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MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
908E626
21
Analog Die I/Os
LIN Physical Layer
The LIN bus terminal provides a physical layer for single-wire
communication in automotive applications. The LIN physical
layer is designed to meet the LIN physical layer specification.
The LIN driver is a low-side MOSFET with internal current
limitation and thermal shutdown. An internal pullup resistor with
a serial diode structure is integrated, so no external pullup
components are required for the application in a slave node.
The fall time from dominant to recessive and the rise time from
recessive to dominant is controlled. The symmetry between
both slew rate controls is guaranteed.
The LIN terminal offers high susceptibility immunity level
from external disturbance, guaranteeing communication during
external disturbance.
The LIN transmitter circuitry is enabled by setting the PSON
bit in the System Control Register (SYSCTL). If the transmitter
works in the current limitation region, the LINCL bit in the
System Status Register (SYSSTAT) is set. Due to excessive
power dissipation in the transmitter, software is advised to
monitor this bit and turn the transmitter off immediately.
TXD Terminal
The TXD terminal is the MCU interface to control the state of
the LIN transmitter (see
Figure 1
, page 2). When TXD is LOW,
LIN output is low (dominant state). When TXD is HIGH, the LIN
output MOSFET is turned off. The TXD terminal has an internal
pullup current source in order to set the LIN bus in recessive
state in the event, for instance, the microcontroller could not
control it during system power-up or power-down.
RXD Terminal
The RXD transceiver terminal is the MCU interface, which
reports the state of the LIN bus voltage. LIN HIGH (recessive
state) is reported by a high level on RXD, LIN LOW (dominant
state) by a low level on RXD.
Analog Multiplexer/ADOUT Terminal
The ADOUT terminal is the analog output interface to the
ADC of the MCU (see
Figure 1
, page 2). An analog multiplexer
is used to read six internal diagnostic analog voltages.
Current Recopy
The analog multiplexer is connected to the four low-side
current sense circuits of the half-bridges. These sense circuits
offer a voltage proportional to the current through the low-side
MOSFET. High or low resolution is selectable: 5.0 V/2.5 A or
5.0 V/500 mA, respectively. (Refer to
Half-Bridge Current
Recopy on page 25
.)
Temperature Sensor
The 908E626 includes an on-chip temperature sensor. This
sensor offers a voltage that is proportional to the actual chip
junction temperature.
V
SUP
Prescaler
The V
SUP
prescaler permits the reading or measurement of
the external supply voltage. The output of this voltage is V
SUP
/
RATIO
VSUP
.
The different internal diagnostic analog voltages can be
selected with the ADMUX Register.
Analog Multiplexer Configuration Register (ADMUX)
SS3, SS2, SS1, and SS0—A/D Input Select Bits
These read/write bits select the input to the ADC in the
microcontroller according to
Table 2
, page 22. Reset clears
SS3, SS2, SS1, and SS0 bits.
Register Name and Address: ADMUX - $07
Bit7
6
5
4
3
2
1
Bit0
Read
0
0
0
0
SS3
SS2
SS1
SS0
Write
Reset
0
0
0
0
0
0
0
0
F
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
.