33911 datasheet(23/45 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33911

FUNCTIONAL DEVICE OPERATIONS

OPERATIONAL MODES

FUNCTIONAL DEVICE OPERATIONS

OPERATIONAL MODES

INTRODUCTION

The 33911 offers three main operating modes: Normal

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

device is active and 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), and in Sleep Mode the

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

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, and Table 5, 25, gives an

overview of the operating modes.

RESET MODE

The 33911 enters the Reset Mode after a power up. In this

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

delay, the 33911 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 a wake-up from Sleep Mode,

or a Normal Request Mode timeout).

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 the Normal Request Mode,

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

these 150ms, the MCU must configure the Timing Control

set = 0, to enter in Normal Mode. If within the 150ms timeout

the MCU does not command the 33911 to Normal Mode, it

will enter in Reset Mode. If the WDCONF pin is grounded in

order to disable the watchdog function, the 33911 goes

directly in Normal Mode after the Reset Mode. If the

WDCONF pin is open, the 33911 stays typically for 150ms in

Normal Request before entering in Normal Mode.

NORMAL MODE

In Normal Mode, all 33911 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 and L2) 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 the 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 the Sleep Mode by sending one SPI

command through the 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, the high side

switches are turned on periodically and the wake-up inputs

are sampled.

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

device goes into 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

33911 is operating in Stop Mode.

The device can enter the Stop Mode only by sending a SPI

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

up from the 33911 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 33911 to

Normal Request Mode and generate an interrupt, except if

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

comes from the RST pin.

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