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Analog Devices Inc. LT3757AIDD#PBF
- Part No.:
- LT3757AIDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3757AIDD#PBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,863
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Product details
Overview
LT3757AIDD#PBF from Analog Devices is a wide-input current-mode DC/DC controller for boost, flyback, SEPIC, and inverting topologies, supporting 2.9V–40V input, programmable 50kHz–1MHz switching frequency, and ±0.8V/1.6V dual-polarity feedback regulation. It drives external N-channel MOSFETs with a 7.2V internal LDO gate supply and features <1µA shutdown current-ideal for automotive battery-powered systems requiring high transient response and AEC-Q100 compliance.
For engineers reviewing the LT3757AIDD#PBF datasheet, LT3757AIDD#PBF pinout, LT3757AIDD#PBF application, or LT3757AIDD#PBF equivalent, key selection considerations include its dual-polarity FBX regulation (±0.8V/1.6V), 10-lead DFN (3mm × 3mm) thermal package, soft-start and frequency foldback for short-circuit protection, and AEC-Q100 qualification for automotive-grade reliability.
Technical Context
The LT3757AIDD#PBF implements fixed-frequency current-mode control with slope compensation, enabling stable operation across wide VIN and VOUT ranges. Its dual-comparator feedback architecture (A1/A2) supports both positive- and negative-output configurations via a single FBX pin, with distinct 1.6V (positive) and –0.8V (negative) regulation references.
It integrates an internal 7.2V LDO for gate drive, programmable UVLO on SHDN/UVLO with hysteresis, and synchronized operation via the SYNC pin-requiring RT biasing 20% below external clock frequency. The 220ns minimum on/off times constrain maximum duty cycle at high frequencies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.9V to 40V - enables direct operation from 3.3V logic rails up to 36V automotive batteries without pre-regulation. |
| Switching Frequency | 50kHz to 1MHz - set by RT resistor; allows trade-off between efficiency (lower f) and component size (higher f). |
| Feedback Regulation | +1.6V or –0.8V - single-pin dual-polarity reference supports boost/flyback (positive) and inverting (negative) outputs. |
| Shutdown Current | <1µA - minimizes battery drain in always-on automotive modules during sleep mode. |
| SENSE Threshold | 110mV (typical) - sets peak switch current limit; enables precise overcurrent protection with low-value sense resistors. |
| INTVCC Regulator | 7.2V ±0.2V - powers gate driver and internal circuitry; bypassing with ≥4.7µF ceramic capacitor is mandatory for stability. |
| AEC-Q100 Grade | Grade I (–40°C to +125°C) - qualified for under-hood automotive applications per stress test requirements. |
Pinout & Package
LT3757AIDD#PBF uses a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for optimal thermal performance (θJA = 43°C/W). Pin numbering follows standard top-view orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Error amplifier compensation node | Connects external RC network to stabilize voltage loop; clamped during soft-start. |
| FBX (Pin 2) | Positive/negative feedback input | Accepts divided output voltage; selects 1.6V (positive) or –0.8V (negative) regulation reference automatically. |
| SS (Pin 3) | Soft-start timing node | 10µA pull-up to 2.5V rail; external capacitor sets ramp time; reset by UV/OV/thermal faults. |
| RT (Pin 4) | Frequency programming input | Resistor-to-GND sets oscillator frequency; open-circuit disables operation. |
| SYNC (Pin 5) | External clock synchronization input | Accepts digital clock; requires RT bias 20% slower than SYNC frequency; ignored when FBX near GND. |
| SENSE (Pin 6) | Current sense input | Kelvin-connected to MOSFET source-side sense resistor; ±0.3V absolute max; triggers immediate shutdown above 110mV. |
| GATE (Pin 7) | N-MOSFET gate driver output | Sources/sinks current between INTVCC and GND; forced low during shutdown/thermal fault/INTVCC UV/OV. |
| INTVCC (Pin 8) | Internal 7.2V LDO output | Powers gate driver and logic; must be bypassed with ≥4.7µF ceramic cap; can be externally powered if >7.5V and <17.5V. |
| SHDN/UVLO (Pin 9) | Enable/undervoltage detection input | 1.22V falling threshold with programmable hysteresis; pulls VIN IQ below 1µA when ≤0.4V. |
| VIN (Pin 10) | Main input supply | 2.9V–40V range; requires local 0.22µF+ ceramic bypass; powers internal LDO and logic. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-polarity feedback regulation | Single FBX pin supports both +1.6V (boost/flyback/SEPIC) and –0.8V (inverting) output configurations without external reconfiguration. |
| Programmable frequency with sync | RT resistor sets 50kHz–1MHz range; SYNC pin enables deterministic phase alignment with system clocks for EMI reduction. |
| Low-quiescent-current shutdown | <1µA VIN current in shutdown-critical for battery longevity in automotive telematics and ADAS modules. |
| Integrated LDO gate driver supply | 7.2V regulated INTVCC eliminates need for external bias supply while supporting fast gate charging of low-RDS(on) MOSFETs. |
| Automotive-grade thermal design | DFN package with exposed pad achieves θJA = 43°C/W; AEC-Q100 Grade I qualification ensures reliability at 125°C junction temperature. |
Applications
| Automotive LED Headlamp Driver | Industrial Isolated Flyback PSU |
|---|---|
Use Scenario: High-brightness LED arrays in adaptive front lighting systems require tightly regulated constant-current output with fast transient response to dimming commands. IC Role / Device Role / Timing Role: LT3757AIDD#PBF operates in boost configuration, regulating LED string current via SENSE feedback while maintaining 1.6V FBX reference and 300kHz switching for compact magnetics. Use Value: Integrated soft-start prevents inrush damage; frequency foldback protects against short-circuit events; AEC-Q100 qualification ensures operation across –40°C to +125°C ambient. | Use Scenario: Programmable logic controllers (PLCs) require isolated 24V auxiliary supply from unregulated 24–48V DC bus with tight load regulation and low standby loss. IC Role / Device Role / Timing Role: LT3757AIDD#PBF configured as flyback controller regulates isolated output using optocoupler feedback to FBX pin, leveraging –0.8V reference for negative secondary winding polarity. Use Value: 2.9V minimum start-up enables brownout recovery; <1µA shutdown current extends system uptime during power-loss events; 40V abs max rating accommodates bus transients. |
| Portable Medical Imaging Power | Telecom DC-DC Intermediate Bus |
Use Scenario: Handheld ultrasound devices demand ultra-low-noise, high-efficiency 5V/3.3V rails from single-cell Li-ion (2.7–4.2V) with minimal board area. IC Role / Device Role / Timing Role: LT3757AIDD#PBF used in SEPIC topology provides non-inverting step-up/step-down capability; FBX senses output via resistor divider while VC loop stabilizes with Type II compensation. Use Value: 220ns minimum on-time enables high-frequency operation (≥500kHz) for tiny inductors; internal LDO eliminates need for external bias rail; DFN package fits space-constrained PCB layouts. | Use Scenario: 48V telecom rectifiers feed intermediate 12V bus powering multiple point-of-load converters; bus must remain stable during rapid load steps. IC Role / Device Role / Timing Role: LT3757AIDD#PBF configured as boost controller generates 12V from 48V input with 100kHz switching; SYNC pin aligns switching edge with master clock to reduce conducted EMI. Use Value: Current-mode control delivers <50µs load transient response; programmable UVLO prevents operation during brownout; 40V VIN rating withstands 48V bus surges. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3757IDD#PBF | Same pinout and function but earlier revision; lacks LT3757A's improved load transient response and tighter FBX regulation tolerance. | Acceptable for non-critical industrial supplies where A-grade performance not required. | Select LT3757AIDD#PBF when AEC-Q100 compliance, faster transient response, or tighter feedback accuracy is mandatory. |
| LM5122MM/NOPB | Wide-input synchronous boost/flyback controller with integrated high-side gate driver; no internal LDO; requires external bias supply. | Better suited for high-efficiency synchronous rectification; lacks dual-polarity FBX and AEC-Q100 qualification. | Choose LM5122MM/NOPB only if synchronous operation and higher efficiency outweigh need for automotive qualification and simplified biasing. |
Compared with LT3757IDD#PBF, the LT3757AIDD#PBF offers superior load transient behavior and tighter feedback reference accuracy-critical for automotive LED drivers and medical imaging. Versus LM5122MM/NOPB, it trades synchronous efficiency for integrated gate drive simplicity, AEC-Q100 compliance, and dual-polarity output flexibility.
Availability
LT3757AIDD#PBF is available at Aetrix Electronics and suitable for automotive LED drivers, industrial flyback PSUs, portable medical imaging power, and telecom intermediate bus converters requiring stable component supply, AEC-Q100 qualification, and long-term lifecycle support.
Supply support for LT3757AIDD#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 (now part of Analog Devices, Inc., a wholly owned subsidiary of Analog Devices, Inc.) designs precision analog, mixed-signal, and digital signal processing ICs for high-reliability applications.
The LT3757A series belongs to Analog Devices' high-voltage DC/DC controller product line, engineered specifically for automotive, industrial, and telecom power conversion where wide input range, robust fault protection, and AEC-Q100 compliance are essential.
FAQ
What is the key functional difference between LT3757AIDD#PBF and LT3757IDD#PBF?
The LT3757AIDD#PBF features improved load transient response and tighter feedback voltage regulation tolerances compared to the LT3757IDD#PBF. Specifically, the LT3757A version exhibits lower output voltage deviation during rapid load steps and more consistent ±0.8V/1.6V FBX reference accuracy across temperature and line variations-making LT3757AIDD#PBF preferred for automotive and precision industrial applications where dynamic regulation is critical.
Can LT3757AIDD#PBF operate from a 3.3V input supply?
Yes, LT3757AIDD#PBF supports a minimum input voltage of 2.9V, making it fully operational from a 3.3V rail. However, at such low VIN, the internal 7.2V LDO may not regulate properly unless the INTVCC pin is externally powered or the gate driver load is minimized. For reliable 3.3V operation, use low-threshold MOSFETs and ensure INTVCC is adequately bypassed with ≥4.7µF ceramic capacitance.
How does the FBX pin support both positive and negative output configurations in LT3757AIDD#PBF?
The LT3757AIDD#PBF detects output polarity via the FBX pin voltage level: when FBX is pulled above GND (e.g., via resistor divider from positive VOUT), the internal comparator A1 activates and regulates to +1.6V; when FBX is pulled below GND (e.g., from negative VOUT), comparator A2 activates and regulates to –0.8V. No external configuration pins or jumpers are needed-the IC auto-selects the correct reference based on FBX bias direction.
Is LT3757AIDD#PBF pin-compatible with LT3757EMSE#PBF?
No, LT3757AIDD#PBF (10-lead DFN) and LT3757EMSE#PBF (10-lead MSOP) share identical pin functions and ordering but differ in physical package dimensions, thermal characteristics (θJA = 43°C/W vs. 40°C/W), and exposed pad implementation. While electrical pinout matches, PCB layout and thermal relief must be redesigned due to different land patterns and soldering requirements-no drop-in replacement is possible without board revision.
What is the purpose of the SYNC pin in LT3757AIDD#PBF, and how should it be configured?
The SYNC pin in LT3757AIDD#PBF allows deterministic synchronization of the internal oscillator to an external clock source, reducing EMI by preventing beat frequencies. To use it, apply a clean digital clock signal (min. 200ns pulse width) and configure the RT resistor to set the free-running frequency 20% lower than the SYNC frequency. If unused, SYNC must be tied directly to GND-not left floating-to ensure predictable operation.
LT3757AIDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive and Negative
- Topology:
- Boost, Flyback, SEPIC
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 2.9V ~ 40V
- Frequency - Switching:
- 100kHz ~ 1MHz
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- No
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
LT3757AIDD#PBF FAQ
1.How can I place an order for LT3757AIDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3757AIDD#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 LT3757AIDD#PBF reliable?
The price and inventory of LT3757AIDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3757AIDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3757AIDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3757AIDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3757AIDD#PBF?
LT3757AIDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3757AIDD#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 LT3757AIDD#PBF?
For technical support, including LT3757AIDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3757AIDD#PBF requirements.
6.How does Aetrix verify that LT3757AIDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3757AIDD#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 LT3757AIDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3757AIDD#PBF?
All LT3757AIDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3757AIDD#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 LT3757AIDD#PBF part is unused and in its original packaging.
Return procedure for LT3757AIDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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