Liftoff, we have a liftoff…
15mm boost driver (v1) working
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Partlist and used Firmware below
Rebuilt on a 2nd board, running fine.
2x 2AA and 3x 1AA (Eneloops) drained so far, about 200 mode changes, all good.
It’s a HQb15 de-luxe with Coilcraft inductor and high value capacitors.
Board is the same layout as in post#72 above.
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Oshpark link for HQb15 v1 EDIT: Obsolete as HQB15 v2 is finished, see post#96
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Driver height with this inductor is 3.7mm (0.2mm less than with the FT inductor). Now take the new Oshpark 0.8mm boards and you’re down to 2.9mm. That’s a whopping 3.0mm less than a Nanjg110.
Enough space around the Attiny13a for the clip after driver assembly.
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Partlist
(source in brackets; see post#25 for more info on the parts)
Switch: PAM2803, SOT-23-6 (FastTech driver)
L1: 2.2yH, Coilcraft XFL4020 (electr. supply)
D1: BAT60A (electr. supply)
C1: 10yF, 0805, X5R (electr. supply)
C2: 20yF, 0805, X5R (electr. supply)
C3: 4.7yF, 0603, X5R (electr. supply)
R1: 0.120Ohm, 0805 (FastTech driver)
R2: 150kOhm, 0605 (FastTech driver)
R3: 33kOhm, 0605 (FastTech driver)
MCU: ATTiny13A-SSU, Package 8S1 (electr. supply)
OTC: not yet
FET: (FastTech driver)
C2 and C3 are by design in parallel (C2 for PAM2803, C3 for ATtiny13A). In this built I used both caps and with high value.
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Firmware
An adapted Dr. Jones MiniDrv firmware for starters.
Frequency changed to 18kHz, on-time-memory, 9 modes
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Output
Eneloops fresh from charger (no resting time)
With 2AA holding ~780mA for quite some time (R1 (=Rs) = 120mOhm)
With 1AA starting >550mA, continuously going down, but surprisingly slow in comparison to Nanjg 110
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loose threads…
no OTC yet
adapting R1 to change output
output at PWM1 is 16mA with fresh cells (1AA and 2AA)
trying different components (inductor, FET)
17mm version
15mm V2, will be a fine tuning of the layout after having built them twice
V1 has an overall size of 15.4mm, the GND copper layer by Oshpark is only 14.8mm. V2 will be increased to 15.6mm.
(EDIT needed after Drupal overhaul)