ADRF5720 power sequence

I measured 11mA transient current on VDD with or without -3.3V. please explain why the sequence is needed.

Hi Dan

Thank for the question. Yes, the power-up sequence is required in order to avoid transient currents occurring that could damage the part.

Could you confirm that you measure 11 mA transient current when VSS=0 while VDD is ramping up? If so, could you share the ramp-up details (a waveform screenshot would be great).

Regards

Gokhan

Hi Gokhan
the transient response was done with 0V on VSS and -3.3V on VSS. the response was the same. 
1.72V on 160ohm resistor (excluding cable loss) = 11mA
Since the response is the same, can I conclude that I can apply negative voltage before positive voltage?

Dan

Hi Dan

Thanks for sharing the waveform. Could you also respond to the following?

1) What is the decoupling cap value connected to the VDD pin?

2) Is it possible to measure the voltage drop at the resistor using a differential probe (I am assuming this measurement is from one end of the resistor to the GND)?

We suggest the correct power-up sequence: VDD is applied before VSS but also wanted to find out the source of the 11mA current value.

Regards

Gokhan