Dear Sir,I am Huy Bui from Applied Micro. I am designing the Server Board using APM CPU. In our design, I use TI chip TPS51117, TPS54231 and TPS73501. About the TPS51117, because I do not have the software simulation in hand, so I design the +1.5V and +1.8V power rail reference to the document slvu179a.pdf which deliver +1.05V rail at 10A. I copy almost the value of resistor, cap, inductor, Fet... from this document to my design.I would like to ask if you can help review the attached schematic for me? I am highly appreciated for your help.I am looking forward for you reply.I also attach the power block diagram.Thank you and Best Regards,Huy
Hi,
I enclose the Power block Diagram.
Thanks and Best Regards,
Huy
Hi Huy,
E2E forum is not the good place to request the schematic or PCB review. Next time please contact TI local FAE to review them. I will do the quick check on TPS51117 and TPS51100 . Get you back soon.
Thanks,
Nancy
Hi Huy,I looked through the TPS54231 components. My only comment after is the SRR7045-4R7M saturation current is lower than I would recommend for a 2A output. The typical inductor current ripple with 4.7uH will be 0.742A. Adding half of this to a 2A output, the peak current will be 2.371A greater than the typical 2.2A saturation current. I recommend a saturation current at least 20% greater than the peak current through the inductor to account for transients during operation and startup.Regards,Anthony
DC/DC Power Applications Engineer
Thanks much Anthony and Nancy,
I am in Applied Micro Asia. Could you please give me the email contact of TI local FAE in Asia for me can send the schematic to review?
Thanks a lot for your help.
Best Regards,
I review the schematic for TPS51117 and TPS51100. Both schematics look good and only need minor changes. Here are my comments.
TPS51117: ( 1.5V and 1.8V)
1. Add 1uF ceramic capacitor close Pin10 V5DRV. This capacitor should be same as the 1uF on the pin4 V5FILT.
2. Remove that 10000pF capacitor on the pin6 PGOOD and it is no need.
3. Recommend change output POSCAP from 2R5TPE470MC to 2R5TPE470MF from Sanyo. This will give you more ripple voltage to the VFB pin since VFB pin needs around 15mV ripple to reduce the PWM jitter. Please refer to datasheet equation 12 for detail.
4. Recommend use TI power block MOSFET for your application. (CSD87350Q5D or CSD87330Q3D). These two MOSFETs has smaller size and superior peformance.
5. Please refer to attached spreadsheet for detail calculation and component selection.
TPS51100:
1. You need to add another 10uF ceramic capacitor on the VTT pin. TPS51100 needs 2x10uF ceramic for VTT output to stabilize the VTT LDO. Please refer to TPS51100 datasheet.
Where is your location? Taiwan or mainland China? If China, which city? I will try to find the local FAE for you.
5102.TPS51117_Component_Calculator_Huy.xls
Thanks a lof for your response Nancy,
I am in Applied Micro Viet Nam. Please help me the contact of FAE in China or Taiwan.
Thanks much in advance,
We have two local FAE can support you, Hung is in HCMC and Trong (myself) is in Hanoi.Feel free to contact us by our email as follows:Hung: thaihung.le@ti.comTrong: thetrong.le@ti.comThanks.
Hi Anh Trong,
I have sent the schematic for review via email. Please help.
Please let me know if you still do NOT receive my email.
Thank you and Best Regards,
Hi Nancy,
Thanks very much for strong support.
Can you please help send me again the attached spreadsheet for detail calculation and component selection on TPS51117? The file may be corrupted after download and I cannot open it.
Here you are.
3364.TPS51117_Component_Calculator_Huy.xls
Hi Nancy, Anthony,
I modify the schematic as your recommend. Can you please help review again? I am highly appreciated for your help. I am waiting for your reply.
I this schematic, I modify:
+1.5V Power Rail: - Change R54 from 200K to 237K --> set switching frequency = 330KHz - Chage couple FET IRF7821, IRF8113 to CSD87350Q5D as you recommend - Change Cap 470uF C63, C64 from 2R5TPE470MC (you recommend 2R5TPE470MF) to RPS0J471MCN1GS. The reason is the Sanyo cap is hard to buy. The ESR of RPS0J471MCN1GS is 15mOhm, the Rated Ripple Current is 4300mA (compared to 3100mA from Sanyo). Is it OK? Can you please help review? - Do we need the GREEN wire because there is already the internal wire between TGR and VSW inside the FET Q21 CSD87350Q5D ?+0.75V VTT: Add one cap 10uF as you request.
+ 1.8V Power Rail:
- Change the same as 1.5V regulator - Change value of L5 to 1.2uH as calculate from the excel sheet TPS51117.xls - By the way, can you please help review the +2.5V power rail circuit using the TI chip TPS73525DRVR in the same page of 1v8 power rail?
+ 1.538V Power Rail: change L2 to Wurth 7447789004 4.7uH, IDC = 2.9A, Isat = 3.9A. Is it OK?
+ 1.2V Power Rail: change L1 to SCRH6D28-3R9 3.9uH, IDC= 2.6, Isat = 2.6A. Is it OK?
6283.apm_requesttoreview_april20.pdf
Hi Huy,The updates done to the TPS54231 circuits look good to me.Best Regards,Anthony
Here are my comments:
+1.5V Power Rail: - Change R54 from 200K to 237K --> set switching frequency = 330KHz
It is wrong:
237k setting: 270k switching frequency
187k setting: 330kHz switching frequency
Please change 237k to 187k for 330kHz setting
Please change current limit R61 to 3.24k since you change MOSFET to CSD87350 with low Rdson
- Chage couple FET IRF7821, IRF8113 to CSD87350Q5D as you recommend
Good
- Change Cap 470uF C63, C64 from 2R5TPE470MC (you recommend 2R5TPE470MF) to RPS0J471MCN1GS. The reason is the Sanyo cap is hard to buy. The ESR of RPS0J471MCN1GS is 15mOhm, the Rated Ripple Current is 4300mA (compared to 3100mA from Sanyo). Is it OK? Can you please help review? Good
- Do we need the GREEN wire because there is already the internal wire between TGR and VSW inside the FET Q21 CSD87350Q5D ?
No needed
+0.75V VTT: Add one cap 10uF as you request.
- Change the same as 1.5V regulator
Please change current limit R78 to 3.24k since you change MOSFET to CSD87350 with low Rdson
- Change value of L5 to 1.2uH as calculate from the excel sheet TPS51117.xls
Good- By the way, can you please help review the +2.5V power rail circuit using the TI chip TPS73525DRVR in the same page of 1v8 power rail?
5141.TPS51117 - 1V5.xls
7230.TPS51117_P42.xls
Thank you very much for strong review. I have some questions regard to your feedback. Please help answer. I am highly appreciated for your help.
+1.5V Power Rail:
[Huy] Change R54 from 200K to 237K --> set switching frequency = 330KHz
[Nancy] It is wrong: 237k setting: 270k switching frequency 187k setting: 330kHz switching frequency Please change 237k to 187k for 330kHz setting
[Huy]: Please see in the TPS51117_P42.xls file that Trong already sent to me. In the Frequency tab, the Rton = 237K will give the Switching Frequency = 326.44KHz ~ 330KHz. I also see in the Figure 1 of datasheet of TPS51117 about the Frequency vs RTon, the RTon should > 200Khz if Frequency = 330Khz. Please correct me if I am wrong.
[Nancy] Please change current limit R61 to 3.24k since you change MOSFET to CSD87350 with low Rdson
[Huy]: In the TPS51117 - 1V5.xls attached file, the Rtrip R61 is recommend to choose >6.48KOhm, so I choose 7.68K. Please correct me if I am wrong.
[Huy] Do we need the GREEN wire because there is already the internal wire between TGR and VSW inside the FET Q21 CSD87350Q5D ?
[Nancy] No needed
[Huy]: I think I need the GREEN wire if we have plan to use the Q22 FET. Now, this FET is not installed (NI) by default.
3010.TPS51117 - 1V5.xls