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Analog Devices Inc. LT3957AEUHE#TRPBF
- Part No.:
- LT3957AEUHE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 36-WFQFN, 28 Leads, Exposed Pad
- Datasheet:
-
LT3957AEUHE#TRPBF.pdf
- Description:
- IC REG BOOST CUK ADJ 5A 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,724
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Product details
Overview
LT3957AEUHE#TRPBF from Analog Devices (formerly Linear Technology) is a wide-input, current-mode DC/DC controller IC with an integrated 5A/40V N-channel power MOSFET, supporting boost, flyback, SEPIC, and inverting topologies. It delivers ±1.6V/–0.8V feedback regulation, programmable 100kHz–1MHz switching frequency, and <1μA shutdown current - ideal for automotive battery-supplied 12V-to-24V systems requiring high-efficiency isolated or non-isolated voltage conversion.
For engineers reviewing the LT3957AEUHE#TRPBF datasheet, LT3957AEUHE#TRPBF pinout, LT3957AEUHE#TRPBF application, or LT3957AEUHE#TRPBF equivalent, key selection considerations include its dual-polarity FBX regulation capability, internal LDO-powered gate driver, thermally enhanced 36-lead QFN package, and frequency foldback protection during startup or short-circuit conditions.
Technical Context
The LT3957AEUHE#TRPBF implements fixed-frequency current-mode control with slope compensation, using SENSE1/SENSE2 for Kelvin current sensing and VC for error amplifier compensation. Its dual-reference FBX pin (1.6V for positive outputs, –0.8V for negative outputs) enables topology flexibility without external op-amps.
It integrates a 5.2V/95mA LDO (INTVCC) for gate drive and logic, supports external synchronization via SYNC with 20% slower RT programming, and features programmable EN/UVLO with 1.22V falling threshold and 20mV hysteresis - all operating across –40°C to 125°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 40V - supports direct connection to automotive batteries (9V–16V nominal) and industrial 24V rails without pre-regulation. |
| Internal Power Switch | 5A/40V N-MOSFET - eliminates external high-side switch; rated for continuous 5A drain current at 125°C. |
| Feedback Regulation | +1.6V / –0.8V on FBX pin - enables single-pin configuration of both positive and negative output voltages. |
| Switching Frequency | 100kHz to 1MHz (RT-programmable) - balances efficiency (lower fSW) vs. size (higher fSW); supports sync to external clock. |
| Shutdown Quiescent Current | <1μA - extends runtime in battery-backed systems during deep sleep or fault lockout. |
| Soft-Start Control | SS pin with 10μA pull-up - sets controlled ramp time via external capacitor; resets on INTVCC UV, thermal lockout, or EN/UVLO undervoltage. |
| Operating Junction Temp | –40°C to 125°C - qualified for under-hood automotive and industrial environments without derating. |
Pinout & Package
LT3957AEUHE#TRPBF is housed in a thermally enhanced 36-lead (5mm × 6mm) plastic QFN package with two exposed pads: Pin 37 (SGND) and Pin 38 (SW), both requiring soldering to dedicated PCB copper planes for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pins 8,9,20,21,38) | Drain of internal N-MOSFET | High-current switching node; must be routed with low-inductance layout and connected to exposed pad (Pin 38) for thermal dissipation. |
| SENSE1 (Pin 6) & SENSE2 (Pin 3) | Current sense input pair | Enable Kelvin sensing across internal RSENSE; SENSE1 connects to MOSFET source, SENSE2 to filter network - critical for accurate peak-current limiting. |
| FBX (Pin 31) | Positive/negative feedback input | Accepts resistor-divider output; regulates to +1.6V (boost/SEPIC/flyback) or –0.8V (inverting) - determines output polarity and setpoint. |
| EN/UVLO (Pin 25) | Enable and input undervoltage lockout | 1.22V falling threshold with programmable hysteresis; disables IC below VIN threshold and resets soft-start on dropout. |
| RT (Pin 33) | Frequency programming | Resistor-to-SGND sets switching frequency (100kHz–1MHz); value defined per Table 1 in datasheet (e.g., 41.2kΩ = 300kHz). |
| SYNC (Pin 34) | External clock synchronization | Accepts TTL/CMOS clock; requires RT setting 20% slower than SYNC frequency; disabled when tied to SGND. |
| VC (Pin 30) | Error amplifier compensation | Connect RC network to SGND for loop stability; sets bandwidth and phase margin in current-mode control architecture. |
| INTVCC (Pin 28) | Internal 5.2V LDO output | Powers gate driver and logic; requires ≥4.7μF ceramic cap to SGND; can be bypassed to VIN or VOUT (if ≤8V) to reduce losses. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-polarity feedback regulation | Single FBX pin supports +1.6V (positive VOUT) or –0.8V (negative VOUT) reference - eliminates need for external level-shifting circuitry in inverting designs. |
| Integrated 5.2V LDO with 95mA output | Powers internal gate driver and logic from VIN; reduces external bias supply count and improves start-up reliability in wide-input systems. |
| Programmable input UVLO with hysteresis | EN/UVLO pin allows precise turn-on/off thresholds (e.g., 9V ON / 7.5V OFF) using external resistive divider - prevents brown-out oscillation in automotive transients. |
| Frequency foldback during low-FBX conditions | Automatically reduces switching frequency when FBX approaches SGND (e.g., during startup or output short) - prevents current runaway due to minimum on-time limitation. |
| Thermally optimized QFN package | 36-lead 5mm×6mm QFN with dual exposed pads (SW and SGND) - achieves θJA = 42°C/W and θJC = 3°C/W for high-power density layouts. |
Applications
| Automotive LED Headlamp Driver | Industrial Isolated Sensor Supply |
|---|---|
Use Scenario: Driving high-brightness LEDs from 9V–16V vehicle battery with tight dimming control and EMI compliance. IC Role / Device Role / Timing Role: Configured as boost converter with FBX regulating +1.6V reference; SW node drives external Schottky and inductor; SYNC pin aligns switching to system clock to reduce conducted noise. Use Value: Integrated 5A switch eliminates external FET, reducing BOM count; <1μA shutdown current preserves battery during ignition-off; 125°C rating ensures under-hood reliability. |
Use Scenario: Generating isolated ±15V rails for precision analog sensor front-ends in factory automation PLCs. IC Role / Device Role / Timing Role: Used in flyback configuration with transformer-coupled secondary; FBX referenced to –0.8V enables negative rail generation; INTVCC powered from auxiliary winding for efficiency. Use Value: Dual-reference FBX simplifies dual-rail design; current-mode control provides fast load transient response to sensor burst-mode operation; –40°C to 125°C range supports uncooled enclosures. |
| Telecom DC-DC Intermediate Bus Converter | Medical Portable Device Power Management |
Use Scenario: Stepping 48V telecom rectified input down to 12V intermediate bus in compact base station modules. IC Role / Device Role / Timing Role: Operated as SEPIC converter to maintain regulation during input dips; RT set to 500kHz for small magnetics; SYNC tied to system timing reference for deterministic EMI. Use Value: 40V absolute max SW rating accommodates 48V transients; frequency foldback prevents inrush damage during hot-swap events; QFN package enables high-density layout. |
Use Scenario: Powering multi-rail subsystems (3.3V, 5V, –5V) in battery-operated ultrasound handheld units with strict leakage and thermal constraints. IC Role / Device Role / Timing Role: Implements inverting topology for –5V rail using FBX at –0.8V; SS pin controls startup slew rate to avoid battery voltage sag; EN/UVLO disables converter below 3.2V. Use Value: <1μA shutdown IQ extends battery life between scans; integrated LDO reduces external regulators; 36-lead QFN allows compact, low-profile assembly compatible with handheld form factor. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3787EUF#PBF | Requires external MOSFETs; no integrated switch; supports up to 40V input but lacks FBX dual-reference capability. | Better suited for high-current (>10A), multi-phase, or synchronous rectified designs where discrete FET optimization is needed. | Select LTC3787EUF#PBF when higher output current, synchronous rectification, or custom FET selection is required - not a drop-in replacement. |
| LM5122MMX/NOPB | Integrated 2.5A/65V switch; fixed 1.5V FB reference only; no negative-output support; lower max input (65V vs 40V absolute on SW). | Optimized for high-voltage boost in solar microinverters or PoE PSE; lacks inverting/SEPIC flexibility and dual-polarity regulation. | Choose LM5122MMX/NOPB for cost-sensitive, single-polarity 48V-input boost applications - not suitable for negative rails or automotive cold-crank robustness. |
Compared with LTC3787EUF#PBF and LM5122MMX/NOPB, LT3957AEUHE#TRPBF uniquely combines integrated 5A switching, dual-polarity FBX regulation, and automotive-grade temperature range in one QFN package - making it the only option among the three capable of standalone inverting or SEPIC operation without external high-side FETs or level-shifters.
Availability
LT3957AEUHE#TRPBF is available at Aetrix Electronics and suitable for automotive lighting, industrial sensor power, telecom intermediate bus, and portable medical device applications requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned reliability.
Supply support for LT3957AEUHE#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving aerospace, automotive, industrial, and communications markets.
The LT3957A product line was designed specifically for flexible, high-efficiency DC/DC conversion in space- and thermal-constrained environments - emphasizing integrated power switches, wide input ranges, and topology-agnostic control for automotive and industrial power systems.
FAQ
What topology configurations does the LT3957AEUHE#TRPBF support?
The LT3957AEUHE#TRPBF supports boost, flyback, SEPIC, and inverting converter topologies using a single FBX pin. Its dual-reference feedback (±1.6V/–0.8V) enables positive or negative output voltage generation without external op-amps or level shifters. The internal 5A/40V N-MOSFET eliminates the need for an external high-side switch in most implementations of these topologies.
How is the switching frequency programmed on the LT3957AEUHE#TRPBF?
The LT3957AEUHE#TRPBF switching frequency is set by connecting a resistor from the RT pin (Pin 33) to SGND. Values range from 10.5kΩ (1MHz) to 140kΩ (100kHz), with standard values tabulated in the datasheet (e.g., 41.2kΩ = 300kHz). For synchronization, the RT resistor must be selected for a frequency 20% slower than the external SYNC clock to ensure reliable locking.
Can the LT3957AEUHE#TRPBF generate negative output voltages?
Yes, the LT3957AEUHE#TRPBF can generate negative output voltages when configured as an inverting converter. In this mode, the FBX pin regulates to –0.8V, and the output voltage is calculated as VOUT = –0.8V × (1 + R2/R1). This capability is built into the IC's internal comparators (A1/A2) and requires no additional components beyond the standard resistor divider and power stage.
What is the purpose of the frequency foldback function in the LT3957AEUHE#TRPBF?
The frequency foldback function in the LT3957AEUHE#TRPBF reduces switching frequency when the FBX pin voltage drops near SGND - such as during startup, output short-circuit, or heavy overload. This prevents peak inductor current from exceeding the 5A limit due to minimum on-time constraints at high frequencies, thereby protecting the internal MOSFET and external magnetics without requiring additional current-limit circuitry.
How should the INTVCC pin be bypassed on the LT3957AEUHE#TRPBF?
The INTVCC pin of the LT3957AEUHE#TRPBF must be bypassed to SGND with a minimum 4.7μF ceramic capacitor placed immediately adjacent to the pin. This capacitor supplies high transient gate-drive currents and stabilizes the internal 5.2V LDO. If INTVCC is externally powered (e.g., from VOUT via diode), the same 4.7μF capacitor remains mandatory - no reduction in capacitance is permitted regardless of external biasing method.
LT3957AEUHE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 36-WFQFN, 28 Leads, Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Boost, Cuk, Flyback, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.6V
- Voltage - Output (Max):
- 40V (Switch)
- Current - Output:
- 5A (Switch)
- Frequency - Switching:
- 100kHz ~ 1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-QFN (5x6)
LT3957AEUHE#TRPBF FAQ
1.How can I place an order for LT3957AEUHE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3957AEUHE#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 LT3957AEUHE#TRPBF reliable?
The price and inventory of LT3957AEUHE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3957AEUHE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3957AEUHE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3957AEUHE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3957AEUHE#TRPBF?
LT3957AEUHE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3957AEUHE#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 LT3957AEUHE#TRPBF?
For technical support, including LT3957AEUHE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3957AEUHE#TRPBF requirements.
6.How does Aetrix verify that LT3957AEUHE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3957AEUHE#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 LT3957AEUHE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3957AEUHE#TRPBF?
All LT3957AEUHE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3957AEUHE#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 LT3957AEUHE#TRPBF part is unused and in its original packaging.
Return procedure for LT3957AEUHE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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