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421 Datasheet(PDF) 1 Page - Willow Technologies Ltd |
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421 Datasheet(HTML) 1 Page - Willow Technologies Ltd |
1 / 6 page 421 Page 1 SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE ©2005 TELEDYNE RELAYS www.teledynerelays.com 421/1205/Q1 SERIES 421 MAGNETIC-LATCHING ESTABLISHED RELIABILITY TO-5 RELAYS SPDT DESCRIPTION The magnetic-latching TO-5 relay, originally conceived and developed by Teledyne, has become one of the industry standards for low-level switching from dry circuit to 0.5 ampere. Designed for high-density PC board mounting, its small size and low coil power dissipation make the 421 relay one of the most versatile ultraminiature relays available. The following unique construction features and manufacturing techniques provide excellent resistance to environmental extremes and overall high reliability: • All welded construction. • Unique uni-frame design providing high magnetic efficiency and mechanical rigidity. • High force/mass ratios for resistance to shock and vibration. • Advanced cleaning techniques provide maximum assurance of internal cleanliness. • Precious metal alloy contacts material with gold plating assures excellent high current and dry circuit switching capabilities. The Series 421D and 421DD utilize discrete silicon diodes for coil suppression and polarity reversal protection. By virtue of its inherently low intercontact capacitance and contact circuit losses, the 421 relay has proven to be an excellent ultraminiature RF switch for frequency ranges well into the UHF spectrum. A typical RF application for this TO-5 relay is in handheld radio transceivers, wherein the combined features of good RF performance, small size, low coil power dissipation and high reliability make it a preferred method of transmit-receive switching (see Figure 1). The Series 421 magnetic-latching relays are ideally suited for applications where coil power dissipation must be minimized. The relays can be operated with a short duration pulse. After the contacts have transferred, no external holding power is required. The magnetic latching feature of the Series 421 provides a “memory” capability, since the relays will not reset upon removal of coil power. PRINCIPLE OF OPERATION Energizing Coil B produces a magnetic field opposing the holding flux of the permanent magnet in Circuit B. As this net holding force decreases, the attractive force in the air gap of Circuit A, which also results from the flux of the permanent magnet, becomes great enough to break the armature free of Core B, and snap it into a closed position against Core A. The armature then remains in this position upon removal of power from Coil B, but will snap back into position B upon energizing Coil A. Since operation depends upon cancellation of a magnetic field, it is necessary to apply the correct polarity to the relay coils as indicated on the relay schematic. When latching relays are installed in equipment, the latch and reset coils should not be pulsed simultaneously. Coils should not be pulsed with less than rated coil voltage and the pulse width should be a minimum of three times the specified operate time of the relay. If these conditions are not followed, it is possible for the relay to be in the magnetic neutral position. COIL A SOFT IRON CORE B SOFT IRON CORE A MAGNETIC CIRCUIT A MAGNETIC CIRCUIT B PERMANENT MAGNET COIL B STATIONARY CONTACT AIR GAP MOVING CONTACT SOFT IRON ARMATURE SOFT IRON CORE A SERIES DESIGNATION RELAY TYPE 421 SPDT basic relay 421D SPDT relay with internal diode for coil transient suppression 421DD SPDT relay with internal diodes for coil transient suppression and polarity reversal protection ENVIRONMENTAL AND PHYSICAL SPECIFICATIONS Temperature (Ambient) –65°C to +125°C Vibration (General Note 1) 30 g’s to 3000 Hz Shock (General Note 1) 100 g’s, 6 msec, half-sine Acceleration 50 g’s Enclosure Hermetically sealed Weight 0.089 oz. (2.52g) max. |
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