TPS55288-Q1: TPS55288-Q1 for 3.3V and 5V regulators

Hi Mohamed,

Thanks for reaching out.

1. May I know what is the project and application here? Is this automotive application? We have more suitable device if not in automotive applications.

2. The minimum rising Vin is 2.8V, will the input voltage at the Buck-boost side drop to lower value due to input cable voltage drop?

3. What is the max output current needed for this application?

4. When Vin and Vout are both lower than 5V, the VCC will be supplied from the max(Vin, Vout).

BRs,

Bryce

Hi Bryce, 

Thanks for your reply! 

Well, our application is not an automotive app, it's a portable computer. that will be powered either by a 3.7V battery ( can drop to 2.8V)  or a 5V USB, and we will need 3.3V and 5V regulation from these inputs, with 6A for each, so basically we need a buck-boost that can work from 2.8V to 5.5V or more, and provide 3.3V or 5V with 6A current. 

Thanks! 

Hi Mohamed,

Thanks for feedback.

Regarding to the power requirement, I want to check:

1. When Vin=2.8V, what is the max output current for 5Vout? Still 6A?

2. And when Vin=2.8V, the max output current for 3.3Vout is also 6A?

I will need to check if TPS55288 can satisfy this.

BRs,

Bryce

Hi Bryce, 

Well, maybe 5A is enough in that state. 

Thanks 

Hi Mohamed,

Thanks, even the max output current is 5A for 2.8Vin and 3.3Vout/5Vout, the only candidate Buck-boost is also TPS552882(non I2C version), I will check if TPS55288 can satisfy the requirements.

BRs,

Bryce

Hi  Bryce,

Thanks!! 

Well, it doesn't need to be I2C, the main requirement is it could provide 5A with 2.8V for 3.3V and 5V regulation. because we will use it as the main voltage regulator for all the devices, we need the two voltage 3.3V and 5V, so if that is safe and can be good at that, we don't need to go with one with an I2C interface. 

Regards. 

Hi Mohamed,

Thanks, will check on bench and reply to you later.

BRs,

Bryce

Hi  Bryce,

Thank you, I appreciate your help. 

Best! 

Hi Bryce, 

Thank you for your answer, what about 3.3V output? 

So we will need a second buck-boost 5V to power VCC? 

Regards. 

Hi Mohamed,

For 2.8Vin and 3.3Vout, the device is ok to output 5A, but since the internal LDO is supplied by max(Vin, Vout), it means the VCC voltage value will be smaller than 3.3V which is close to the VCC UVLO voltage when Vin=2.8V and Vout=3.3V, thus, it is recommended to select external VCC supply on MODE pin, and connect external 5V supply with VCC pin. You can use a Boost to do this if the system doesn't have this power rail.

Another solution is: you can use two stage DC/DC to replace one Buck-boost converter, for example, the first stage Boost output 6V, and use the second stage Buck to output 3.3V or 5V.

BRs,

Bryce

BRs,

Bryce

Hi Bryce,

I appreciate your support!! 

Can you please recommend a boost regulator to use for VCC? 

Also Can you please recommend a a part number for the two MOSFETs and the inductor used in the TPS55288 design that are suitable for our design? 

Best Regards!