My Inquiry
My Account
Analog Devices Inc. LT3571EUD#PBF
- Part No.:
- LT3571EUD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3571EUD#PBF.pdf
- Description:
- IC REG BOOST ADJ 370MA 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,259
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3571EUD#PBF from Analog Devices (acquired Linear Technology) is a current-mode step-up DC/DC converter IC designed specifically for avalanche photodiode (APD) biasing in optical receivers, delivering up to 75V output with integrated 370mA switch, high-side APD current monitor (±10% accuracy over –40°C to 125°C), and constant-current/constant-voltage dual-loop regulation.
For engineers reviewing the LT3571EUD#PBF datasheet, LT3571EUD#PBF pinout, LT3571EUD#PBF application, or LT3571EUD#PBF equivalent, this page provides verified technical context, validated pin functions, confirmed APD biasing specifications, and real-world design constraints including 5V APD voltage drop, 250kHz–2MHz adjustable switching frequency, and QFN-16 thermal performance data.
Technical Context
The LT3571EUD#PBF implements a constant-frequency current-mode control architecture with dual feedback loops: a voltage loop (FB pin, 1V reference) and a dedicated high-side current loop (MONIN–APD sensing). It transitions seamlessly between constant-voltage and constant-current modes based on which loop dominates at the error amplifier input.
Its integrated 75V/370mA power switch, on-chip Schottky diode, and fixed 5V voltage-drop APD current monitor (VMONIN – VAPD = 5.0V ±0.2V) enable compact, low-noise APD bias supplies. The CTRL pin allows real-time output voltage adjustment (0–1V FB setpoint) without polarity inversion, supporting digitally programmable bias tuning.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | Up to 75V - supports high-gain APDs requiring >60V reverse bias in fiber optic receivers. |
| Switch Current Limit | 370mA typical - sets maximum APD drive capability; programmable via RSENSE across VOUT/MONIN. |
| APD Monitor Accuracy | ±10% over –40°C to 125°C - enables stable photocurrent measurement across industrial temperature range. |
| Switching Frequency | 250kHz to 2MHz - adjustable via RT resistor or external SYNC clock; avoids EMI-sensitive bands. |
| Input Voltage Range | 2.7V to 20V - compatible with single-cell Li-ion, USB, or industrial 5V/12V rails. |
| Feedback Reference | 1.000V ±15mV - precise voltage regulation baseline; overridden by CTRL pin (0–1V range). |
| APD Voltage Drop | 5.00V ±0.20V - fixed high-side sense offset enabling accurate IAPD monitoring independent of VOUT. |
Pinout & Package
LT3571EUD#PBF is housed in a thermally enhanced 16-lead 3mm × 3mm plastic QFN package (UD) with exposed pad (Pin 17) soldered to PCB ground for optimal thermal dissipation (θJC = 4.2°C/W). The package complies with JEDEC MO-220 WEED-2 outline and supports reflow-compatible lead-free assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| APD (Pin 2) | APD cathode connection node | High-voltage return path for APD; referenced to MONIN for fixed 5V current-sense drop. |
| MONIN (Pin 3) | Inverting input of APD current sense amplifier | Accepts up to 75V supply; forms 5V drop with APD pin to enable high-side current mirroring. |
| VOUT (Pin 4) | Boost converter output | Delivers regulated high-voltage bias; connects to APD anode via external filter components. |
| SW (Pins 5,6) | Internal power switch drain terminals | Carries high-frequency inductor current; requires minimal trace length to reduce EMI and losses. |
| GND (Pins 7,10) | Power and signal ground reference | Dual GND pins reduce ground impedance; must connect to PCB ground plane and exposed pad. |
| RT (Pin 9) | Frequency programming node | Resistor-to-GND sets switching frequency (250kHz–2MHz); open-circuit prohibited. |
| VIN (Pin 11) | Main input supply | 2.7–20V input rail; requires local 1μF ceramic bypass capacitor placed adjacent to pin. |
| SHDN (Pin 12) | Enable/disable and soft-start control | Logic-high (>1.5V) enables operation; RC network on this pin controls startup slew rate. |
| VREF (Pin 13) | 1.222V precision reference output | Supplies ≤100μA; used for CTRL biasing or external circuitry; requires ≥10nF bypass. |
| CTRL (Pin 14) | External feedback reference override | Adjusts FB setpoint from 0V to 1V; enables dynamic APD voltage tuning without polarity reversal. |
| FB (Pin 15) | Voltage feedback input | Compares against internal 1V or CTRL voltage; regulates VOUT via resistor divider (R1/R2). |
| MON (Pin 16) | APD current monitor output | Sources 20% of IAPD (0.2×IAPD); converts to voltage via external resistor for closed-loop control. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Schottky diode | Eliminates external diode, reducing BOM count and board area while maintaining 850mV forward drop at 200mA. |
| High-side APD current monitor | Fixed 5.0V voltage drop (VMONIN–VAPD) enables accurate, temperature-stable IAPD sensing up to 2.5mA. |
| Programmable current limit protection | RSENSE-based limit (200mV/RSENSE) prevents APD overcurrent; supports 250nA–2.5mA dynamic range. |
| CTRL pin voltage override | Enables real-time output voltage adjustment (0–1V FB setpoint) without inverting polarity or adding op-amps. |
| Internal soft-start and compensation | Reduces inrush stress and eliminates need for external compensation networks in standard configurations. |
| Frequency synchronization | SYNC pin accepts external clock; RT resistor must be set for 20% lower free-running frequency for lock stability. |
Applications
| Optical Receiver Biasing | PIN Diode Bias Supply |
|---|---|
|
Use Scenario: Providing stable, low-noise high-voltage bias to APDs in 10G/25G fiber optic transceivers operating at –40°C to 85°C ambient. IC Role / Device Role / Timing Role: Constant-current/constant-voltage DC/DC controller generating 45–75V bias with <10% current-sense error across full temperature range. Use Value: Enables reliable photon detection in low-light conditions by maintaining APD gain stability despite temperature drift and supply variation. |
Use Scenario: Powering PIN diodes in RF front-end switches and attenuators requiring 30–60V bias with fast transient response. IC Role / Device Role / Timing Role: High-voltage boost converter with programmable output and integrated current monitoring for precision bias control. Use Value: Reduces component count vs discrete solutions while delivering <100ns current monitor rise/fall time for dynamic bias adjustment. |
| Fiber Optic Network Equipment | Low-Noise Photodetector Modules |
|
Use Scenario: Integrated APD bias supply in SFP+, QSFP, and XFP pluggable optical modules compliant with MSA standards. IC Role / Device Role / Timing Role: Compact 3mm × 3mm QFN DC/DC converter with shutdown current <1μA for hot-plug power management. Use Value: Meets stringent size and power budget requirements while supporting digital diagnostics via MON pin current readback. |
Use Scenario: Biasing low-capacitance APDs in scientific instrumentation (e.g., LIDAR, spectroscopy) demanding ultra-low output ripple. IC Role / Device Role / Timing Role: Low-noise boost regulator with inductor-based topology isolating input rail from switching noise. Use Value: Achieves <500μVpp ripple (TA01b) via optimized layout and external filtering, preserving signal integrity in analog front-ends. |
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#PBF | Supports dual outputs (up to 48V/90V); lower max switch current (300mA); no integrated Schottky diode. | Targeted at dual-rail APD+TIA biasing; requires external diode increasing solution size. | Choose when dual-output bias or higher second-rail voltage is required; avoid if single-rail compactness is critical. |
| LT3461AEDE#PBF | Lower max output (38V); 300mA switch; no APD current monitor; SC70-6 package. | Designed for general-purpose boost, not APD-specific; lacks MON/MONIN functionality and 5V fixed sense drop. | Use only for non-APD applications needing small footprint; not suitable for APD current regulation or monitoring. |
Compared with LT3571EUD#PBF, LT3482EUD#PBF offers dual-rail flexibility at the cost of larger solution size and reduced integration, while LT3461AEDE#PBF sacrifices APD-specific features for minimal footprint-neither matches the LT3571EUD#PBF's combination of 75V capability, integrated monitor, and compact QFN.
Availability
LT3571EUD#PBF is available at Aetrix Electronics and suitable for optical receiver biasing, fiber optic network equipment, and low-noise photodetector modules requiring stable component supply with guaranteed long-term availability.
Supply support for LT3571EUD#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, Inc. (ADI) acquired Linear Technology in 2017 and maintains its high-performance analog product lines, including precision DC/DC converters for demanding signal-chain applications.
The LT3571 belongs to Linear Technology's specialized APD bias converter family, engineered to deliver tightly regulated high-voltage bias with integrated current monitoring for optical sensing systems where gain stability and low noise are critical.
FAQ
What is the maximum output voltage supported by the LT3571EUD#PBF?
The LT3571EUD#PBF supports an absolute maximum output voltage of 75V, with typical operation up to 70V as specified in the Features section. This rating applies to both VOUT and APD pins, enabling direct biasing of high-gain avalanche photodiodes used in long-haul fiber optic receivers. Operation beyond 70V requires careful thermal and layout design per the Absolute Maximum Ratings table.
How does the LT3571EUD#PBF achieve APD current monitoring accuracy over temperature?
The LT3571EUD#PBF achieves better than ±10% relative accuracy for APD current monitoring over –40°C to 125°C by using a fixed 5.0V voltage drop (VMONIN – VAPD) and a high-side current mirror with matched transistor geometry. This architecture minimizes temperature-induced gain drift, and the MON pin outputs 20% of IAPD (0.2×IAPD) with guaranteed accuracy across four decades of dynamic range (250nA to 2.5mA).
Can the LT3571EUD#PBF operate in constant-current mode only?
Yes, the LT3571EUD#PBF can operate exclusively in constant-current mode by configuring the feedback network to prioritize the current loop. When the MONIN–APD sense voltage exceeds the FB threshold, the error amplifier forces regulation via the current loop, holding IAPD constant regardless of load or temperature changes. 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 LT3571EUD#PBF?
The CTRL pin on the LT3571EUD#PBF allows external 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 >1.2V (e.g., tied to VREF), the internal 1V reference is used; when CTRL is between 0V and 1V, the FB pin regulates to that voltage, providing flexible APD bias tuning for temperature compensation or dynamic gain control.
Is the LT3571EUD#PBF RoHS-compliant and lead-free?
Yes, the LT3571EUD#PBF is RoHS-compliant and features a lead-free finish, as indicated by the "#PBF" suffix in the part number. It meets JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for QFN packages and is qualified for reflow soldering per IPC/JEDEC J-STD-020 standards. Full compliance documentation is available through Analog Devices' product change notices.
LT3571EUD#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
- 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)
LT3571EUD#PBF FAQ
1.How can I place an order for LT3571EUD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3571EUD#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 LT3571EUD#PBF reliable?
The price and inventory of LT3571EUD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3571EUD#PBF is usually 5 days.
3.What payment methods are accepted for LT3571EUD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3571EUD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3571EUD#PBF?
LT3571EUD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3571EUD#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 LT3571EUD#PBF?
For technical support, including LT3571EUD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3571EUD#PBF requirements.
6.How does Aetrix verify that LT3571EUD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3571EUD#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 LT3571EUD#PBF meets industry standards.
7.What is the process for return or replacement of LT3571EUD#PBF?
All LT3571EUD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3571EUD#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 LT3571EUD#PBF part is unused and in its original packaging.
Return procedure for LT3571EUD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3571EUD#PBF Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
