CC2640R2F: slew rate of R2F

Albin Zhang

Part Number: CC2640R2F

Hi,

I tested the Rising supply-voltage slew rate on launch pad.

yes, with the power of Lauchpad (5V to 3.3V), it is about 56mV/us, it meets the requirement.

but, when I power the VDDS line (after the bead FL1) with Power supply (3V, not a battery), even with a 10uS cap after, it can reach about 3000/6.25uS= 480mV/us. it is definitely over the limit of spec.

if we assume there is no current limit or zero inner resistance of the power supply, the cap won't help to decrease the slew rate any more.

do you suggest other solution for this kind of power supply topology with high efficiency?

BR. Albin

over 7 years ago

0 Fredrik K over 7 years ago

TI__Guru** 106705 points

Hi Albin,

Aren´t you actually presenting the solution in your experiment? Do not remove the bead :-)

Fredrik

0 Albin Zhang over 7 years ago in reply to Fredrik K

TI__Expert 6200 points

haha, the bead is exclusive.

I redo the test with bead included. but it is 191mV/uS now. still failed.

as below, i power the line with 3V/3A power supply, and test the post of bead.

BR. Albin

0 Fredrik K over 7 years ago in reply to Albin Zhang

TI__Guru** 106705 points

Is the measurement done by the yellow cable or on the opposite side? It should be on the opposite side.

0 Albin Zhang over 7 years ago in reply to Fredrik K

TI__Expert 6200 points

Hi, Fredrik,

Yes, I power the yellow cable and probe on the opposite side with osiliscope.

BR. Albin

0 Fredrik K over 7 years ago in reply to Albin Zhang

TI__Guru** 106705 points

Hi Albin,

In such situations some kind of inrush current limiter should be implemented to stay within the datasheet limits.

BR Fredrik

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CC2640R2F: slew rate of R2F