MCP2021-330E-P MICROCHIP [Microchip Technology], MCP2021-330E-P Datasheet - Page 13

• Manufacturer Part Number: MCP2021-330E-P
• Description: LIN Transceiver with Voltage Regulator
• Manufacturer: MICROCHIP [Microchip Technology]

1.4.8
Fault Detect Output and Transmitter Enable Input
bidirectional pin.
This pin is an open-drain output. Its state is defined as
shown in
whenever this pin is low (‘0’), either from an internal
fault condition or by external drive. This allows the
transmitter to be placed in an off state and still allow the
voltage regulator to operate. Refer to
The FAULT/TXE also signals a mismatch between the
TXD input and the L
detect a bus contention. Since the bus exhibits a
propagation delay, the sampling of the internal
compare is debounced to eliminate false faults.
TABLE 1-2:
1.4.9
RESET is an open-drain output pin. This pin reflects an
internal signal that tracks the internal system voltage
has reached a valid, stable level.
As long as the internal voltage is valid, this pin will keep
high impedance. When the system voltage drops below
the minimum required, the voltage regulator will shut
down and immediately convert the RESET output to
short to GND. A pull-up resistor is needed to change
the output to high/low voltage. When connected to a
micro-controller input, this can provide a warning that
the voltage regulator is shutting down (see
Alternately, it can act as an external brown-out by con-
necting the RESET output to MCLR (see
addition to monitoring the internal voltage, RESET is
asserted immediately upon entering the Power-Down
mode.
© 2005-2012 Microchip Technology Inc.
Legend: x = don’t care
Note 1:
TXD
In
H
H
L
L
x
x
Table
RXD
Out
H
H
The FAULT/TXE is valid after approximately 25 µs after TXD falling edge. This is to eliminate false fault
reporting during bus propagation delays.
L
L
RESET
x
x
FAULT/TXE
1-2. The transmitter driver is disabled
FAULT/TXE TRUTH TABLE
LIN
GND
GND
V
V
V
V
I/O
BUS
BB
BB
BB
BB
BUS
level. This can be used to
Override
Thermal
OFF
OFF
OFF
OFF
ON
x
Table
Figure
Figure
1-1.
External
1-2). In
Input
1-2).
H
H
H
H
H
L
FAULT/TXE
Output
Driven
This
approximately 750 kΩ.
The FAULT/TXE pin sampled at a rate faster than every
10 µs.
H
H
H
L
L
x
Note 1: The FAULT/TXE pin is true (0) whenever
pin
MCP2021/2/1P/2P
2: FAULT/TXE is true (0) when V
FAULT, TXD driven low, LIN
V
OK
OK
OK, data is being received from the LIN
FAULT, transceiver in thermal shutdown
NO FAULT, the CPU is commanding the
transceiver to turn off the transmitter driver
BB
has
the internal circuits have detected a short
or thermal excursion and have disabled
the L
and has disabled the L
(Note 1)
BUS
an
output driver.
internal
Definition
pull-up
BUS
DS22018F-page 13
BUS
output driver.
shorted to
REG
resistor
not OK
BUS
of