Battery consumption for MCU

The datasheet will give you the sleep consumption. You then tell us the amount of time you want the system to be awake and the input impeedance on the ADC and the current consumption of the external SPI device and the I2C device..

Cheers

I'll tell you now, the calculations from the datasheet will be considerably lower than in real life, at least in my experience.

I do a LOT of low power micro-controller designs, using PIC's and mostly using a 32KHz xtal on TMR1 to create 1 second interrupts for an RTCC, and also waking up from the change of various I/O pins.

For advice, shut down EVERYTHING you can when in sleep - use I/O pins to switch power to external devices, so there's no power at all to them in sleep, disable all internal peripherals, and also set the I/O low (or high) to prevent any current leakage that way.

In general, anything below 100uA is usually considered 'satisfactory', and I would suggest you buy a "Current Ranger", which gives you mA, uA and nA current ranges. Normal meters aren't very good for low currents.

My current design project runs at 50-60uA, and only goes higher when you operate the display on it to display readings, the unit also auto-switches OFF if you don't press a button for a certain period, adjustable from 10 seconds to 90 seconds. You need to make certain people don't just leave it turned ON.

When you do low power work also look at parts that can turn off individual
internal peripherals off. Like ARM based mixed signal parts like PSOC.



These are parts that have internal capabilities shown below, multiple copies of
those resources in most cases :



Regards, Dana.

danadak said:

When you do low power work also look at parts that can turn off individual
internal peripherals off.

Click to expand...

Don't most devices include that functionality?.

Nigel Goodwin said:

Don't most devices include that functionality?.

Click to expand...

I'll let you do the survey of manufacturers and device families.

ChatGPT says :

Most modern microcontrollers (MCUs) and microprocessors (MPUs) allow some form of peripheral power management, such as gating clocks or switching off power domains to peripherals, to save power. However, some manufacturers and families do not provide full control over internal peripheral power, especially in lower-end or older devices.


Here are a few general examples of microprocessor or microcontroller families where turning off internal power to peripherals is limited or not possible:

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Microcontroller Families with Limited or No Peripheral Power Gating:​

1. Microchip PIC16 and PIC18 (8-bit families)​

• These MCUs typically lack fine-grained power gating.
• You can disable clocks to peripherals (via registers like PMCON or PIE), but cannot truly shut off power to them.
• Power savings are mostly achieved through sleep modes or reducing clock speed.

2. Atmel (now Microchip) AVR 8-bit MCUs​

• Similar to PIC, you can disable clocks to peripherals using PRR (Power Reduction Register).
• Power is not fully cut—just clock gating is available.
• No deep power domain isolation for individual peripherals.

3. Older STM32 Families (e.g., STM32F1)​

• STM32F1 does not support advanced power domains per peripheral.
• Peripheral clocks can be turned off via RCC, but not full power gating.
• Later STM32 families (like STM32L4, STM32H7) have better peripheral power management.

4. Texas Instruments MSP430​

• Very low-power focus but still lacks true per-peripheral power control.
• You can stop clocks and enter low-power modes, but internal power to peripherals isn't usually switchable individually.

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Key Distinction:​

Most MCUs disable peripheral clocks, not actual internal power to the silicon area. True power gating is more common in:

• High-end MPUs (e.g., ARM Cortex-A with power domains)
• SoCs (e.g., Qualcomm Snapdragon, NXP i.MX)
• FPGAs with soft-core MCUs and custom power domains

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Summary Table:​

Manufacturer	MCU Family	Can Turn Off Peripheral Power?
Microchip	PIC16/PIC18	Clock only
Microchip (Atmel)	AVR (ATmega328)	Clock only
STMicroelectronics	STM32F1	Clock only
STMicroelectronics	STM32L4/H7	Partial (some peripherals)
Texas Instruments	MSP430	Clock only
NXP	LPC8xx	Limited
NXP	i.MX RT	Yes (advanced power domains)
Nordic Semiconductor	nRF51	Clock only
Nordic Semiconductor	nRF52/nRF53	Better power control

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Would you like details on a specific family or project use case?

Click to expand...

Either a very poor list, or a very antiquated one

Most PIC's have long since allowed peripherals to be powered down via the PWD registers, with many devices being called 'nanoPower.

In my experience, it is not only static mA consumption but the mA-Hr consumption that matters. And this not only depends on the tasks that the microcontroller is executing, but also how it is executing them.
For instance, speaking of I2C communications: operation in HS mode vs Std mode may yield lower mA-Hr consumption in the former, even though the actual mA consumption is a little higher. For the simple reason that the I2C bus is active for a shorter time period.

And I agree with Nigel; you have to actually measure the values.

Nigel Goodwin said:

Either a very poor list, or a very antiquated one

Most PIC's have long since allowed peripherals to be powered down via the PWD registers, with many devices being called 'nanoPower.

Click to expand...

uChip has ~ 20% of Market, how about the rest ? Not to minimize how much
of the HW is controllable of total chip HW. What is being powered off, complete clock
trees or a node or two.

Most PIC's have long since

Click to expand...

"Most", "long",,,,,,very precise terms.

Yes, ChatGPT is learning.

@OP, Note as schmitt trigger implies end application greatly affects power consumption,
datasheet values just a guide to consider.

Also, your quoted battery capacity is only rated for a continuous, low current value of only 0.19 mA.
Higher continuous current, or worse high current pulses, will decrease the actual mA-Hr capacity.

See attached file