33742 datasheet(21/52 Pages) MOTOROLA

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MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

33742

In Normal Request mode, the VDD regulator is ON, the V2

regulator is OFF, and the RST terminal is HIGH. As soon as the

33742 enters the Normal Request mode, an internal 350 ms

timer is started (parameter tNRTOUT). During these 350 ms, the

MCU of the application must address the 33742 via SPI and

configure the TIM1 subregister to select the watchdog period.

This is the condition for the 33742 to stop the 350 ms timer and

go into the Normal or Standby mode and set the watchdog timer

according to the configuration.

Normal Request Entered and No Watchdog Configuration

Occurs

If the Normal Request mode is entered after the 33742

powers up or after a wake-up from Stop mode, and if no

watchdog configuration occurs while the 33742 is in Normal

Request mode, the 33742 goes into Reset mode after the

350 ms time period has expired before again going into Normal

Request mode. If no watchdog configuration is achieved, the

33742 alternatively goes from Normal Request mode, to Reset

mode, to Normal Request mode, and so on.

If the Normal Request mode is entered after a wake-up from

Sleep mode, and if no watchdog configuration occurs while the

33742 is in Normal Request mode, the 33742 goes back to

Sleep mode.

Normal Mode

In Normal mode, both the VDD and V2 regulators are ON.

This corresponds to the normal application operation. All

functions are available in this mode (watchdog, wake-up input

reading through SPI, HS activation, and CAN communication).

Watchdog software is running and must be periodically cleared

through SPI.

Standby Mode

In Standby mode, only the VDDregulator is ON. The V2

regulator is turned OFF by disabling the V2CTRL terminal. The

CAN interface is not able to send messages. If a CAN message

is received, the CANWU bit is set. Other functions available are

L0:L3 input reading through SPI and HS activation. Watchdog

is running.

Sleep Mode

In Sleep mode, the VDD and V2 regulators are OFF. Current

from the VSUP terminal is reduced. In Sleep mode, the 33742

can be awakened by L0:L3 inputs, by cyclic sense of the L0:L3

inputs, by the automatic forced wake-up timer, and from the

CAN physical interface receiving an incoming CAN message.

When a wake-up occurs, the 33742 goes first into the Reset

mode before entering Normal Request mode.

Stop Mode

The V2 regulator is turned OFF by disabling the V2CTRL

terminal. The VDD regulator is activated in a special low power

mode, allowing the delivery of a few mA. The objective is to

maintain power on the MCU of the application while the MCU is

turned into power-saving condition (i.e, Stop or Wait modes). In

Stop mode, the device supply current from VPWR is very low.

When the application is in Stop mode (both MCU and

33742), the application can wake up from either the 33742 side

(for example, cyclic sense, forced wake-up, CAN message,

wake-up inputs, and overcurrent on VDD) or the MCU side (key

wake-up, etc.).

Stop mode is always selected by SPI. In Stop mode, the

watchdog software may be either running or not running

depending upon selection by SPI (Reset Control Register

[RCR], bit WDSTOP). To clear the watchdog if it is running, the

33742 must be awakened by the CS terminal (SPI wake-up). In

Stop mode, the 33742 wake-up capability is identical to that in

Sleep mode, with the addition of CS and VDD overcurrent wake-

up. Refer to Table 2, page 20.

Application Wake-Up from 33742 Side

When the application is in Stop mode, it can wake up from

the 33742 side. When a wake-up is detected by the 33742 (for

example, CAN, wake-up input), the 33742 turns itself into

Normal Request mode and generates an interrupt pulse at the

INT

terminal.

Application Wake-Up from MCU Side

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

may come from the MCU side. In this case the MCU signals to

the 33742 by a LOW-to-HIGH transition on the CS terminal.

Then the 33742 goes into Normal Request mode and generates

an interrupt pulse at the INT terminal.

Stop Mode Current Monitor

If the VDD output current exceeds an internal threshold

(IDDS-WU), the 33742 goes automatically into Normal Request

mode and generates an interrupt at the INT terminal. The

interrupt is not maskable and the INTR register will have no flag

set.

Interrupt Generation When Wake-Up from Stop Mode

When the 33742 wakes up from Stop mode, it first enters the

Normal Request mode before generating a pulse (10

µs typical)

on the INT terminal. These interrupts are not maskable, and the

wake-up event can be read through the SPI registers, CANWU

bit in the CAN Register (CANR), and LCTRx bit in the Wake-Up

overcurrent or from forced wake-up, no bit is set. After the INT

pulse, the 33742 accepts SPI command after a time delay

(tS-1STSPI).

Watchdog Software in Stop Mode

If watchdog is enabled, the MCU has to wake up

independently of the 33742 before the end of the 33742

watchdog time. In order to do this, the MCU must signal the

wake-up to the 33742 through the SPI wake-up (CS activation).

The 33742 then wakes up and jumps into the Normal Request

mode. The MCU has to configure the 33742 to go to either

Normal or Standby mode. The MCU can then decide to go back

to the Stop mode.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

33742 Datasheet(PDF) 21 Page - Motorola, Inc

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