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TPS65910: Application schematics for DDR3L

na na78
Guru 16770 points
Part Number: TPS65910
Other Parts Discussed in Thread: AM3352, TPS65218D0

Hi

We are considering use of TPS65910 for AM3352.

The following is requirement.
- Battery is not used
- DDR3L is used (1.5V is acceptable)

I know TPS65910 is not support DDR3L (1.35V) but 1.5V can be used.

And the questions follow.

1. Regarding to VDDIO
SWCA139B schematic checklist shows the VDDIO should connect to VIO.
However, VIO is used as 1.5V for DDR3L and that is not acceptable for VDDIO.
Instead, is it correct that VDDIO is connected to VAUX33?

2. Regarding to power sequence
Where can we see timing diagram in use of DDR3 (1.5V)?
Is there no issue with power sequence when VDDIO is connected to VAUX33?

3.
What is the correct connection of BOOT0 and BOOT1?
I could not see settings for AM3352 in datasheet.

BestRegards

  • 0
    TI__Mastermind 30310 points
    na na78,

    Would you consider using the TPS65218D0 for this application?

    The DC34_SEL pin allows you to choose which DDR voltage is set on the DCDC3 power rail.

    The answers to your questions are below, if you choose to continue using the TPS65910:
    1. I would connect VDDIO to any 1.8V rail available. This is the most common IO rail and will also work for 2.5V or 3.3V IOs (VIH is a percentage of VDDIO)
    2. The timing diagram of DDR3 voltage (VIO) is in this User's Guide in Figure 3 on page 6, www.ti.com/.../swcu093f.pdf
    3. If you want to use TPS65910 for AM335x then you must use the full part number TPS65910A3A1. The correct connection of BOOT1 = short to VRTC, BOOT0 = short to GND, which is shown in Figure 1 on page 3 of the same User's Guide mentioned above.
  • 0 in reply to Brian Berner
    Guru 16770 points

    Hi Brian

    Thank you for your reply.

    >1. I would connect VDDIO to any 1.8V rail available. This is the most common IO rail and will also work for 2.5V or 3.3V IOs (VIH is a percentage of VDDIO)

    I believe we can connect to 3.3V LDO (e.g, VAUX33) , is it right?

    > 3. If you want to use TPS65910 for AM335x then you must use the full part number TPS65910A3A1. The correct connection of BOOT1 = short to VRTC, BOOT0 = short to GND, which is shown in Figure 1 on page 3 of the same User's Guide mentioned above.

    Is there reason why you recommend TPS65910A3A1, not TPS65910A31A1?

    BestRegards

  • 0 in reply to na na78
    TI__Mastermind 30310 points
    1. VAUX33 will ONLY work if ALL of the I/O pins on the Processor are connected to 3.3V rail also. If any I/Os are driven by 1.8V supply, it is easy to see why VAUX33 won't work: VOH of output = 1.8V max, and VDDIO = 3.3V; VIH,SLEEP = 0.65*VDDIO = 2.145V, and VIH,I2C = 0.7*VDDIO = 2.3V
    If you can confirm all VIH minimum values will be met, then VDDIO = VAUX33 is acceptable.

    2. TPS65910AA1 is for DDR2, TPS65910A3A1 is for DDR3, and TPS65910A31A1 is for DDR3 with VRTC in high-power mode by default. They are all for AM335x processors (www.ti.com/.../swcu093f.pdf). You can use whichever variant works in your system.