LIN Transceiver Problem

sunilkasar — Tue, 25 Oct 2016 07:17:00 GMT

Hello all,

I am using NXP's TJA1028T/5V0/20/1J LIN transceiver with STM8 board. To bring LIN transceiver into "Normal Mode", is it mandatory to feed 5V supply to EN pin and VBATT pin of transceiver? I have fed 3.3V to EN pin and 3V to VBATT pin. It is not working. Other pins I have connected correctly.

Note: The LIN transceiver is activated when the TJA1028 enters Normal mode.In Normal mode, the transceiver can transmit and receive data via the LIN bus. Thereceiver detects data streams on the LIN pin and transfers them to the microcontroller viapin RXD. LIN recessive is represented by a HIGH level on RXD, LIN dominant by a LOWlevel. (This is mentioned in data sheet)

Re: LIN Transceiver Problem

RadekS — Wed, 02 Nov 2016 12:50:36 GMT

Hi Sunil,

According to the Fig 3. State diagram the conditions from state change from OFF to STANDBY mode is:

VBAT > Vth(det)pon AND Tvj < Tth(rel)otp

And the conditions from state change from STANDBY to NORMAL mode is:

EN = 1 AND RSTN = 1.

The Vth(det)p threshold is defined between 3V and 5.25V. The VBAT operating range is from 4.5 V to 28 V.

The overtemperature protection release threshold Tth(rel)otp is defined as 138°C (126°C min; 150°C max).

The EN pin switching threshold voltage is defined in range 0.8V~2V.

The RSTN is output pin influenced mainly by VCC voltage level

The output voltage on pin VCC is monitored continuously and a system reset signal is generated (pin RSTN goes LOW) if an undervoltage event is detected (VCC < Vuvd for tdet(uv)(VCC)). Pin RSTN will go HIGH again once the voltage on VCC exceeds the undervoltage recovery threshold (Vuvr) for trst.

Where

Vuvd = 4.5~4.75V for VCC=5V

tdet(uv)(VCC) = 1~15us

Vuvr = 4.6~4.9V for VCC=5V

Trst = 2~8ms

Your version contains 5V regulator. Therefore you need to provide at least 5.5V to VBATT (there should be voltage in range 5.5 V to 28 V) AND at least 2V at EN pin AND temperature has to be below 126°C.

I hope it helps you.

Have a great day,
Radek

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