33889 datasheet(26/60 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33889

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

INTRODUCTION

The device has four modes of operation, normal, stand-by,

sleep and stop modes. All modes are controlled by the SPI.

An additional temporary mode called “normal request mode”

is automatically accessed by the device (refer to state

machine) after wake-up events. Special mode and

configurations are possible for software application debug

and flash memory programming.

NORMAL MODE

In this mode both regulators are ON, and this corresponds

to the normal application operation. All functions are

available in this mode (watchdog, wake-up input reading

through the SPI, HS1 activation, and CAN communication).

The software watchdog is running and must be periodically

cleared through the SPI.

STANDBY MODE

Only the Regulator 1 is ON. Regulator 2 is turned OFF by

disabling the V2CTRL pin. The CAN cell is not available, as

powered from V2. Other functions are available: wake-up

input reading through the SPI and HS1 activation. The

watchdog is running.

SLEEP MODE

Regulators 1 and 2 are OFF. In this mode, the MCU is not

powered. The device can be awakened internally by cyclic

sense via the wake-up input pins and HS1 output, from the

forced wake function, the CAN physical interface, and the SPI

(CS pin).

STOP MODE

Regulator 2 is turned OFF by disabling the V2CTRL pin.

Regulator 1 is activated in a special low power mode which

allows it to deliver 2.0 mA. The objective is to supply the MCU

of the application while it is turned into a power saving

condition (i.e stop or wait mode).

Stop mode is entered through the SPI. Stop mode is

dedicated to powering the Microcontroller when it is in low

power mode (stop, pseudo stop, wait etc.). In these modes,

the MCU supply current is less than 1.0 mA. The MCU can

restart its software application very quickly without the

complete power up and reset sequence.

When the application is in stop mode (both MCU and

SBC), the application can wake-up from the SBC side (ex

cyclic sense, forced wake-up, CAN message, wake-up

inputs) or the MCU side (key wake-up etc.).

When Stop mode is selected by the SPI, stop mode

becomes active 20

µs after end of the SPI message. The “go

to stop” instruction must be the last instruction executed by

the MCU before going to low power mode.

In Stop mode, the Software watchdog can be “running” or

“not running” depending on the selection by the SPI. Refer to

the SPI description, RCR register bit WDSTOP. If the W/D is

enabled, the SBC must wake-up before the W/D time has

expired, otherwise a reset is generated. In stop mode, the

SBC wake-up capability is identical as in sleep mode.

STOP MODE: WAKE-UP FROM SBC SIDE, INT PIN

ACTIVATION

When an application is in stop mode, it can wake-up from

the SBC side. When a wake-up is detected by the SBC (CAN,

Wake-up input, forced wake-up, etc.), the SBC turns itself

into Normal request mode and activates the VDD1 main

regulator. When the main regulator is fully active, then the

wake-up is signalled to the MCU through the INT pin. The INT

pin is pulled low for 10

µs and then returns high. Wake-up

events can be read through the SPI registers.

STOP MODE: WAKE-UP FROM MCU SIDE

When the application is in stop mode, the wake-up event

may come to the MCU. In this case, the MCU has to signal to

the SBC that it has to go into Normal mode in order for the

VDD1 regulator to be able to deliver full current capability.

This is done by a low to high transition of the CS pin. The CS

pin low to high activation has to be done as soon as possible

after the MCU. The SBC generates a pulse at the INT pin.

Alternatively the L0 and L1 inputs can also be used as wake-

up from the Stop mode.

STOP MODE CURRENT MONITORING

If the current in Stop mode exceeds the IDD1S-WU

threshold, the SBC jumps into Normal request mode,

activates the VDD1 main regulator, and generates an

interrupt to the MCU. This interrupt is not maskable and a not

bit are set into the INT register.

SOFTWARE WATCHDOG IN STOP MODE

If the watchdog is enabled (register MCR, bit WDSTOP

set), the MCU has to wake-up independently of the SBC

before the end of the SBC watchdog time. In order to do this,

the MCU has to signal the wake-up to the SBC through the

SPI wake-up (CS pin low to high transition to activated the

SPI wake-up). Then the SBC wakes up and jumps into the

normal request mode. The MCU has to configure the SBC to

go to either into normal or standby mode. The MCU can then

choose to go back into stop mode.

If no MCU wake-up occurs within the watchdog timing, the

SBC will activate the reset pin and jump into the normal

request mode. The MCU can then be initialized.

33889 Datasheet(PDF) 26 Page - Freescale Semiconductor, Inc

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