UMX9989AP Datasheet, PDF (1/5 Pages) Microsemi Corporation – DUAL ULTRA LOW MAGNETIC MOMENT FAST DIODES FOR MRI APPLICATIONS

UMX9989AP™
DUAL ULTRA LOW MAGNETIC MOMENT
FAST DIODES FOR MRI APPLICATIONS
RoHS compliant
DESCRIPTION
The UMX9989AP is the first MRI
2) Passive switching of surface coil
switching diode module, designed to detuning and blocking circuits. In this case,
optimize performance and reduce
the flow of loop current during transmitter
assembly labor, cost, and polarity
pulse turns on the diodes, without a switch
errors.
driver.
There are two principle applications for
which the UMX9989AP modules are If the UMX9989AP is combined with a PIN
intended:
diode (UM7201SM) the combination can
1) MRI receiver protection from high be used to implement a semi-active detune
RF energy fields, including long RF or block circuit design. The UMX9989AP’s
pulses and RF spike pulses present in turn on the PIN diode (used for higher
most MRI machines. The UMX9989AP power switching) during the sinc(x)
acts as a passive protector (limiter) for sidelobes, before the main pulse of the
the MRI receiver’s LNA.
transmitter waveform, sinc(x) = [sin (x)]/x,
The diode assembly exhibits extremely occurs. The mechanical drawing shows the
low insertion loss, both in the “on” state structure of the diode pair. Manufacture of
(high power present) and the “off” state dual anti-parallel pairs of UMX9989’s
(receiver power present) so the
ensures that the matched pair of diodes can
Receiver’s Noise Figure is not
be inserted in a coil with the correct diode
increased by the protector circuit.
polarities and with the minimum parasitic
inductance and capacitance, thermal
impedance and labor for the coil
manufacturer.
IMPORTANT: Forthemostcurrentdata,consultMICROSEMI’s website: http://www.microsemi.com
ABSOLUTE MAXIMUM RATINGS AT 25º C
(UNLESS OTHERWISE SPECIFIED)
Rating
Symbol
Value
Unit
Non-Repetitive Peak Forward Surge Current
8.3ms Single half sine wave
I_FSM
2
A
Storage Temperature
T stg -65 to +150
ºC
Operating Temperature
T op -65 to +150
ºC
KEY FEATURES
ƒ Ultra low magnetic construction
ƒ RoHS compliant
ƒ Matched pairs available
ƒ Surface mount package.
ƒ Metallurgical bond
ƒ Planar passivated chip
ƒ Non cavity design
ƒ Thermally matched configuration
ƒ Low capacitance at 0 V bias
ƒ Low conductance at 0 V bias
ƒ Compatible with automatic
insertion equipment
APPLICATIONS/BENEFITS
ƒ MR passive receiver protection
ƒ MR passive blocking circuits
ƒ MR passive detuning circuits
ƒ MR passive disable circuits
Copyright  2005
Rev. 0, 2005-09-08
Microsemi
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