A17DD Driver does not switch modes

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seben
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A17DD Driver does not switch modes

I’ve just completed a A17DD-SO8 v44

Flashed Toykeepers Starry and seem to be unable to switch modes.

Short press usually turns the light off, but sometimes(every 10-20x) it switches to the next mode.

My first thought was bad supply – so i put a 1F Cap on the output of my lab supply. Nothing changed.
Other Drivers do work fine in this test setup.

Switching modes by pulling down PIN1-Reset of the MCU works!

Something I’ve noticed: OTC gets charged to VCC – correct or should this be 1V?

seben
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Looks like i screwed something up in Firmware.

Flashed the current Star_offtime. Now mode switches work.

Now I’ve found something else. The light will not turn on if the supply is >4.1V
If i switch it on at 4V the voltage can be raised without the driver shutting down(Tested to 9V(driver gets 5.1V from Zener).

Is there some overvoltage protection in Firmware?(found nothing on the first look)

Low Voltage protection works as expected, although resistor values need to be changed for multicell operation.
At 4.1V the divider output is a 0.73V(should result in an ADC value of around 170)

seben
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Did some further testing – all tests in MED mode PWM 39:

Input 4V/0,11A
MCU Pin 2,3,5,8: 3,7V
OTC: 3,7V
MCU Pin 6: 0,5V
MCU Pin 5 and Voltage Divider: 0,7V

Input 5V/0,22A
MCU Pin 2,3,5,8: 4,6V
OTC: 4,6V
MCU Pin 6: 0,7V
MCU Pin 5 and Voltage Divider: 0,9V

Input 8V/0,5A
MCU Pin 2,3,5,8: 5,1V
OTC: 5,1V
MCU Pin 6: 0,8V
MCU Pin 5 and Voltage Divider: 1,4V

Going past 4V the light goes off if the mode is switched. Pin6: 0V – (sleep mode?)
It is possible to switch modes by pulling Pin1 down at any Voltage.

any ideas?

seben
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Update:

Just soldered another board, all new components. This time with correct Resistors for 2S operation.

Same result – above 4,1V I’m unable to switch modes. Switch via reset works fine.

seben
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Components list:

R1: 22k 0805 1%
R2: 4k7 0805 1%
OTC: 1uF X7R 25V
C1: 4.7uF X5R 25V
D1: 200R 0805
Z1: 5.1V 0.5W 2%
MCU: 13A SSU
FET: PSMN0R9

Components changed on the second driver:

R2: 2k2
C1: 10uF X7R

Any errors here?

finges
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Shouldn’t you be using a 4.7v zener diode?

Try and build a board without the zener for single cell use, does this work?

RMM
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finges wrote:
Shouldn't you be using a 4.7v zener diode? Try and build a board without the zener for single cell use, does this work?

4.3v is fine, as is 5.1v.  The problem is that the board layout doesn't work well with the zener diode.  You need to put the 10uF capacitor in parallel with the zener diode.  Unsolder it from the current location and solder it to the zener pads then stack the zener onto the capacitor.

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finges
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RMM wrote:

finges wrote:
Shouldn’t you be using a 4.7v zener diode? Try and build a board without the zener for single cell use, does this work?

4.3v is fine, as is 5.1v.  The problem is that the board layout doesn’t work well with the zener diode.  You need to put the 10uF capacitor in parallel with the zener diode.  Unsolder it from the current location and solder it to the zener pads then stack the zener onto the capacitor.


I thought this is solved in v044?

If not, try it like posted here.

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v044 is the same circuit as the earlier revisions.  The capacitor is closer, which can help in some instances, but in my testing that still doesn't work 100% of the time.  

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seben
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RMM wrote:

You need to put the 10uF capacitor in parallel with the zener diode.

That did it. Thanks so much!
I’ve soldered a 4.7uF to the Zener, left the 10uF in place for this one. On future drivers I’ll move the 10uF.