Under-Voltage Lockout (UVLO) threshold voltage.

IoT Modules WP Series
1

Hi
I found in WP8548 spec information about Under-Voltage Lockout (UVLO).
There’s information that “threshold voltage, falling” is programmable value.
How can I change this value?

2

Would like to know the same thing as our WP8548 modules does not power up sometimes when the power supply is plugged in.
Our 24V power supply takes almost 50ms to reach 24V and we have a voltage drop when voltage is initially at 3.6V that probably activates this under-voltage lockout.
Is there a way to delay boot or early power usage in software or adjust this UVLO threshold?

3

Hi,
For WP8548, you can use “AT!PCVOLTLIMITS” command to set voltage limit values, but these values should be suitable for Product Technical Specification.
Command: AT!PCVOLTLIMITS=hc,hn,ln,lw,lc

at!pcvoltlimits?
HI CRIT: 4400
HI NORM: 4300
LO NORM: 3400
LO WARN: 3350
LO CRIT: 3300
OK
at!pcvoltlimits=5000,4500,3200,3100,3000
OK
at!pcvoltlimits?
HI CRIT: 5000
HI NORM: 4500
LO NORM: 3200
LO WARN: 3100
LO CRIT: 3000
OK
Thanks,

4

Yes know these can be set but do they really trigger a power down on the WP8548 or just an event?
https://docs.legato.io/latest/c_ips.html

And is it the same with WP76xx?

5

@nilsarve,

By default the unit will go into low power mode if the upper or lower limits are breached. Yes it is the same for WP76.

Regards

Matt

6

Ok. So if I set a wakeup timer to say 60 seconds it will wake up again?
Will try it out.

7

@nilsarve

I think the unit will exit LPM when the voltage is back within the operating range, it might need a reset, not sure, all the time it is outside of the range it will definitely remain in LPM.

Regards

Matt

8

@mlw
We only have a small voltage drop on cold start that puts the module in LPM and it stays in LMP until I reset it.
Tried the wakeup timer now but that does not work unless I put it in LPM with !POWERMODE.
So I guess we have to replace all our power supplies.