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Analog Devices Inc. LT3482EUD#PBF
- Part No.:
- LT3482EUD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3482EUD#PBF.pdf
- Description:
- IC REG BST CHARGE PUMP ADJ 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:424
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Product details
Overview
LT3482EUD#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency current-mode boost DC/DC converter with integrated voltage doubler, designed specifically to bias avalanche photodiodes (APDs) in optical receivers. It delivers up to 90V output from 2.5V–16V input, features a high-side APD current monitor with ±10% accuracy across four decades (250nA–2.5mA), and integrates power switch, Schottky diodes, and compensation. Used in fiber-optic network equipment requiring stable, low-noise high-voltage bias.
For engineers reviewing the LT3482EUD#PBF datasheet, LT3482EUD#PBF pinout, LT3482EUD#PBF application, or LT3482EUD#PBF equivalent, key selection factors include APD current monitoring accuracy, dual switching frequency options (650kHz/1.1MHz), 48V/280mA internal switch rating, 3mm × 3mm QFN package constraints, and CTRL-pin-based output voltage programmability without polarity inversion.
Technical Context
The LT3482EUD#PBF employs constant-frequency current-mode control with an internal 1.235V reference and externally adjustable feedback via the CTRL pin. Its functional block includes a PWM comparator with ramp compensation, error amplifier, 5:1 APD current mirror, and integrated oscillator with fSET-selectable frequencies.
It implements a two-stage topology: primary boost stage (VOUT1) plus charge-pump voltage doubler (VOUT2/PUMP) enabling 90V output. The high-side MONIN/MON interface supports direct APD current sensing with 11.5V clamped output and <5V voltage drop at 1mA, while maintaining input ripple-free operation via inductor-based architecture.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Up to 90V - enables biasing of high-gain APDs in long-haul fiber receivers. |
| Input Voltage Range | 2.5V to 16V - supports single-cell Li-ion, 3.3V/5V/12V rails without pre-regulation. |
| Switch Rating | 48V VCE(SAT), 280mA limit - handles peak currents for APD loads up to 2.5mA with margin. |
| Switching Frequency | 650kHz or 1.1MHz - selectable via fSET pin; higher frequency reduces inductor/capacitor size. |
| APD Current Monitor Accuracy | ±10% over –40°C to 85°C, 250nA–2.5mA range - ensures reliable closed-loop APD gain control. |
| Feedback Reference | 1.235V (internal) or 0–1.2V (external via CTRL) - allows digital or analog output voltage adjustment. |
| Shutdown Current | <1µA - preserves battery life in portable optical modules during sleep mode. |
Pinout & Package
LT3482EUD#PBF is housed in a 3mm × 3mm, 16-lead plastic QFN package with exposed thermal pad (Pin 17 = GND). The package supports high-density optical module layouts and requires soldering of the exposed pad for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| APD (Pin 2) | APD Cathode Connection | High-side node for avalanche photodiode cathode; rated to 90V. |
| MONIN (Pin 3) | Monitor Supply Input | Accepts up to 90V supply for current mirror; enables low-pass filtering of supply noise. |
| VOUT2 (Pin 4) | Voltage Doubler Output | Second-stage output; forms charge pump with PUMP and external capacitor to reach 90V. |
| VOUT1 (Pin 5) | Primary Boost Output | Main 48V-capable output; used directly for ≤45V APD bias or as doubler input. |
| PUMP (Pin 6) | Charge Pump Terminal | Connects flying capacitor to complete voltage-doubling path with internal Schottky diodes. |
| SW (Pins 7, 8) | Power Switch Node | Drains internal 280mA NPN switch; requires short, low-inductance PCB trace for EMI control. |
| GND (Pins 9, 10) | Ground Return | Dual ground pins internally connected; both must tie to low-impedance PCB ground plane. |
| VIN (Pin 11) | Input Supply | 2.5V–16V input; requires local 1µF ceramic bypass capacitor placed adjacent to pin. |
| SHDN (Pin 12) | Enable/Soft-Start Control | Logic-high (>1.5V) enables device; ramping voltage between 1.5V–2V controls soft-start timing. |
| CTRL (Pin 13) | Reference Override | Sets FB threshold from 0V to 1.2V; enables real-time APD voltage tuning without polarity inversion. |
| FB (Pin 14) | Feedback Input | Compares resistor-divider output against CTRL or internal 1.235V reference for regulation. |
| fSET (Pin 15) | Frequency Selection | GND = 650kHz; >1.5V = 1.1MHz - selects trade-off between size and efficiency. |
| MON (Pin 16) | Current Monitor Output | Sources 20% of APD current (IMON = 0.2 × IAPD); converts to voltage via external RMON. |
| Exposed Pad (Pin 17) | Thermal & Electrical GND | Mandatory solder connection to PCB ground plane for thermal dissipation and noise reduction. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Schottky Diodes | Eliminates 2 external diodes in boost + charge-pump path, reducing BOM count and footprint. |
| High-Side APD Current Monitor | Delivers 20% mirrored current with ±10% accuracy over 4-decade dynamic range - enables precise optical gain calibration. |
| Adjustable Output Voltage | CTRL pin accepts 0–1.2V reference to set FB threshold, allowing analog/digital programming of APD bias without signal inversion. |
| Low Shutdown Current | <1µA quiescent draw in shutdown - critical for battery-powered optical transceivers needing extended standby time. |
| Internal Compensation | Reduces external component count; eliminates need for external compensation network in standard configurations. |
| Soft-Start via SHDN Pin | Gradual enable via controlled SHDN voltage ramp prevents inrush current spikes into output capacitors. |
Applications
| Optical Receiver Biasing | PIN Diode Bias Supply |
|---|---|
|
Use Scenario: Providing stable, low-noise 70–90V bias to APDs in SFP+ and XFP optical transceivers operating at 10Gbps. IC Role / Device Role / Timing Role: Primary high-voltage DC/DC converter with integrated current monitoring for closed-loop gain control. Use Value: ±10% APD current measurement accuracy enables automatic gain control (AGC) within 0.5dB tolerance across temperature and aging. |
Use Scenario: Generating 30–60V bias for PIN photodiodes in passive optical network (PON) ONT front-ends. IC Role / Device Role / Timing Role: Compact boost converter delivering regulated high voltage with minimal external components. Use Value: Integrated Schottky diodes and 3mm × 3mm QFN reduce solution size by >40% vs discrete alternatives. |
| Fiber Optic Line Cards | Test & Measurement Photodetectors |
|
Use Scenario: Multi-channel APD bias on DWDM line cards where board space and thermal density are constrained. IC Role / Device Role / Timing Role: High-efficiency (≥60% at 2mA) boost converter with predictable 650kHz/1.1MHz switching noise for EMI filtering. Use Value: Constant-frequency operation simplifies output filtering; voltage-doubler architecture avoids need for ultra-high-VOUT magnetics. |
Use Scenario: Lab-grade photodetector modules requiring calibrated, low-drift APD bias with real-time current readback. IC Role / Device Role / Timing Role: Precision current-sensing power supply with MON pin output referenced to system ground. Use Value: MON pin's 11.5V clamp and open-circuit protection prevent damage during probe disconnect or load fault events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar APD bias converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3461AEDD#PBF | Lower max output (38V), no voltage doubler, no APD current monitor, 1.3MHz only. | Suitable for PIN diodes or low-voltage APDs; lacks closed-loop bias control capability. | Select when output ≤38V suffices and current monitoring is handled externally. |
| LT3573EDE#PBF | Higher switch rating (60V/500mA), no integrated APD monitor, supports SEPIC/boost, 2.2MHz. | Used in multi-rail optical modules needing higher current or non-inverting topologies; requires external sensing. | Choose for designs needing >2.5mA APD drive or dual-output flexibility, accepting added sensing complexity. |
Compared with LT3482EUD#PBF, LT3461AEDD#PBF offers smaller size but sacrifices 90V capability and integrated monitoring; LT3573EDE#PBF provides higher current headroom and frequency but adds design overhead for APD current feedback implementation.
Availability
LT3482EUD#PBF is available at Aetrix Electronics and suitable for optical receiver biasing, fiber optic network equipment, PIN diode biasing, and test & measurement photodetector systems requiring stable component supply, long-lifecycle support, and consistent parametric performance.
Supply support for LT3482EUD#PBF 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
Analog Devices acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for legacy Linear parts including the LT3482 series.
The LT3482 belongs to Linear's precision high-voltage DC/DC converter family, engineered specifically for optical sensing applications demanding accurate, low-noise APD bias with integrated current monitoring and compact packaging.
FAQ
What is the maximum output voltage achievable with the LT3482EUD#PBF?
The LT3482EUD#PBF supports up to 90V output using its integrated voltage doubler architecture-combining the primary boost stage (VOUT1) and charge-pump stage (VOUT2/PUMP). This is confirmed in the Absolute Maximum Ratings table and typical application circuits (e.g., Figure 3482 TA01a showing 85V at 2.5mA). Operation beyond 90V risks violating absolute maximum limits and is not supported.
How does the APD current monitor on the LT3482EUD#PBF achieve ±10% accuracy across temperature?
The LT3482EUD#PBF achieves ±10% APD current monitor accuracy over –40°C to 85°C through a trimmed 5:1 current mirror with on-chip temperature compensation and a MONIN supply range of 10V–90V. Electrical Characteristics tables specify this accuracy applies across the full dynamic range (250nA–2.5mA) and is validated in Typical Performance Characteristics (Figure 3482 G05/G06).
Can the LT3482EUD#PBF operate without external compensation components?
Yes, the LT3482EUD#PBF includes internal compensation, eliminating the need for external Type-II or Type-III compensation networks in standard configurations. This is explicitly stated in the FEATURES list and verified in the Functional Diagram (Block "CONTROL BLOCK") and Application Information section on internal compensation.
What is the role of the CTRL pin in the LT3482EUD#PBF, and how does it affect regulation?
The CTRL pin on the LT3482EUD#PBF overrides the internal 1.235V reference, allowing the FB pin threshold to be set between 0V and 1.2V. When CTRL is held >1.5V (e.g., tied to VIN), the internal reference is used; when CTRL is 0–1.2V, the output regulates so that FB = CTRL. This enables real-time APD voltage adjustment without signal inversion, as confirmed in the Functional Description and Application Information sections.
Is the LT3482EUD#PBF pin-compatible with other variants like LT3482IUD#PBF?
Yes, the LT3482EUD#PBF is pin-compatible with LT3482IUD#PBF and all other UD-package variants (e.g., LT3482EUD#TRPBF). They share identical 16-lead QFN (3mm × 3mm) footprints, pinout, and electrical functionality-the only difference is operating temperature grade (0°C–85°C for E-grade vs –40°C–125°C for I-grade), per the ORDER INFORMATION table.
LT3482EUD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost, Charge Pump
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- 90V
- Current - Output:
- 280mA (Switch)
- Frequency - Switching:
- 650kHz ~ 1.1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LT3482EUD#PBF FAQ
1.How can I place an order for LT3482EUD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3482EUD#PBF 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 LT3482EUD#PBF reliable?
The price and inventory of LT3482EUD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3482EUD#PBF is usually 5 days.
3.What payment methods are accepted for LT3482EUD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3482EUD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3482EUD#PBF?
LT3482EUD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3482EUD#PBF 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 LT3482EUD#PBF?
For technical support, including LT3482EUD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3482EUD#PBF requirements.
6.How does Aetrix verify that LT3482EUD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3482EUD#PBF 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 LT3482EUD#PBF meets industry standards.
7.What is the process for return or replacement of LT3482EUD#PBF?
All LT3482EUD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3482EUD#PBF, 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 LT3482EUD#PBF part is unused and in its original packaging.
Return procedure for LT3482EUD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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