MCP2025-500ESLASHP datasheet(4/38 Pages) MICROCHIP

4 / 38 page

MCP2025

DS20002306B-page 4

 2012-2014 Microchip Technology Inc.

1.1.1

POWER-ON RESET MODE

Upon application of VBB, or whenever the voltage on

VBB is below the threshold of regulator turn-off voltage

VOFF (typically 4.50V), the device enters Power-On

Reset (POR) mode. During this mode, the device

maintains the digital section in a Reset mode and waits

until the voltage on the VBB pin rises above the

threshold of regulator turn-on voltage VON (typically

5.75V) to enter Ready mode. In Power-On Reset

mode, the LIN physical layer and voltage regulator are

disabled and the RESET pin is switched to ground.

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

the 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 it is thus 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 the 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 the 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

connected only in this mode.

The device goes into 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 Transmitter

Off mode can be reached from Ready mode by setting

CS/LWAKE to high when the TXD pin is low, or from

Operation mode by pulling down CS/LWAKE to low.

In Transmitter Off mode, the receiver is enabled but the

LBUS transmitter is off. It is a lower-power mode.

In order to minimize power consumption, the regulator

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

GBW product and it is thus 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 the TXD pin to low from Transmitter

Off mode. In Power-Down mode, the transceiver 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 regulator

output has stabilized (approximately 0.3 ms to 1.2 ms),

it can go into either 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 transition to Transmitter Off

mode and then jump to Power-Down

mode after a deglitch delay of about

20 µs.

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