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AWR1642: Accuracy of rlRfGetTemperatureReport() during high temperature testing

Part Number: AWR1642

Hello;

Per the data sheets, the AWR1642 is rated up to a maximum junction temperature of 125C.

We have been testing our device in an 85C temperature chamber using rlRfGetTemperatureReport() to analyze junction temperatures.

Should the values from this temperature report stay below 125C for reliable operation? Is there a more accurate way of measuring junction temperature?

What recommendations do you have for keeping the junction temperatures below 125C? Even at less than 1% duty cycle, our temperature reports were at 123C.

Additionally, if the device cannot operate above 125C, why does "rlRxGainTempLutData_t' have unique RX gain control all the way up to 140C+?

/*! \brief
* RX gain temperature LUT inject
*/
typedef struct rlRxGainTempLutData
{
    /**
     * @brief  This field indicates the profile Index for which this configuration applies.
     */
    rlUInt8_t  profileIndx;
    /**
     * @brief  Reserved for Future use
     */
    rlUInt8_t  reserved0;
    /**
     * @brief  Byte0: RX gain code for temperature < -30 deg C \n
     *         Byte1: RX gain code for temperature [-30, -20) deg C \n
     *         Byte2: RX gain code for temperature [-20, -10) deg C \n
     *         Byte3: RX gain code for temperature [-10, 0) deg C \n
     *         Byte4: RX gain code for temperature [0, 10) deg C \n
     *         Byte5: RX gain code for temperature [10, 20) deg C \n
     *         Byte6: RX gain code for temperature [20, 30) deg C \n
     *         Byte7: RX gain code for temperature [30, 40) deg C \n
     *         Byte8: RX gain code for temperature [40, 50) deg C \n
     *         Byte9: RX gain code for temperature [50, 60) deg C \n
     *         Byte10: RX gain code for temperature [60, 70) deg C \n
     *         Byte11: RX gain code for temperature [70, 80) deg C \n
     *         Byte12: RX gain code for temperature [80, 90) deg C \n
     *         Byte13: RX gain code for temperature [90, 100) deg C \n
     *         Byte14: RX gain code for temperature [100, 110) deg C \n
     *         Byte15: RX gain code for temperature [110, 120) deg C \n
     *         Byte16: RX gain code for temperature [120, 130) deg C \n
     *         Byte17: RX gain code for temperature [130, 140) deg C \n
     *         Byte18: RX gain code for temperature >= 140 deg C \n
     *         Byte19: Reserved \n
     *         Each byte is encoded as follows \n
     *         #### Bits Definition #### \n
     *             [4:0]   IF_GAIN_CODE \n
     *                     IF gain is IF_GAIN_CODE * 2 - 6 dB \n
     *                     Valid values: 0 to 17 \n
     *                     1 LSB = 2 dB \n
     *             [7:5]   RF_GAIN_CODE \n
     *                     Value    RF Gain \n
     *                     0     Maximum RF gain \n
     *                     1     Maximum RF gain - 2dB \n
     *                     2     Maximum RF gain - 4dB \n
     *                     3     Maximum RF gain - 6dB \n
     *                     4     Maximum RF gain - 8dB \n
     */
    rlUInt8_t  rxGainTempLut[RL_MAX_NUM_OF_TEMP10_RANGES + 1U];
    /**
     * @brief  Reserved for Future use
     */
    rlUInt16_t  reserved1;
} rlRxGainTempLutData_t;

Thanks,

Erik

  • Hi Erik,

    We will check and get back to you. Can you confirm your active frame time and total frame time?

    Regards,

    Kaushal

  • Hello Kaushal,

    What I consider "Active Frame Time" is time for ALL ramping during a frame for all chirps and transmitters. This does NOT include idle time between ramps.

    Active frame time: 54us

    Total frame time: 10ms

    54us/10000us = .0054 = .54% Duty Cycle

    Thank you,

    Erik

  • Dear Erik,

    Thanks for checking. This is very low duty cycle and don't expect Junction temperature to reach 123C. Referring to datasheet  Section 5.9, Junction temperature should increase 22.3deg C/Watt. Referring to section 5.4 of datasheet, device consumes about ~2Watt at 50% duty cycle.

    so 123C Junction temperature at 85C ambient points to approximately 45% duty cycle. 

    Please confirm below:

    • 54uS frame time seems too low. Are you configuring only 1 chirp in a frame. Can you check again on below parameters in rlFrameCfg_t.
      • chirpStartIdx
      • chirpEndIdx
      • numLoops
    • Is this Custom board or AWR1642 EVM - Just checking if we need to debug at board/system level.

    Regards,

    Kaushal