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TPS546D24A: cross differences with TPS543C20

Collin Rusch
Prodigy 120 points
Part Number: TPS546D24A
Other Parts Discussed in Thread: TPS543C20, TPS543C20A

Hi,

I have a customer who has the below questions on cross differences between TPS543C20 and TPS546D24A. 

"I have been working with a team on an internal development board utilizing a TPS543C20 which was imported from another design.  As the TPS543C20 part is out of stock for what appears to be for some time we are looking to redesign for the TPS546D24A which is in stock.

 

From looking at the datasheets it looks like the original design (Inductors/caps/layout) is portable as long as the I/Os that changed between parts are re-strapped appropriately.  Is this evaluation accurate?  Are these two parts similar as far as the converter controller is concerned?  I am asking to see how much re-testing/redesign of the actual power converter is required."

Best,

Collin

  • 0
    TI__Expert 5310 points

    Hi Collin,

    Depending on the available supply. The easiest swap would be to use the TPS543C20A in place of the TPS543C20.

    As you mentioned, the TPS546D24A may add additional BOM components in order to set the pin strapping appropriately. If there is no intention on using the PMBus interface, those pins may be grounded. The layout and power stage component selection may be similar between the two devices. The TPS543C20 uses an emulated current mode control scheme in which an internal ramp signal emulates the inductor current waveform. This part is internally compensated with the exception of the external RAMP resistor. The TPS546D24A uses an average current mode control scheme which has programmable current and voltage integration loops and does sense the inductor current as opposed to emulating the waveform internally.

    I would highly recommend using the design tools available here:https://www.ti.com/product/TPS546D24A#design-tools-simulation

    This will allow the customer to utilize their current inductors, output caps, and then tune the pinstrapping to their application. Both of these devices support similar applications (typically 12Vin, 0.6-5 Vout, 40A) and may utilize similar layout practices in the input/output stages. As far as the retesting/redesign go, I would need some additional information regarding the application/system requirements to provide further guidance on the extent of the redesign and retesting that may be needed.

    Regards,

    Alec Biesterfeld

  • 0 in reply to Alec Biesterfeld
    TI__Prodigy 120 points

    Thanks Alec for the info and tool.

    Customer has an additional question for TPS546D24A on EN/UVLO to help clarify the operation.  It looks like EN/UVLO can be used to control the converter with a simple 0V/5V signal.  Is this accurate and can the levels be controlled via the resistor divider configuration while being controlled discretely?  Or is this an output only pin.

  • 0 in reply to Collin Rusch
    TI__Expert 5310 points

    Hi Collin,

    The EN/UVLO pin may be controlled by a resistor divider. The logic high level on a rising voltage is 1.05V and the logic low level on a falling voltage is 0.9V, so a 0V/5V can drive the enable pin as well as the resistor divider. In a logic high state, EN will enable switching of the device.

    The customer may also use the PMBus interface to configure/disable the EN pin with the (02h) ON_OFF_CONFIG command. The part will refer to its default enable logic by default however.

    Regards,

    Alec Biesterfeld