LIN Transcvr
Drives a single LIN line (referenced to the 12 V battery) low with a 30 kΩ-strength pull-down to send dominant bits, and lets a master-side 1 kΩ pull-up restore the recessive state. Receives the same line back into the MCU as logic-level RXD with hysteresis.
An open-drain NMOS driver pulls the LIN pin to LIN-GND for a dominant 0, slewing at a controlled 1–3 V/µs rate to keep emissions inside CISPR-25 Class 5. The receiver is a comparator with ~40 % / 60 % VBAT thresholds and Schmitt hysteresis. A wake-up detector watches for a >250 µs dominant pulse from a slave so the MCU can sleep at <50 µA between LIN frames.
In plain terms
Like a doorbell wire running from house to garden gate — one slow rusty conductor that doesn't need to win arbitration, just announce that someone leaned on the seat-heater button.
Why designers use it
- Replace point-to-point wiring on slow body-electronics nodes — one twisted wire and a ground link 16 LIN slaves to a master ECU, cutting harness weight and connector count.
- Cost — at roughly $0.30 per transceiver in volume, LIN slots in below CAN where data rate doesn't justify a more expensive PHY.
- Slave-task simplicity — LIN's master-driven schedule doesn't need bit-by-bit arbitration, so even an 8-bit MCU with no hardware controller can bit-bang the protocol.
- Battery-line tolerance — every LIN transceiver is rated for −40 V to +60 V on the bus pin, surviving a polarity-reversed jump-start without escaping smoke.
Best for
- Mirror nodes
- Seat motors
- HVAC sensors
Key specifications
- Bit rate: Up to 20 kbit/s
- Bus voltage: 8 V – 18 V (12 V vehicle bus)
- ESD: ±8 kV HBM, ±15 kV bus pin
- Sleep current: 5 – 30 µA
- Slew rate: Programmable for EMC
When not to use it
- For >20 kbit/s — LIN is hard-locked to 19.2 kbit/s typical; pull CAN-FD or 100BASE-T1 once you need bandwidth.
- Where bus arbitration matters — LIN is master/slave, so collision-prone multi-master traffic belongs on CAN.
Common mistakes
- Forgetting the master's 1 kΩ pull-up to VBAT — the bus floats and every slave reads the line as a stuck dominant 0.
- Sourcing a slave ECU's logic supply through the LIN line's reverse diode and skipping a proper 12 V regulator — the diode pops on the first load-dump pulse and the ECU dies first time a wiper arm cycles.
Where you will find it
- TI describes a LIN transceiver translating between a microcontroller's logic interface and the single-wire bus.
- Commander and responder connections differ. Follow the chosen transceiver's application circuit and fault ratings rather than assuming every LIN device withstands the same transient voltage.
A short history
A LIN transceiver links a microcontroller to a single-wire automotive bus, converting logic-level TXD and RXD signals into bus voltage levels and back. The bus typically operates as an open-drain circuit with a pullup resistor holding it recessive (high); the transceiver drives it dominant (low) when active. One commander node usually controls communication with up to several responder nodes, offering a simple, low-cost alternative to more complex differential buses like CAN.
Good to know
- LIN was created in 1999 as a low-cost alternative to CAN for non-critical body electronics — mirrors, seat memory, sunroofs, ambient lighting.
- A LIN bus has one master and up to 15 slaves on a single wire (the chassis is the return), running at 20 kbit/s — fast enough for human-perceivable controls.
- Wake-up on LIN bus uses a deliberately low-current 'dominant' state; the transceiver sips microamps until traffic appears, then powers up the local microcontroller.