ADP5090 Energy Storage Element Parameters

Hi John,

Generally, the downstream devices should not be enabled before the cold start as you know the efficiency is very low. For your case, as you're using the supercap, I recommend you to use ADP5091 that would be much faster than ADP5090. 

BRs,

Kevin

Hi Kevin, 

Noted with thanks. 

Customer also feedback on the power requirement for ADP509x too high in 33mW. Any idea to improve this? 

Thanks. 

Hi John,

The efficiency is very low so my suggestion is to remove the load at SYS pin. Actually cold start only needs 16uW. But if the supercap voltage at BAT pin is lower than the end of cold start threshold VSYS_TH, you will take very long time to charge it. That's the reason I recommend the ADP5091. 

BRs,

Kevin

Hi Kevin, With ADP5091, estimate can increase the how many % efficiency in Cold_start? 

Hi John, 

The efficiency is same but ADP5091 will not charge supercap before the cold start completion that means you only need few uW to complete the cold start and then use the high efficiency boost regulator to charge the supercap. The efficiency would be at least more than 50% that depends on the SETSD threshold. 

BRs,

Kevin

Thanks Kevin.

I will apply ADP5091 EVK to evaluate this. 

Thanks! 

Hi Kevin,

ADP5091 EVK received and tested. 
Customer's end product is Beacon. 

1) The solar cell used can produce about an open circuit voltage of 0.62V and short cicrcuit current of 55uA at lighting condition of 300lux.This is sufficient to provide net positive charge to a beacon under normal operation.

2) The minimum battery voltage required before turning on the Beacon is 3.1V.
Once battery voltage falls below this value, it is not able to boot the Beacon even with sufficient input voltage.

3) PGood voltage must be changed from 2.6V to 3.1V

4) 820uF super cap is able to hold charge for beacon to operate for approximately 20sec.
 

Problem: - 

During normal operations, the beacon has net positive energy given certain parameters. However, during Beacon boot, the current surge or cold start is not able to provide sufficient energy if the voltage of the battery is below 3.1V.

Any suggestion? 

Hi John,

What's the UVLO of this beacon? You may need measure the voltage droop during the beacon startup and then you can get how much energy you need. If you want to keep the PGOOD as low as possible, you need more capacitor at BAT pin. 

BRs,

Kevin

Hi Kevin,

Possible to share the doc with you via email? 

Thanks. 

Hi John,

Please send the doc to me via email.

BRs,

Kevin

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Thanks 

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