www.MICROSEMI.com UM9989 UM9989 UM9989 FAST MRI PROTECTION DIODES TM RoHS Compliant Versions Available KEY FEATURES DESCRIPTION Available in surface mount The UM9989 diode series was designed to protect MRI receivers from high RF package. energy fields including long RF pulses and RF spike pulses present in most MRI machines. The UM9989 acts as a passive protector (limiter) for the MRI receiver. No Metallurgical bond forward bias voltage is required to turn on the diode. It is self-biased by the RF transmitter pulse power. A switch driver is not needed for this receiver protection Planar passivated chip application. Receiver protector diodes appear directly across the input port of the receiver. They Ultra Low magnetic construction are connected in anti-parallel pairs to limit the RF carrier excursion in both polarities. They must, therefore, exhibit extremely low insertion loss, both in the on state (high Non cavity design power present) and the off state (receiver power present) so as not to decrease the receivers sensitivity. The UM9989 diodes are available in two package Thermally matched configuration configurations for flexibility in design. Low capacitance at 0 V bias IMPORTANT: For the most current data, visit our website: www.MICROSEMI.com Low conductance at 0 V bias ABSOLUTE MAXIMUM RATINGS AT 25 C (UNLESS OTHERWISE SPECIFIED) Compatible with automatic insertion equipment Rating Symbol Value Unit RoHS Compliant Versions 1 Available Peak Repetitive Reverse Voltage V RRM Working Peak Reverse Voltage V 75 V RWM DC Blocking Voltage V R RMS Reverse Voltage V 50 V R (RMS) Non-Repetitive Peak Forward Surge Current I 2.5 A FSM 8.3ms Single half sine wave APPLICATIONS/BENEFITS Storage Temperature T -65 to +150 C STG MRI receiver protection Operating Temperature T -65 to +150 C OP Body coil isolation THERMAL CHARACTERISTICS (UNLESS OTHERWISE SPECIFIED) Thermal Resistance Note 1: RoHS compliant versions are supplied with a matte Tin finish. Lead length = 3/8 inches R 100 C/Watt RoHS part numbers are: OLA UMX9989B UMX9989SM Style B Style SM Microsemi Page 1 Copyright 2007 Microwave Products Rev: 2009-11-09 75 Technology Drive, Lowell, MA. 01851, 978-442-5600, Fax: 978-937-3748 www.MICROSEMI.com ELECTRICALS ELECTRICALS UM9989 FAST MRI PROTECTION DIODES TM RoHS Compliant Versions Available ELECTRICAL PARAMETERS 25 C (unless otherwise specified) Parameter Symbol Conditions Min Typ. Max Units I = 10 mA , T = 25 C 1.0 V F J Forward Voltage (Note 1) V F I = 100 mA , T = 25 C 1.2 V F J Reverse Break Down Voltage V I = 100 uA 75 V BR R (Note 1) V = 20 V, T = 25 C 50 nA R J Reverse Current (Note1) I R V = 50 V, T = 25 C 500 nA R J Capacitance C V = 0V, F = 1 MH 1.2 5 pF T R Z Conductance G V = 0 V, F = 64 MHz 40 uS R Note: 1 Short duration test pulse used to minimize self heating effect. Microsemi Page 2 Copyright 2007 Microwave Products Rev: 2009-11-09 75 Technology Drive, Lowell, MA. 01851, 978-442-5600, Fax: 978-937-3748