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Analog Devices Inc. LT3571IUD#TRPBF
- Part No.:
- LT3571IUD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3571IUD#TRPBF.pdf
- Description:
- IC REG BOOST ADJ 370MA 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:12,439
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Product details
Overview
LT3571IUD#TRPBF from Analog Devices (acquired Linear Technology) is a 75V current-mode step-up DC/DC converter optimized for avalanche photodiode (APD) biasing in optical receivers. It integrates a 75V/370mA power switch, Schottky diode, and high-side APD current monitor with ±10% accuracy over 250nA–2.5mA dynamic range. It supports constant-voltage or constant-current regulation via dual feedback loops and operates from 2.7V to 20V input.
For engineers reviewing the LT3571IUD#TRPBF datasheet, LT3571IUD#TRPBF pinout, LT3571IUD#TRPBF application, or LT3571IUD#TRPBF equivalent, key selection criteria include APD current monitoring accuracy, programmable output voltage up to 75V, adjustable switching frequency (250kHz–2MHz), integrated protection features, and QFN-16 thermal performance in optical module designs.
Technical Context
The LT3571IUD#TRPBF employs a constant-frequency current-mode control architecture with dual-loop regulation: a voltage loop (FB pin, 1V reference) and a unique current loop (MONIN–APD sensing). The APD current mirror delivers 20% of IAPD at MON pin with fixed 5V voltage drop (VMONIN – VAPD) and 11.5V output clamp.
It uses internal soft-start, programmable frequency via RT resistor or external SYNC signal, and supports digitally adjusted output via CTRL pin (0–1V override). The integrated Schottky diode and high-side current sense amplifier eliminate external components while maintaining low-noise APD biasing with <100ns transient response on rising/falling edges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | Up to 75V - enables direct biasing of high-voltage APDs without external boost stages. |
| Switch Rating | 75V / 370mA - supports high-voltage, moderate-current APD loads with integrated MOSFET. |
| APD Current Monitor Accuracy | ±10% over –40°C to 125°C - ensures stable optical receiver gain calibration across industrial temperature range. |
| Switching Frequency Range | 250kHz to 2MHz - allows EMI optimization and compact magnetics selection (e.g., 10–22μH inductors). |
| Input Voltage Range | 2.7V to 20V - compatible with single-cell Li-ion, USB, and intermediate rail supplies. |
| Feedback Reference | 1.00V ±1.5% (TYP) - sets precise output voltage via resistor divider; adjustable down to 0V using CTRL pin. |
| Shutdown Current | <1μA - enables ultra-low-power standby in battery-operated optical modules. |
Pinout & Package
LT3571IUD#TRPBF is housed in a thermally enhanced 3mm × 3mm, 16-lead plastic QFN package (UD) with exposed pad (Pin 17) soldered to PCB ground for optimal thermal dissipation (θJA = 68°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| APD (Pin 2) | APD cathode connection | High-side APD return path; accepts up to 75V; fixed 5V voltage drop relative to MONIN. |
| MONIN (Pin 3) | Current monitor supply & sense input | Serves as inverting input of current-sense amp; connects to VOUT via RSENSE to set APD current limit (200mV/RSENSE). |
| VOUT (Pin 4) | Boost output & current-sense non-inverting input | Delivers regulated high-voltage output; also provides reference for current-sense amplifier. |
| SW (Pins 5,6) | Power switch node | Drives external inductor; requires minimal trace length to reduce EMI and switching losses. |
| GND (Pins 7,10) | Ground reference | Dual GND pins internally connected; both must be tied to low-impedance PCB ground plane. |
| SYNC (Pin 8) | Frequency synchronization input | Accepts external clock; RT resistor must be set for 20% lower free-running frequency to ensure lock. |
| RT (Pin 9) | Frequency programming | Resistor-to-GND sets switching frequency (e.g., 12.1kΩ = 1MHz); open-circuit prohibited. |
| VIN (Pin 11) | Main input supply | 2.7V–20V input; requires local 1μF ceramic bypass capacitor placed adjacent to pin. |
| SHDN (Pin 12) | Enable/disable & soft-start control | Logic-high (>1.5V) enables; RC filter on this pin controls startup ramp rate and inrush management. |
| VREF (Pin 13) | 1.222V precision reference output | Supplies up to 100μA; used for CTRL biasing or external circuitry; requires ≥10nF bypass. |
| CTRL (Pin 14) | Feedback reference override | 0–1V input adjusts FB threshold dynamically; >1.2V selects internal 1V reference. |
| FB (Pin 15) | Voltage feedback input | Regulates output by comparing divider tap to CTRL or internal 1V reference; bias current ≤100nA. |
| MON (Pin 16) | APD current monitor output | Sources 0.2×IAPD; requires external resistor to convert to voltage; clamped at 11.5V. |
| NC (Pin 1) | No connect | Unbonded; must remain floating per datasheet. |
| Exposed Pad (Pin 17) | Thermal & electrical ground | Mandatory solder connection to PCB ground plane for thermal management and noise reduction. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated APD current monitor | Fixed 5V voltage drop (VMONIN–VAPD) with ±10% accuracy over 4-decade dynamic range (250nA–2.5mA). |
| Dual-loop regulation | Simultaneous constant-voltage (via FB/CTRL) and constant-current (via MONIN–APD sense) operation with seamless mode transition. |
| Programmable switching frequency | 250kHz–2MHz via RT resistor or SYNC pin - enables EMI shaping and layout optimization for sensitive optical front-ends. |
| Low-noise APD biasing | Inductor-based topology isolates input from switching noise; 0.1μF capacitor at APD pin suppresses high-frequency ripple. |
| Robust protection suite | Programmable current limit, internal soft-start, shutdown current <1μA, and MON output clamp at 11.5V. |
Applications
| Optical Receiver Biasing | Fiber Optic Transceiver Modules |
|---|---|
|
Use Scenario: Providing stable, low-noise high-voltage bias to APDs in 10G/25G SFP+ and QSFP transceivers. IC Role / Device Role / Timing Role: Primary APD bias generator with integrated current monitoring for real-time gain control. Use Value: Eliminates discrete high-voltage charge pumps and external current sense amplifiers, reducing BOM count by ≥4 components. |
Use Scenario: Generating programmable 45–75V bias in pluggable optical modules compliant with SFF-8472 and CMIS standards. IC Role / Device Role / Timing Role: Digitally adjustable APD supply with CTRL-pin interface for host MCU-controlled bias tuning. Use Value: Enables closed-loop bias compensation via MON output, improving bit-error-rate stability over temperature and aging. |
| PIN Diode Bias Supply | Industrial Laser Detection Systems |
|
Use Scenario: Biasing PIN photodiodes in LIDAR receivers and optical time-domain reflectometers (OTDR). IC Role / Device Role / Timing Role: High-efficiency step-up converter delivering 30–50V at sub-mA currents with fast transient response. Use Value: Achieves <100ns current monitor rise/fall time, enabling accurate pulse-width discrimination in time-of-flight measurements. |
Use Scenario: Powering APDs in ruggedized fiber-optic sensors deployed in oil/gas downhole monitoring or factory automation. IC Role / Device Role / Timing Role: Industrial-grade DC/DC converter rated for –40°C to 125°C junction temperature with robust ESD and latch-up immunity. Use Value: Guaranteed performance over full temperature range eliminates need for external calibration or derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar APD bias converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3482EUD#TRPBF | Lower max output (48V/90V dual-output), no integrated Schottky, 3mm × 3mm QFN | Designed for dual-rail APD/PIN bias; lacks LT3571IUD#TRPBF's single-rail 75V capability and MONIN–APD fixed-drop architecture | Select when dual-output bias or higher efficiency at <40V is required; not drop-in for 75V single-rail designs. |
| LTC3873EMS#TRPBF | External MOSFET controller (no integrated switch), supports >100V outputs, 2-phase capable | Targets high-power, multi-APD arrays; requires external high-voltage FET and Schottky; larger solution size | Choose for >75V or >500mA APD bias where thermal headroom and scalability outweigh integration benefits. |
Compared with LT3482EUD#TRPBF and LTC3873EMS#TRPBF, the LT3571IUD#TRPBF delivers superior integration for single-rail 75V APD biasing-reducing component count, PCB area, and design validation effort-while maintaining ±10% current monitoring accuracy critical for optical gain stability.
Availability
LT3571IUD#TRPBF is available at Aetrix Electronics and suitable for optical transceivers, fiber network equipment, LIDAR receivers, and industrial laser detection systems requiring stable component supply and guaranteed long-term availability.
Supply support for LT3571IUD#TRPBF 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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, formed through the acquisition of Linear Technology in 2017.
The LT3571IUD#TRPBF belongs to ADI's precision power conversion portfolio, designed specifically for low-noise, high-voltage biasing of photodetectors in optical communication and sensing applications.
FAQ
What is the maximum output voltage supported by the LT3571IUD#TRPBF?
The LT3571IUD#TRPBF supports an absolute maximum output voltage of 75V, with typical operation up to 70V as specified in its features list. This rating applies to both VOUT and APD pins, enabling direct biasing of high-gain avalanche photodiodes without cascaded converters. Operation beyond 70V requires careful thermal and layout design due to increased switching losses and voltage stress on internal components.
How does the APD current monitor in the LT3571IUD#TRPBF achieve ±10% accuracy?
The LT3571IUD#TRPBF achieves ±10% APD current monitoring accuracy through a dedicated high-side current mirror with fixed 5V voltage drop (VMONIN – VAPD) and trimmed gain. Its error is characterized over the full –40°C to 125°C temperature range and across four decades of input current (250nA to 2.5mA), with MON output clamped at 11.5V to prevent saturation. No external calibration is required.
Can the LT3571IUD#TRPBF operate in constant-current mode only?
Yes, the LT3571IUD#TRPBF can operate exclusively in constant-current mode by configuring the feedback network to prioritize the current loop. When the MONIN–APD sense voltage dominates the error amplifier input over the FB voltage, the device regulates APD current regardless of output voltage. This behavior is inherent to its dual-loop architecture and does not require external circuitry.
What is the purpose of the CTRL pin on the LT3571IUD#TRPBF?
The CTRL pin on the LT3571IUD#TRPBF allows dynamic adjustment of the FB reference voltage between 0V and 1V, enabling real-time programming of the output voltage without polarity inversion. When CTRL is held above 1.2V (e.g., tied to VREF), the internal 1V reference is used. This feature supports digital bias tuning in optical modules via MCU DAC output or temperature-compensation networks.
Is the LT3571IUD#TRPBF pin-compatible with other Linear Technology QFN-16 DC/DC converters?
No, the LT3571IUD#TRPBF has a unique pinout optimized for APD biasing-including dedicated APD, MONIN, and MON pins-not shared with general-purpose boost converters like LT3461 or LT1930. Pin mapping, function allocation, and internal routing differ significantly; PCB redesign is required for substitution.
LT3571IUD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 20V
- Voltage - Output (Min/Fixed):
- 2.7V
- Voltage - Output (Max):
- 75V (Switch)
- Current - Output:
- 370mA (Switch)
- Frequency - Switching:
- 250kHz ~ 2MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LT3571IUD#TRPBF FAQ
1.How can I place an order for LT3571IUD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3571IUD#TRPBF 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 LT3571IUD#TRPBF reliable?
The price and inventory of LT3571IUD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3571IUD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3571IUD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3571IUD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3571IUD#TRPBF?
LT3571IUD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3571IUD#TRPBF 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 LT3571IUD#TRPBF?
For technical support, including LT3571IUD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3571IUD#TRPBF requirements.
6.How does Aetrix verify that LT3571IUD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3571IUD#TRPBF 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 LT3571IUD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3571IUD#TRPBF?
All LT3571IUD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3571IUD#TRPBF, 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 LT3571IUD#TRPBF part is unused and in its original packaging.
Return procedure for LT3571IUD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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