This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS62876-Q1: TPS62876-Q1

Part Number: TPS62876-Q1
Other Parts Discussed in Thread: TPSM8287B30, TPS62870, TPSM8287A06

Tool/software:

Tool/software:

Hi,

Please help to deal with the following materials and products. 

Attached is power supply design and PCB layout of 1_6T OSFP AEC BCM83854, please help review.

1600G_AEC_OSFP_Broadcom_20250429.brd1_6T OSFP AEC BCM83854 SYSTEM POWER 20250425.pdf

Thanks~

  • Hello Albert,

    Thanks for reaching out to us.

    Before we check review the schematic and PCB layout, can you confirm the end equipment for this project? Is it Automotive or Industrial application?

    Best regards,

    Excel

  • Hi,Excel,

    Industrial application, It's Active Electrical Cable (AEC) Solutions with OSFP interconnects which is applied to the interconnection between servers and data centers.

  • Hi Albert,

    Thanks for the quick response.

    I will let our expert in Industrial/Comms application to respond to your queries.

    Best regards,

    Excel

  • Thanks, Excel, for looping me in.

    Hi Albert,

    Thanks for sending your design for review.

    We're sampling a power module version of the TPS62876-Q1: TPSM8287B30.  Efficiency is a bit higher and size is smaller.  The power module also allows you to set the start-up voltage to many more values.

    For the TPS62870, we also have a power module version: TPSM8287A06.  Or, you could use another TPSM82866CA3 to make the size much smaller.

    For the TPS62870 circuit, I would change the compensation to the same values as used with the TPS62876-Q1: 1k and 8.2nF.  Is there a reason for having a higher Rcomp?

    The TPSM82866CA3 looks fine, but why is the startup voltage set to 1.1V, when the rail is 1.5V it seems?  We also just released the TPSM82866CA2 device, which offers different output voltages and I2C addresses.

    On the layout:

    For the TPS62876-Q1, U32:

    Move C497 and C882 down, so that it is symmetrical with the right side of the IC.

    Move C888 to the left side of the IC, so that it is symmetrical.

    For the TPS62876-Q1, U26:

    Move C657 down to get it closer to the IC.  Move C428 and C656 down, so that they are symmetrical with the left side of the IC.

    Move C662 to the right side of the IC, so that it is symmetrical.

    For the TPS62870:

    Move C956 down a little bit, so that it is symmetrical with the right side of the IC.

    Rotate C954 so that it is symmetrical and its GND connects to the GND pins of the IC.

    Move 2 of those 22uF Cout (one on each side) down next to the inductor to have a shorter connection back to the IC GND.

    The GOSNS pin (pin 2) needs to be routed next to the VOSNS trace to that output cap above the inductor.

    The GND of C949 and C948 needs to connect to pin 2.

    For the TPSM82866CA3, I would move C642 and C643 to the left, to get them closer to the VOUT pins.

    Thanks,

    Chris

  • Hi,Chris,

    Thanks for your support!

    feedback as follows:

    Albert: The heat dissipation capability of the PMIC also needs to be considered. What about TPSM8287B30‘s heat dissipation capability? The size of the TPSM8287B30(above) is larger in the Datasheet.

    We're sampling a power module version of the TPS62876-Q1: TPSM8287B30.  Efficiency is a bit higher and size is smaller.  The power module also allows you to set the start-up voltage to many more values.

    Albert: What about TPSM8287A06's heat dissipation capability?

    For the TPS62870, we also have a power module version: TPSM8287A06.  Or, you could use another TPSM82866CA3 to make the size much smaller.

    Albert: The results obtained by substituting the design parameters into the calculation formula in the Datasheet. The Ccomp selected on your EVM is lower, and the Rcomp is higher. Which performance aspects of the DC - DC converter are mainly affected by these parameters?

    For the TPS62870 circuit, I would change the compensation to the same values as used with the TPS62876-Q1: 1k and 8.2nF.  Is there a reason for having a higher Rcomp?

    Albert: Considering the possible overshoot during power - on, the startup voltage is designed to be lower than the final output voltage to avoid affecting the DSP. Is TPSM82866CA2 already in mass production?

    The TPSM82866CA3 looks fine, but why is the startup voltage set to 1.1V, when the rail is 1.5V it seems?  We also just released the TPSM82866CA2 device, which offers different output voltages and I2C addresses.

    Albert: Have TPSM8287B30 and TPSM8287A06 been mass - produced? Is it convenient to provide the corresponding EVM (Evaluation Module) so that we can conduct relevant performance evaluation tests?

    Looking forward to your reply! 

  • Hi Albert,

    The TPSM devices are power modules, which integrate the die and an inductor and sometimes some capacitors.  So, they are larger than just the TPS6287x IC.  All of these devices are designed for your application, with high efficiency and small size.  The TPSM devices have SOA curves in the D/S, to show the the heat dissipation capability.

    Can you share your design parameters that you used to compute the compensation?  These are very specific to the design, so you can't just copy the values in the D/S.  As well, there are calculator tools here: https://www.ti.com/tool/download/TPSM8287A-COMPONENT-CALCULATOR and https://www.ti.com/tool/download/TPSM8287B-CALC 

    The Rcomp and Ccomp affect stability and transient response.  In your application, there are typically not strong transients, so I steer the compensation to increase stability.

    There is not power-on overshoot with these devices.  Yes, TPSM82866CA2 is in MP: https://www.ti.com/product/TPSM82866C#order-quality

    TPSM8287A06 is in MP.  An EVM is here: https://www.ti.com/tool/TPSM8287A06BASEVM

    TPSM8287B30 is not yet MP, but is sampling.  An EVM is here: https://www.ti.com/tool/TPSM8287B30LAPEVM 

    Chris

  • Hi,Chris,

    Albert: OK, we will first conduct a material evaluation test for the material, and then confirm whether it can be used on the devices.

    The TPSM devices are power modules, which integrate the die and an inductor and sometimes some capacitors.  So, they are larger than just the TPS6287x IC.  All of these devices are designed for your application, with high efficiency and small size.  The TPSM devices have SOA curves in the D/S, to show the the heat dissipation capability.

    Albert:The design parameters, calculation formulas and calculation results are as attached. Some parameters were selected incorrectly previously, which led to the incorrect calculation results. The recalculation has been done here, and the results are almost the same as the recommended values you provided.

    Rcomp&Ccomp Calculator.xlsx

    Can you share your design parameters that you used to compute the compensation?  These are very specific to the design, so you can't just copy the values in the D/S.  As well, there are calculator tools here: https://www.ti.com/tool/download/TPSM8287A-COMPONENT-CALCULATOR and https://www.ti.com/tool/download/TPSM8287B-CALC 

    Albert:Here is the PD design on your official website. May I ask if the parameter values in it are accurate and if they are of reference value?

    Albert:OK.

    There is not power-on overshoot with these devices.  Yes, TPSM82866CA2 is in MP: https://www.ti.com/product/TPSM82866C#order-quality

    TPSM8287A06 is in MP.  An EVM is here: https://www.ti.com/tool/TPSM8287A06BASEVM

    TPSM8287B30 is not yet MP, but is sampling.  An EVM is here: https://www.ti.com/tool/TPSM8287B30LAPEVM 

  • Hi Albert,

    On the Webench design, that is Webench's recommendation based on a balancing of cost, size, efficiency, and component availability.  It is a starting point for a design.

    Your schematic looks fine, with the updated compensation values.

    Chris

  • Hi,Chris,

    OK, we will conduct an evaluation test on the material. Could you please provide the detailed test report of TPS62876-Q1 or the test report of the EVM so that I can compare it with the test results?

  • Hi Albert,

    The D/S contains the performance data for the device, which is based on the EVM.

    Chris

  • Hi Chris,

    Regarding the protection functions of TPS62876-Q1, the following need to be confirmed: Datasheet states that it has protection functions of UVLO, OVLO and OCP. It does not mention whether it has short-circuit protection and over-temperature protection functions. Please confirm whether these two protection functions are available.

    Thanks!

  • Yes, it has both those features as well.  Please see sections 8.3.14 and 8.3.17 in the D/S.

    https://www.ti.com/lit/ds/symlink/tps62876-q1.pdf 

    Chris