33689D datasheet(22/31 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33689

FUNCTIONAL DESCRIPTION

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

As described below and depicted in Figure 1 below and

Table 1 on page 23, the 33689 has three operational modes:

Normal, Sleep, and Stop. Operational modes are controlled

by MODE1 and MODE2 bits in the SPI Register (refer to

Logic Commands and Registers on page 24). In additional,

there are two transitional modes: Reset and Normal Request.

RESET MODE

At power up, the 33689 switches automatically to Reset

Mode for 1 ms if VDD goes high. If VDD stays low, after

150 ms the 33689 goes in Sleep Mode.

NORMAL REQUEST MODE

Before entering in Normal Request Mode, the 33689 stays

for 1 ms in Reset Mode. In this mode, the LIN bus can

transmit and receive information.

Figure 1. 33689 Modes State Diagram

Power

Reset

Stop

Normal

Sleep

VDD HIGH & Reset Counter (1.0 ms)

Expired & Watchdog Selected

VDD LOW OR

(Normal Request

Timeout Occurs

[150 ms] & Watchdog

Selected)

Wake-Up

VDD LOW

VDD HIGH & Reset Counter (1.0 ms) Expired & Watchdog Not Selected

VDD LOW OR (Watchdog

Fail & Watchdog Selected)

Legend

Watchdog Selected: External resistor between WDC pin and GND or WDC pin open.

Watchdog Not Selected: WDC pin connected to GND.

Watchdog Fail: Watchdog trigger occurs in closed window or no SPI Watchdog trigger command.

Stop Command: SPI stop command.

Sleep Command: SPI sleep request followed by SPI sleep command.

Wake-Up: L1 or L2 state change or LIN bus wake-up or CS rising edge.

VDD LOW (150 ms) Expired & VSUV Bit = Logic [0]

Down

Normal

Request

33689D Datasheet(PDF) 22 Page - Freescale Semiconductor, Inc

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