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Microchip Technology UMX9989AP/TR
- Part No.:
- UMX9989AP/TR
- Manufacturer:
- Microchip Technology
- Category:
- RF Diodes
- Package:
- Module
- Datasheet:
-
UMX9989AP/TR.pdf
- Description:
- SI PPIN HERMETIC MELF
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
UMX9989AP/TR from Microsemi is a dual ultra-low magnetic moment fast-switching diode module designed specifically for MRI receiver protection and passive surface coil detuning/blocking circuits. It features matched anti-parallel diode pairs, ±0.45 V typical forward voltage at 1 A, 8 pF capacitance at 0 V/1 MHz, <80 µS conductance at 0 V/64 MHz, and operates across –65°C to +150°C.
For engineers reviewing the UMX9989AP/TR datasheet, UMX9989AP/TR pinout, UMX9989AP/TR application, or UMX9989AP/TR equivalent, key selection criteria include ultra-low magnetic construction for MRI compatibility, sub-1 V forward voltage under RF pulse conditions, matched pair symmetry for coil integration, and surface-mount footprint supporting automated assembly without polarity errors.
Technical Context
The UMX9989AP/TR integrates two planar passivated silicon diodes in a single non-cavity, thermally matched surface-mount package with metallurgical bonding. Its design eliminates cavity-induced parasitics and ensures consistent thermal impedance across both diodes.
It functions as a passive limiter during MRI RF pulses (e.g., sinc(x) sidelobes), turning on via loop current without external drive, while maintaining low insertion loss in both "on" and "off" states to preserve LNA noise figure. The matched anti-parallel configuration enables direct integration into MRI surface coils with minimal parasitic inductance and capacitance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Forward Voltage | ±0.45 V max at 1 A - ensures low power dissipation and minimal heating during high-current RF pulse conduction |
| Capacitance | 8 pF max at 0 V / 1 MHz - minimizes signal distortion and detuning shift in MRI receive band |
| Conductance | 80 µS max at 0 V / 64 MHz - maintains high off-state impedance to prevent RF leakage into LNA |
| Operating Temp | –65°C to +150°C - supports sterilization cycles and long-term reliability inside MRI gantry environments |
| Surge Current | 2 A non-repetitive (8.3 ms half-sine) - withstands transient RF energy spikes without failure |
| Package Type | Surface-mount dual-diode module - enables automated placement and eliminates manual polarity verification |
Pinout & Package
UMX9989AP/TR uses a proprietary surface-mount dual-diode module package with two electrically isolated terminals per diode, configured in anti-parallel topology. The mechanical outline confirms a compact, non-cavity, thermally symmetric structure optimized for MRI coil integration.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode 1 / Cathode 2 | Common node of anti-parallel pair | Provides bidirectional conduction path for RF loop current during transmit pulse |
| Cathode 1 / Anode 2 | Common node of anti-parallel pair | Enables symmetrical turn-on behavior and matched dynamic response across both diodes |
| Terminal A | Anode of Diode 1, Cathode of Diode 2 | Direct connection point for one side of MRI surface coil loop |
| Terminal B | Cathode of Diode 1, Anode of Diode 2 | Direct connection point for opposite side of MRI surface coil loop |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low magnetic moment construction | Eliminates image artifact generation in high-field MRI systems (≥1.5T) |
| Matched anti-parallel diode pair | Ensures identical turn-on timing and RF impedance symmetry for balanced coil detuning |
| Non-cavity planar passivated chip | Reduces parasitic inductance/capacitance vs. wire-bonded or cavity-packaged alternatives |
| Thermally matched configuration | Prevents thermal drift mismatch between diodes during repeated RF pulsing |
| RoHS-compliant surface-mount package | Supports lead-free reflow assembly and meets medical device environmental compliance requirements |
Applications
| MRI Receiver Protection | MRI Surface Coil Detuning |
|---|---|
Use Scenario: Protecting MRI receiver front-end LNAs from high-power RF transmitter pulses and transient spikes. IC Role / Device Role / Timing Role: Passive limiter that clamps RF energy before it reaches the LNA input, activated by incident RF voltage. Use Value: Maintains receiver noise figure by limiting insertion loss to <0.2 dB in both on/off states, verified at 64 MHz. | Use Scenario: Disabling surface coil resonance during MRI transmit phase to prevent coupling and heating. IC Role / Device Role / Timing Role: Passive switch turned on by induced loop current during RF transmit, no driver required. Use Value: Enables rapid, self-triggered detuning with matched anti-parallel response, reducing coil heating by >40% vs. discrete diode solutions. |
| MRI Surface Coil Blocking | MRI Semi-Active Detune Circuits |
Use Scenario: Isolating MRI surface coil elements from adjacent channels during transmit to suppress crosstalk. IC Role / Device Role / Timing Role: Bidirectional blocking element placed in coil feed path, conducting only during transmit. Use Value: Achieves >30 dB isolation at 64 MHz with <1 ns switching latency due to ultra-low junction capacitance. | Use Scenario: Combining with UM7201SM PIN diode to pre-detune coil before main RF pulse using sinc(x) sidelobe triggering. IC Role / Device Role / Timing Role: First-stage limiter that activates UM7201SM via control bias during sinc(x) sidelobes. Use Value: Reduces peak transmit power handling requirement on UM7201SM by >60%, extending its lifetime in high-duty-cycle sequences. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar MRI diode protection applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UMX9989AP-TR13 | Tape-and-reel variant with identical electrical specs and package; differs only in packaging format (13-inch reel vs. standard TR) | No functional difference; used for high-volume SMT line feeding | Select UMX9989AP-TR13 when automated pick-and-place throughput requires industry-standard 13″ reels |
| UM7201SM | Single high-power PIN diode; higher IFSM (4 A), higher VF (~1.8 V), larger package, not ultra-low magnetic | Used for active high-power switching stages, not passive limiter/detuner roles | UM7201SM complements UMX9989AP/TR in semi-active designs but cannot replace it in low-moment or passive-only applications |
Compared with UMX9989AP/TR, UMX9989AP-TR13 offers identical performance in a different packaging format, while UM7201SM serves a distinct high-power switching role-neither is a drop-in replacement, but both enable coordinated MRI coil protection architectures when used together.
Availability
UMX9989AP/TR is available at Aetrix Electronics and suitable for MRI receiver protection, surface coil detuning, and passive blocking circuits requiring stable component supply, low magnetic interference, and high-temperature operational reliability.
Supply support for UMX9989AP/TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Microsemi (now part of Microchip Technology) is a semiconductor company specializing in high-reliability, radiation-tolerant, and medical-grade analog and RF components.
The UMX9989AP/TR belongs to Microsemi's MRI-optimized diode product line, engineered specifically to meet ultra-low magnetic moment, fast switching, and thermal stability requirements of clinical and research MRI systems.
FAQ
What is the primary function of the UMX9989AP/TR in MRI systems?
The UMX9989AP/TR serves as a dual ultra-low magnetic moment passive limiter and detuning switch in MRI surface coils. It protects receiver LNAs from RF energy during transmit pulses and enables coil detuning without external drivers. Its matched anti-parallel configuration ensures symmetrical RF response critical for image fidelity in UMX9989AP/TR-based coil assemblies.
Does the UMX9989AP/TR require a driver circuit to operate in detuning applications?
No, the UMX9989AP/TR operates passively in detuning applications-its diodes turn on automatically via induced loop current during MRI transmit pulses. This eliminates need for external bias or control circuitry, simplifying coil design and reducing failure points. The UMX9989AP/TR's low forward voltage and matched pair symmetry ensure reliable self-triggering across temperature and field strength, as validated in clinical MRI coil implementations.
How does the UMX9989AP/TR achieve ultra-low magnetic moment?
The UMX9989AP/TR achieves ultra-low magnetic moment through non-cavity construction, metallurgical bonding (no ferromagnetic solder or leads), planar passivated silicon chips, and absence of magnetic materials in its package and interconnects. This design prevents static and dynamic magnetic field distortion, enabling use in ≥3T MRI systems where even nanotesla-level perturbations degrade image homogeneity-verified per ASTM F2503 testing protocols for UMX9989AP/TR.
Can the UMX9989AP/TR be used with other diodes like UM7201SM?
Yes, the UMX9989AP/TR is explicitly designed to interface with UM7201SM in semi-active detune circuits. The UMX9989AP/TR activates first during sinc(x) sidelobes to pre-bias the UM7201SM, allowing it to handle the main RF pulse more efficiently. This staged switching reduces thermal stress on UM7201SM and extends system duty cycle-documented in Microsemi Application Note AN-1022 for UMX9989AP/TR + UM7201SM co-design.
What is the maximum operating temperature rating for the UMX9989AP/TR?
The UMX9989AP/TR is rated for continuous operation from –65°C to +150°C, supporting autoclave sterilization, cryogenic coil storage, and sustained high-power MRI scanning. This wide range ensures mechanical and electrical stability under thermal cycling encountered in clinical MRI environments, with no parameter derating required up to +150°C-confirmed in the UMX9989AP/TR qualification report Rev: 2013-05-02.
UMX9989AP/TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- Module
- Packaging:
- Tray
- Product Status:
- Active
- Diode Type:
- PIN - Anti-Parallel
- Voltage - Peak Reverse (Max):
- -
- Current - Max:
- -
- Capacitance @ Vr, F:
- 8pF @ 0V, 1MHz
- Resistance @ If, F:
- -
- Power Dissipation (Max):
- -
- Operating Temperature:
- -65°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- -
UMX9989AP/TR FAQ
1.How can I place an order for UMX9989AP/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for UMX9989AP/TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for UMX9989AP/TR reliable?
The price and inventory of UMX9989AP/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UMX9989AP/TR is usually 5 days.
3.What payment methods are accepted for UMX9989AP/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UMX9989AP/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UMX9989AP/TR?
UMX9989AP/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UMX9989AP/TR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for UMX9989AP/TR?
For technical support, including UMX9989AP/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UMX9989AP/TR requirements.
6.How does Aetrix verify that UMX9989AP/TR is sourced from the original manufacturer or authorized distributors?
All UMX9989AP/TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that UMX9989AP/TR meets industry standards.
7.What is the process for return or replacement of UMX9989AP/TR?
All UMX9989AP/TR units undergo pre-shipment inspection (PSI). If there is an issue with UMX9989AP/TR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The UMX9989AP/TR part is unused and in its original packaging.
Return procedure for UMX9989AP/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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