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ADS129x Test Signal

Alex Looi
Prodigy 135 points

Hi,

In the datasheet page 54, it says " The test signals are multiplexed and transmitted out of the device at the TESTP_PACE_OUT1 and TESTN_PACE_OUT2 pins." But in the input multiplexer diagram (Figure 47) at page 53, TestP signal switch is controlled by INT_TEST and TESTP_PACE_OUT1 is controlled by nINT_TEST ? That means if I select internal test signal (i.e. INT_TEST switch is closed), then nINT_TEST switch will be opened and TESTP_PACE_OUT1 will be disconnected?

So page 54 description and page 53 diagram is telling conflicting information ?

Please advise.

  • 0
    TI__Guru 66246 points

    Hi Alex,

    Welcome to our forum!

    Thank you for bringing this to our attention. I completely agree that Figure 47 and the relative text in the datasheet are conflicting. This is something that I plan to update in a future datasheet revision.

    Figure 47 was drawn to simplify the description of the ADS129x internal MUX. INT_TEST (CONFIG2[4]) is used to activate/deactivate the internal test signal. When INT_TEST = 1, the internal test signal is active and present on both the TEST_PACE_OUT pins as well as any channel with MUX[2:0] = 101. When INT_TEST = 0, the internal test signal is deactivated. The test signal circuitry goes high-impedance in order to allow for other signals to be driven on the TEST_PACE_OUT pins (i.e. when routing an auxiliary input into the device, or when routing the PACE amplifier output to external circuitry). When using the pins as an auxiliary input, make sure that both the internal test signal and the PACE amplifiers are powered down.

    Best Regards,

  • 0
    Prodigy 135 points
    Hi Ryan,

    Thanks for your clarification. If I want to use the TEST_PACE_OUT pins as BOTH pacer out AND internal test signal, but not both at the same time, can it be done ? With the external pacer hardware connected to the pin affect the internal test signal in any way ? My idea is to use internal test signal to test the system during initial power up. After that, the internal test signal will be disabled and the TEST_PACE_OUT pin will be used as external pacer pin. If this ok ?