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GePl_1641041
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We have defective units coming back from customers with the voltage on the VDDR & VDD stuck at 1.67volt. We are using module Cyble 222014 (BLE 4.2 with PSoC 4).

The module is powered using LiPo battery and step down regulator to 3.3V. We know the power supply is not defective because when we remove the Cypress module, power is back at 3.3V on the VDDR & VDD PCB trace. The Cyble module is bringing down the voltage to 1.67v and we do not know why.

Power schema to the cyble 222014 is like Figure 7 of the CYBLE-222014-01 datasheet (single ferrite option).

We are using capacitors, fuse and TVS diode to protect the power input from surge, voltage inversion. It is not possible for input voltage to go over 4.2V (well below the maximum authorized in the datasheet of 5.5V VDD1)

What conditions will create this situation? Can the module recover from that or it must be replaced? We have replaced all defective units so far.

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Vasanth
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250 sign-ins 500 solutions authored First question asked

Hi,

Schematic looks fine in the first look. To eliminate on doubt can you program an empty project on the failed board and check the voltages on VDDR & VDD. How much load current can your regulator provide ? Also will you be able to check how much current the failed modules are consuming when they are programmed/not programmed?

Best Regards,
Vasanth

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Vasanth
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250 sign-ins 500 solutions authored First question asked

Hi,

Does any of the input to the any GPIO pins exceed the device maximum in the project ? Could you make sure that it is not happening by mistake ? Is there any chance for spikes on the pin too ? How often do you see the failure ? Will you able to share the schematic for checking ?

Best Regards,
Vasanth

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GPIO pins do not exceed the device maximum. Checked all pins on a unit, all well below VDD. We tried to recreate the issue by injecting voltage spikes in the charging port but it did not trigger the issue. The failure is about 5% to 10% of units shipped. Units are all tested and working fine before shipping to customers. The problem appears thereafter. 

Schematic is here:

schematic_1_67v_issue.jpg - Google Drive

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Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

Hi,

Schematic looks fine in the first look. To eliminate on doubt can you program an empty project on the failed board and check the voltages on VDDR & VDD. How much load current can your regulator provide ? Also will you be able to check how much current the failed modules are consuming when they are programmed/not programmed?

Best Regards,
Vasanth

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