 7.0 V

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