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TLV62130A: Two-sided layout ?

Charles-henri Mousset
Prodigy 110 points
Part Number: TLV62130A
Other Parts Discussed in Thread: TLV62130, TPS62135, TPS82130, TPS62230, LMZ21701, TPS62821

Hello,

du to some size constraints, fitting all the components on the same side of the board like on the reference layout was a bit difficult: since we need 6 different rails I was concerned that different converters would be too close to each other and start to interact (VOS or feedback picking switching noise from nearby converter).

I did follow the layout guidelines of the datasheet though. All rails are layed out the same way. Only feedback resistors values change.
Special care has been taken to have short current loops, and as may solid GND planes as possible, especially below the IC and over the VOS line.

This layout is similar to other power supplies we already successfully designed with other converters, but I don't know if there are some reason it would not work with the TLV62130. Do TI know of some similar designs working on the field?

Feedback would be much appreciated befor we launch that in production!

Input voltage : 6V (if powered via battery) to 12V (if powered from an isolated DC/DC)

Output voltages: 5V, 3.8V, 3.3V, 2.5V or 1.2V depending on the rail

Output currents: from ~100mA (3.3V, 2.5V and 1.2V rail) to 2.8A (3.8V and 5V)

schematics:

Top layer : input and output caps

VSYS is the input voltage

VOUT* are the output rails

Internal layer 1 : VOS and GND plane

Internal 2: GND plane

Internal 3: GND plane and ENable / PGood signals

Internal 4: GND plane

Bottom: IC, inductor, feedback resistors, SS cap, 0.1uF input cap

  • 0
    TI__Guru*** 142750 points
    Hi Charles,

    Here is the app note I wrote on this topic, from this IC's product page: www.ti.com/.../slyt614.pdf It is most important to keep the input and output caps on the same layer as the IC.

    However, we have smaller devices that are more suited to your challenge: TPS62135/6 and the very small module TPS82130.

    As well, I think you can get a lot smaller if you cascade some power supplies. The 3x 100 mA supplies can be powered from the 5V rail by the super small TPS62230 family.
  • 0 in reply to Chris Glaser
    Prodigy 110 points

    Hi Chris,

    Thanks for the tip.

    I saw your app note, it's very clear and thorough.
    I thought that the added vias should not be an issue, since their calculated combined impedance (~0.3nH) is lower than a typical 0402 MLCC's ESL (~1nH). But since you advise otherwise I'll change my design.

    I'll try to keep the TLV62130 if possible, since we already have a bit of experience with it.
    TPS62135 looks nice, but if it still requires single layer layout I'm not sure the total footprint will be much different.
    TPS82130, well after the still unresolved issue we have with the LMZ21701 e2e.ti.com/.../2759173 we're not confident using such type of module.

    TPS62230 lacks PG pin so that's no option.

  • 0 in reply to Charles-henri Mousset
    TI__Guru*** 142750 points
    Thanks for explaining.

    We need to avoid any extra inductance in the input cap routing, which handles the switching currents.

    The TPS82130 is a different device from a different design team, so it won't necessarily have the same issue as another TI (or competitor) part.

    If you need PG, TPS62821 can work. It is a bit larger than TPS62230 but still much smaller than a TPS621xx device.