Electronics Weekly Electronics Design & Components Tech News
Called MK33, they are bare glass surface-mount reed switches with a footprint only 2.2mm wide and only 2.3mm high.
Construction is with a short length of 1mm diameter wire welded transversely across the ends for pre-solder-flow stability.
“Mechanically, the MK33 offers excellent lead coplanarity,” said the company. “The wider base is more robust, preventing the switch from tipping and allowing consistent pick and place assembly. A larger contact surface also means dependable solderability. Being hermetically sealed, the switch is impervious to most environments.”
There are two basic models:
- MK33-66 18mm long (14mm glass) carry 1A switch 0.5A
- MK33-87 13mm long (10mm glass) carry 0.5A switch 0.4A
They are normally-open, can close in 700μs including bounce, and re-open in 50μs.
Magnetic sensitivity is indicated by a -x suffix, where the x is a letter between B and G, with B indicating 10-15 ampere-turns and G indicating 35-40 ampere-turns.
Capacitance across the open contacts is 200fF for the shorter version and 300fF for the longer one.
Lifetime is very dependent on load current and voltage during operation.
With loads below 5V and 10mA, typical operating life is over a billion operations from either length device.
At 100V 10mA, predicted life is under 10 million operations for the ..87 and under 20 million for the ..66. At 20V 500mA, life is a bit longer in each case – assuming the graphs in the data sheet are representative – they are labelled KSK-1A87 and KSK-1A66 instead of MK33 and only have eight lines in each decade of their log scales. Electronics Weekly has asked for clarification.
Operation is over -40 to 130°C.
Applications are foreseen in proximity, motion and position detection, as well as in switch ladders for liquid level sensing. Their zero static power consumption suites reed switches to battery-powered devices.
Find the MK33 reed switch data sheet here
