SIM7070 2G Modem Not Entering Low Power Sleep Mode

Projects Networking, Protocols, and Devices
1

Hello everyone,

I’m working on a low-power IoT application using an STM32L0 series microcontroller (programmed via the Arduino IDE) along with the STM32 Low Power library.

I’m trying to achieve ultra-low current consumption during deep sleep mode. The STM32 side seems fine, but the problem is with the SIM7070 2G modem — it continues to draw around 30–40 mA even when the MCU is in deep sleep.

According to the SIM7070 datasheet, the module should enter sleep mode with a current consumption of around 1–2 mA when the following steps are applied:

Send the command:

AT+CSCLK=1

Then set the DTR pin HIGH and keep it HIGH for about 15–20 seconds.

I have implemented these steps in my firmware, but the modem still appears to remain in an active state (current draw doesn’t drop).

Here’s what I’ve confirmed so far:

The modem successfully responds to AT commands.

I send AT+CSCLK=1 and then set DTR HIGH before putting STM32 to sleep.

However, current consumption stays high (~30–40 mA), suggesting the modem never actually enters sleep.

Has anyone successfully implemented SIM7070 (2G mode) low-power sleep in a similar setup?
Are there additional commands, timing sequences, or hardware signals (like PWRKEY or RI) that need to be managed for proper sleep entry?

Any guidance, working examples, or power measurement tips would be greatly appreciated.

Thanks in advance for your help!

2

Are there any LED's still lit on the board?
The 30 to 40 sounds right for a Dev board, the 1 to 2 mA will be just the SOC.

3

Fot my SIM7080G I got good help in this Application Note for Low Power:

With a BK-7080G V2 breakout board powerd with 3,3V, the current lows to 90µA when the SIM7080G is in PSM mode (LTE CAT-M) and GNSS active antenna is unconnected.
I’ve never played witn SIM7070

(SIMCOM SIM7070 and SIM7080 use same SOC from Broadcom, but of course no PSM mode in 2G)

However, current consumption stays high (~30–40 mA), suggesting the modem never actually enters sleep.

Active GNSS antenna connected ?

What breakout board do you use ?
many low cost ones have an ‘old time’ pseudo LDO with high standby current

4

If you connect the antenna or not, it doesn’t matter. You have to activate GNSS and power off it once you don’t need it anymore.
With AT+CGNSPWR?

The deepsleep (do you mean AT+CSCLK ?) is for the modem.