UM9989_09

UM9989 TM ® FAST MRI PROTECTION DIODES RoHS Compliant Versions Available DESCRIPTION The UM9989 diode series was designed to protect MRI receivers from high RF 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 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 application. Receiver protector diodes appear directly across the input port of the receiver. They 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 power present) and the “off” state (receiver power present) so as not to decrease the receiver’s sensitivity. The UM9989 diodes are available in two package configurations for flexibility in design. IMPORTANT: For the most current data, visit our website: www.MICROSEMI.com KEY FEATURES  Available in surface mount package. www.MICROSEMI.com  Metallurgical bond  Planar passivated chip  Ultra Low magnetic construction  Non cavity design  Thermally matched configuration  Low capacitance at 0 V bias  Low conductance at 0 V bias  Compatible with automatic insertion equipment  RoHS Compliant Versions Available1 ABSOLUTE MAXIMUM RATINGS AT 25º C (UNLESS OTHERWISE SPECIFIED) Rating Peak Repetitive Reverse Voltage Working Peak Reverse Voltage DC Blocking Voltage RMS Reverse Voltage Non-Repetitive Peak Forward Surge Current 8.3ms Single half sine wave Storage Temperature Operating Temperature Symbol VRRM VRWM VR V R (RMS) IFSM TSTG TOP Value Unit 75 50 2.5 -65 to +150 -65 to +150 V V A ºC ºC APPLICATIONS/BENEFITS  MRI receiver protection  Body coil isolation THERMAL CHARACTERISTICS (UNLESS OTHERWISE SPECIFIED) Thermal Resistance @ Lead length = 3/8 inches ROLA 100 ºC/Watt Note 1: RoHS compliant versions are supplied with a matte Tin finish. RoHS part numbers are: UMX9989B UMX9989SM UM9989 UM9989 Style “B” Style “SM” Copyright  2007 Rev: 2009-11-09 Microsemi Microwave Products 75 Technology Drive, Lowell, MA. 01851, 978-442-5600, Fax: 978-937-3748 Page 1 UM9989 TM ® FAST MRI PROTECTION DIODES RoHS Compliant Versions Available ELECTRICAL PARAMETERS @ 25C (unless otherwise specified) Parameter Symbol Conditions IF = 10 mA , TJ = 25 ºC IF = 100 mA , TJ = 25 ºC Min Typ. Max 1.0 1.2 Units V V V www.MICROSEMI.com Forward Voltage (Note 1) Reverse Break Down Voltage (Note 1) Reverse Current (Note1) VF VBR IR IR = 100 uA VR = 20 V, TJ = 25 ºC VR = 50 V, TJ = 25 ºC 75 50 500 1.2 5 40 nA nA pF uS Capacitance Conductance CT G VR = 0V, F = 1 MHZ VR = 0 V, F = 64 MHz Note: 1 Short duration test pulse used to minimize self heating effect. ELECTRICALS ELECTRICALS Copyright  2007 Rev: 2009-11-09 Microsemi Microwave Products 75 Technology Drive, Lowell, MA. 01851, 978-442-5600, Fax: 978-937-3748 Page 2 UM9989 TM ® FAST MRI PROTECTION DIODES RoHS Compliant Versions Available VF VS IF CONDUCTANCE VS FREQUENCY www.MICROSEMI.com CAPACITANCE VS FREQUENCY GRAPHS GRAPHS Copyright  2007 Rev: 2009-11-09 Microsemi Microwave Products 75 Technology Drive, Lowell, MA. 01851, 978-442-5600, Fax: 978-937-3748 Page 3 UM9989 TM ® FAST MRI PROTECTION DIODES RoHS Compliant Versions Available UM9989B UM9989SM www.MICROSEMI.com SM STYLE SOLDER FOOTPRINT MECHANICAL MECHANICAL Copyright  2007 Rev: 2009-11-09 Microsemi Microwave Products 75 Technology Drive, Lowell, MA. 01851, 978-442-5600, Fax: 978-937-3748 Page 4