ESP32 Deep Sleep Hardware
Edit on GitHubThe hardware reality of deep sleep: what powers down, what does not, and the board-level fixes for a clean sleep.
ESP32 Deep Sleep Hardware
The firmware requests deep sleep; the hardware decides what actually sleeps. This page is the hardware reality: the peripherals, the board parts, and the fixes.
What the chip powers down
In deep sleep the ESP32:
- Stops the CPU and most peripherals
- Keeps the RTC domain (timer, RAM, GPIO state) running (see ESP32 RTC Notes)
- Drops to roughly 10 - 150 uA chip-level draw
What the chip cannot power down
| Part | Problem |
|---|---|
| The dev board’s regulator | Stays on, drawing 50 - 200 uA |
| Power LEDs | 0.5 - 2 mA, always on |
| The USB-UART chip | 1 - 5 mA unless its enable pin is driven low |
| The charger module | Small quiescent draw |
The board’s parts often draw 10 - 100x the chip’s own sleep current. This is why the Sleep Current page exists: the chip is not the problem, the board is.
The board fixes
| Fix | Effect |
|---|---|
| Cut the power LED trace | Saves 0.5 - 2 mA |
| Drive the UART chip’s EN low in sleep | Saves 1 - 5 mA |
| Use a low-quiescent regulator board | Saves 50 - 200 uA |
| Power-switch the GPS | Saves the module’s draw (see GPS Power Saving) |
The measurement
The only way to know your board’s sleep current: measure it (see Power Measurement). The Current Draw by Mode table shows the target numbers; your board’s number is the truth.
Related pages
- Firmware Deep Sleep for the firmware side
- Sleep Current for the budget
- ESP32 Board Guide for choosing a board