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J421D-26M Datasheet, PDF (1/6 Pages) Teledyne Technologies Incorporated – MAGNETIC-LATCHING ESTABLISHED RELIABILITY TO-5 RELAYS
MAGNETIC-LATCHING
ESTABLISHED RELIABILITY
TO-5 RELAYS
SPDT
SERIES
421
SERIES
DESIGNATION
421
421D
421DD
RELAY TYPE
SPDT basic relay
SPDT relay with internal diode for coil transient suppression
SPDT relay with internal diodes for coil transient suppression and polarity
reversal protection
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
PERMANENT MAGNET
MAGNETIC CIRCUIT B
MAGNETIC CIRCUIT A
SOFT IRON CORE A
Energizing Coil B produces a magnetic field
opposing the holding flux of the permanent magnet COIL B
COIL A
in Circuit B. As this net holding force decreases, the SOFT IRON
attractive force in the air gap of Circuit A, which also CORE B
results
from
the
flux
of
the
permanent
magnet, SOFT IRON
ARMATURE
becomes great enough to break the armature free
SOFT IRON
CORE A
AIR GAP
MOVING
CONTACT
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
STATIONARY
CONTACT
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.
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.
421 Page 1
SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE
www.teledynerelays.com
©2005 TELEDYNE RELAYS
421/1205/Q1