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PRODUCT PREVIEW
FEATURES
1
2
3
4
8
7
6
5
RXD
EN
NWake
TXD
INH
V
SUP
LIN
GND
D PACKAGE
(TOP VIEW)
DESCRIPTION
TPIC1021
LIN Physical Interface
SLIS113 OCTOBER 2004
·
Dominant State Timeout Protection on TXD
Pin
·
LIN Physical Layer Specification Revision 2.0
compliant. Conforms to SAEJ2602
·
Wake-Up Request on RXD Pin
Recommended Practice for LIN
·
Control of External Voltage Regulator (INH
·
LIN Bus Speed up to 20 kbps
Pin)
·
ESD Protection to 12 kV (Human Body Model)
·
Integrated Pull-Up Resistor and Series Diode
on LIN Pin
for LIN Slave Applications
·
LIN Pin Handles Voltage from -40 V to +40 V
·
Low EME (Electromagnetic Emissions), High
EMI (Electromagnetic Immunity)
·
Survives Transient Damage in Automotive
Environment (ISO 7637)
·
Bus Terminal Short-Circuit Protected for
Short to Battery or Short to Ground
·
Operation with Supply from 7 V to 27 V DC
·
Thermally Protected
·
Two Operation Modes: Normal and Low
Power (Sleep) Mode
·
Ground Disconnection Fail Safe at System
Level
·
Low Current Consumption in Low Power
Mode
·
Ground Shift Operation at System Level
·
Wake-Up Available from LIN Bus, Wake-Up
·
Unpowered Node Does Not Disturb the
Input (External Switch) or Host MCU
Network
·
Interfaces to MCU with 5 V or 3.3 V I/O Pins
The TPIC1021 is the LIN (Local Interconnect Network) physical interface, which integrates the serial transceiver
with wake up and protection features. The LIN bus is a single wire, bi-directional bus typically used for low-speed
in-vehicle networks using baud rates between 2.4 kbps and 20 kbps.
The LIN bus has two logical values: the dominant state (voltage near ground) represents a logic `0' and the
recessive state (voltage near battery) and represents logic `1'.
In the recessive state the LIN bus is pulled high by the TPIC1021's internal pull-up resistor (30k
) and series
diode, so no external pull-up components are required for slave applications. Master applications require an
external pull-up resistor (1k
) plus a series diode.
The LIN Protocol output data stream on the TXD pin is converted by the TPIC1021 into the LIN bus signal
through a current limited, wave-shaping low-side driver with control as outlined by the LIN Physical Layer
Specification Revision 2.0. The receiver converts the data stream from the LIN bus and outputs the data stream
via the RXD pin.
In Low Power mode, the TPIC1021 requires very low quiescent current even though the wake-up circuits remain
active allowing for remote wake up via the LIN bus or local wake ups via NWake or EN pins.
The TPIC1021 has been designed for operation in the harsh automotive environment. The device can handle LIN
bus voltage swing from +40 V down to ground and survive -40 V. The device also prevents back feed current
through the LIN pin to the supply input in case of a ground shift or supply voltage disconnection. It also features
under-voltage, over temperature, and loss of ground protection. In the event of a fault condition the output is
immediately switched off and remains off until the fault condition is removed.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCT PREVIEW information concerns products in the forma-
Copyright © 2004, Texas Instruments Incorporated
tive or design phase of development. Characteristic data and other
specifications are design goals. Texas Instruments reserves the
right to change or discontinue these products without notice.
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PRODUCT PREVIEW
TERMINAL FUNCTIONS
LIN Bus Pin
Transmit Input Pin (TXD)
Receive Output Pin (RXD)
TPIC1021
LIN Physical Interface
SLIS113 OCTOBER 2004
Terminal Assignments
PIN NAME
PIN NO.
PIN TYPE
DESCRIPTION
RXD
1
O
RXD output (open drain) pin interface reporting state of LIN bus voltage
EN
2
I
Enable input pin
NWake
3
I
High voltage input pin for device wake up
TXD
4
I
TXD input pin interface to control state of LIN output
GND
5
I
Ground connection
LIN
6
I/O
LIN bus pin single wire transmitter and receiver
V
SUP
7
Supply
Device supply pin (connected to battery in series with external reverse blocking diode)
INH
8
O
Inhibit pin controls external voltage regulator with inhibit input
This I/O pin is the single-wire LIN bus transmitter and receiver.
Transmitter Characteristics
The driver is a low side transistor with internal current limitation and thermal shutdown. There is an internal
30-k
pull-up resistor with a serial diode structure to V
sup
so no external pull-up components are required for LIN
slave mode applications. An external pull-up resistor of 1 k
plus a series diode to V
sup
must be added when the
device is used for master node applications.
Voltage on the LIN pin can go from -40 V to +40 V DC without any currents other than through the pull-up
resistance. There are no reverse currents from the LIN bus to supply (V
sup
), even in the event of a ground shift or
loss of supply (V
sup
).
The LIN thresholds and ac parameters are compatible LIN Protocol Specification Revision 2.0.
During a thermal shut down condition the driver is disabled.
Receiver Characteristics
The receiver's characteristic thresholds are ratio-metric with the device supply pin. Typical thresholds are 50%,
with a hysteresis between 5% and 17.5% of supply.
This pin is the interface to the MCU's LIN Protocol Controller or SCI/UART used to control the state of the LIN
output. When TXD is low, LIN output is dominant (near ground). When TXD is high, LIN output is recessive (near
battery). TXD input structure is compatible with microcontrollers with 3.3 V and 5.0 V I/O. This pin has an internal
pull-down resistor.
TXD Dominant State Timeout
If the TXD pin is inadvertently driven permanently low by a hardware or software application failure, the LIN bus
is protected by TPIC1021's Dominant State Timeout Timer. This timer is triggered by a falling edge on the TXD
pin. If the low signal remains on the TXD pin for longer than t
DST
, the transmitter is disabled thus allowing the LIN
bus to return to the recessive state and communication to resume on the bus. The timer is reset by a rising edge
on TXD pin.
This pin is the interface to the MCU's LIN Protocol Controller or SCI/UART, which reports the state of the LIN
bus voltage. LIN recessive (near battery) is represented by a high level on RXD and LIN dominant (near ground)
is represented by a low level on RXD. The RXD output structure is an open-drain output stage. This allows the
TPIC1021 to be used with 3.3 V and 5 V I/O microcontrollers. If the microcontroller's RXD pin does not have an
integrated pull-up, an external pull-up resistor to the microcontroller I/O supply voltage is required.
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PRODUCT PREVIEW
Supply Voltage (V
SUP
)
Ground (GND)
Enable Input Pin (EN)
NWake Input Pin (NWake)
Inhibit Output Pin (INH)
TPIC1021
LIN Physical Interface
SLIS113 OCTOBER 2004
RXD Wake-up Request
When the TPIC1021 has been in low power mode and encounters a wake-up event from the LIN bus or NWake
pin the RXD pin will go LOW while the device enters and remains in Standby Mode (until EN is re-asserted high
and the device enters Normal Mode).
The TPIC1021 device power supply pin. This pin is connected to the battery through an external reverse battery
blocking diode. The continuous DC operating voltage range for the TPIC1021 is from 7 V to +27 V. The V
SUP
is
protected to for harsh automotive conditions of up to + 40 V.
The device contains a reset circuit to avoid false bus messages during under-voltage conditions when V
SUP
is
less than V
SUP_UNDER
.
TPIC1021 device ground connection. The TPIC1021 can operate with a ground shift as long as the ground shift
does not reduce V
SUP
below the minimum operating voltage. If there is a loss of ground at the ECU level, the
TPIC1021 will not have a significant current consumption on the LIN pin while in the recessive state (<100 µA
sourced via the LIN pin) and for the dominant state the pull-up resistor should be active.
The enable input pin controls the operation mode of the TPIC1021 (Normal or Low Power Mode). When enable
is high, the TPIC1021 is in normal mode allowing a transmission path from TXD to LIN and from LIN to RXD.
When the enable input is low, the device is put into low power (sleep) mode and there are no transmission paths.
The device can enter normal operating mode only after being woken up. The enable pin has an internal
pull-down resistor to ensure the device remains in low power mode even if the enable pin floats.
The NWake input pin is a high-voltage input used to wake up the TPIC1021 from low power mode. NWake is
usually connected to an external switch in the application. A falling edge on NWake with a low that is asserted
longer than the filter time (t
NWAKE
) results in a local wake-up. The NWake pin provides an internal pull-up current
source to V
SUP
.
The inhibit output pin is used to control an external voltage regulator that has an inhibit input. When the
TPIC1021 is in normal operating mode, the inhibit high-side switch is enabled and the external voltage regulator
is activated. When TPIC1021 is in low power mode, the inhibit switch is turned off, which disables the voltage
regulator. A wake-up event on for the TPIC1021 will return the INH pin to V
SUP
level. The INH pin output current
is limited to 2 mA. The INH pin can also drive an external transistor connected to an MCU interrupt input.
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PRODUCT PREVIEW
Functional Block Diagram
RXD
TXD
NWake
INH
EN
LIN
GND
Driver
Slope Control
Receiver
Filter
Filter
2
1
8
3
4
7
6
5
V
SUP
V
SUP
/2
Wake-Up
and
Vreg Control
Dominant
State
Timeout
Fault
Detection and
Protection
with
OPERATING STATES
Unpowered
System
Standby
Mode
Normal Mode
Low Power
Mode
A
C
A
B
EN = 1
EN = 1
EN = 0
A
LIN Bus Wake-UP
or
NWake Pin Wake-Up
V
SUP
< V
SUP_under
TXD: off
RXD: LOW
IHN: HIGH (high
side switched on)
Term: 30 k
W
TXD: on
RXD: LIN bus data
IHN: HIGH (high
side switched on)
Term: 30 k
W
TXD: off
RXD: floating
IHN: high
impedance (high
side switched off)
Term: high
W
A: V
SUP
< V
SUP_under
B: V
SUP
> V
SUP_unde
, EN = 0
C:V
SUP
> V
SUP_unde
, EN = 1
TPIC1021
LIN Physical Interface
SLIS113 OCTOBER 2004
Figure 1. Operating States Diagram
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PRODUCT PREVIEW
Normal Mode
Low Power Mode
Wake-Up Events
Standby Mode
TPIC1021
LIN Physical Interface
SLIS113 OCTOBER 2004
OPERATING STATES (continued)
Operating Modes
MODE
EN
RXD
LIN BUS
INH
TRANSMITTER
COMMENTS
TERMINATION
Low Power
0
Floating
High impedance
High impedance
Off
Standby
0
Low
30 k
(typical)
High
Off
Wake-up event detected,
waiting on MCU to set EN
Normal
1
LIN bus data
30 k
(typical)
High
On
This is the normal operational mode where the receiver and driver are active. The receiver detects the data
stream on the LIN bus and outputs it on the RXD pin for the LIN controller where recessive on the LIN bus is a
digital high and dominate on the LIN bus is digital low. The driver will transmit input data on the TXD pin to the
LIN bus.
The power saving mode for the TPIC1021 and the default state after power-up (assuming EN=0). Even with the
extremely low current consumption in this mode, the TPIC1021 can still wake-up from LIN bus activity, a falling
edge on the NWake pin or if EN is set high. The LIN bus and NWake pins are filtered to prevent false wake-up
events. The wake-up events must be active for their respective time periods: t
LINBUS
, t
NWake
.
The low power mode is entered by setting the EN pin low.
While the device is in low power mode the following conditions exist:
·
The LIN bus driver is disabled and the internal LIN bus termination is switched off (to minimize power loss if
LIN is short-circuited to ground).
·
The normal receiver is disabled.
·
The INH pin is high impedance.
·
EN input, NWake input and the LIN wake-up receiver are active.
There are three ways to wake-up the TPIC1021 from Low Power Mode.
·
Remote wake-up via recessive (high) to dominant (low) state transition on LIN Bus where dominant bus state
of 50% threshold is detected. The dominant state must be held for t
LINBUS
filter time (to eliminate false wake
ups from disturbances on the LIN Bus).
·
Local wake-up via falling edge on NWake pin which is held low for filter time t
NWake
(to eliminate false wake
ups from disturbances on NWake).
·
Local wake-up via EN being set high
This mode is entered whenever a wake-up event occurs via the LIN bus or NWake pin while the TPIC1021 is in
low power mode. The LIN bus slave termination circuit and the INH pin are turned on when standby mode is
entered. The application system will power up once the INH pin is turn assuming it is using a voltage regulator
connected via INH pin. Standby Mode is signaled via a low level on RXD pin.
When EN pin is set high while the TPIC1021 is in Standby Mode the device returns to Normal Mode and the
normal transmission paths from TXD to LIN bus and LIN bus to RXD are turned on.
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