MLX90821

Relative Pressure Sensor IC

Page 23 of 40

REV 004 – 4 MAR 2021

3901090821

SENT Configuration

The SENT output is designed to be compliant with the SAE J2716 rev. Apr 2016 SENT standard. The tick time is

configurable in EEPROM using parameter TICK_DIV. The available tick time settings are 3us, 4us, 6us, 10us, 12us

and 16us. A pause pulse can also be enabled to have a fixed frame length of 282 ticks. This can be done using

parameter PAUSE. The default configuration for option code DBA-100 is 3us tick time and pause pulse enabled.

Fast Channel Configuration

On the fast channel, 8 different options are available to configure channel 1 and channel 2. An overview of these

different options and how to configure them can be found in Table 15.

#

FC_CFG

setting

Fast Channel 1

Fast Channel 2

Remark

1

0

Pressure (3x 4 bit)

Inverse of Pressure (3x 4 bit)

2

1

Pressure (3x 4 bit)

Rolling counter (2x 4 bit) and

inverse of MSN of Pressure

(1x 4 bit)

Default for option code DBA-100.

3

2

Pressure (3x 4 bit)

Medium temperature

(3x 4 bit)

Media temperature can either be

NTC or sensing element temperature.

4

3

Pressure (3x 4 bit)

Internal temperature

(3x 4 bit)

Internal temperature can either be

PTAT or sensing element

5

4

Pressure only (3x 4 bit)

/

6

5

Pressure only (4x 3 bit)

/

7

6

Data indicated by pointer 1

(3x 4 bit)

Data indicated by pointer 2

(3x 4 bit)

In this mode no diagnostics are

available. FC configuration only used

by Melexis.

8

7

Pressure (3x 4 bit)

0 (3x 4 bit)

Table 15: Fast channel configuration options

The selection of the fast channel output mode can be done by changing the parameter ‘FC_CFG’ in the EEPROM.

In case Medium temperature is selected to be available on fast channel 2, the type of media can be defined in

EEPROM using parameter ‘Tmedium_Select’. When selecting 0, linearized NTC temperature will be available.

Selecting 1 enables sensing element temperature. Sensing element temperature is not calibrated by default.

For Internal temperature, also two options are available defined in EEPROM parameter ‘Tinternal_Select’ where

0 corresponds to on chip factory calibrated PTAT temperature and 1 corresponds to sensing element

temperature. The same comment regarding the calibration of the sensing element temperature calibration as

made above applies here.

Slow Channel Configuration

The Slow Serial Channel is implemented according to the Enhanced Serial Message Format using 12 bit data and 8

bit message ID as described in the reference SENT protocol standard SAE J2716 rev. Apr 2016.