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Microchip Technology MML4401-GM3/TR
- Part No.:
- MML4401-GM3/TR
- Manufacturer:
- Microchip Technology
- Category:
- RF Diodes
- Package:
- 4-SMD, No Lead
- Datasheet:
-
MML4401-GM3/TR.pdf
- Description:
- SI LIMITER NON HERMETIC PLASTIC
- Quantity:
- Payment:
- Shipping:
Inventory:8,732
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Product details
Overview
MML4401-GM3/TR from Microsemi is a RoHS-compliant fast surface-mount MRI protection diode in anti-parallel unconnected pair configuration, rated for 75 V breakdown voltage, 1.5 pF capacitance at 0 V, 2.5 Ω series resistance at 100 MHz, 10 ns turn-on time, and 40 µs conductance at 64 MHz. It serves as a passive limiter for MRI receiver low-noise amplifiers exposed to high-RF energy fields.
For engineers reviewing the MML4401-GM3/TR datasheet, MML4401-GM3/TR pinout, MML4401-GM3/TR application, or MML4401-GM3/TR equivalent, key selection criteria include RF pulse handling in MRI detuning circuits, low insertion loss under both on/off states, magnetic-free packaging, and compatibility with automatic insertion equipment and 260 °C reflow.
Technical Context
The MML4401-GM3/TR implements an anti-parallel (unconnected) dual-diode topology optimized for passive switching in MRI surface-coil circuits-enabling detuning and blocking without active drivers. Its low 1.5 pF junction capacitance and 2.5 Ω dynamic series resistance minimize signal distortion across 64–100 MHz MRI operating bands.
Designed for operation between –55 °C and +150 °C, it delivers 10 ns typical turn-on latency during RF transmitter pulses and maintains ≤40 µs conductance decay at 64 MHz, ensuring rapid recovery between transmit/receive cycles while preserving LNA noise figure integrity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Breakdown Voltage (VB) | 75 V minimum - ensures reliable clamping against MRI RF transients exceeding 60 V peak. |
| Junction Capacitance (CT0) | 1.5 pF maximum at 0 V - minimizes capacitive loading on MRI receive paths, preserving bandwidth and SNR. |
| Series Resistance (RS) | 2.5 Ω maximum at 100 MHz - limits insertion loss in limiter mode, maintaining LNA noise figure stability. |
| Turn-On Time (tL) | 10 ns typical - enables synchronization with sinc(x)-shaped RF pulses for pre-pulse detuning activation. |
| Conductance Decay (G) | 40 µs maximum at 64 MHz - guarantees full recovery before next receive window, preventing signal blanking. |
| Thermal Resistance (θP) | 20 °C/W maximum - supports continuous operation under pulsed RF power dissipation in compact coil assemblies. |
Pinout & Package
Package: GM3 - low-magnetic, surface-mount, anti-parallel unconnected dual-diode configuration in a 2.515 mm × 2.489 mm × 1.016 mm body (typical), compatible with automated placement and 260 °C lead-free reflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode 1 | First diode anode | Connects to one side of MRI surface-coil loop; forms first half of anti-parallel limiter path. |
| Cathode 1 | First diode cathode | Connects to LNA input; conducts during RF transmit to shunt energy away from sensitive amplifier. |
| Anode 2 | Second diode anode | Electrically isolated from Anode 1; completes anti-parallel symmetry for bidirectional RF limiting. |
| Cathode 2 | Second diode cathode | Electrically isolated from Cathode 1; provides reverse-path conduction during negative RF excursions. |
Key Features
| Feature | Design Value |
|---|---|
| Anti-parallel unconnected pair | Enables bidirectional RF limiting without shared terminals-critical for MRI coil detuning without cross-talk. |
| Low 0 V capacitance (1.5 pF max) | Preserves >95% of MRI receive-band signal integrity by minimizing parasitic coupling into LNA front-end. |
| Passivated silicon die | Ensures long-term reliability in high-humidity MRI gantry environments and repeated thermal cycling. |
| RoHS-compliant & 260 °C reflow rated | Supports modern lead-free manufacturing flow without delamination or parametric shift post-assembly. |
Applications
| MRI Receiver Protection | MRI Surface-Coil Detuning |
|---|---|
Use Scenario: Installed between MRI RF coil and LNA input to protect against high-power transmit pulses. IC Role / Device Role / Timing Role: Passive limiter that clamps transient voltages above 75 V while maintaining sub-2.5 Ω on-state impedance. Use Value: Prevents LNA saturation and permanent damage without degrading receive-band noise figure due to <1.5 pF off-state capacitance. | Use Scenario: Integrated into MRI surface-coil tuning networks to disable resonance during transmit phase. IC Role / Device Role / Timing Role: Self-triggered switch activated by RF loop current-no external driver required. Use Value: Enables precise sinc(x)-sidelobe timing alignment (10 ns turn-on) for artifact-free image acquisition. |
| MRI Blocking Circuits | MRI Coil Disable Circuits |
Use Scenario: Placed in series with MRI coil feed lines to isolate receive electronics during high-power transmission. IC Role / Device Role / Timing Role: Bidirectional RF shunt using anti-parallel topology to absorb forward and reverse pulse energy. Use Value: Eliminates need for active PIN diode drivers and associated control timing circuitry-reducing BOM count and layout complexity. | Use Scenario: Used in multi-coil MRI arrays to selectively disable unused coils during scanning. IC Role / Device Role / Timing Role: Fast-recovery limiter (40 µs conductance decay) enabling rapid enable/disable cycling between sequences. Use Value: Supports dynamic coil selection without residual RF memory effects, improving spatial encoding fidelity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar MRI protection diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UM7201SM | Single PIN diode; higher power handling but requires external bias driver; 0.3 pF capacitance, 0.25 Ω RS. | Used *with* MML4401-GM3/TR in semi-active designs-not standalone replacement. | Select UM7201SM only when higher RF power switching (>10 W) and active control are needed alongside MML4401-GM3/TR. |
| MML4402-GM3 | Same GM3 package; higher 2.0 pF CT0, lower 1.5 Ω RS, 20 ns tL - trade-off between capacitance and on-resistance. | Preferred where lower insertion loss is critical and slightly higher capacitance is acceptable in receive path. | Choose MML4402-GM3 if system-level simulation shows CT0 margin allows 2.0 pF without SNR penalty. |
Compared with UM7201SM and MML4402-GM3, the MML4401-GM3/TR offers the lowest capacitance (1.5 pF) in the GM3 form factor-making it optimal for ultra-sensitive MRI receive chains where even 0.5 pF increase risks measurable SNR degradation.
Availability
MML4401-GM3/TR is available at Aetrix Electronics and suitable for MRI receiver protection, surface-coil detuning, and MRI blocking circuits requiring stable component supply, magnetic-free construction, and RoHS-compliant reflow processing.
Supply support for MML4401-GM3/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 Corporation (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, RF, and timing solutions for aerospace, defense, communications, and medical imaging markets.
The MML4400 series was developed specifically for MRI system manufacturers needing passive, driverless RF protection and detuning components that operate reliably in high-field, high-pulse-density magnetic environments.
FAQ
What is the primary function of the MML4401-GM3/TR in MRI systems?
The MML4401-GM3/TR functions as a passive RF limiter and detuning enabler in MRI systems. It protects low-noise amplifiers from high-power transmit pulses and self-activates during RF coil current flow-eliminating need for external drivers. Its anti-parallel GM3 configuration ensures bidirectional protection while maintaining <1.5 pF off-state capacitance critical for receive-path signal integrity in the MML4401-GM3/TR.
Does the MML4401-GM3/TR require a bias voltage or control signal to operate?
No, the MML4401-GM3/TR operates passively-its diodes turn on solely in response to RF-induced loop current in MRI surface coils. No external bias, driver circuitry, or timing control is needed. This self-triggering behavior is intrinsic to its anti-parallel unconnected pair design and enables simplified, high-reliability MRI coil interface architecture in the MML4401-GM3/TR.
What does "GM3 package" signify for the MML4401-GM3/TR?
The GM3 package denotes a low-magnetic, surface-mount dual-diode housing with anti-parallel (unconnected) terminal arrangement, measuring 2.515 mm × 2.489 mm × 1.016 mm (typical). It is qualified for 260 °C lead-free reflow and designed to avoid magnetic interference in MRI gantries. The GM3 mechanical outline and pin isolation are integral to the MML4401-GM3/TR's role in high-fidelity RF signal paths.
How does the MML4401-GM3/TR differ from the MML4401-GM2 variant?
The MML4401-GM3/TR uses the GM3 package-featuring anti-parallel unconnected diodes-while the MML4401-GM2 uses the GM2 package with a different pinout and single-diode configuration. Both share identical electrical specs (75 V VB, 1.5 pF CT0, 2.5 Ω RS), but only the GM3 version supports true bidirectional passive switching required for advanced MRI detuning topologies in the MML4401-GM3/TR.
Is the MML4401-GM3/TR suitable for 3T and 7T MRI systems?
Yes-the MML4401-GM3/TR is specified for operation up to 150 °C and exhibits stable RF performance at 64 MHz (1.5T), 128 MHz (3T), and 298 MHz (7T) frequencies. Its 10 ns turn-on time and 40 µs conductance decay meet timing requirements across field strengths, and its non-magnetic GM3 package prevents image distortion-making the MML4401-GM3/TR appropriate for clinical and research-grade MRI platforms.
MML4401-GM3/TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 4-SMD, No Lead
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Diode Type:
- PIN - 2 Independent
- Voltage - Peak Reverse (Max):
- 75V
- Current - Max:
- -
- Capacitance @ Vr, F:
- 1.5pF @ 0V, 1MHz
- Resistance @ If, F:
- 2.5Ohm @ 100mA, 100MHz
- Power Dissipation (Max):
- -
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- -
MML4401-GM3/TR FAQ
1.How can I place an order for MML4401-GM3/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for MML4401-GM3/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 MML4401-GM3/TR reliable?
The price and inventory of MML4401-GM3/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MML4401-GM3/TR is usually 5 days.
3.What payment methods are accepted for MML4401-GM3/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MML4401-GM3/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MML4401-GM3/TR?
MML4401-GM3/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MML4401-GM3/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 MML4401-GM3/TR?
For technical support, including MML4401-GM3/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MML4401-GM3/TR requirements.
6.How does Aetrix verify that MML4401-GM3/TR is sourced from the original manufacturer or authorized distributors?
All MML4401-GM3/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 MML4401-GM3/TR meets industry standards.
7.What is the process for return or replacement of MML4401-GM3/TR?
All MML4401-GM3/TR units undergo pre-shipment inspection (PSI). If there is an issue with MML4401-GM3/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 MML4401-GM3/TR part is unused and in its original packaging.
Return procedure for MML4401-GM3/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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