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Analog Devices Inc. LT3757EDD#PBF
- Part No.:
- LT3757EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3757EDD#PBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,055
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Product details
Overview
LT3757EDD#PBF from Analog Devices is a wide-input current-mode DC/DC controller for boost, flyback, SEPIC, and inverting topologies, driving external N-channel MOSFETs with an internal 7.2V LDO gate driver. It operates from 2.9V to 40V input, supports ±1.6V/–0.8V feedback regulation, delivers programmable 50kHz–1MHz switching, and features <1µA shutdown current - enabling high-efficiency battery-powered LED drivers and automotive power supplies.
For engineers reviewing the LT3757EDD#PBF datasheet, LT3757EDD#PBF pinout, LT3757EDD#PBF application, or LT3757EDD#PBF equivalent, key selection considerations include its dual-polarity feedback capability, soft-start and frequency foldback for short-circuit protection, AEC-Q100 qualification (E-grade), and thermal performance in the 3mm × 3mm DFN package with exposed pad.
Technical Context
The LT3757EDD#PBF implements fixed-frequency current-mode control with slope compensation, where SENSE voltage plus ramp is compared to VC to determine MOSFET on-time. Its error amplifier supports both positive (1.6V) and negative (–0.8V) FBX reference modes, enabling seamless topology reconfiguration without hardware change.
It integrates a 7.2V LDO regulator (INTVCC) with UVLO (2.7V) and OVLO (17.5V) protection, programmable SHDN/UVLO threshold (1.22V nominal falling), and SYNC pin for external clock synchronization - requiring RT resistor programming 20% below SYNC frequency when used.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.9V to 40V - supports direct connection to 12V/24V automotive rails and single-cell Li+ to multi-cell battery stacks. |
| Feedback Reference | +1.6V or –0.8V - enables single-pin polarity selection for boost/flyback (positive) or inverting (negative) output configurations. |
| Switching Frequency | 50kHz to 1MHz via RT resistor - trade-off between efficiency (lower f) and magnetics size (higher f); minimum on/off time = 220ns. |
| Shutdown Current | <1µA at SHDN/UVLO = 0V - preserves battery life in always-on systems like telematics or sensor nodes. |
| SENSE Threshold | 110mV typical - sets peak inductor current limit; supports precise overcurrent protection with Kelvin sensing. |
| INTVCC Regulation | 7.2V ±0.2V - powers gate driver and internal circuitry; bypass requires ≥4.7µF ceramic capacitor adjacent to pin. |
| Operating Temp | –40°C to +125°C junction - qualified per AEC-Q100 Grade E for under-hood automotive use. |
Pinout & Package
LT3757EDD#PBF uses a thermally enhanced 10-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 11) soldered to PCB ground for optimal thermal dissipation (θJA = 43°C/W).
| 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 | Dual-reference pin: regulates to +1.6V (boost/flyback/SEPIC) or –0.8V (inverting); triggers frequency foldback near GND. |
| SS (Pin 3) | Soft-start timing node | 10µA pull-up to 2.5V rail; external capacitor sets startup ramp; reset by UV/OV/thermal faults. |
| RT (Pin 4) | Frequency programming input | Resistor to GND sets oscillator frequency (50kHz–1MHz); must not be left floating. |
| SYNC (Pin 5) | External clock synchronization input | Accepts digital clock; overrides RT setting if active; tie to GND for free-running operation. |
| SENSE (Pin 6) | Current sense input | Kelvin-connected to MOSFET source resistor; compares against 110mV threshold for cycle-by-cycle current limiting. |
| GATE (Pin 7) | N-channel MOSFET gate driver output | Swings between INTVCC and GND; forced low during shutdown, thermal lockout, or INTVCC fault. |
| INTVCC (Pin 8) | Internal LDO output | 7.2V regulated supply for gate driver and logic; bypass with ≥4.7µF ceramic; can be externally powered above 7.5V. |
| SHDN/UVLO (Pin 9) | Enable and input undervoltage detection | 1.22V falling threshold with programmable hysteresis; pulls VIN IQ below 1µA when ≤0.4V. |
| VIN (Pin 10) | Main input supply | 2.9V–40V input; bypass with ≥0.22µF ceramic capacitor close to pin. |
| Exposed Pad (Pin 11) | Ground and current sense return | Must be soldered to PCB ground plane; serves as SENSE negative reference and primary thermal path. |
Key Features
| Feature | Design Value |
|---|---|
| Topology Flexibility | Single IC supports boost, flyback, SEPIC, and inverting converters via FBX polarity selection - eliminates need for multiple controller SKUs. |
| Low-Power Shutdown | <1µA VIN quiescent current enables >10-year battery life in remote sensors and always-on telematics modules. |
| Robust Fault Protection | Integrated frequency foldback, overvoltage lockout (±8%/±11% hysteresis), thermal shutdown, and INTVCC UV/OV monitoring prevent damage during transients. |
| Automotive-Ready Packaging | 3mm × 3mm DFN with exposed pad meets AEC-Q100 Grade E requirements and provides 43°C/W thermal resistance for under-hood reliability. |
| Programmable Timing | RT resistor and SYNC pin allow precise frequency control and system-level clock alignment - critical for EMI reduction in automotive EMC testing. |
Applications
| Automotive LED Headlamp Driver | Industrial Isolated Flyback PSU |
|---|---|
Use Scenario: Driving high-brightness LEDs from 12V vehicle battery with tight thermal constraints and EMI limits. IC Role / Device Role / Timing Role: Boost controller regulating constant current to LED string; synchronizes switching to avoid AM band interference. Use Value: 50kHz–1MHz programmability enables optimal trade-off between inductor size and efficiency; <1µA shutdown extends battery runtime during vehicle sleep mode. | Use Scenario: Generating isolated 15V/1A auxiliary supply from 24V industrial bus with reinforced insulation. IC Role / Device Role / Timing Role: Primary-side flyback controller with optocoupler feedback; uses FBX to regulate secondary-side voltage via reflected winding. Use Value: Dual-reference FBX simplifies feedback design across input voltage variations; 125°C operating range ensures reliability in enclosed control cabinets. |
| Portable Medical Instrument Power | Telecom DC-DC Intermediate Bus |
Use Scenario: Powering analog front-end and ADC in handheld ultrasound device from single Li-ion cell (2.9V–4.2V). IC Role / Device Role / Timing Role: SEPIC controller delivering stable 5V/2A output despite deep battery discharge; employs soft-start to limit inrush. Use Value: 2.9V minimum VIN enables full battery utilization; frequency foldback prevents inductor saturation during output short-circuit events. | Use Scenario: Stepping down –48V telecom supply to +12V intermediate bus for downstream POL converters. IC Role / Device Role / Timing Role: Inverting controller generating positive 12V from negative 48V rail; uses –0.8V FBX reference for accurate regulation. Use Value: Single-controller solution avoids discrete inverter stages; AEC-Q100 qualification supports telecom infrastructure with extended lifetime requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3757AEDD#PBF | Improved load transient response; identical pinout, specs, and package; higher cost. | Better suited for dynamic load applications like RF power amplifiers or burst-mode data acquisition. | Select LT3757AEDD#PBF only when measured load step recovery time must be <5µs. |
| LM5122MM/NOPB | Wider 3V–65V input; integrated high-side gate driver; no negative FBX capability; MSOP-10 only. | Requires external level-shifting for inverting topologies; lacks dual-polarity feedback architecture. | Choose LM5122MM/NOPB for higher-VIN industrial systems where topology flexibility is secondary to input range. |
Compared with LT3757AEDD#PBF, the LT3757EDD#PBF offers identical functionality at lower cost but slower transient recovery; versus LM5122MM/NOPB, it provides unique ±FBX capability for inverting designs but narrower input range and no integrated high-side drive.
Availability
LT3757EDD#PBF is available at Aetrix Electronics and suitable for automotive LED drivers, industrial flyback PSUs, portable medical instruments, and telecom intermediate bus converters requiring stable component supply and AEC-Q100-compliant sourcing.
Supply support for LT3757EDD#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and automotive markets.
The LT3757 product line delivers versatile, high-voltage current-mode controllers optimized for rugged, compact DC/DC conversion in automotive, industrial, and telecom power systems - emphasizing topology flexibility, fault resilience, and thermal robustness.
FAQ
What is the maximum switching frequency supported by the LT3757EDD#PBF?
The LT3757EDD#PBF supports a programmable switching frequency range of 50kHz to 1MHz using an external resistor on the RT pin. At 10.5kΩ to GND, it achieves 1MHz operation; minimum on-time and off-time are both 220ns, limiting practical maximum duty cycle at high frequencies. The LT3757EDD#PBF datasheet specifies this range under standard conditions (VFBX = 1.6V, TA = 25°C), with temperature drift less than ±5% across –40°C to 125°C.
Can the LT3757EDD#PBF generate a negative output voltage?
Yes, the LT3757EDD#PBF can generate a negative output voltage using inverting topology. It achieves this via the FBX pin's dual-reference capability: when configured for negative regulation, FBX is pulled to –0.8V, activating comparator A2 for non-inverting amplification to VC. This allows single-pin polarity selection without external component changes. The LT3757EDD#PBF's block diagram and application notes confirm inverting converter implementation with proper resistor divider biasing.
What is the purpose of the exposed pad on the LT3757EDD#PBF DFN package?
The exposed pad (Pin 11) on the LT3757EDD#PBF serves two critical functions: it is the primary thermal conduction path to the PCB ground plane (reducing θJA to 43°C/W), and it acts as the reference return for the SENSE pin's Kelvin connection. Per the datasheet, it must be soldered directly to a solid copper ground plane; failure to do so risks thermal runaway and inaccurate current sensing. The LT3757EDD#PBF's absolute maximum ratings specify that the exposed pad is electrically GND.
How does the LT3757EDD#PBF handle overvoltage conditions on the FBX pin?
The LT3757EDD#PBF includes dedicated overvoltage comparators for both polarities: A11 triggers when FBX exceeds +1.6V by 8% (≈+1.728V), and A12 triggers when FBX falls below –0.8V by 11% (≈–0.888V). Both generate reset pulses to the main SR latch, forcing GATE low and halting switching until FBX returns within safe bounds. This protects downstream components during start-up overshoot or short-circuit recovery. The LT3757EDD#PBF datasheet confirms these thresholds and hysteresis values in the Electrical Characteristics table.
Is the LT3757EDD#PBF pin-compatible with the LT3757AEDD#PBF?
Yes, the LT3757EDD#PBF is fully pin-compatible and footprint-compatible with the LT3757AEDD#PBF. Both share identical DFN-10 (3mm × 3mm) packaging, pin numbering, electrical connections, and functional pin definitions. The LT3757AEDD#PBF adds improved load transient performance but maintains backward compatibility - allowing drop-in replacement in existing designs where enhanced dynamic response is required. The LT3757EDD#PBF and LT3757AEDD#PBF are explicitly listed in the same order table with matching marking codes (LDYW) and package descriptions.
LT3757EDD#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)
LT3757EDD#PBF FAQ
1.How can I place an order for LT3757EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3757EDD#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 LT3757EDD#PBF reliable?
The price and inventory of LT3757EDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3757EDD#PBF is usually 5 days.
3.What payment methods are accepted for LT3757EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3757EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3757EDD#PBF?
LT3757EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3757EDD#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 LT3757EDD#PBF?
For technical support, including LT3757EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3757EDD#PBF requirements.
6.How does Aetrix verify that LT3757EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3757EDD#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 LT3757EDD#PBF meets industry standards.
7.What is the process for return or replacement of LT3757EDD#PBF?
All LT3757EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3757EDD#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 LT3757EDD#PBF part is unused and in its original packaging.
Return procedure for LT3757EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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