TPS55340: TPS55340RTER

Hi Suraj,

Can you share you input and output voltage and current?

You may limit the input current referring Input Current Limit Solution for USB-Supplied Power System

Please note the inrush current to the output cap before the converter starts cannot be controlled with this method.

Best Regards,

Feng

Hi Feng,

I am connecting two USB 3.0 port in parallel OR-Network and then having a Boost converter using TPS55340. The output rating is 12V 1.4A. Assuming that each USB 3.0 will provide 0.8A resulting total of 1.6A. Will that be enough or any suggestion all welcome.

Hi Suraj,

Thank you for sharing the specs, please expect a reply from our expert by tomorrow.

Best regards

Yezi 

Hi Suraj,

What is the input voltage?

Best Regards,

Feng

Input is comming from USB +5V. I am looking for recomendation for boost converter and limit the inrush current for this application.

Hi Suraj,

I have a question about the usage.

When output is 12V,1.4A the power is 16.8W and input current will reach 16.8/5=3.36A.

Two USB with 1.6A capability is far from enough.

Is it intended to limit the input power at this application?

Would it ok to use TPS61376?

TPS61376 23VIN , 25VOUT , 4.5A, Boost Converter with up to ±2.5% Accuracy Input Average Current Limit and True Load Disconnection datasheet (Rev. B)

The device has input current limit with 2.5% accuracy.

For more accuracy input current limitation, the current method in the application note is recommended.

Input Current Limit Solution for USB-Supplied Power System

The boost can be replaced with a Fully Integrated Synchronous Boost to gain a higher efficiency, like TPS61377.

Best Regards,

Fergus

Hi Fergus,

Thanks for the suggestion of TPS61377.

The intention is to design to use for USB 3.0 to USB-C onwards. As USB 3.0 can deliver +5V, 900mA. We have max +5V, 1.8A Max. So the boost converter should be efficient and should not draw any inrush current more than this.

Few more questions

1. May I know the advantage of using TPS61377 over TPS61376.

2. Also I plan to use LM73100RPWT Ideal diode instead of 1N4007 to avoid the voltage drop. Any view on this.

3. Any reference schematic for the USB-C connector EMI-EMC protection to be added near the connector.

4. For 3.3V, I am planning to use LMZ10503, any other latest IC. (Input is from USB +5V, Output required 3.3V@ 250mA.) We dont want any heating in LDO and less noise.

Hi Suraj,

I did not see any schematic including IN4007 or 3.3V, am I missing something?

For the advantage and disadvantages,

TPS61376 provides an input current limit without external circuit and the device is true load disconnected (when not enabled, Vout is 0).

But it is non-synchronous so the efficiency will be a little lower and the current accuracy is 2.5%(accuracy would be worse when current is small).

TPS61377 is full synchronous boost, and its efficiency is higher (diode is not needed, small solution),

but it needs external circuit to make the input current limit (shown in the application note), the current accuracy could be made stabler and higher.

For the Buck choose, we are not familiar with Buck modules, shall I assign this to Buck team if you have any questions?

Best Regards,

Fergus

Hi Fergus,

I will attach the schematic in next reply. few more query: 

1. Is TSP55340 be better than TPS61377 any reason?

2. Do we have webench simulation for TPS 61377

Hi Suraj,

1. TPS61377 is full synchronous boost, and its efficiency is higher than TPS55340.

2. Yes, we have a Simplis simulation for TPS61377 with input current limit.

But the parameters may not fit your scenario.

Best Regards,

Fergus

Hi,

Sorry I got confused. Can you ellobrate the parameters may not fit your scenario. I need your suggestion for the specification 12V@ 1.4A which device is ok for us. TPS61377 , TPS61376 or TPS55340.

I understood that TPS61377 is full synchronous and have higher efficiency does not have diode. Can we not use the ILIM pin of 61377 to limit its output current, which in return will limit the input current.

Best Regards,

Suraj

Hi, I have done the simulation and found that TPS55340 draw 1.5A peak at 12V @0.5A, while I dont have simulation model for TPS61377, can you suggest what will be the maximum peak current when we draw 12V @0.5A from TPS61377 or TPS61376.

Hi Suraj,

When Vin = 5V, Vout = 12V and Iout = 0.5A.

• For TPS61377 (650kHz), suppose 10μH inductor is used, the maximum inductor peak current is around 1.61A.
• For TPS61376 (1.2MHz), suppose 4.7μH inductor is used, and the input current limit is not triggered, the maximum inductor peak current is around 1.65A 

Regards

Lei