2012 Microchip Technology Inc.
DS22299B-page 3
MCP2050
1.0
FUNCTION DESCRIPTION
The MCP2050 provides a physical interface between a
microcontroller and a LIN half-duplex bus. It is intended
for automotive and industrial applications with serial
bus baud rates up to 20 kbaud. This device will trans-
late the CMOS/TTL logic levels to LIN logic levels, and
vice versa. The device offers optimum EMI and ESD
performance; it can withstand high voltage on the LIN
bus. The device supports two low-power modes to
meet automotive industry power consumption require-
ments. The MCP2050 also provides a +5V or 3.3V
70 mA regulated power output.
1.1
Modes of Operation
The MCP2050 works in five modes: POWER-ON-
RESET mode, POWER-DOWN mode, READY mode,
OPERATION mode, and TRANSMITTER OFF mode.
For an overview of all operational modes, please refer
to
Table 1-1. For the operational mode transition,
FIGURE 1-1:
STATE DIAGRAM
1.1.1
POWER-ON-RESET MODE
Upon application of VBB, or whenever the voltage on
VBB is below the threshold of regulator turn off voltage
VOFF (typically. 4.50V), the device enters POWER-ON-
RESET mode (POR). During this mode, the device
maintains the digital section in a reset mode and waits
until the voltage on pin VBB rises above the threshold
of regulator turn on voltage VON (typically 5.75V) to
enter into READY mode. In POWER-ON-RESET
mode, the LIN physical layer and voltage regulator are
disabled, and RESET output is forced to LOW.
POR
(2)
VREG OFF
RX OFF
TX OFF
READY
VREG ON
RX ON
TX OFF
TX OFF
VREG ON
RX ON
TX OFF
POWER-DOWN
VREG OFF
RX OFF
TX OFF
OPERATION
VREG ON
RX ON
TX ON
VBB>VON
CS/LWAKE=1&
FAULT/TXE=0&
VREG_OK=1
(1)
CS/LWAKE=0
CS/LWAKE=1 &
FAULT/TXE=1
(3) &
TXD=1&
VREG_OK=1
(1)
CS/LWAKE=1&
FAULT/TXE=1
(3)&
TXD=1
CS/LWAKE=1&
FAULT/TXE=0
CS/LWAKE=0
CS/LWAKE=1 OR
Voltage Rising Edge on LBUS
CS/LWAKE=0 or FAULT/TXE=0 or TXD=0
Note 1: VREG_OK: Regulator Output Voltage > 0.8VREG_NOM.
2: If the voltage on pin VBB falls below VOFF, the device will enter POWER ON RESET mode from all other
modes, which is not shown in the figure.
3: FAULT/TXE = 1 represents input High and no fault conditions. FAULT/TXE = 0 represents input Low or a
fault condition. Refer to Table 1-3.