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Analog Devices Inc./Maxim Integrated MAX3768CUB+
- Part No.:
- MAX3768CUB+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Special Purpose Amplifiers
- Package:
- -
- Datasheet:
-
MAX3768CUB+.pdf
- Description:
- IC AMP LIMITING 1.25GBPS 10-UMAX
- Quantity:
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Inventory:1,846
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Product details
Overview
MAX3768CUB+ from Maxim Integrated is a 1.25Gbps PECL-output limiting amplifier designed for optical receiver front-ends in Gigabit Ethernet and Fibre Channel systems. It features +3.0V to +5.5V supply operation, programmable loss-of-signal (LOS) detection via external RTH, 300ps max edge speed, 14ps deterministic jitter, and operates in a 10-pin µMAX-EP package with exposed paddle for thermal management.
For engineers reviewing the MAX3768CUB+ datasheet, MAX3768CUB+ pinout, MAX3768CUB+ application, or MAX3768CUB+ equivalent, key selection criteria include its PECL-compatible output interface, 1.25Gbps data rate, LOS threshold programmability, low deterministic jitter, and suitability for small-form-factor (SFF) optical receivers requiring stable high-speed signal conditioning.
Technical Context
The MAX3768CUB+ implements a multistage limiting amplifier architecture with integrated RMS power detection and offset-correction loop (via CAZ1/CAZ2 pins). Its input buffer provides 100Ω differential impedance and accepts signals from transimpedance amplifiers like MAX3266/MAX3267, while the PECL output stage is terminated to VCC – 2V for optimal signal integrity.
It supports programmable LOS assertion using an external resistor (RTH) on the TH pin, with three threshold levels (low/medium/high) selectable via resistance value. The squelch function is internally enabled (SQUELCH tied to VCC), forcing OUT+ high and OUT– low when input falls below LOS threshold - critical for noise suppression in burst-mode optical links.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Data Rate | 1.25Gbps - supports full-rate Gigabit Ethernet and Fibre Channel 1x operation without oversampling. |
| Deterministic Jitter | 14ps (p-p) - ensures reliable bit-error-rate performance in high-speed serial links with tight timing budgets. |
| Input Voltage Range | 10mV to 1200mV (differential p-p) - accommodates wide dynamic range from optical preamplifiers under varying link conditions. |
| PECL Output Levels | VOH = –0.880V, VOL = –1.620V (referenced to VCC) - meets industry-standard PECL logic thresholds for interoperability with FPGA/CPLD receivers. |
| LOS Hysteresis | 2.5dB to 4.4dB - prevents false toggling during marginal optical signal conditions, improving system robustness. |
| Supply Voltage | +3.0V to +5.5V - enables direct compatibility with common telecom and networking rail voltages including 3.3V and 5V systems. |
| Power Supply Current | 50mA to 76mA (typ.) - balances performance and power efficiency for space-constrained SFF modules. |
Pinout & Package
MAX3768CUB+ is housed in a 10-pin µMAX-EP package (3.0mm × 3.0mm, 0.8mm height) with exposed paddle soldered to PCB ground for thermal dissipation and EMI control.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2 | VCC | Positive supply input - dual VCC pins reduce supply inductance and improve high-frequency PSRR. |
| 3 | IN– | Inverted differential input - forms 100Ω matched pair with IN+ for balanced signal reception. |
| 4 | IN+ | Noninverted differential input - 100Ω input impedance optimized for TIA interfacing. |
| 5 | TH | LOS threshold programming node - sets input voltage level at which LOS asserts via external RTH to GND. |
| 6 | CAZ1 | Offset correction loop capacitor terminal - used with CAZ2 to stabilize DC offset correction time constant. |
| 7, 10 | GND | Ground reference - includes exposed paddle (EP) connected to internal die substrate and thermal path. |
| 8 | LOS | Noninverted loss-of-signal output - TTL-compatible open-collector output asserted high when input drops below threshold. |
| 9 | OUT– | Inverted PECL data output - requires termination to VCC – 2V for proper logic levels and signal integrity. |
| 10 | OUT+ | Noninverted PECL data output - differential pair with OUT– delivers controlled edge speeds up to 300ps. |
Key Features
| Feature | Design Value |
|---|---|
| PECL output interface | Standards-compliant positive-referenced ECL outputs enable direct connection to legacy and FPGA-based receivers without level-shifting. |
| Programmable LOS threshold | Three selectable sensitivity levels (via RTH = 2.5kΩ/7kΩ/20kΩ) allow precise adaptation to optical link budget and receiver sensitivity. |
| Integrated squelch function | Squelch is permanently enabled (SQUELCH internally tied to VCC), eliminating need for external control logic and reducing BOM count. |
| Low deterministic jitter | 14ps p-p jitter ensures minimal eye closure at 1.25Gbps, supporting BER < 10−12 in production optical modules. |
| µMAX-EP package | 10-pin 3×3mm thermally enhanced package enables compact SFF/SFP module designs with superior thermal performance over standard SOIC. |
Applications
| Gigabit Ethernet Optical Receiver | Fibre Channel 1x Receiver |
|---|---|
|
Use Scenario: Front-end signal conditioning in SFP transceivers receiving 1.25Gbps optical data over multimode fiber. IC Role / Device Role / Timing Role: Limiting amplifier that restores signal amplitude and edge fidelity after TIA amplification, providing clean PECL-level data to MAC or PHY ICs. Use Value: Enables reliable 1.25Gbps operation with <14ps deterministic jitter, meeting IEEE 802.3 and FC-PI-2 jitter compliance requirements. |
Use Scenario: Signal recovery in Fibre Channel storage area network (SAN) optical modules operating at 1062.5MBd. IC Role / Device Role / Timing Role: High-gain limiting stage converting low-amplitude TIA output into robust PECL logic for FC framing logic or serializer. Use Value: Programmable LOS threshold adapts to varying optical power budgets across SAN topologies, reducing false disconnect events. |
| Small-Form-Factor (SFF) Transceiver | Optical Interconnect Module |
|
Use Scenario: Space-constrained optical receiver in enterprise switch line cards where board real estate is limited. IC Role / Device Role / Timing Role: Compact 10-pin µMAX-EP limiting amplifier delivering PECL outputs with minimal layout footprint and thermal overhead. Use Value: Exposed paddle design reduces junction-to-board thermal resistance to <40°C/W, enabling continuous operation at 70°C ambient. |
Use Scenario: High-reliability optical backplane interconnect in telecom chassis requiring stable signal regeneration. IC Role / Device Role / Timing Role: Signal integrity conditioner that suppresses baseline wander and maintains duty-cycle stability across temperature. Use Value: Offset correction loop (CAZ1/CAZ2) stabilizes DC operating point, preventing deterministic jitter increase over –40°C to +85°C range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar limiting amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX3268CUB+ | Same 1.25Gbps PECL limiting amplifier, identical pinout and electrical specs; differs only in internal squelch enable state (SQUELCH tied to VCC in MAX3768CUB+, unconnected in MAX3268CUB+). | MAX3268CUB+ requires external TTL-high control for squelch; MAX3768CUB+ provides always-on squelch without external logic. | Select MAX3768CUB+ when automatic squelch activation is required; choose MAX3268CUB+ if squelch must be externally gated. |
| MAX3264CUE+ | 16-pin TSSOP CML-output variant (not PECL); same 1.25Gbps rate and LOS functionality but different output interface and package. | Designed for GBIC-style modules with CML-compatible host interfaces; incompatible with PECL-only receivers without level translation. | Choose MAX3768CUB+ for PECL-native systems and compact SFF layouts; use MAX3264CUE+ only when CML interface and larger TSSOP footprint are acceptable. |
Compared with MAX3268CUB+, MAX3768CUB+ simplifies system design by eliminating external squelch control, while versus MAX3264CUE+, it offers superior board-area efficiency and native PECL compatibility - both critical for next-generation SFP modules.
Availability
MAX3768CUB+ is available at Aetrix Electronics and suitable for Gigabit Ethernet optical receivers, Fibre Channel 1x receivers, and small-form-factor transceivers requiring stable component supply, lead-free compliance, and guaranteed industrial temperature performance.
Supply support for MAX3768CUB+ 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
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog and mixed-signal ICs for communications, computing, and industrial applications.
The MAX3768CUB+ belongs to Maxim's optical receiver front-end product line, engineered specifically for 1.25Gbps PECL-based SFF optical modules where size, jitter, and LOS reliability are critical design constraints.
FAQ
What is the primary function of the MAX3768CUB+ in an optical receiver chain?
The MAX3768CUB+ serves as a limiting amplifier that restores signal amplitude and edge sharpness after the transimpedance amplifier (TIA) stage. It converts low-voltage differential input signals into full-swing PECL logic outputs while providing programmable loss-of-signal detection and built-in squelch functionality - all essential for reliable 1.25Gbps optical data recovery in MAX3768CUB+ based systems.
How does the TH pin on the MAX3768CUB+ configure loss-of-signal detection?
The TH pin on the MAX3768CUB+ sets the input voltage threshold at which the LOS output asserts. An external resistor (RTH) connected from TH to ground determines the sensitivity level: 2.5kΩ yields low-threshold detection (~2.2mV), 7kΩ provides medium threshold (~9.9mV), and 20kΩ enables high-threshold operation (~18.0mV). This allows precise tuning of MAX3768CUB+ behavior to match optical link budget and system noise margin.
Does the MAX3768CUB+ require external components for basic operation?
Yes - the MAX3768CUB+ requires external termination resistors (50Ω to VCC – 2V for PECL outputs), a pull-down resistor on TH for LOS configuration, and optional capacitors on CAZ1/CAZ2 for offset correction loop stabilization. Input coupling capacitors (≥0.01µF) are also recommended to minimize deterministic jitter. These components are mandatory for compliant MAX3768CUB+ operation per the datasheet design guidelines.
What is the significance of the exposed paddle (EP) in the MAX3768CUB+ µMAX package?
The exposed paddle in the MAX3768CUB+ µMAX package is electrically and thermally connected to the internal die substrate and must be soldered to the PCB ground plane. This provides a low-thermal-resistance path (<40°C/W) for heat dissipation and improves high-frequency PSRR and EMI performance - critical for maintaining signal integrity and long-term reliability in densely packed optical modules using MAX3768CUB+.
Can the MAX3768CUB+ be used in place of the MAX3268CUB+ without hardware changes?
No - although MAX3768CUB+ and MAX3268CUB+ share identical pinout, package, and core specifications, their squelch behavior differs: MAX3768CUB+ has SQUELCH internally tied to VCC (always enabled), whereas MAX3268CUB+ leaves SQUELCH unconnected (requires external TTL-high control). Substituting MAX3768CUB+ for MAX3268CUB+ may cause unintended squelching unless the host system expects autonomous LOS-driven muting - verify functional impact before replacement in existing MAX3768CUB+ designs.
MAX3768CUB+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- *
- Package/Case:
- -
- Packaging:
- Product Status:
- Obsolete
- Type:
- -
- Applications:
- -
- Mounting Type:
- -
- Grade:
- -
- Qualification:
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- Supplier Device Package:
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MAX3768CUB+ FAQ
1.How can I place an order for MAX3768CUB+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX3768CUB+ 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 MAX3768CUB+ reliable?
The price and inventory of MAX3768CUB+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX3768CUB+ is usually 5 days.
3.What payment methods are accepted for MAX3768CUB+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX3768CUB+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX3768CUB+?
MAX3768CUB+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX3768CUB+ 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 MAX3768CUB+?
For technical support, including MAX3768CUB+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX3768CUB+ requirements.
6.How does Aetrix verify that MAX3768CUB+ is sourced from the original manufacturer or authorized distributors?
All MAX3768CUB+ 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 MAX3768CUB+ meets industry standards.
7.What is the process for return or replacement of MAX3768CUB+?
All MAX3768CUB+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX3768CUB+, 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 MAX3768CUB+ part is unused and in its original packaging.
Return procedure for MAX3768CUB+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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