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[FAQ] Multiphase FAQ & Answers - TPS53647, TPS53667, TPS53681

Other Parts Discussed in Thread: TPS53647, TPS53667, TPS53681, TPS53622, TPS53659, TPS53679

Q1: How to properly turn off phases if you don’t need the max phase number?

Pull the appropriate CSP line up to the controller supply voltage V3R3 to select the number of active phases in your design. The unused CSP lines can either be left floating or pulled up to the same 3.3V supply as well.

TPS53647

TPS53667

TPS53681 (see Section 7.3.1.5 on page 43 of the datasheet for n+1 or n+3 settings)

Q2: How do I properly connect the EN/FCCM pin of the power stages


On the TPS53647/67 the power stage EN/FCCM pins can be connected directly to the VDD pin of that IC if discontinuous conduction mode (DCM)  is not needed. Should DCM be need for a particular application the phase 1 EN/FCCM pin should be routed to the SKIP#-NVM pin of the controller. The other phases should have EN/FCCM tied to VDD of their power stages.

For the TPS53681 connect all EN/FCCM pins to the power stage VDD.

Q3:  What is the proper power sequencing for the controller and FETs? 

TPS53647/67 - ensure the rising slew rate on the 3.3V supply is > 1.5V/ms as the controller requires a minimum of 1.2ms to properly complete the pin strap setting read. Follow chart below:

TPS53681 - Have both the controller and power stage enable ready before 12V input voltage is applied. This allows for pre-startup OVP protection and fault monitoring. If 3.3V can not be powered up first, it's recommended the controller enable is set high last after all the power rails (3.3V, 5V, 12V) are ready. Similarly on shutdown, the controller enable should be disabled first. Follow chart below:

Q4: How to request the full datasheet or design spreadsheet for NDA governed parts?

All the materials for the TPS53647/67 and TPS53681 can be downloaded directly on each of the controller's product pages. For other parts such as the TPS53622, TPS53659, or TPS53679 an NDA needs to be in place before materials can be shared. 

Submit a NDA link: lawndaportal.itg.ti.com/ 

Datasheet request Email : vr@list.ti.com

Q5: How should be parts be programmed during assembly or purchased pre-programmed?

On the TPS53647/67 using the pin-strapping settings avoids all programming of the parts.

For the TPS53681, or if not using pin-strapping, use the Fusion Manufacturing Tool to quickly program the desired settings to the part. Pre-programmed controllers can be purchased for a fee from Avnet. Contact Andy Sotirin [sotirin at ti dot com] regarding this matter.