JTAG-SMT4 Decoupling Capacitors

[rpatel]

Hello is there a requirement or recommendation for decoupling capacitors for the JTAG-SMT4 module? 

[JColvin]

Hi @rpatel,

I received confirmation from the design engineer that all of the needed decoupling is built into the SMT4 module, so you will not need to implement anything extra for that.

Let me know if you have any questions.

Thanks,
JColvin

[rpatel]

Thanks @JColvin. Do you know what the typical and max current usage is of the JTAG-SMT4 module?

[JColvin]

Hi @rpatel,

For the SMT4, I have been informed that the worst case for Vdd is 115 mA and the typical usage is 90 mA with JTAG running at max speed and UART running at 1 MBaud. The Vref current at 30 MHz is 12.5 mA typical and 35 mA max (unless you short the outputs, then Vref would probably peak out around 170 mA).

You didn't ask about minimums, but when the USB controller is held in reset, the current consumption is ~20 mA. When it comes out of reset and enumerates on the bus it's ~87.5 mA.

Let me know if you have any questions.

Thanks,
JColvin