microsemi page 1 copyright ? 2005 rev. 0, 2005-09-08 www. microsemi . com UMX9989AP? dual ultra low magnetic moment fast diodes for mri applications rohs com p liant description the UMX9989AP is the first mri switching diode module, designed to optimize performance and reduce assembly labor, cost, and polarity errors. there are two principle applications for which the UMX9989AP modules are intended: 1) mri receiver pr otection from high rf energy fields, including long rf pulses and rf spike pulses present in most mri machines. the UMX9989AP acts as a passive protector (limiter) for the mri receiver?s lna. the diode assembly exhibits extremely low insertion loss, both in the ?on? state (high power present) and the ?off? state (receiver power present) so the receiver?s noise figure is not increased by the protector circuit. 2) passive switching of surface coil detuning and blocking circuits. in this case, the flow of loop current during transmitter pulse turns on the diodes, without a switch driver. if the UMX9989AP is combined with a pin diode (um7201sm) the combination can be used to implement a semi-active detune or block circuit design. the UMX9989AP?s turn on the pin diode (used for higher power switching) during the sinc(x) sidelobes, before the main pulse of the transmitter waveform, sinc(x) = [sin (x)]/x, occurs. the mechanical drawing shows the structure of the diode pair. manufacture of dual anti-parallel pairs of umx9989?s ensures that the matched pair of diodes can be inserted in a coil with the correct diode polarities and with the minimum parasitic inductance and capacitance, thermal impedance and labor for the coil manufacturer. important: for the most current data, consult microsemi ?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 ? ultra low magnetic construction ? rohs compliant ? matched pairs available ? surface mount package. ? metallurgical bond ? planar passivated chip ? non cavity design ? thermally matched configuration ? low capacitance at 0 v bias ? low conductance at 0 v bias ? compatible with automatic insertion equipment applicati ons/benefits ? mr passive receiver protection ? mr passive blocking circuits ? mr passive detuning circuits ? mr passive disable circuits u u m m x x 9 9 9 9 8 8 9 9 a a p p ? ?
microsemi page 2 copyright ? 2005 rev. 0, 2005-09-08 www. microsemi . com UMX9989AP? dual ultra low magnetic moment fast diodes for mri applications rohs com p liant note: 1 short duration test pulse used to minimize self ? heating effect . electrical parameters @ 25 c (unless otherwise specified) parameter symbol conditions min typ. max units forward voltage (note 1) v f i f = 10 a i f = 1 a 0.38 1.2 0.4 1.4 v v capacitance conductance c t g v r = 0v, f = 1 mh z v r = 0 v, f = 64 mhz v r = 0 v, f = 64 mhz 4 4 8 8 80 pf pf us parallel resistance r p v r = 0 v, f = 64 mhz 12 kohms e e l l e e c c t t r r i i c c a a l l
microsemi page 3 copyright ? 2005 rev. 0, 2005-09-08 www. microsemi . com UMX9989AP? dual ultra low magnetic moment fast diodes for mri applications rohs com p liant product preliminary data ? information contained in this document is pre-production data, and is proprietary to microsemi corp. it may not be modified in any way without the express written consent of microsemi corp. product referred to herein is not guaranteed to achieve preliminary or production status and product specifications, configurations, and availability may change at any time. e e l l e e c c t t r r i i c c a a l l
microsemi page 4 copyright ? 2005 rev. 0, 2005-09-08 www. microsemi . com UMX9989AP? dual ultra low magnetic moment fast diodes for mri applications rohs com p liant style ?um9989ap? outline style ?um9989ap? footprint notes: 1. these dimensions will match the term inals and provide for additional solder fillets at the outboard ends at least as wide as the terminals themselves , assuming accuracy of device placement within .005 inches 2. if the mounting method chosen requires use of an a dhesive separate from th e solder compound, a round (or square) spot of cement as s hown should be centrally located. 3. dimensions shown are in inches. m m e e c c h h a a n n i i c c a a l l
microsemi page 5 copyright ? 2005 rev. 0, 2005-09-08 www. microsemi . com UMX9989AP? dual ultra low magnetic moment fast diodes for mri applications rohs com p liant notes: n n o o t t e e s s
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