TPS2549-Q1: Setting method

Koji Hayashi

Intellectual 955 points

Part Number: TPS2549-Q1
Other Parts Discussed in Thread: TPS2549

Hi All,

My customer's specification

・USB power supply only, no Data communication

・Whatever kind of device is connected, at most 2.1 A is supplied.

In the above case,

CTL1=0

CTL2=0

CTL3=1

R(ILIM_HI) = 20 kΩ

Is it correct?

Please advise me if you have any better idea/method other than above I listed here.

Best Regards
Koji Hayashi

over 8 years ago

0 Yongqiang Sun over 8 years ago

TI__Intellectual 2685 points

Hi,

1. CTL1=0, CTL2=0, CTL3=1
2. you need at least 25.6Kohm resistor to limit the output current to 2.1A.

0 Koji Hayashi over 8 years ago in reply to Yongqiang Sun

Intellectual 955 points

Hi Yongqiang,

Thank you for your reply.

With the above setting, it is possible to use Divider 3 mode and 1.2 V mode, but is it possible to always supply 2.1 A in either mode regardless of the connected device?

Please tell me how to handle unused pins.
DM_OUT,DP_OUT and ILIM_LO.

Best Regards
Koji Hayashi

0 Yongqiang Sun over 8 years ago in reply to Koji Hayashi

TI__Intellectual 2685 points

Hi Hayashi,

yes, TPS2549 supports divider3 which is apple 2.4A charging protocol. I think customer should set the ILIM_HI to 2.1A, if output current exceeds 2.1A, TPS2549 will limit the current to 2.1A.

DM_OUT and DP_OUT floating.

Please connect 750Kohm resistor from ILIM_LO to GND.

0 Koji Hayashi over 8 years ago in reply to Yongqiang Sun

Intellectual 955 points

Hi Yongqiang,

Thank you for your reply.

I thought ,ILIM_LO is floating.

Because the TPS2549 device is configured as DCP(001) or CDP(111).

Do you need "The TPS2549 device is configured as DCP(001) or CDP(111)" and "Load detection is not used" ?

Why is 750 kohm required?

And how did you calculate it?

Best Regards
Koji Hayashi

0 Yongqiang Sun over 8 years ago in reply to Koji Hayashi

TI__Intellectual 2685 points

Hi Hayashi,

if you do not need status pin to indicate load attached, then you can float the ILIM_LO pin.
status will assert if output current exceeds a current threshold which is determined by ILIM_LO. if you float ILIM_LO pin, that means the current threshold is 0A.

I recommend a 750K0hm resistor because the range of resistance connected at ILIM_LO pin is from 16.9Kohm to 750Kohm. so it's better to connect a 750Kohm resistor than floating.

0 Koji Hayashi over 8 years ago in reply to Yongqiang Sun

Intellectual 955 points

Hi Yongqiang,

Thank you very much for your help.

I was understood.

Best Regards
Koji Hayashi

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TPS2549-Q1: Setting method