MCP2003 datasheet(4/32 Pages) MICROCHIP

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MCP2003/4

DS22230A-page 4

 2010 Microchip Technology Inc.

1.3

Modes of Operation

For an overview of all operational modes, refer to

Table 1-1.

1.3.1

POWER-DOWN MODE

In Power Down mode, the transmitter and VREN are

both off. Only the receiver section and the wake-up

circuits are operational. This is the lowest power

mode.

On bus activity (e.g. a BREAK character), CS going to

a high level, or on a falling edge on WAKE, the device

will immediately enter Ready mode. If CS is held high

as the device transitions from Power Down to Ready

mode, the device will transition to Operation mode as

soon as internal voltages stabilize.

1.3.2

READY MODE

Upon entering the Ready mode, VREN is enabled and

the receiver detect circuit is powered up. The transmit-

ter remains disabled and the device is ready to receive

data but not to transmit.

Upon VBB supply pin power-on, the device will remain

in Ready mode as long as CS is low. If CS transitions

high, the device will enter Operation mode. However, if

the TXD pin is held low when CS goes high, the device

will transition to Transmitter Off mode instead of

Operation mode.

1.3.3

OPERATION MODE

In this mode, all internal modules are operational.

The MCP2003/4 will go into the Power Down mode on

the falling edge of CS. The MCP2003/4 will enter

Transmitter Off mode in the event of a Fault condition.

These include: thermal overload, bus contention and

TXD timer expiration.

The MCP2004 device can also enter Transmitter Off

mode if the FAULT/TXE pin is pulled low

1.3.4

TRANSMITTER OFF MODE

Transmitter Off mode is reached whenever the

transmitter is disabled either due to a Fault condition or

pulling the nFAULT/TXE pin low on the MCP2004. The

fault

conditions

include:

thermal

overload,

bus

contention or TXD timer expiration.

The MCP2003/4 will go into Power Down mode on

falling edge of CS, or return to Operation mode if all

faults are resolved and the FAULT/TXE pin on the

MCP2004 is high.

FIGURE 1-2:

OPERATIONAL MODES STATE DIAGRAM – MCP2003

Note:

Bus activity is defined as LBUS dropping

below VIL(LBUS) for longer than the Bus

Activity Debounce time (tBDB).

Operation

Mode

VREN ON

RX ON

TX ON

Ready

Mode

VREN ON

RX ON

TX OFF

TOFF

Mode

VREN ON

RX ON

TX OFF

Sleep Mode

VREN OFF

RX OFF

TX OFF

VBB > 5.5V

CS = 1 and TXD = 0

CS=0

CS = 1 and TXD = 1

CS=0

Falling edge

on LIN

or CS = 1

CS = 1 and

TXD = 1

and No Fault

Fault

(Thermal or Timer)

POR

VREN OFF

RX OFF

TX OFF

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