AM2431: Inquiry regarding product development using AM2431

Hi,

The AM243 devices in ALX package do not support DDR4/LPDDR4 memory subsystem (DDRSS). In this scenario you do not need to integrate a 1.1V rail in the power solution. I would recommend using LP87334D PMIC which comes pre-programmed to meet the voltage/sequence requirements. The following apps note can be used as a guide to select the power solution for AM243: https://www.ti.com/lit/an/slda059/slda059.pdf

Alternatively, you could also consider using a user-programmable PMIC (i.e TPS6521905). This option require customers to program the PMIC settings. 

Thanks,

Brenda

Correct. The TPS65219 PMIC apps note only covers AM243 ALV package where DDR voltage is required. 

The closest TPS65219 variant to the LP87334D PMIC is TPS6521907. This PMIC variant could be used to power AM243x in ALX package but it will require to include the external passive components for any PMIC unused rail if they are enabled by default. For example, even though Buck3 (1.2V) is not used, it still requires the input and output capacitors as well as the inductor. 

Thanks,

Brenda 

In the LP87334D diagram, the EthernetPHY 2.5V/1.1V supplies are not integrated in the PMIC. They are supplied with external discrete regulators so they are independent from the selected PMIC.   

TPS65219 PMIC has enough regulators to integrate all the EthernetPHY supplies but this would require a new orderable part number with unique NVM settings. If you decide to use an existing NVM config like TPS6521907, then AM243_ALX would only use Buck1, Buck2, LDO2 and LDO3. Any unused regulator will still require the external passive components (i.e input/output caps, inductors, etc). To supply the EthernetPHY, here are the options you can consider:

• supply all the EthernetPHY with external discrete components and use one of the TPS6521907 GPIOs (i.e. GPO1) to enable/disable the external rails.
• supply the VDDA2P5 rail with the LDO4 from TPS6521907 and use GPO1 to enable external discrete devices used to supply the remaining supply pins of the ethernetPHY.

Note: If the design implementation does not allow ramping all the DP83869 rails together, the sequencing requirements must be met (see sequence diagram in the datasheet).  

Thanks,

Brenda

Hi,

The AM243 evaluation modules use discrete power solution instead of PMIC. These designs (listed below) can be used as a reference for the supply groups. It will help you understand which rails can be grouped and supplied with the same regulator. 

Note: If the total current on the 1.8V IO (including AM243 and external peripherals) is higher than the PMIC LDO rating, then I recommend using discrete power solution. 

• LP-AM243: https://www.ti.com/tool/LP-AM243
• TMDS243EVM: https://www.ti.com/tool/TMDS243EVM

Thanks,

Brenda

Hi,

The AM243_ALX only requires 3-4 supplies (CORE, 3.3V IO, 1.8V IO and VDDA_1V8). Any other supply in the EVM is application dependent and not necessarily required by the MCU. The power supply implementation of this MCU is simple enough for easy implementation with discrete or PMIC. If you don't feel comfortable with the power supply design process I would recommend re-using the validated power solution from the LP-AM243 EVM.  

However, if you proceed with the PMIC, here are some notes to assist the design process. Let us know if there are any questions. 

• LP87334D comes pre-programmed to meet the voltage/current/sequence requirements of the AM243_ALX MCU. Customers are responsible for performing a system level power analysis to make sure the 3.3V and 1.8V IO supplies (i.e LP87334D BUCK1 and LDO0) have enough current rating to supply the MCU and peripherals which are specific to your application. 
• If you are planning to use the EthernetPHY in a two-supply configuration and driving the VDDIO with 3.3V as implemented in LP-AM243 EVM, then there shouldn't be any issues with the PMIC current rating. Here is a high level supply diagram that you could consider. Please refer to EthernetPHY datasheet for information about two-supply configuration and sequencing requirements). 

Thanks,

Brenda

The sequence requirements of the EthernetPHY can be found in the DP83869 datasheet (see capture below). It requires powering all supplies together or supplying VDDIO after the 2.5V/1.1V rails. The LP87334D was configured to turn-ON BUCK1 (3.3V) first in sequence (see second capture below). If you are enabling the external 2.5V/1.1V rails with the PMIC GPO2, then the next step in the design process would be controlling the enable of the VDDIO. How do you make sure VDDIO turns-ON at the same time or after the 2.5V/1.1V rails? One option would be using a power switch instead of connecting the PMIC Buck1 directly to DP83869.

From DP83869 datasheet 

From LP87334D Technical Reference Manual

Thanks,

Brenda