MCP2003 datasheet(3/32 Pages) MICROCHIP

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DS22230A-page 3

MCP2003/4

1.0

DEVICE OVERVIEW

The MCP2003/4 provides a physical interface between

a microcontroller and a LIN bus. This device will

translate the CMOS/TTL logic levels to LIN logic level,

and vice versa. It is intended for automotive and

industrial applications with serial bus speeds up to

20 Kbaud.

LIN specification 2.1 requires that the transceiver of all

nodes in the system is connected via the LIN pin, refer-

enced to ground and with a maximum external

termination resistance of 510

 from LIN bus to battery

supply. The 510

 corresponds to 1 master and

15 slave nodes.

The VREN pin can be used to drive the logic input of an

external voltage regulator. This pin is high in all modes

except for Power Down mode.

1.1

External Protection

1.1.1

REVERSE BATTERY PROTECTION

An external reverse-battery-blocking diode should be

used to provide polarity protection (see Example 1-1).

1.1.2

TRANSIENT VOLTAGE

PROTECTION (LOAD DUMP)

An external 43V transient suppressor (TVS) diode,

between VBB and ground, with a 50

 transient

protection resistor (RTP) in series with the battery

supply and the VBB pin serve to protect the device from

power transients (see Example 1-1) and ESD events.

While this protection is optional, it is considered good

engineering practice.

1.2

Internal Protection

1.2.1

ESD PROTECTION

For component-level ESD ratings, please refer to the

maximum operation specifications.

1.2.2

GROUND LOSS PROTECTION

The LIN Bus specification states that the LIN pin must

transition to the recessive state when ground is

disconnected. Therefore, a loss of ground effectively

forces the LIN line to a high-impedance level.

1.2.3

THERMAL PROTECTION

The thermal protection circuit monitors the die

temperature and is able to shut down the LIN

transmitter.

There are two causes for a thermal overload. A thermal

shut down can be triggered by either, or both, of the

following thermal overload conditions.

• LIN bus output overload

• Increase in die temperature due to increase in

environment temperature

Driving the TXD and checking the RXD pin makes it pos-

sible to determine whether there is a bus contention

(Rx = low, Tx = high) or a thermal overload condition

(Rx = high, Tx = low). After a thermal overload event,

the device will automatically recover once the die tem-

perature has fallen below the recovery temperature

threshold. See Figure 1-1.

FIGURE 1-1:

THERMAL SHUTDOWN

STATE DIAGRAM

Operation

Mode

Transmitter

Shutdown

LIN bus

Shorted

to VBB

Temp < SHUTDOWN

TEMP

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