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TMP451-Q1: "ALERT" function is need to be calibrated?

Part Number: TMP451-Q1
Other Parts Discussed in Thread: TMP451,


Regarding the "ALERT" function. The action is base on "status register (0x2, bit [2:6])".
I did a test and put the DUT into the -40C chamber, and found TMP451 ALERT pull-low after booting
To read the register 0x2 = 0xA8 = 1010 1000 = local/remote low temperature limit

but our temperature low limit setting as below,
reg 0x6 => 0x13 = Local temperature low limit = -45C
reg 0x8 => 0x9 = Remote temperature low limit = -55C

The ambient temperature is only -40C, we read that the TMP451 is only -39C, it does not touch the lower limit.
so "ALERT" function is need to be calibrated? (or temperature limit )

Thank you.

  • Hi Hsin,

    Can you please send a register dump?


  • Hi Jalen,

    Please refer the register dump value. Thank you.

    REG Value
    0x00 0x64
    0x01 0x86
    0x02 0x00
    0x03 0x04
    0x04 0x08
    0x05 0xa4
    0x06 0x13
    0x07 0xd6
    0x08 0x09
    0x10 0x00
    0x11 0x00
    0x12 0x00
    0x13 0x00
    0x14 0x00
    0x15 0x90
    0x19 0xd6
    0x20 0xa9
    0x21 0x0a
    0x22 0x81
    0x23 0x00
    0x24 0x00
    0xFE 0x55
  • Hi Hsin,

    I believe you are configuring the registers correctly, but due to the timing characteristics of the TMP451-Q1 it may not be able to change the register setting as the first conversions start which does not allow you to get the ALERT response you are looking for upon power up. 

    I would suggest two options:

    1. Ignore or mask the first alert upon power up
    2. Set the device to extended more and wait for the first proper conversion (30 ms). After this conversion is complete I would then write to the registers to set the limits.