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Analog Devices Inc. LT3791IFE#TRPBF
- Part No.:
- LT3791IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3791IFE#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,611
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Product details
Overview
LT3791IFE#TRPBF from Analog Devices is a 60V synchronous 4-switch buck-boost LED driver controller in a 38-lead TSSOP package with exposed pad. It regulates LED current up to 52V output with input voltages from 4.7V to 60V, supports True Color PWM™ and analog dimming, achieves ±6% LED current accuracy, and enables seamless transitions between buck, boost, and buck-boost modes - ideal for automotive headlamps and industrial lighting systems.
For engineers reviewing the LT3791IFE#TRPBF datasheet, LT3791IFE#TRPBF pinout, LT3791IFE#TRPBF application, or LT3791IFE#TRPBF equivalent, key selection considerations include its 200kHz–700kHz adjustable switching frequency, dual current-sense architecture (LED and input), open/shorted LED fault protection, 38-pin TSSOP thermal performance, and compatibility with high-power 100W+ LED strings requiring VIN above, below, or equal to VOUT.
Technical Context
The LT3791IFE#TRPBF implements a constant-frequency, forced-continuous conduction mode control architecture with independent input and output current regulation loops. Its proprietary 4-switch single-inductor topology uses two separate gate drivers (TG1/BG1 and TG2/BG2) to manage four external N-channel MOSFETs, enabling bidirectional power flow without top-MOSFET refresh cycles in pure buck or boost operation.
It integrates dual high-side current sense amplifiers (for ISP/ISN and IVINP/IVINN), a 2.00V reference (±2%), VC error amplifier with 0.7V–1.9V range, and dedicated fault comparators for OPENLED (1.15V FB threshold) and SHORTLED (400mV FB threshold), all operating across –40°C to +125°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.7V to 60V - supports wide automotive battery transients and industrial DC rails without pre-regulation. |
| Output Voltage Capability | 0V to 60V (52V LED string max) - enables direct drive of multi-series LED arrays without intermediate conversion. |
| LED Current Accuracy | ±6% over 0V ≤ VLED < 52V - ensures consistent luminance across temperature and line variations. |
| Switching Frequency | 200kHz to 700kHz (RT-programmable) - balances EMI, efficiency, and inductor size for compact high-power designs. |
| Current Sense Threshold | V(ISP–ISN) = 100mV default (adjustable via CTRL pin) - sets precise LED current with 10× ISMON monitor scaling. |
| Fault Protection | Open LED (FB > 1.15V), Short LED (FB < 400mV), OVLO (>3V), thermal shutdown - autonomous safety response without host intervention. |
| Package | 38-Lead TSSOP with exposed pad - provides 28°C/W θJA for reliable 100W+ operation with standard PCB copper. |
Pinout & Package
Package: 38-Lead Plastic TSSOP with Exposed Pad (Pin 39 = SGND). Exposed pad must be soldered to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CTRL (1) | Analog dimming threshold adjust | Sets V(ISP–ISN) threshold linearly from 200mV to 1.1V; 100mV default when tied to VREF. |
| SS (2) | Soft-start & fault timer | Controls startup inrush; latches off on open/short LED if pulled to VREF via 500kΩ resistor. |
| PWM (3) | Digital dimming enable | Active-low signal halts switching and disconnects VC; drives PWMOUT for external LED disconnect MOSFET. |
| OPENLED (4) | Open-circuit fault indicator | Open-drain output asserting when FB > 1.15V and V(ISP–ISN) < 10mV - requires external pull-up. |
| SHORTLED (5) | Short-circuit fault indicator | Open-drain output asserting when FB < 400mV - requires external pull-up. |
| VREF (6) | 2.00V precision reference | Stable 2.00V ±2% output; supplies bias for CTRL divider and supports up to 200µA load. |
| ISMON (7) | LED current monitor | 10× scaled V(ISP–ISN); outputs 1V at 100mV sense voltage for accurate current telemetry. |
| IVINMON (8) | Input current monitor | 20× scaled V(IVINP–IVINN); outputs 1V at 50mV sense voltage for input power limiting. |
| EN/UVLO (9) | Enable & undervoltage lockout | 1.2V falling threshold with 15mV hysteresis; sub-µA bias above threshold, 3µA pull-down below. |
| ISP / ISN (25/26) | LED current sense inputs | Differential pair for high-side LED current sensing; common-mode range 0V–60V. |
| IVINP / IVINN (10/11) | Input current sense inputs | Differential pair for input current limiting; common-mode range 3V–60V, 50mV threshold. |
| TG1 / BG1 (14/18), TG2 / BG2 (24/19) | N-channel gate drivers | High-side (TG) drivers use bootstrap (BST1/BST2); low-side (BG) drivers referenced to PGND. |
| SW1 / SW2 (16/21) | Switch node connections | SW1 connects to VIN-side inductor node; SW2 connects to VOUT-side inductor node. |
| PGND (17,20) | Power ground return | Low-impedance return path for bottom MOSFET sources and high-current paths. |
| SGND (30,39) | Signal ground reference | Reference for all small-signal pins (FB, CTRL, SS, etc.); must connect to PGND at single point. |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor architecture | Enables continuous VIN > VOUT (buck), VIN < VOUT (boost), and VIN ≈ VOUT (buck-boost) operation without mode discontinuities. |
| True Color PWM™ dimming | Preserves LED color fidelity across dimming range by maintaining constant current during PWM on-time. |
| Dual independent current regulation | Simultaneous LED current (ISP/ISN) and input current (IVINP/IVINN) control prevents overloading source or LED string. |
| No top-MOSFET refresh cycle | Eliminates unnecessary switching losses in pure buck or boost modes, improving efficiency by ~1–2%. |
| VOUT disconnected from VIN during shutdown | Prevents backfeed from LED string into input supply when EN/UVLO is low, enhancing system safety. |
| Integrated fault diagnostics | Hardware-based OPENLED/SHORTLED flags and OVLO shutdown reduce firmware dependency and improve reliability. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting systems requiring dynamic beam shaping and high-lumen output from 12V/24V vehicle batteries. IC Role / Device Role / Timing Role: Primary LED current controller managing 3A–5A strings across varying battery voltage (6V–16V) and load conditions. Use Value: Seamless buck-boost transition maintains constant LED brightness during cold cranking (6V) and alternator surge (16V) without flicker or dropout. | Use Scenario: 100W+ LED fixtures for warehouse and factory floor illumination powered from 24V–48V DC distribution. IC Role / Device Role / Timing Role: Constant-current regulator driving 33.3V × 3A LED arrays with programmable dimming and input current limiting. Use Value: ±6% LED current accuracy ensures uniform light output across parallel fixtures; 98.5% peak efficiency reduces thermal load in enclosed housings. |
| Battery-Powered Emergency Lighting | UV-C Disinfection Systems |
Use Scenario: Portable or backup lighting using Li-ion or lead-acid batteries (10V–58V range) with strict runtime and thermal constraints. IC Role / Device Role / Timing Role: Buck-boost LED driver enabling full-power operation across entire battery discharge curve without voltage conversion stages. Use Value: 4.7V minimum VIN allows deep discharge utilization; 0.1µA shutdown IQ extends battery life during standby. | Use Scenario: High-intensity UV-C LED arrays (365nm–275nm) requiring precise current control to maintain germicidal efficacy and diode lifetime. IC Role / Device Role / Timing Role: Precision current source regulating UV-C LEDs at fixed current despite forward voltage drift with temperature. Use Value: ±6% LED current accuracy prevents under-dosing (reduced kill rate) or over-driving (premature LED failure) in critical disinfection applications. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8391EFE#TRPBF | Successor IC with improved efficiency (up to 99%), lower IQ (2.5mA vs 4mA), integrated boost converter for gate drive, and enhanced spread-spectrum EMI reduction. | Designed for new designs requiring higher power density and stricter EMI compliance; not drop-in compatible due to different pinout and control logic. | Select LT8391EFE#TRPBF for new projects where efficiency, EMI, and integration outweigh legacy design continuity. |
| LTC3789EGN#TRPBF | 4-switch buck-boost controller with 40V rating, no integrated LED-specific features (no OPENLED/SHORTLED, no ISMON/IVINMON), and narrower VIN range (4.5V–38V). | General-purpose DC/DC conversion only; lacks LED protection, dimming interfaces, and current monitor outputs required for lighting applications. | Use LTC3789EGN#TRPBF only for non-LED power conversion where LED-specific functions are unnecessary. |
Compared with LT8391EFE#TRPBF and LTC3789EGN#TRPBF, the LT3791IFE#TRPBF delivers purpose-built LED control with hardware fault flags and dual current monitoring, while the LT8391 offers superior specs for new designs and the LTC3789 serves general DC/DC needs without lighting-specific circuitry.
Availability
LT3791IFE#TRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, and battery-powered emergency lighting requiring stable component supply, long-term lifecycle support, and guaranteed temperature-grade performance.
Supply support for LT3791IFE#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.
The LT3791IFE#TRPBF belongs to ADI's Power by Linear™ LED driver controller product line, engineered specifically for high-efficiency, high-reliability LED lighting systems operating across wide input/output voltage ranges in demanding environments.
FAQ
What is the operating temperature range for the LT3791IFE#TRPBF?
The LT3791IFE#TRPBF is rated for operation from –40°C to +125°C junction temperature. This I-grade temperature specification ensures reliable performance in automotive under-hood and industrial ambient environments where thermal stress is significant. The device includes internal overtemperature protection that activates above 150°C to prevent permanent damage.
Does the LT3791IFE#TRPBF support both analog and PWM dimming simultaneously?
Yes, the LT3791IFE#TRPBF supports True Color PWM™ dimming and analog dimming concurrently. Analog dimming is implemented via the CTRL pin to adjust the LED current sense threshold, while PWM dimming uses the PWM pin to rapidly enable/disable switching. Both methods preserve LED color consistency and can be used together for fine-grained brightness control in applications like adaptive lighting.
How does the LT3791IFE#TRPBF handle open or shorted LED faults?
The LT3791IFE#TRPBF detects open LED faults when FB exceeds 1.15V while V(ISP–ISN) falls below 10mV, asserting the OPENLED pin. It detects shorted LED faults when FB drops below 400mV, asserting the SHORTLED pin. Both pins are open-drain and require external pull-up resistors. Fault conditions trigger automatic latch-off unless SS is configured for auto-restart.
Can the LT3791IFE#TRPBF drive LED strings with forward voltages exceeding 52V?
No, the LT3791IFE#TRPBF is specified for LED strings up to 52V maximum output voltage. While its VOUT capability reaches 60V, the datasheet explicitly states "52V LED" as the practical limit for regulated LED current operation. Driving strings beyond 52V risks violating the ±6% current accuracy specification and may compromise fault protection thresholds.
What is the purpose of the TEST1 and TEST2 pins on the LT3791IFE#TRPBF?
TEST1 (Pin 29) must be connected to SGND, and TEST2 (Pin 32) must be connected to INTVCC for proper operation of the LT3791IFE#TRPBF. These pins are reserved for factory testing and have no user functionality; leaving them unconnected will prevent the IC from initializing correctly or cause erratic behavior in the gate drive and control loops.
LT3791IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- True Color PWM™
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 4.7V
- Voltage - Supply (Max):
- 60V
- Voltage - Output:
- 0V ~ 60V
- Current - Output / Channel:
- -
- Frequency:
- 200 ~ 700kHz
- Dimming:
- Analog, PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP-EP
LT3791IFE#TRPBF FAQ
1.How can I place an order for LT3791IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3791IFE#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 LT3791IFE#TRPBF reliable?
The price and inventory of LT3791IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3791IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3791IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3791IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3791IFE#TRPBF?
LT3791IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3791IFE#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 LT3791IFE#TRPBF?
For technical support, including LT3791IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3791IFE#TRPBF requirements.
6.How does Aetrix verify that LT3791IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3791IFE#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 LT3791IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3791IFE#TRPBF?
All LT3791IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3791IFE#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 LT3791IFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3791IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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