LT3791IFE#PBF - 60V 4-Switch Sync Buck-Boost LED Driver | ADI
MPN: LT3791IFE#PBF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.51 | $6.51 |
| 10 | $5.95 | $59.50 |
| 100 | $5.2 | $520.00 |
| 500 | $4.8 | $2,400.00 |
| 1,000 | $4.5 | $4,500.00 |
LT3791IFE#PBF Overview
A buck-boost LED driver controller is a power management IC that regulates current through an LED string by stepping up or stepping down the input voltage as needed. Unlike a simple buck or boost converter, the 4-switch topology allows seamless transition between modes, ensuring stable LED current even when the input voltage fluctuates around the output voltage. This makes it ideal for automotive, industrial, and architectural lighting where input voltage variations are common.
Key features include a wide 4.7V to 60V input range, output voltage up to 52V, and the ability to drive high-power LEDs with efficiency exceeding 95%. The controller integrates four external MOSFET drivers, supports spread spectrum for low EMI, and includes protection features such as overvoltage, overcurrent, and thermal shutdown. Its constant-frequency operation simplifies EMI filtering and allows synchronization to an external clock.
The LT3791 uses a current mode control architecture with a precision reference, enabling accurate LED current regulation. The forced-continuous mode ensures low output ripple and predictable operation across all load conditions. The device also features a low supply current of 4000uA, making it efficient for battery-powered applications.
Typical applications include automotive LED headlights, industrial high-bay lighting, architectural lighting, and general-purpose constant-current LED drivers. Its wide input range and buck-boost capability make it versatile for systems with varying supply voltages, such as those powered by batteries or solar panels.
When designing with the LT3791, ensure proper PCB layout with short, low-inductance paths for the switching nodes and adequate thermal management for the external MOSFETs. The exposed pad on the TSSOP-EP package should be soldered to a large copper area for heat dissipation.
Drop-in alternatives for LT3791IFE#PBF — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LT3791IFE#PBF (same form factor and footprint) — differing in Dimming, Switching Frequency, Input Voltage Range, Operating Temperature Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LT3791EFE#PBF
✅ Drop-In✓ In Stock
$10.76 / Unit
View Datasheet →LT3791HFE#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT3791IFE-1#PBF
✅ Drop-In📋 Reference alternative (not in catalog)
LT3791EFE#TRPBF
✅ Drop-In✓ In Stock
$5.5 / Unit
View Datasheet →TPS92630
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
NCL30051
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MAX16832
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LT3791IFE#PBF Maximum Ratings & Electrical Characteristics
| Topology | Buck-Boost |
| Number of Outputs | 1 |
| Input Voltage Range | 4.7 V to 60 V |
| Output Voltage Range | Up to 52 V |
| Switching Frequency | 200 kHz to 700 kHz |
| Dimming | Analog, PWM |
| Supply Current | 4000 uA |
| Package | 38-TSSOP-EP |
| Mounting Style | SMD/SMT |
| Operating Temperature Range | -40C to +125C |
| RoHS | Compliant |
| Series | LT3791 |
| Product Category | LED Lighting Drivers |
| Control Architecture | Current Mode |
| Synchronous Rectification | Yes |
LT3791IFE#PBF Pin Configuration
| Pin 1 | BOOST1 — Bootstrap for top FET 1 |
| Pin 2 | TG1 — Top gate drive 1 |
| Pin 3 | SW1 — Switch node 1 |
| Pin 4 | BG1 — Bottom gate drive 1 |
| Pin 5 | VIN — Input supply |
| Pin 6 | VIN — Input supply |
| Pin 7 | BG2 — Bottom gate drive 2 |
| Pin 8 | SW2 — Switch node 2 |
| Pin 9 | TG2 — Top gate drive 2 |
| Pin 10 | BOOST2 — Bootstrap for top FET 2 |
| Pin 11 | VOUT — Output voltage sense |
| Pin 12 | VOUT — Output voltage sense |
| Pin 13 | SENSE+ — Positive current sense |
| Pin 14 | SENSE- — Negative current sense |
| Pin 15 | CTRL — Current control input |
| Pin 16 | PWM — PWM dimming input |
| Pin 17 | SS — Soft-start |
| Pin 18 | FREQ — Frequency set |
| Pin 19 | SYNC — Synchronization input |
| Pin 20 | MODE — Mode select |
| Pin 21 | VREF — Reference output |
| Pin 22 | FB — Feedback |
| Pin 23 | VC — Compensation |
| Pin 24 | OVP — Overvoltage protection |
| Pin 25 | UVLO — Under-voltage lockout |
| Pin 26 | RUN — Enable |
| Pin 27 | GND — Ground |
| Pin 28 | GND — Ground |
| Pin 29 | GND — Ground |
| Pin 30 | GND — Ground |
| Pin 31 | GND — Ground |
| Pin 32 | GND — Ground |
| Pin 33 | GND — Ground |
| Pin 34 | GND — Ground |
| Pin 35 | GND — Ground |
| Pin 36 | GND — Ground |
| Pin 37 | GND — Ground |
| Pin 38 | GND — Ground |
Typical Applications
LT3791IFE#PBF is suitable for 6 applications: Automotive LED Headlights, Industrial High-Bay Lighting, Architectural Lighting, Battery-Powered LED Lighting, Solar-Powered Street Lighting, General-Purpose Constant-Current LED Driver.
Automotive LED Headlights
The LT3791IFE#PBF is ideal for automotive LED headlights due to its wide 4.7V to 60V input range, which accommodates load-dump and cold-crank conditions. Its 4-switch buck-boost topology maintains constant LED current even when battery voltage fluctuates above or below the LED string voltage. The controller supports PWM dimming for adaptive driving beams and has a low 4000uA supply current for efficiency. With output up to 52V, it can drive multiple high-power LEDs in series, ensuring uniform brightness. Its robust protection features, including overvoltage and thermal shutdown, enhance reliability in harsh automotive environments.
Recommended
Industrial High-Bay Lighting
For industrial high-bay lighting, the LT3791IFE#PBF provides efficient constant-current regulation for LED arrays with input voltages from 24V to 48V. Its buck-boost capability ensures stable light output even with long cable runs causing voltage drops. The adjustable 200kHz-700kHz switching frequency allows optimization for EMI and efficiency, crucial in industrial environments. The controller's analog dimming enables simple 0-10V dimming interfaces, while PWM dimming supports high-frequency dimming for advanced lighting control. Its wide temperature range (-40C to +125C) suits unheated warehouses and outdoor installations.
Recommended
Architectural Lighting
The LT3791IFE#PBF excels in architectural lighting where precise current control and dimming are essential. Its 4-switch buck-boost topology allows operation from a wide range of supply voltages, accommodating both 12V and 24V systems. The controller supports both analog and PWM dimming, enabling smooth dimming curves for aesthetic lighting effects. With output voltage up to 52V, it can drive long LED strips or multiple fixtures in series. The constant-frequency operation ensures predictable EMI, simplifying compliance with lighting standards. Its small 38-TSSOP-EP package fits compact luminaire designs.
Recommended
Battery-Powered LED Lighting
In battery-powered LED lighting, the LT3791IFE#PBF's wide input range (4.7V to 60V) allows operation from various battery chemistries, including Li-ion and lead-acid. Its buck-boost topology maintains constant LED current as the battery discharges, ensuring consistent brightness. The low 4000uA supply current minimizes battery drain, extending runtime. The controller's high efficiency (up to 95%) reduces heat generation, important for portable designs. PWM dimming allows brightness control without wasting power, making it suitable for flashlights, lanterns, and portable work lights.
Recommended
Solar-Powered Street Lighting
The LT3791IFE#PBF is well-suited for solar-powered street lighting, where input voltage from solar panels varies widely with sunlight intensity. Its 4.7V to 60V input range handles the output of solar panels, and the buck-boost topology ensures constant LED current regardless of panel voltage. The controller's high efficiency maximizes energy harvest from the solar panel, and its low supply current reduces standby power. With output up to 52V, it can drive high-power LEDs used in streetlights. The wide temperature range and robust protection make it reliable for outdoor installations.
Recommended
General-Purpose Constant-Current LED Driver
As a general-purpose constant-current LED driver, the LT3791IFE#PBF offers flexibility for a wide range of LED applications, from signage to decorative lighting. Its adjustable frequency and dimming options allow designers to tailor performance to specific needs. The 4-switch buck-boost topology eliminates the need for separate buck and boost converters, simplifying design and reducing component count. The controller's current mode architecture provides stable operation and fast transient response. Its 38-TSSOP-EP package is suitable for space-constrained designs, and the wide input range makes it adaptable to various power sources.
Recommended
Recommended Products Summary
Engineering reference data for LT3791IFE#PBF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LT3791EFE#PBF | LT3791HFE#PBF | LT3791IFE-1#PBF | TPS92630 |
|---|---|---|---|---|---|
| Package | 38-TSSOP-EP | 38-TSSOP-EP | 38-TSSOP-EP | 38-TSSOP-EP | 38-TSSOP-EP |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Texas Instruments |
Key Differentiators
- Wide input voltage range of 4.7V to 60V (vs TPS92630)
- 4-switch synchronous buck-boost topology (vs MAX16832)
- Adjustable frequency up to 700kHz (vs NCL30051)
Design Notes
For the LT3791IFE#PBF, ensure the switching nodes (SW1, SW2) have minimal trace length and area to reduce parasitic inductance and EMI. Use a solid ground plane and place the input and output capacitors close to the VIN and VOUT pins. The exposed pad (pin 38) should be soldered to a large copper area for thermal dissipation. Follow the layout guidelines in the datasheet for optimal performance.
The LT3791IFE#PBF itself dissipates minimal power, but the external MOSFETs and inductor generate significant heat in high-power LED applications. Ensure adequate heatsinking for the MOSFETs and use a PCB with sufficient copper weight (2oz or more) for the power path. The TSSOP-EP package's exposed pad should be connected to a thermal via array to the ground plane to keep the controller cool.
A common pitfall is improper bootstrap capacitor selection for the top FETs. Use a 0.1uF ceramic capacitor with low ESR for BOOST1 and BOOST2. Also, ensure the sense resistor is placed correctly between SENSE+ and SENSE- to avoid ground noise. Do not exceed the absolute maximum ratings on any pin, and verify the UVLO resistor divider to prevent unintended shutdown.
Compliance Information
RoHS compliant per Analog Devices product page. AEC-Q100 qualification not specified; for automotive, consider LT3791HFE#PBF or verify with manufacturer.
