AX5043/AX5243 power consumption in POWERDOWN

After sending POWERDOWN to PWRMODE register, AX5243 supply current goes down to 29ua, but this is way higher than 400na stated in the datasheet. All other functions work fine - I have packets flying back and forth, but when I want to go sleep conserving power, somewhat fails. Interesting that it consumes slightly more in DEEPSLEEP, while it should be even less. I am running out of ideas, any help would be valuable.


May I know how what equipment/setup, have you used to measure currents in range of nA? (PWRMODE registers Deep sleep , Powerdown etc.)

Best Regards,

The measurements were done by Fluke 789. The na readings are not needed as 29ua is far enough from that. I do understand your idea, but I observed the current gradually coming down to measured zero for PIC as I switched off pull-up resistors one-by-one. But it never came below 29ua for AX5243.

I am having the same issue. The current consumption of AX5043 in POWERDOWN mode is much higher than expected (approx. 1.5mA) while going to DEEPSLEEP do reduce the current down to uA range ( I’m not able to measure current < 10uA accurately).

My setup is a custom made board referred to eval board, VDD=3.3V, TCXO not soldered, current measured by Nordic’s Power Profiler Kit II. I observed that even PWRMODE reg return all 0, 1.8V still present on VDD_ANA pin, I guess the regulator didn’t actually turn off and it might be the cause.

The sequence to reproduce this issue:

  1. Write 0x80 to PWRMODE(Reset)
  2. Delay 1ms
  3. Write 0x00 to PWRMODE(Clear reset and go to POWERDOWN)

The hardware setup is very simple - the SPI comms comes from PIC16LF1503. None of AX5243 GPIOs are used:

  • IRQ goes to PIC IO pin where pull-up is off. For testing it was configured as output zero. No change.
  • TCXO_EN is unconnected and configured as output zero
  • SYSCLK is unconnected and configured as output zero

After sending and receiving some data over RF, the AX5243 PWRMODE is set to 0. After that, supply current to AX5243 comes from 10+ma to 29…30ua, while expected to be below measurable limit. At this time the PIC supply current is zero, so I can’t suspect any leakage at MISO MOSI SEL CLK and IRQ pins.

I want to make AX5243 enter POWER-DOWN mode, how to set related registers

Hi! To put the AX5243 into POWERDOWN mode you will need to disable what is not needed (IRQ, LPOSC) and then set PWRMODE into POWERDOWN. You can see how this is implemented in our easyax5043.c radio driver.
The main two functions will be:

void ax5043_off(void)

void ax5043_off_xtal(void)
	radio_write8(AX5043_REG_IRQMASK0, 0x00); // IRQ off
	radio_write8(AX5043_REG_IRQMASK1, 0x00);
	radio_write8(AX5043_REG_PWRMODE, AX5043_PWRSTATE_XTAL_ON);
	radio_write8(AX5043_REG_LPOSCCONFIG, 0x00); // LPOSC off
	axradio_trxstate = trxstate_off;