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ADC12010/20/40 VS ADC12L063/066 How TO use ＊OEinput

Shuichi Uno
Prodigy 130 points

Other Parts Discussed in Thread: ADC12010, ADC12L063, ADC12040

Hello,

Customer worry about the following notation about ADC12010/20/40
[The OE pin should NOT be used to multiplex devices together to drive a common bus as this will result in
excessive capacitance on the data output pins, reducing SNR and SINAD performance of the converter. See Section 3.0.]
However ADC12L063/066 There is no such mention as follows.
[The OE pin, when high, puts the output pins into a high impedance state. When this pin is low the outputs are in the active state. The ADC12L063 will continue to convert whether this pin is high or low, but the output can not be read while the OE pin is high.]
Customer follow the instruction of DATA OUTPUTS mention,about ADC12010/20/40.
＊OE pin used to multiplex devices together to drive a common bus.
 
Best regards
Shuichi Uno
  • 0
    TI__Expert 4340 points

    Hello,

    Conceptually, the additional noise created in the ADC12040 as a result of additional capacitance on the digital output pins is the same for ADC12L063/066. In both cases, the additional capacitance causes additional current to flow on the digital supplies during transients that can couple to the analog input as noise. The amount of coupling may be different between these devices but I would say that the warning applies to both devices.

    If you multiplex the digital bus, the ADCs should still functionally work, but the AC performance may degrade due to the added noise. You can minimize the added noise by minimizing the trace lengths of the bus and buffer the bus with a low-input-capacitance buffer device.

    Regards, Josh