What This MTA-156 IDC Receptacle Does in a Harness
The 0.156" (3.96mm) pitch matches the MTA-156 header pin row, so the board footprint is set by that spacing. The single-row, 3-position layout is meant for low-circuit-count signal or low-power distribution — think sensor leads, control panel wiring, or internal appliance harnesses where three wires need a reliable, mass-terminated connection to a PCB header. The blue housing carries a closed end and polarizing key, which together prevent the connector from being inserted backwards or over-inserted onto the header — a practical safeguard on an assembly line where orientation mistakes cost rework. The locking ramp snaps over the mating header latch for positive retention under vibration or cable tug.
Termination and Wire Fit — IDC Only, 26 AWG
This is an IDC (insulation displacement) receptacle, not a crimp type. The specified wire gauge is 26 AWG; that is the only supported size for reliable IDC termination. Using a different gauge risks an intermittent or open connection because the slot geometry is fixed for that wire diameter.
Mating and Mounting — Free-Hanging Receptacle
The 3-643821-3 is a free-hanging (in-line) receptacle, so it does not mount to a PCB — it terminates the cable end and mates with a board-mounted MTA-156 header. The single-row, 3-position layout means the mating header will have three pins at 0.156" pitch. Because the housing has a closed end, the receptacle cannot be pushed past the last header pin — a small detail that prevents pin damage during blind mating in a crowded enclosure.
RoHS compliance is confirmed, so the part meets the restriction-of-hazardous-substances requirements for European and most global markets.