8-button through-hole isolator with debouncing

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STD 8-button through-hole isolator with debouncing

License: Public Domain

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Update time： 2024-01-28 13:58:44

Creation time： 2019-07-17 08:08:59

Description

Untested! 51mm × 51mm board, for isolating up to 8 buttons or switches, using only through-hole components. Switches are connected between SWn and SWGND. There are pads for eight 100nF (0.1uF) debouncing capacitors. The current to each optoisolator is roughly 5mA. The isolated DC-DC converter provides approximately 150mA to +4.5V. Components have been chosen for easy ordering from LCSC.com. Multiple boards can be used in parallel, with their SW#, SWGND, and +4.5V lines connected. This allows the same buttons to provide signals to e.g. multiple microcontrollers. When multiple boards are connected in parallel, the diodes ensure the DC-DC converters are not backfed. The 250 Ohm resistor ensures the converter output is loaded by 20mA at all times. For use with USB-connected microcontrollers using 3.3V signal levels, like Teensy LC/3.0/3.1/3.5/3.6, connect +5VIN to VUSB, OVCC to 3.3V, OGND to GND, and SW1 through SW8 to suitable input pins.

Design Drawing

schematic diagram

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PCB

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BOM

BOM download Purchase Parts

ID	Name	Designator	Footprint	Quantity
1	TLP521GB	U1,U2,U3,U4,U5,U6,U7,U8	DIP-4	8
2	680	R1,R2,R3,R4,R5,R6,R7,R8	RD-3.2X1.8-1/8W	8
3	10K	R9,R10,R11,R12,R13,R14,R15,R16,R17,R18,R19,R20,R21,R22,R23,R24	AXIAL-0.3	16
4	100n	C1,C2,C3,C4,C5,C6,C7,C8	CAP-0.2	8
5	Pad	SW1,SW2,SW3,SW4,SW5,SW6,SW7,SW8,OVCC,OUT1,OUT2,OUT3,OUT4,OUT5,OUT6,OUT7,+5VIN,+4.5V,OUT8	PTH-1	19
6	Pad	SWGND,OGND	PTH-1-SQUARE	2
7	100K	R25,R26,R27,R28,R29,R30,R31,R32	AXIAL-0.3	8
8	B0505S-1WR3	U9	DIP-11.6X6.0X10.16	1
9	4.7uF	C10	CAP-TAN-S2.5	1
10	10uF	C9	CAP-TAN-S2.5	1
11	250	R33	AXIAL-6.3X2.4	1
12	1N5817RLG	D1	DO-15	1