TMP451-Q1: ALERT is turned off at startup.

Koji Hayashi92

Mastermind 6970 points

Part Number: TMP451-Q1

Hi TI-team

My customer use TMP451-Q1.

ALERT output does not operate normally at startup.

After starting up, it once becomes High, but after about 200ms it becomes Low.

When customer read register (02h), it was d0. (BUSY, LHIGH, RHIGH flags are on)

Please tell me about the following two points.

1. What is the cause of the alert becoming L ?

2.What are the measures to keep ALERT going high after startup ?

Best Regards,

Koji Hayashi

over 4 years ago

0 David Vaseliou over 4 years ago

TI__Expert 6820 points

Hi Koji,

Alert Pin will be low when either the Remote or local temperature limits (high or low) are crossed. Also, if the remote junction is detected as open the the Alert pin will go low.

If the status register is reading that LHIGH and RHIGH flags are "1" this means the device has detected the local and remote temperature are higher than the set values in registers 0x07, and 0x05.

To keep Alert high the measured temperatures must be within the temperature limit range. You can use the MASK1 bit in register 0x03 to mask the fault and keep the pin high if the temperature is not within the limits.

Thanks,

0 Koji Hayashi92 over 4 years ago in reply to David Vaseliou

Mastermind 6970 points

Hi David-san

Thank you for response.

This phenomenon occurs when starting up within the temperature limit range.

After register 0x07 is read, the flag disappears and ALERT output is also H output.

Please answer questions 1 and 2.

Best Regards,

Koji Hayashi

0 David Vaseliou over 4 years ago in reply to Koji Hayashi92

TI__Expert 6820 points

Hi Koji-san,

Can you please read the temperature and status register (0x00,0x10,0x01,0x15, and 0x02) when Alert pin is Low. As stated above the alert pin should only be low if outside the temperature limits or remote junction is detected as open.

Can you also send me the schematic and an oscilloscope screenshot of alert pin going low and the pull-up voltage rail after start up?

Thanks,

0 Koji Hayashi92 over 4 years ago in reply to David Vaseliou

Mastermind 6970 points

Hi David-san

Thank you for response.

I sent a circuit and an oscilloscope waveform to David's private message.

Because there are customer information.

Best Regards,

Koji Hayashi

0 David Vaseliou over 4 years ago in reply to Koji Hayashi92

TI__Expert 6820 points

Koji-san,

Thank you for the schematic and waveform. Did you get a chance to read the temperature and status registers as well while alert is low?

Thanks,

0 Koji Hayashi92 over 4 years ago in reply to David Vaseliou

Mastermind 6970 points

Hi David-san

Thank you for response.

I sent a register to David's private message.

Because there are customer information.

Best Regards,

Koji Hayashi

0 David Vaseliou over 4 years ago in reply to Koji Hayashi92

TI__Expert 6820 points

Hi Koji,

I have responded via private message.

Thanks,

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TMP451-Q1: ALERT is turned off at startup.