UM9989 Datasheet, PDF (1/6 Pages) Microsemi Corporation – FAST MRI PROTECTION DIODES

UM9989
FAST MRI PROTECTION DIODES
DESCRIPTION
The UM9989 diode series was designed Receiver protector diodes appear directly
to protect MRI receivers from high RF across the input port of the receiver. They
energy fields including long RF pulses are connected in anti-parallel pairs to limit
and RF spike pulses present in most the RF carrier excursion in both polarities.
MRI machines. The UM9989 acts as a They must, therefore, exhibit extremely low
passive protector (limiter) for the MRI insertion loss, both in the “on” state (high
receiver. No forward bias voltage is power present) and the “off” state (receiver
required to turn on the diode. It is self- power present) so as not to decrease the
biased by the RF transmitter pulse
receiver’s sensitivity. The UM9989 diodes
power. A switch driver is not needed are available in two package configurations
for this receiver protection application. for flexibility in design.
IMPORTANT: Forthemostcurrentdata,consultMICROSEMI’s website: http://www.microsemi.com
ABSOLUTE MAXIMUM RATINGS AT 25º C
(UNLESS OTHERWISE SPECIFIED)
Rating
Symbol
Value
Unit
Peak Repetitive Reverse Voltage
V_RRM
Working Peak Reverse Voltage
V_RWM
75
V
DC Blocking Voltage
V_R
RMS Reverse Voltage
V _{R (RMS)}
50
V
Non-Repetitive Peak Forward Surge Current
8.3ms Single half sine wave
I_FSM
2.5
A
Storage Temperature
T stg -65 to +150
ºC
Operating Temperature
T op -65 to +150
ºC
KEY FEATURES
ƒ Available in surface mount
package.
ƒ
ƒ Metallurgical bond
ƒ
ƒ Planar passivated chip
ƒ
ƒ Non-magnetic construction
ƒ
ƒ Non cavity design
ƒ
ƒ Thermally matched configuration
ƒ
ƒ Low capacitance at 0 V bias
ƒ
ƒ Low conductance at 0 V bias
ƒ
ƒ Compatible with automatic
insertion equipment
APPLICATIONS/BENEFITS
ƒ MRI receiver protection
ƒ
ƒ Body coil isolation
THERMAL CHARACTERISTICS
(UNLESS OTHERWISE SPECIFIED)
Thermal Resistance
@ Lead length = 3/8 inches
R_OLA
100
ºC/Watt
Style “B”
Copyright  2003
Rev. 0, 2004-10-26
Style “SM”
Microsemi
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