MCP2003 datasheet(9/34 Pages) MICROCHIP

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DS22230D-page 9

MCP2003/4/3A/4A

1.5

Pin Descriptions

TABLE 1-2:

PINOUT DESCRIPTIONS

1.5.1

RECEIVE DATA OUTPUT (RXD)

The Receive Data Output pin is an open drain (OD)

output and follows the state of the LIN pin, except in

Power Down mode.

1.5.2

CS (CHIP SELECT)

This is the Chip Select Input pin. An internal pull-down

resistor will keep the CS pin low. This is done to ensure

that no disruptive data will be present on the bus while

the microcontroller is executing a Power-on Reset and

an I/O initialization sequence. The pin must detect a

high level to activate the transmitter. An internal Low-

Pass filter, with a typical time constant of 10 µS,

prevents unwanted wake-up (or transition to Power

Down mode) on glitches.

If CS = 0 when the VBB supply is turned on, the device

goes to Ready mode as soon as internal voltages sta-

bilize, and stays there as long as the CS pin is held low

(0). In Ready mode, the receiver is on, and the LIN

transmitter driver is off.

If CS = 1 when the VBB supply is turned on, the device

will proceed to Operation mode, or TXOFF (refer to

Figure 1-2 – Figure 1-5), as soon as internal voltages

stabilize.

This pin may also be used as a local wake-up input

(refer to Example 1-1). In this implementation, the

microcontroller I/O controlling the CS should be

converted to a high-impedance input allowing the

internal pull-down resistor to keep CS low. An external

switch, or other source, can then wake-up both the

transceiver and the microcontroller (if powered). Refer

to Section 1.3 “Modes of Operation”, for detailed

operation of CS.

1.5.3

WAKE UP INPUT (WAKE)

This pin is only available on the MCP2003/2003A.

The WAKE pin has an internal 800K pull up to VBB. A

falling edge on the WAKE pin causes the device to

wake from Power-Down mode. Upon waking, the

MCP2003/3A will enter Ready mode.

1.5.4

FAULT/TXE

This pin is only available on the MCP2004/2004A. This

pin is bidirectional and allows disabling of the

transmitter, as well as fault reporting related to

disabling the transmitter. This pin is an open-drain

output, with states as defined in TABLE 1-3: “FAULT/

TXE Truth Table”. The transmitter is disabled

whenever this pin is low (‘0’), either from an internal

Pin Name

8-Pin

PDIP,

SOIC

8-Pin

DFN

MCP2003/2003A

MCP2004/2004A

Normal Operation

RXD

Receive Data Output (OD), HV

tolerant

Receive Data Output (OD), HV tol-

erant

Chip Select (TTL), HV tolerant

Chip Select/Local WAKE (TTL),

HV tolerant

WAKE

(MCP2003/2003A only)

FAULT/TXE

(MCP2004/2004A only)

Wake up, HV tolerant

Fault Detect Output (OD)

Transmitter Enable (TTL)

HV tolerant

TXD

Transmit Data Input (TTL), HV

tolerant

Transmit Data Input (TTL), HV tol-

erant

VSS

Ground

LBUS

LIN Bus (bidirectional)

VBB

Battery Positive

VREN

Voltage Regulator Enable Output Voltage Regulator Enable Output

—

Exposed Thermal Pad. Do not

electrically connect or connect to

Vss

Exposed Thermal Pad. Do not

electrically connect or connect to

Vss

Legend: TTL = TTL Input Buffer; OD = Open-Drain Output

Note:

It is not recommended to tie CS high as

this can result in the device entering

Operation

mode

before

the

microcontroller is initialized and may result

in unintentional LIN traffic.

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