MintyBoost voltage drops under load

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vizzini
 
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MintyBoost voltage drops under load

Post by vizzini »

Without any load (i.e. no phone attached), the output voltage of my MintyBoost is 5.0V (+/- 0.03V or so) and the voltage on the D+ and D- pins is 2.0V. Since my iPhone wouldn't charge--I initially get the chime indicating it's charging, but then immediately I get the "This accessory may not be supported" message--I did some troubleshooting using a 15 ohm resistor as a load. With the resistor attached the output voltage of the MintyBoost drops to 3.1V even it I supply the MintyBoost 3.0V from a regulated bench power supply.

I checked and double-checked component placement and solder joints. Any suggestions on what to do next?

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adafruit_support_bill
 
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Re: MintyBoost voltage drops under load

Post by adafruit_support_bill »

even it I supply the MintyBoost 3.0V from a regulated bench power supply
What is the current rating of the bench supply? Measure the actual input voltage to the Minty under load.
If you post photos of the front and back of the board we can check over the assembly.

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vizzini
 
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Re: MintyBoost voltage drops under load

Post by vizzini »

The bench supply is rated for 2.0A continuous. Voltage at the supply measures 3.01V powering only the MintyBoost; 2.99V with Minty under load.
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adafruit_support_bill
 
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Re: MintyBoost voltage drops under load

Post by adafruit_support_bill »

2A should be plenty on the input side, and the voltage drop is minimal Your assembly looks excellent too. I suspect either a bad chip or a marginal inductor. If you contact [email protected] with a link to this thread we can send you a replacement MintyBoost kit.

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