EG91 Pulse in VDD_EXT line

[SLed]

Hi,

I’ve developed a custom board with EG91 module. Most of boards starts and works correctly according to timing (figure 12 on pag 36 of EG91 Hardware Design). However, some boards does not start. Power is supplied to board but STATUS line is not activated. I see that VDD_EXT power line is on during 1 second aproximately and then is off. The same with VDD_SIM.

Some suggestion?

Thanks.

Regards.

[fiona.fang]

@SLed

I’ve developed a custom board with EG91 module. Most of boards starts and works correctly according to timing (figure 12 on pag 36 of EG91 Hardware Design). However, some boards does not start. Power is supplied to board but STATUS line is not activated. I see that VDD_EXT power line is on during 1 second aproximately and then is off. The same with VDD_SIM.

Could you please give me more information about it, such as schematic or any AT results?I guess it is the problem about power supply.

[SLed]

Hi Fiona,

How could I send to you schematic???
There is no AT results because module does not respond; it seems uart communication is not operating because module seems powered off…

Thanks!