This is the single-channel version of the Hexagon HQ4D driver board for 4x 7135 and OTC.
All AMC7135 (Q1-4) are connected to Pin6 of the ATtiny13A.
This board is a direct adaptation of the HQ4D brd-file, so it should work, but is yet untested. For more information see the HQ4D thread.
This driver replaces the Nanjg101 and NanjgAK47 driver, removing the stars, but allowing for an OTC that does not obstruct the ATtiny13A. Greatest advantage is the Oshpark option of 0.8mm PCB, giving extra room in tight lights.
The board is slightly oversized (17.6mm) to compensate for the 0.3mm missing copper on the edge of Oshpark boards. This will result in a 17.6mm PCB with a copper GND ring of 17.0mm (and the need to file down the board in most cases).
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Partlist
MCU: ATtiny13a-SSU
Q1-Q4: AMC7135
D1: Schottky ~0.25V, SOD-323
C1: 4.7µF, X5R or X7R, 0805
OTC: 1µF, X5R or X7R, 0603
R1: 19.1k, 0603, (see comment)
R2: 4.7k, 0603, (see comment)
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Annotations
The circuit follows the Nanjg drivers, so the resistors for low voltage protection and C1 are behind the diode. A Nanjg can be used for harvesting parts, although R1 and R2 in my board have a 0603 footprint, but the stock Nanjg105 resistors (0805) do fit if soldered carefully.
Other combinations of R1/R2 should work, if you either keep the ratio of ~4.06 (I use 33k and 8.2k) or adapt the LVP values in the firmware.
You can use either 350mA or 380mA current regulators (Q1-Q4).