Regarding operation of “Solar Powered IoT Device Kit” with coin battery.

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YuMa_1534086
Level 7
Level 7
Distributor - Macnica (Japan)
500 replies posted 250 sign-ins 10 likes received

Hello.

User would like to operate “Solar Powered IoT Device Kit” by using coin battery.

User mounted a battery holder, then they inserted CR1220(3V) into this holder.

But IoT kit did not operate.

And I tried whether IoT kit operates correctly or not by using external power supply.

I used VBAT pin(#2) of J1.

But IoT kit did not operate even if external power supply ups to 5V.

It seems that S6E101A did not output any voltage even if there is VBAT voltage(3V to 5V).

J4 is in EH side.

How should user operate IoT kit with coin battery?

Please advise.

Best Regards.

Yutaka Matsubara

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1 Solution
Yuva
Moderator
Moderator
Moderator
250 replies posted 250 sign-ins 100 solutions authored

Hi Matsubara-san,

Please refer to the application note in the following link. As you see the input resistance between VBAT and VSTORE1 of S6AE101A is around 5Kohm so the charging time is longer. After the VSTORE1 is charged it will be transferred to VOUT1. If the load current is more then the discharge time will much shorter than the charging time. Due to this cycle there will effectively no voltage at VOUT1. This is the reason to optimize the load current to lower value. The device will be able to provide upto 100mA but the duration it can provide will be very short. If you need more current then you can choose S6AE102A/S6AE103A.

http://www.cypress.com/file/303131/download

Thanks,

Yuva.

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10 Replies
Yuva
Moderator
Moderator
Moderator
250 replies posted 250 sign-ins 100 solutions authored

Hello Matsubara-san,

Which pin are you observing the output voltage? I provided voltage from externally power supply(3.3-5V) to VBAT pin and measured the voltage of 3.2V at VOUT pin.

Thanks,

Yuva.

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YuMa_1534086
Level 7
Level 7
Distributor - Macnica (Japan)
500 replies posted 250 sign-ins 10 likes received

Dear Yuva-san.

I checked #1pin of J4.

When J4 jumper was removed(#1, #2 and #3 pin of J4 are OPEN), I confirmed a voltage(about 3V).

But when J4 jumper was shorted between #1 and #2 pin to supply a voltage to BLE module, I could not confim any voltage.

In this time, a voltage level is about 0V.

Attached files are FW for EH motherboard and usb dongle.

EH mothrerboard’s LED lights up at USB power, then BLE communication operates correctly.

But LED does not light up at COIN battery or external power supply from VBAT pin.

Best Regards.

Yutaka Matsubara

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Yuva
Moderator
Moderator
Moderator
250 replies posted 250 sign-ins 100 solutions authored

Dear Matsubara-san,

I am also able to reproduce the effect with your project and pins 1 and 2 of J4 connected. When I use the example project with the kit, there is no issue. I suspected the high load current is causing the issue and made some changes to your project (put the BLE module deep-sleep and disabled external clock). After these changes the output voltage comes stable to 3.2 V, so the issue seems to be related to high load current. Can you estimate the current consumption and optimize it?

Thanks,

Yuva.

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YuMa_1534086
Level 7
Level 7
Distributor - Macnica (Japan)
500 replies posted 250 sign-ins 10 likes received

Dear Yuva-san.

How low should VDD current be lowered at coin battery(CR1220)?

And my project did not work correctly when I used external power supply(Not coin battery).

I think that there is not current limit in external power supply.

In this time, why did my project not work correctly?

Please advise about this.

Best Regards.

Yutaka Matsubara

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Yuva
Moderator
Moderator
Moderator
250 replies posted 250 sign-ins 100 solutions authored

Dear Matsubara-san,

Eventhough the power supply/battery, the load current limit is due to the S6E101A device. I will check your 'BLE Demo' project for the low current optimization. Meanwhile you can also check if you can optimize the current consumption.

Thanks,

Yuva.

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YuMa_1534086
Level 7
Level 7
Distributor - Macnica (Japan)
500 replies posted 250 sign-ins 10 likes received

Dear Yuva-san.

Thank you for your support.

Could you please let us know VBAT pin current limit spec?

Does a document describe this spec?

Is it OK that VBAT pin and J4 #1pin are shorted, if user uses only coin battery(only VBAT pin)?

User does not use solar cell(VDD pin).

Best Regards.

Yutaka Matsubara

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Yuva
Moderator
Moderator
Moderator
250 replies posted 250 sign-ins 100 solutions authored

Hi Matsubara-san,

I will check regarding the spec of the current and update. But I see the 'BLE Demo' project is not optimize for power. Can you check the example project for the kit (attached for reference) and check if you are able to get proper output voltage? I recommend you to follow the template as this project to get low power. The project which you refer to optimized for power (clocking and coding). Shorting VBAT with J4#1 is like bypassing the harvester.

Thanks,

Yuva.

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Yuva
Moderator
Moderator
Moderator
250 replies posted 250 sign-ins 100 solutions authored

Hi Matsubara-san,

Please refer to the application note in the following link. As you see the input resistance between VBAT and VSTORE1 of S6AE101A is around 5Kohm so the charging time is longer. After the VSTORE1 is charged it will be transferred to VOUT1. If the load current is more then the discharge time will much shorter than the charging time. Due to this cycle there will effectively no voltage at VOUT1. This is the reason to optimize the load current to lower value. The device will be able to provide upto 100mA but the duration it can provide will be very short. If you need more current then you can choose S6AE102A/S6AE103A.

http://www.cypress.com/file/303131/download

Thanks,

Yuva.

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YuMa_1534086
Level 7
Level 7
Distributor - Macnica (Japan)
500 replies posted 250 sign-ins 10 likes received

Dear Yuva-san.

Is “100mA current limit spec” explained somewhere in datasheet?

Best Regards.

Yutaka Matsubara

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Yuva
Moderator
Moderator
Moderator
250 replies posted 250 sign-ins 100 solutions authored

Hello Matsubara-san,

This value is based on the measurement done in our evaluation kit. I will propose to add this information to the datasheet.

Thanks,

Yuva.

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