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Analog Devices Inc. LT3757AIDD#TRPBF
- Part No.:
- LT3757AIDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LT3757AIDD#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,109
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Product details
Overview
LT3757AIDD#TRPBF 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 ±1µA shutdown current. It drives external N-channel MOSFETs with an internal 7.2V LDO, features soft-start, frequency foldback, and AEC-Q100 qualification for automotive systems.
For engineers reviewing the LT3757AIDD#TRPBF datasheet, LT3757AIDD#TRPBF pinout, LT3757AIDD#TRPBF application, or LT3757AIDD#TRPBF equivalent, key selection criteria include its dual-polarity feedback capability (1.6V/–0.8V FBX thresholds), 10-lead DFN package thermal performance (θJA = 43°C/W), and improved load transient response versus LT3757.
Technical Context
The LT3757AIDD#TRPBF implements fixed-frequency current-mode control with slope compensation, enabling stable regulation across wide VIN and VOUT ranges. Its error amplifier supports both positive (1.6V) and negative (–0.8V) feedback references, and the SENSE pin monitors switch current via a 110mV threshold with ±10mV tempco.
Frequency programming uses a single RT resistor (e.g., 41.2kΩ for 300kHz), while SYNC pin allows external clock synchronization with 200ns minimum pulse width. The IC integrates undervoltage lockout on SHDN/UVLO (1.22V falling threshold) and INTVCC (2.7V UV, 17.5V OV), plus thermal shutdown at 165°C.
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 industrial bus supplies. |
| Switching Frequency | 50kHz to 1MHz - set by RT resistor; 300kHz typical with 41.2kΩ, balancing efficiency and magnetics size. |
| FBX Regulation Voltage | +1.6V or –0.8V - single-pin polarity selection for positive/negative output configurations without external logic. |
| SENSE Threshold | 110mV (typ) - defines peak inductor current limit; ±10mV variation over temperature ensures consistent overcurrent protection. |
| Shutdown Current | <1µA - minimizes battery drain in always-on automotive modules during sleep mode. |
| INTVCC Regulator | 7.2V LDO - powers gate driver and internal circuitry; bypassed with ≥4.7µF ceramic capacitor near pin 8. |
| Package | 10-Lead DFN (3mm × 3mm) - exposed pad soldered to PCB ground for θJA = 43°C/W thermal performance. |
Pinout & Package
LT3757AIDD#TRPBF is housed in a thermally enhanced 10-lead plastic DFN package (3mm × 3mm) with exposed pad (Pin 11) that must be soldered to PCB ground for optimal thermal conduction (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (1) | Error amplifier compensation node | Connects external RC network to stabilize voltage loop; clamped during soft-start. |
| FBX (2) | Feedback input | Accepts +1.6V or –0.8V reference; determines output polarity and regulates via external resistor divider. |
| SS (3) | Soft-start control | 10µA pull-up to 2.5V rail; external capacitor sets ramp time; reset by UV/OV/thermal events. |
| RT (4) | Frequency programming | Resistor to GND sets oscillator frequency; open-circuit disables operation. |
| SYNC (5) | External clock sync input | Accepts digital clock; requires RT setting 20% below SYNC frequency; tied to GND if unused. |
| SENSE (6) | Current sense input | Kelvin-connected to MOSFET source-side sense resistor; triggers immediate shutdown above 110mV. |
| GATE (7) | MOSFET driver output | Swings between INTVCC and GND; forced low during shutdown, thermal fault, or INTVCC UV/OV. |
| INTVCC (8) | Internal LDO output | 7.2V regulated supply; powers gate driver and logic; requires ≥4.7µF local bypass. |
| SHDN/UVLO (9) | Enable and input UV detection | 1.22V falling threshold with programmable hysteresis; pulls VIN IQ below 1µA when ≤0.4V. |
| VIN (10) | Main power input | 2.9V–40V supply; bypassed with ≥0.22µF ceramic capacitor close to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-polarity feedback architecture | Single FBX pin supports both +1.6V and –0.8V regulation references, eliminating need for external polarity-select logic in inverting or SEPIC designs. |
| Programmable frequency with sync capability | RT resistor sets 50kHz–1MHz range; SYNC pin accepts external clocks up to 1MHz with 200ns minimum pulse width. |
| Low-quiescent-current shutdown | <1µA VIN current in shutdown - critical for battery-powered automotive telematics and infotainment modules. |
| Integrated LDO with UV/OV protection | 7.2V INTVCC regulator includes 2.7V UV lockout (100mV hysteresis) and 17.5V OV lockout to prevent MOSFET gate damage. |
| AEC-Q100 qualified | Rated for –40°C to +125°C junction temperature - validated for automotive power conversion in ADAS and body control units. |
Applications
| Automotive LED Headlamp Driver | Industrial Isolated Flyback PSU |
|---|---|
Use Scenario: Driving high-brightness LEDs in adaptive front lighting systems requiring precise current regulation and cold-crank operation down to 2.9V. IC Role / Device Role / Timing Role: Boost controller regulating constant current through LED string using SENSE feedback; FBX configured for positive output. Use Value: 110mV current sense threshold enables accurate LED current control; AEC-Q100 qualification ensures reliability under automotive thermal cycling. | Use Scenario: Generating isolated 12V/500mA auxiliary supply from 24V factory bus for PLC I/O modules with reinforced insulation requirements. IC Role / Device Role / Timing Role: Flyback controller implementing optocoupler-based secondary-side regulation via FBX pin; INTVCC powered from auxiliary winding. Use Value: 40V absolute max VIN rating accommodates 24V bus transients; 300kHz operation reduces transformer size while maintaining >85% efficiency. |
| Portable Medical Imaging Power | Telecom DC-DC Intermediate Bus Converter |
Use Scenario: Generating ±15V rails for analog front-end amplifiers in handheld ultrasound devices powered by single-cell Li-ion batteries. IC Role / Device Role / Timing Role: Inverting controller producing negative output; FBX referenced to –0.8V; soft-start prevents inrush into capacitive loads. Use Value: Dual-reference FBX architecture eliminates need for separate inverting IC; <1µA shutdown current extends battery runtime between scans. | Use Scenario: Stepping 48V telecom rectified bus down to 12V intermediate bus for downstream POL converters in base station RF cards. IC Role / Device Role / Timing Role: High-efficiency boost controller operating at 500kHz; synchronized to system clock via SYNC pin to reduce EMI. Use Value: RT-programmable frequency allows EMI band avoidance; 10-lead DFN package enables compact layout in space-constrained RF card assemblies. |
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#TRPBF | Same pinout and function but standard grade (–40°C to +125°C); lacks LT3757A's improved load transient response. | Suitable for non-automotive industrial boost/flyback where tighter transient regulation is not required. | Select LT3757AIDD#TRPBF when fast load step response is critical, e.g., in LED drivers with PWM dimming. |
| LM51571RGER | 3.5V–60V input, 2.1MHz max frequency, integrated 100V MOSFET driver; no negative FBX capability. | Targeted at high-frequency, high-VIN boost applications; cannot replace LT3757A in inverting or SEPIC topologies. | Choose LM51571RGER only for simple boost converters needing higher VIN range and smaller magnetics. |
Compared with LT3757IDD#TRPBF, the LT3757AIDD#TRPBF delivers superior dynamic response for LED current regulation and battery-powered systems; compared with LM51571RGER, it supports dual-polarity outputs and lower minimum input voltage but requires external MOSFETs.
Availability
LT3757AIDD#TRPBF 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 and AEC-Q100 compliance.
Supply support for LT3757AIDD#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3757A product line delivers robust, wide-input DC/DC controllers optimized for automotive-grade reliability and flexible topology support including boost, flyback, SEPIC, and inverting configurations.
FAQ
What is the minimum input voltage supported by the LT3757AIDD#TRPBF?
The LT3757AIDD#TRPBF supports a minimum input voltage of 2.9V, enabling direct operation from single-cell Li-ion batteries or 3.3V logic rails. This low VIN threshold is maintained across the full –40°C to +125°C operating temperature range, making LT3757AIDD#TRPBF suitable for cold-crank automotive applications and portable equipment.
How does the LT3757AIDD#TRPBF handle negative output voltage generation?
The LT3757AIDD#TRPBF generates negative output voltages using its dual-reference FBX pin, which regulates to –0.8V when configured in inverting topology. The internal error amplifier A2 activates for noninverting amplification from FBX to VC, allowing precise negative rail control without external level-shifting circuitry - a capability unique to LT3757AIDD#TRPBF among its peers.
What thermal considerations apply to the LT3757AIDD#TRPBF in a 10-lead DFN package?
The LT3757AIDD#TRPBF in the 10-lead DFN package has a junction-to-ambient thermal resistance (θJA) of 43°C/W when the exposed pad (Pin 11) is properly soldered to a solid PCB ground plane. To avoid exceeding the 125°C maximum junction temperature, designers must limit total power dissipation - especially gate drive current (IDRIVE = f × QG) - and ensure adequate copper area under the device per Analog Devices' layout guidelines for LT3757AIDD#TRPBF.
Can the LT3757AIDD#TRPBF be synchronized to an external clock, and what are the timing requirements?
Yes, the LT3757AIDD#TRPBF can be synchronized to an external clock via the SYNC pin, accepting digital signals up to 1MHz. The external clock must have a minimum pulse width of 200ns, and the RT resistor must be selected to program a free-running frequency 20% slower than the SYNC frequency. If synchronization is unused, SYNC must be tied to GND - leaving it floating will cause erratic operation of LT3757AIDD#TRPBF.
What is the purpose of the SHDN/UVLO pin on the LT3757AIDD#TRPBF, and how is hysteresis programmed?
On the LT3757AIDD#TRPBF, the SHDN/UVLO pin serves dual functions: enabling/disabling the IC and detecting input undervoltage. Its 1.22V nominal falling threshold is fixed, while rising hysteresis is programmed externally using two resistors (R3, R4) to form a voltage divider from VIN to GND. The rising threshold equals 1.22V × (R3+R4)/R4 + 2µA × R3, allowing precise turn-on/turn-off voltage windows for battery-powered LT3757AIDD#TRPBF systems.
LT3757AIDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3757AIDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3757AIDD#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 LT3757AIDD#TRPBF reliable?
The price and inventory of LT3757AIDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3757AIDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3757AIDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3757AIDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3757AIDD#TRPBF?
LT3757AIDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3757AIDD#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 LT3757AIDD#TRPBF?
For technical support, including LT3757AIDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3757AIDD#TRPBF requirements.
6.How does Aetrix verify that LT3757AIDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3757AIDD#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 LT3757AIDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3757AIDD#TRPBF?
All LT3757AIDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3757AIDD#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 LT3757AIDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3757AIDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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