Hi everyone,
I’m working on a custom board’s power budget but struggling because key components (RTL8211F-CG PHY and STM32MP157FAC1) don’t clearly specify load currents in their datasheets. Without these numbers, I’m unsure how to confidently estimate total system power.
Has anyone encountered this before? How would you:
- Approximate missing current specs?
- Allocate power across rails like VDD_CORE/VDD_DDR when only “ΣVDD” is given?
I’d really appreciate any benchmarks, measurement tips, or design rules-of-thumb you’ve used in similar situations
STM32MP157FAC1 current characteristics
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Thanks in advance for your wisdom!
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Such ICs you will not find a straight forward current mapping. Since the pins can be multiplexed, you will have to check various operation sections in the datasheet to check for the current consumption in different modes and then add all the currents to identify your current consumption as per the mode of operation and frequency. However kindly check the attached image for 440mA on internal layer of 0.5oz with 10 degree temperature rise, trace width is only approx 5 mils so if you can use 15 mils or 20 mils, if possible even more for all your VDD lines then it should be completely fine. Simple rule is if unknown go for the maximum. You can check on our current calculator tool https://www.protoexpress.com/tools/trace-width-and-current-capacity-calculator/
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Thank you for the clarification regarding the processor. I am in the process of estimating power consumption and determining the load current for a design using the STM32MP157FAC1 processor. Regarding the Gigabit Ethernet PHY, if the Realtek PHY datasheet does not provide sufficient information on power consumption, would it be acceptable to use a different Gigabit PHY model for load power estimation?
I feel the IC manufacturer should be the right point of contact to answer that question for you. I would recommend looking for a similar IC from the same manufacturer with most of the features same as your original IC.
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Can we use the IDDCORE and IDD values from the datasheet to determine the required trace widths for VDDCORE and VDD?
