Datasheet

 2010-2013 Microchip Technology Inc. DS20002230E-page 9
MCP2003/4/3A/4A
1.5 Pin Descriptions
TABLE 1-2: PINOUT DESCRIPTIONS
1.5.1 RECEIVE DATA OUTPUT (R
XD)
The Receive Data Output pin is an open drain (OD)
output and follows the state of the LIN pin, except in
Power Down mode.
1.5.1.1 RXD Monitoring
The RXD pin is internally monitored. It has to be at a
high level (> 2.5V typical) while L
BUS is recessive
during Operation mode. Otherwise, an internal fault will
be created and the device will transition to Transmitter
Off mode. On the MCP2004/2004A, the nFAULT/TXE
pin will be driven low to indicate the Transmitter Off
state.
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 V
BB 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.
Pin Name
8-Pin
PDIP,
SOIC
8-Pin
DFN
MCP2003/2003A MCP2004/2004A
Normal Operation Normal Operation
R
XD 1 1 Receive Data Output (OD), HV
tolerant
Receive Data Output (OD), HV tol-
erant
CS 2 2 Chip Select (TTL), HV tolerant Chip Select/Local WAKE (TTL),
HV tolerant
WAKE
(MCP2003/2003A only)
FAULT/TXE
(MCP2004/2004A only)
3 3 Wake up, HV tolerant Fault Detect Output (OD)
Transmitter Enable (TTL)
HV tolerant
TXD 4 4 Transmit Data Input (TTL), HV
tolerant
Transmit Data Input (TTL), HV
tolerant
VSS 5 5 Ground Ground
L
BUS 6 6 LIN Bus (bidirectional) LIN Bus (bidirectional)
V
BB 7 7 Battery Positive Battery Positive
V
REN 8 8 Voltage Regulator Enable Output Voltage Regulator Enable Output
EP — 9 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.