MCP2025-330ESLASHP datasheet(4/36 Pages) MICROCHIP

4 / 36 page

 2012 Microchip Technology Inc.

DS22306A-page 4

MCP2025

1.1.2

READY MODE

The device enters READY mode from POR mode after

the voltage on VBB rises above the threshold of

regulator turn on voltage VON or from POWER-DOWN

mode when a remote or local wake-up event happens.

Upon entering READY mode, the voltage regulator and

receiver section of the transceiver are powered up. The

transmitter remains in an off state. The device is ready

to receive data but not to transmit. In order to minimize

the power consumption, the regulator operates in a

reduced power mode. It has a lower GBW product and

thus is slower. However, the 70 mA drive capability is

unchanged.

The device stays in READY mode until the output of the

voltage regulator has stabilized and CS/LWAKE pin is

HIGH (‘1’).

1.1.3

OPERATION MODE

If the CS/LWAKE pin changes to high while VREG is OK

(VREG > 0.8*VREG_NOM) and TXD pin is HIGH, the part

enters OPERATION mode from either READY or

TRANSMITTER-OFF mode.

In this mode, all internal modules are operational. The

internal pull-up resistor between LBUS and VBB is con-

nected only in this mode.

The device goes to TRANSMITTER-OFF mode at the

falling edge on the CS/LWAKE pin or when a fault is

detected.

1.1.4

TRANSMITTER OFF MODE

If VREG is OK (VREG > 0.8*VREG_NOM), the TRANSMIT-

TER-OFF mode can be reached by setting CS/LWAKE

to HIGH when TXD pin is LOW from READY mode; or

by pulling down CS/LWAKE to low from OPERATION

mode.

In TRANSMITTER-OFF mode, the receiver is enabled

but the LBUS transmitter is off. It is a lower power mode.

In order to minimize the power consumption, the regu-

lator operates in a reduced power mode. It has a lower

GBW product and thus is slower. However, the 70 mA

drive capability is unchanged.

The transmitter is also turned off whenever the voltage

regulator is unstable or recovering from a fault. This

prevents unwanted disruption on the bus during times

of uncertain operation.

1.1.5

POWER-DOWN MODE

POWER-DOWN mode is entered by pulling down both

the CS/LWAKE pin and TXD to low from TRANSMIT-

TER-OFF mode. In POWER-DOWN mode, the trans-

ceiver and the voltage regulator are both off. Only the

Bus Wake-up section and the CS/LWAKE pin wake-up

circuits are in operation. This is the lowest power mode.

If any bus activity (e.g. a BREAK character) occurs or

CS/LWAKE is set to HIGH during POWER-DOWN

mode, the device will immediately enter READY mode

and enable the voltage regulator. Then, once the regu-

lator output has stabilized (approximately 0.3 ms to

1.2 ms) it can go to either the OPERATION mode or

TRANSMITTER-OFF mode. Refer to Section 1.1.6

“Remote Wake-up”

for more details.

1.1.6

REMOTE WAKE-UP

The remote wake-up sub module observes the LBUS in

order to detect bus activity. In POWER-DOWN mode,

the normal LIN recessive/dominant threshold is

disabled, and the LIN bus Wake-Up Voltage Threshold

VWK(LBUS) is used to detect bus activities. Bus activity

is detected when the voltage on the LBUS falls below

the LIN bus Wake-Up Voltage Threshold VWK(LBUS)

(approximately 3.4V) for at least tBDB (a typical duration

of 80 µs ) followed by a rising edge. Such a condition

causes the device to leave POWER-DOWN mode.

Note:

The TXD pin needs to be set high before

setting the CS/LWAKE pin to low in order

to jump and stay in TRANSMITTER-OFF

mode. If the TXD pin is set or maintained

low before setting the CS/LWAKE pin to

low, the part will transit to TRANSMITTER-

OFF mode and then jump to POWER-

DOWN mode after a deglitch delay of

about 20 µs.

TABLE 1-1:

OVERVIEW OF OPERATIONAL MODES

State

Transmitter

Receiver

Internal

Wake Module

Voltage

Regulator

Operation

Comments

POWER-ON-

RESET

OFF

Transfer to READYmode after VBB > VON

READY

OFF

If CS/LWAKE is high, then proceed to OPERATION

or TRANSMITTER-OFF mode

Bus Off state

OPERATION

OFF

If CS/LWAKE is low level, then TRANSMITTER-

OFF mode

Normal operation

mode

POWER-DOWN

OFF

Activity Detect

OFF

On LIN bus rising edge or CS/LWAKE high level, go

to READY mode

Lowest power mode

TRANSMITTER-

OFF

If TXD and CS/LWAKE low level, then POWER-

DOWN

If TXD and CS/LWAKE high level, then OPERATION

Bus Off state, lower

power mode

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