33912 Datasheet, PDF(25/47 Page) Freescale Semiconductor, Inc – LIN System Basis Chip with DC Motor Pre-driver and Current

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33912 Datasheet, PDF (25/47 Pages) Freescale Semiconductor, Inc – LIN System Basis Chip with DC Motor Pre-driver and Current

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FUNCTIONAL DEVICE OPERATIONS

OPERATIONAL MODES

FUNCTIONAL DEVICE OPERATIONS

OPERATIONAL MODES

Introduction

The 33912 offers three main operating modes: Normal

(Run), Stop, and Sleep (Low Power). In Normal Mode, the

device is active and is operating under normal application

conditions. The Stop and Sleep Modes are low-power modes

with wake-up capabilities.

In Stop Mode, the voltage regulator still supplies the MCU

with VDD (limited current capability), while in Sleep Mode the

voltage regulator is turned off (VDD = 0 V).

Wake-up from Stop Mode is initiated by a wake-up

interrupt. Wake-up from Sleep Mode is done by a reset and

the voltage regulator is turned back on.

The selection of the different modes is controlled by the

MOD1:2 bits in the Mode Control Register (MCR).

Figure 15 describes how transitions are done between the

different operating modes. Table 5, 27, gives an overview of

the operating modes.

RESET MODE

The 33912 enters the Reset Mode after a power up. In this

mode, the RST pin is low for 1ms (typical value). After this

delay, it enters the Normal Request Mode and the RST pin is

driven high.

The Reset Mode is entered if a reset condition occurs (VDD

low, watchdog trigger fail, after wake-up from Sleep Mode,

Normal Request Mode timeout occurs).

NORMAL REQUEST MODE

This is a temporary mode automatically accessed by the

device after the Reset Mode, or after a wake-up from Stop

Mode.

In Normal Request Mode, the VDD regulator is ON, the

RESET pin is High, and the LIN is operating in RX Only

Mode.

As soon as the device enters in the Normal Request Mode

an internal timer is started for 150ms (typical value). During

these 150ms, the MCU must configure the Timing Control

MOD2 and MOD1 bits set = 0, to enter the Normal Mode. If

within the 150ms timeout, the MCU does not command the

33912 to Normal Mode, it will enter in Reset Mode. If the

WDCONF pin is grounded in order to disable the watchdog

function, it goes directly in Normal Mode after the Reset

Mode. If the WDCONF pin is open, the 33912 stays typically

for 150ms in Normal Request before entering in Normal

Mode.

NORMAL MODE

In Normal Mode, all 33912 functions are active and can be

controlled by the SPI interface and the PWMIN pin.

The VDD regulator is ON and delivers its full current

capability.

If an external resistor is connected between the WDCONF

pin and the Ground, the window watchdog function will be

enabled.

The wake-up inputs (L1-L4) can be read as digital inputs

or have its voltage routed through the analog-multiplexer.

The LIN interface has slew rate and timing compatible with

the LIN protocol specification 2.0. The LIN bus can transmit

and receive information.

The high side and low side switches are active and have

PWM capability according to the SPI configuration.

The interrupts are generated to report failures for VSUP

over/under -voltage, thermal shutdown, or thermal shutdown

prewarning on the main regulator.

SLEEP MODE

The Sleep Mode is a low power mode. From Normal

Mode, the device enters into Sleep Mode by sending one SPI

command through the Mode Control Register (MCR). All

blocks are in their lowest power consumption condition. Only

some wake-up sources (wake-up inputs with or without cyclic

sense, forced wake-up and LIN receiver) are active. The 5V

regulator is OFF. The internal low-power oscillator may be

active if the IC is configured for cyclic-sense. In this condition,

one of the high side switches is turned on periodically and the

wake-up inputs are sampled.

Wake-up from Sleep Mode is similar to a power-up. The

device goes in Reset Mode except that the SPI will report the

wake-up source and the BATFAIL flag is not set.

STOP MODE

The Stop Mode is the second low power mode, but in this

case the 5V regulator is ON with limited current drive

capability. The application MCU is always supplied while the

33912 is operating in Stop Mode.

The device can enter into Stop Mode only by sending the

SPI command. When the application is in this mode, it can

wake-up from the 33912 side (for example: cyclic sense,

force wake-up, LIN bus, wake inputs) or the MCU side (CS,

RST pins). Wake-up from Stop Mode will transition the 33912

to Normal Request Mode and generates an interrupt except

if the wake-up event is a low to high transition on the CS pin

or comes from the RST pin.

Analog Integrated Circuit Device Data

Freescale Semiconductor

33912

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