TEXAS INSTRUMENTS TPIC1021A-Q1 Technical data

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FEATURES

RXD

TXD

NWake

INH

EN

LIN

GND

Receiver

Filter

TPIC1021A

V

SUP

V

SUP

Wake Up, State,

and INH Control

Fault

Detection

and Protection

Driver
With Slope
Control

Dominant

State

Timeout

V

SUP

/2

Filter

• LIN Physical Layer Specification Revision 2.0 • Dominant State Timeout Protection

Compliant and Conforms to SAEJ2602
Recommended Practice for LIN

• LIN Bus Speed up to 20-kbps LIN Specified

Maximum

• Sleep Mode: Ultralow Current Consumption,

Allows Wake-Up Events From LIN Bus,
Wake-Up Input (External Switch), or Host MCU

• High-Speed Receive Capable

• ESD Protection to ± 12 kV (Human-Body

Model) on LIN Pin

• LIN Pin Handles Voltage From –40 V to 40 V

• Survives Transient Damage in Automotive

Environment (ISO 7637)

• Extended Operation With Supply From 7 V to

27 V DC (LIN Specification 7 V to 18 V)

• Interfaces to MCU With 5-V or 3.3-V I/O Pins

• Wake-Up Request on RXD Pin

• Control of External Voltage Regulator

(INH Pin)

• Integrated Pullup Resistor and Series Diode

for LIN Slave Applications

• Low Electromagnetic Emission (EME), High

Electromagnetic Immunity (EMI)

• Bus Terminal Short Circuit Protected for

Short to Battery or Short to Ground

• Thermally Protected

• Ground Disconnection Fail Safe at System

Level

• Ground Shift Operation at System Level

• Unpowered Node Does Not Disturb the

Network

• Supports ISO9141 (K-Line)-Like Functions

TPIC1021A-Q1

LIN PHYSICAL INTERFACE

SLIS117 – AUGUST 2007

FUNCTIONAL BLOCK DIAGRAM

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.

PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.

Copyright © 2007, Texas Instruments Incorporated

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1
2
3
4

8
7
6
5

RXD

EN

NWake

TXD

INH
V

SUP

LIN
GND

D PACKAGE

(TOP VIEW)

TPIC1021A-Q1
LIN PHYSICAL INTERFACE

SLIS117 – AUGUST 2007

DESCRIPTION

The TPIC1021A is the Local Interconnect Network (LIN) physical interface, which integrates the serial
transceiver with wake-up and protection features. The LIN bus is a single-wire bidirectional bus typically used for
low-speed in-vehicle networks using data rates between 2.4 kbps and 20 kbps. The LIN protocol output data
stream on TXD is converted by the TPIC1021A into the LIN bus signal through a current-limited wave-shaping
driver 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 RXD. The LIN bus has two states: dominant state (voltage
near ground) and the recessive state (voltage near battery). In the recessive state, the LIN bus is pulled high by
the TPIC1021A’s internal pullup resistor (30 k Ω ) and series diode, so no external pullup components are
required for slave applications. Master applications require an external pullup resistor (1 k Ω ) plus a series diode
per the LIN specification.

In sleep mode, the TPIC1021A requires low quiescent current even though the wake-up circuits remain active,
allowing for remote wake up via the LIN bus or local wake up via the NWake or EN pins.

The TPIC1021A has been designed for operation in the harsh automotive environment. The device can handle
LIN bus voltage swings from 40 V down to ground and survive –40 V. The device also prevents back-feed
current through LIN to the supply input, in case of a ground shift or supply voltage disconnection. It also features
undervoltage, overtemperature, 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.

TERMINAL FUNCTIONS

TERMINAL ASSIGNMENTS

PIN

NAME NO.

RXD 1 O RXD output (open drain) interface reporting state of LIN bus voltage
EN 2 I Enable input
NWake 3 I High voltage input for device wake up
TXD 4 I TXD input interface to control state of LIN output
GND 5 GND Ground
LIN 6 I/O LIN bus single-wire transmitter and receiver
V

SUP

INH 8 O Inhibit controls external voltage regulator with inhibit input

PART NUMBER PACKAGE

TPIC1021A-Q1 SOIC-8 – D TPIC1021AQDRQ1 (reel) T1021A

(1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI

web site at www.ti.com .

(2) Package drawings, thermal data, and symbolization are available at www.ti.com/packaging .

7 Supply Device supply voltage (connected to battery in series with external reverse blocking diode)

TYPE DESCRIPTION

ORDERING INFORMATION

(2)

(1)

ORDERABLE PART NUMBER TOP-SIDE MARKING

2

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TPIC1021A-Q1

LIN PHYSICAL INTERFACE

SLIS117 – AUGUST 2007

Local Interconnect Network (LIN) Bus

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 Ω pullup resistor with a serial diode structure to V
slave mode applications. An external pullup resistor of 1 k Ω , plus a series diode to V
the device is used for master node applications.

Voltage on LIN can go from –40-V to 40-V dc without any currents other than through the pullup resistance.
There are no reverse currents from the LIN bus to supply (V
supply (V

).

SUP

The LIN thresholds and ac parameters are LIN Protocol Specification Revision 2.0 compliant.
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.

The receiver is capable of receiving higher data rates (>100 kbps) than supported by LIN or SAEJ2602
specifications. This allows the TPIC1021A to be used for high-speed downloads at end-of-line production or
other applications. The actual data rates acheivable depend on system time constants (bus capacitance and
pullup resistance) and driver characteristics used in the system.

, so no external pullup components are required for LIN

SUP

), even in the event of a ground shift or loss of

SUP

must be added when

SUP

Transmit Input (TXD)

TXD 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, the LIN output is dominant (near ground). When TXD is high, the LIN output is
recessive (near battery). The TXD input structure is compatible with microcontrollers with 3.3-V and 5-V I/O.
TXD has an internal pulldown resistor.

TXD Dominant State Timeout

If TXD is inadvertently driven permanently low by a hardware or software application failure, the LIN bus is
protected by TPIC1021A’s dominant state timeout timer. This timer is triggered by a falling edge on TXD. If the
low signal remains on TXD for longer than t

, the transmitter is disabled, thus allowing the LIN bus to return to

DST

the recessive state and communication to resume on the bus. The timer is reset by a rising edge on TXD.

Receive Output (RXD)

RXD 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
TPIC1021A to be used with 3.3-V and 5-V I/O microcontrollers. If the microcontroller’s RXD pin does not have
an integrated pullup, an external pullup resistor to the microcontroller I/O supply voltage is required.

RXD Wake-up Request

When the TPIC1021A has been in low-power mode and encounters a wake-up event from the LIN bus or
NWake pin, RXD goes low, while the device enters and remains in standby mode (until EN is reasserted high
and the device enters normal mode).

Supply Voltage (V

V

is the TPIC1021A device power supply pin. V

SUP

)

SUP

is connected to the battery through an external reverse

SUP

battery blocking diode. The continuous dc-operating voltage range for the TPIC1021A is from 7 V to 27 V. V
is protected for harsh automotive conditions up to 40 V.

The device contains a reset circuit to avoid false bus messages during undervoltage conditions when V
less than V

SUP_UNDER

.

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SUP

is

SUP

3

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TPIC1021A-Q1
LIN PHYSICAL INTERFACE

SLIS117 – AUGUST 2007

Ground (GND)

GND is the TPIC1021A device ground connection. The TPIC1021A can operate with a ground shift as long as
the ground shift does not reduce V
ECU level, the TPIC1021A does not have a significant current consumption on LIN bus.

Enable Input (EN)

EN controls the operation mode of the TPIC1021A (normal or sleep mode). When EN is high, the TPIC1021A is
in normal mode allowing a transmission path from TXD to LIN and from LIN to RXD. When EN is low the device
is put into sleep mode and there are no transmission paths available. The device can enter normal mode only
after being woken up. EN has an internal pulldown resistor to ensure the device remains in low-power mode
even if EN floats.

NWake Input (NWake)

NWake is a high-voltage input used to wake up the TPIC1021A from low-power mode. NWake is usually
connected to an external switch in the application. A low on NWake that is asserted longer than the filter time
(t

) results in a local wake-up. NWake provides an internal pullup source to V

NWAKE

Inhibit Output (INH)

INH is used to control an external voltage regulator that has an inhibit input. When the TPIC1021A is in normal
operating mode, the inhibit high-side switch is enabled and the external voltage regulator is activated. When
TPIC1021A is in low-power mode, the inhibit switch is turned off, which disables the voltage regulator. A
wake-up event on for the TPIC1021A returns INH to V
connected to an MCU interrupt input.

below the minimum operating voltage. If there is a loss of ground at the

SUP

.

SUP

level. INH can also drive an external transistor

SUP

4

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OPERATING STATES

Unpowered System

V V

sup sup_under

£

Standby Mode

Driver : Off

RXD: Low

INH: High (On)

Termination: 30 kW

EN = high

EN = low

EN = high

LIN Bus Wake-Up

or

Nwake Pin Wake-Up

V > V

EN = low

sup sup_under

V V

sup sup_under

£

V V

sup sup_under

£

V V

sup sup_under

£V > V

EN = high

sup sup_under

Sleep Mode

Driver : Off

RXD: Floating

INH: High impedance (Off)

Termination:Weak pullup

Normal Mode

Driver : On

RXD: LIN bus data

INH: High (On)

Termination: 30 kW

TPIC1021A-Q1

LIN PHYSICAL INTERFACE

SLIS117 – AUGUST 2007

MODE EN RXD INH TRANSMITTER COMMENTS

Sleep Low Floating Weak current pullup High impedance Off
Standby Low Low 30 k Ω (typ) High Off
Normal High LIN bus data 30 k Ω (typ) High On LIN transmission up to 20 kbps

Normal Mode

This is the normal operational mode, in which the receiver and driver are active, and LIN transmission up to the
LIN specified maximum of 20 kbps is supported. The receiver detects the data stream on the LIN bus and
outputs it on RXD 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 transmits input data on TXD to the LIN bus. Normal mode is entered as EN
transitions high while the TPIC1021A is in sleep or standby mode.

Sleep Mode

Sleep mode is the power saving mode for the TPIC1021A and the default state after power up (assuming EN is
low during power up). Even with the extremely low current consumption in this mode, the TPIC1021A can still
wake up from LIN bus via a wake-up signal, a low on NWake, or if EN is set high. The LIN bus and NWake are
filtered to prevent false wake-up events. The wake-up events must be active for their respective time periods
(t

LINBUS

The sleep mode is entered by setting EN low.

Figure 1. Operating States Diagram

Table 1. Operating Modes

LIN BUS

, t

NWake

).

TERMINATION

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Wake-up event detected, waiting
on MCU to set EN

5

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INH

High Impedance

TXD

MODE

Sleep

Normal

EN

RXD

Floating

LIN

t > t

go_to_operate

V

sup

V

sup

TPIC1021A-Q1
LIN PHYSICAL INTERFACE

SLIS117 – AUGUST 2007

While the device is in sleep 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). However, the weak current pullup is active to prevent false wake-up events
in case an external connection to the LIN bus is lost.

• The normal receiver is disabled.

• INH is high impedance.

• EN input, NWake input, and the LIN wake-up receiver are active.

Wake-Up Events

There are three ways to wake up the TPIC1021A from sleep mode:

• Remote wake-up via recessive (high) to dominant (low) state transition on LIN bus. The dominant state must
be held for t
from disturbances on the LIN bus or if the bus is shorted to ground).

• Local wake-up via a low on NWake, which is asserted low longer than the filter time t
wake-ups from disturbances on NWake)

• Local wake-up via EN being set high

Standby Mode

This mode is entered whenever a wake-up event occurs via LIN bus or NWake while the TPIC1021A is in sleep
mode. The LIN bus slave termination circuit and INH are turned on when standby mode is entered. The
application system powers up once INH is turned on, assuming the system is using a voltage regulator
connected via INH. Standby mode is signaled via a low level on RXD.

When EN is set high while the TPIC1021A 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 enabled.

filter time and then the bus must return to the recessive state (to eliminate false wake-ups

LINBUS

NWake

(to eliminate false

Figure 2. Wake-Up Via EN

6

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