MCP2021/2
TABLE 1-1:
State
POR
READY
OPERATION
OVERVIEW OF OPERATIONAL MODES
Transmitter
OFF
OFF
ON
Receiver
OFF
Activity
Detect
ON
Voltage
Regulator
OFF
ON
ON
Operation
Read CS/LWAKE, if LOW, then READY,
if HIGH, Operational mode
If CS/LWAKE high level, then Operation
mode
Bus Off state
Comments
If CS/LWAKE low level, then Power down Normal
If FAULT/TXE low level, then Transmitter- Operation
Off mode
mode
On LIN bus falling, go to READY mode.
On CS/LWAKE high level, go to
Operational mode
If CS/LWAKE low level, then Power down
If FAULT/TXE high, then Operation mode
Low Power
mode
POWER DOWN
OFF
Activity
Detect
ON
OFF
TRANSMITTER-
OFF
OFF
ON
1.4
Typical Applications
TYPICAL MCP2021 APPLICATION
+12
+12
EXAMPLE 1-1:
WAKE-UP
43V
(5)
220 kΩ
V
DD
TXD
RXD
I/O
I/O
(3)
R
TP
(5)
C
F
Master Node Only
+12
C
G
V
REG
TXD
V
BB
1 kΩ
RXD
CS/LWAKE
FAULT/TXE
V
SS
L
BUS
27V
(4)
LIN Bus
100nF
Note 1:
See
for correct capacity and ESR for stable operation.
.
2:
C
F
is the filter capacitor for the external voltage supply.
3:
This diode is only needed if CS/LWAKE is connected to 12V supply.
4:
Transient suppressor diode. Vclamp L = 43V.
5:
These components are required for additional load dump protection above 43V..
©
2009 Microchip Technology Inc.
DS22018E-page 5
MICROCHIP [ MICROCHIP TECHNOLOGY ]
