SERIES
MAGNETIC-LATCHING
ESTABLISHED RELIABILITY
TO-5 RELAYS
DPDT
SERIES
DESIGNATION
420/422
420D/422D
420DD/422DD
DPDT basic relay
DPDT relay with internal diode for coil transient suppression
DPDT relay with internal diodes for coil transient suppression and polarity
reversal protection
RELAY TYPE
420/422
ESTABLISHED RELIABILITY
DESCRIPTION
The Series 420D/422D and 420DD/422DD utilize discrete diodes for
coil suppression and polarity reversal protection.
By virtue of its inherently low intercontact capacitance and contact
circuit losses, these TO-5 relays have proven to be excellent
ultraminiature RF switches for frequency ranges well into the UHF
spectrum. A typical RF application for these TO-5 relays is in
handheld radio receivers, wherein the combined features of good RF
performance, small size, very low coil power dissipation and high
reliability make it a preferred method of transmit-receive switching
(see Figure 1).
The Series 420/422 magnetic-latching relays are ideally suited for
applications where 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 420/422 relays provide
a “memory” capability, since the relays will not reset upon removal of
coil power.
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 1 ampere. Designed for
high-density PC board mounting, its small size and low coil power
dissipation make the 420 and 422 relays some 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.
PERMANENT MAGNET
MAGNETIC CIRCUIT A
SOFT IRON FRAME
PRINCIPLE OF OPERATION
MAGNETIC CIRCUIT B
+
+
Energizing Coil B produces a magnetic field
COIL A
COIL B
opposing the holding flux of the permanent magnet
SOFT IRON
in Circuit B. As this net holding force decreases, the
SOFT IRON
COIL A
COIL B
-
-
attractive force in the air gap of Circuit A, which also
AIR GAP
SOFT IRON
ARMATURE
results from the flux of the permanent magnet,
STATIONARY
CONTACT
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
MOVING
CONTACT
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.
ENVIRONMENTAL AND
PHYSICAL SPECIFICATIONS
Temperature
(Ambient)
Vibration
(General Note 1)
Shock
(General Note 1)
Acceleration
Enclosure
Weight
–65°C to +125°C
30 g’s to 3000 Hz
100 g’s,
6 msec, half-sine
50 g’s
Hermetically sealed
0.10 oz. (2.84g) max.
420 422 Page
1
420 422/1203/Q1
©2003 TELEDYNE RELAYS
SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE
www.teledynerelays.com
TELEDYNE [ TELEDYNE TECHNOLOGIES INCORPORATED ]
