TPS54202: 4x higher quiescent current compared to datasheet

Jesse van der Zouw

Part Number: TPS54202
Other Parts Discussed in Thread: TPS62177

I have used a TPS54202 in a design with a low power microcontroller which needs to go in low power shutdown (<100uA) to preserve battery life. However, I have build up the PCB with only the DCDC circuit and measured the 3V3 like expected but the input current without any load is ~180uA. This is 4 times the quiescent current specified in the datasheet (45uA). What can be causing this? Do I need a different converter?

over 7 years ago

0 Jason Wang (BSR-MV) over 7 years ago

TI__Genius 9550 points

Hi,

please notice the test condition, VFB =1V (tie FB to 1V, then the device do not switching).

in your setup, the device is under low frequency switching, so Iq is higher than 45uA.

0 Jesse van der Zouw over 7 years ago in reply to Jason Wang (BSR-MV)

Expert 1045 points

Hi,

Ok, but why is this listed as opposed to 'no load input current'. If you don't want the TPS to switch, you would put it in shutdown right (via EN pin) right? What are the advantages of using VFB=1?

0 Jason Wang (BSR-MV) over 7 years ago in reply to Jesse van der Zouw

TI__Genius 9550 points

hi,
EN low, device internal circuit/block doesn't work; EN High & FB pin 1V, device internal circuit/block will be active but no switching.

0 Jesse van der Zouw over 7 years ago in reply to Jason Wang (BSR-MV)

Expert 1045 points

But what's the use of that? If it's not switching it has no output right? Or is this just for testing purposes? I'm looking for a low energy (<60uA) solution on which I can keep my microcontroller running, that means I have to look at even lower IQ devices right?

0 Chris Glaser over 7 years ago in reply to Jesse van der Zouw

TI__Guru**** 150950 points

Hi Jesse,

Perhaps my app note can shed some light on your question: www.ti.com/.../slyt412.pdf

What is your Vin range and load current needed? The TPS62177 is designed exactly for powering a low power MCU, as detailed here: www.ti.com/.../spma066.pdf

0 Jesse van der Zouw over 7 years ago in reply to Chris Glaser

Expert 1045 points

Ok, thanks. The TPS62177 looks interesting. One thing I don't get though is how it can maintain it's voltage rail without switching?

0 Chris Glaser over 7 years ago in reply to Jesse van der Zouw

TI__Guru**** 150950 points

Hi Jesse,

Your question is not clear to me. Both these devices have a low power mode which pauses switching for periods to reduce current consumption. Figure 30 in the D/S shows this behavior. As the load increases, so does the switching. Vout is always maintained.

0 Jason Wang (BSR-MV) over 7 years ago in reply to Jesse van der Zouw

TI__Genius 9550 points

Jesse,
yes, you can think this parameter is just for testing purpose. For most of the buck devices, use the same setup when test this Iq.

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TPS54202: 4x higher quiescent current compared to datasheet