The MAX6816/MAX6817/MAX6818 from Maxim Integrated (now part of Analog Devices) are switch debouncers that solve a small but persistent problem: a mechanical switch or relay does not make a clean contact - it bounces, producing a burst of fast transitions that a processor reads as multiple presses. These devices interface directly to the switch and output a single, debounced logic transition. The MAX6816 is the single-switch version (the MAX6817 is dual, the MAX6818 octal); MAX6816EUS+T is the RoHS ("+"), tape-and-reel ("T") 4-pin SOT143.

The protection is what lets the switch wire run anywhere. The input withstands voltages to ±25 V - beyond the supply rails - and is ESD-protected to ±15 kV Human Body Model (and ±8 kV contact / ±15 kV air per IEC 1000-4-2), so a panel switch on a long cable cannot damage the input. An internal pull-up means the switch simply connects the input to ground, and the debouncer takes care of the rest.

It is built to disappear into the design. There are no external components - no RC network to size, no firmware debounce routine to write - because the debounce period is generated internally. The supply current is a tiny 6 µA, so the part sits permanently on a battery rail, and it runs from +2.7 V to +5.5 V over the extended -40 °C to +125 °C range in the four-pin SOT143, one of the smallest packages available.

Note: Values are taken from the Maxim MAX6816/MAX6817/MAX6818 datasheet. Confirm every parameter (including the internal debounce period) against the latest official documentation before committing a design.

MAX6816EUS+T ships in the 4-pin SOT143 (package outline 21-0052) - one of the smallest packages available, which is the point: a debouncer with no external parts in a SOT143 takes almost no board area next to the switch or connector. With four pins (GND, IN, OUT, V_CC) the layout is trivial - run IN to the switch, OUT to the logic input, and bypass V_CC. The package image is shown below.

The 4-pin SOT143 carries the switch input, debounced output, supply and ground (per the MAX6816 datasheet):

• Pin 1 - GND: Ground.
• Pin 2 - IN: Switch input; connect the mechanical switch from here to ground (internal pull-up sets the idle level). Tolerates ±25 V, ±15 kV ESD.
• Pin 3 - OUT: CMOS debounced output - a single clean logic transition per switch closure.
• Pin 4 - V_CC: Supply, +2.7 V to +5.5 V; bypass to GND.

Within the family the MAX6817 (dual) and MAX6818 (octal) add channels. The slug-listed parts below are related Maxim µP-system peripherals (supervisors, references, supplies) that commonly share a board with a switch debouncer.

Selection Tips: Choose the MAX6816 for a single rugged, zero-external-part switch debouncer in the smallest SOT143; step to the MAX6817 for two switches or the MAX6818 for eight (with a 3-state µP bus interface). The supervisors, reference and supplies above round out the processor's support circuitry.

Maxim Integrated, now part of Analog Devices, Inc. (ADI), built the MAX6816/MAX6817/MAX6818 to take the bounce, the RC network and the firmware out of reading a mechanical switch - a rugged, ESD-protected debouncer that drops in beside the switch in a tiny package.

ADI maintains the datasheet, the debounce-timing and ESD specifications, and the switch-interface guidance for the family - the basis for a clean, reliable switch input to a processor.