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Analog Devices Inc. LT3796IFE#PBF
- Part No.:
- LT3796IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3796IFE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:524
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Product details
Overview
LT3796IFE#PBF from Analog Devices (formerly Linear Technology) is a 100V constant-current/constant-voltage DC/DC controller optimized for high-power LED driving with dual current sensing, 3000:1 true-color PWM dimming, and programmable open-LED protection. It supports boost, buck-boost, SEPIC, and flyback topologies, operates from 6V to 100V input, delivers up to 100V output, and regulates LED current with ±1% full-scale accuracy via ISP/ISN inputs.
For engineers reviewing the LT3796IFE#PBF datasheet, LT3796IFE#PBF pinout, LT3796IFE#PBF application, or LT3796IFE#PBF equivalent, key selection criteria include its dual-loop capability (current + voltage), rail-to-rail ISP/ISN common-mode range (0–100V), independent top-gate PMOS driver (TG), 100kHz–1MHz adjustable switching frequency, and integrated C/10 battery charging detection.
Technical Context
The LT3796IFE#PBF implements fixed-frequency current-mode control with two ground-referred feedback pins (FB1, FB2) enabling simultaneous constant-current and constant-voltage regulation. Its dual current sense architecture includes a primary ISP/ISN amplifier (0–100V common mode, ±3mV offset) and a secondary high-side CSOUT amplifier configurable via external resistors.
It features an independent top-gate driver (TG) with 7V gate clamp for PMOS disconnect, a dedicated PWM input for high-ratio dimming, and VMODE/FAULT open-collector flags for fault reporting. The device integrates a 7.7V LDO (INTVCC), soft-start with fault restart timer, and programmable undervoltage lockout with hysteresis on EN/UVLO.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports wide-range industrial and automotive input rails without pre-regulation |
| Output Current Sense Range | 0–100V common-mode on ISP/ISN - enables high-side or low-side LED string sensing in boost/flyback configurations |
| Switching Frequency | 100kHz to 1MHz (RT-programmable) - balances efficiency vs. size for high-power LED drivers |
| Current Regulation Accuracy | ±1% full-scale (250mV threshold) - ensures precise LED brightness control across temperature |
| Dimming Ratio | 3000:1 true-color PWM - maintains color consistency at ultra-low duty cycles without flicker |
| Integrated Protection | C/10 battery detection, open-LED (VMODE), overcurrent (375mV ISP–ISN), thermal shutdown - reduces external component count for charger and lighting systems |
| Package | 28-Lead TSSOP with exposed pad - provides thermal performance for >5W dissipation in compact layouts |
Pinout & Package
LT3796IFE#PBF is housed in a 28-lead plastic TSSOP (FE package) with exposed thermal pad (Pin 29 = GND). The package supports surface-mount assembly and requires soldering of the exposed pad to PCB ground plane for thermal integrity and electrical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP (1) | Positive current sense input / TG driver rail | Serves as high-side current sense node and power supply for TG driver; rated to 100V |
| ISN (2) | Negative current sense input | Completes ISP–ISN differential pair; supports rail-to-rail common-mode operation (0–100V) |
| TG (3) | Top-gate PMOS driver output | Drives external PMOS disconnect switch with internal 7V clamp; enables safe LED string isolation |
| GND (4,17,21,22,29) | Power and signal ground | Multiple ground pins reduce noise coupling; exposed pad (29) must be soldered to PCB ground plane |
| ISMON (5) | Current monitor output | Provides scaled replica of LED current (VISMON = ILED × RLED × 4); used for system-level monitoring |
| FB2 (6) | Voltage loop feedback 2 | Regulates second output (e.g., auxiliary rail or second LED string) to 1.25V; triggers TG/GATE shutdown if driven >1.3V |
| FB1 (7) | Voltage loop feedback 1 | Enables constant-voltage mode or open-LED detection; asserts VMODE flag when V(ISP–ISN) <25mV and FB1 >1.19V |
| VC (8) | Error amplifier output | Integrates error signal for current/voltage loop; high-impedance during PWM low to retain state |
| CTRL (9) | Current threshold programming | Sets ISP–ISN regulation threshold (0.25×VCTRL + offset); 0.2–1.2V range enables analog dimming |
| VREF (10) | 2.015V reference output | Stable reference for CTRL biasing and external circuitry; supplies up to 100µA |
| SS (11) | Soft-start / fault timer | Controls startup ramp and latches faults; pulled down to restart after discharge below 0.2V |
| RT (12) | Frequency programming | Resistor-to-GND sets oscillator frequency (100kHz–1MHz); tolerance directly impacts switching accuracy |
| TGEN (13) | Top-gate enable (LT3796-1 variant) | Independent control of TG driver; allows disabling one current loop without affecting PWM or oscillator |
| PWM (14) | Digital dimming input | Active-low signal disables switching, idles oscillator, and forces TG high; enables 3000:1 dimming |
| FAULT (15) | Open-collector fault flag | Pulled low on FB1 overvoltage, INTVCC UVLO, LED overcurrent, or thermal shutdown; latched during PWM low |
| VMODE (16) | Open-LED status flag | Pulled low when FB1 >1.19V and V(ISP–ISN) <25mV - indicates LED string open-circuit condition |
| SENSE (18) | Switch current sense input | Kelvin-connected to high-side of RSENSE; monitors NMOS switch current for cycle-by-cycle limiting |
| GATE (19) | NMOS gate driver output | Drives external N-channel MOSFET between INTVCC and GND; 20ns rise/fall time into 3300pF |
| INTVCC (20) | Internal LDO output | 7.7V regulated supply for gate drivers and logic; bypassed with 4.7µF ceramic capacitor |
| VIN (23) | Main input supply | Accepts 6–100V; locally bypassed with ≥0.22µF capacitor; powers INTVCC LDO |
| EN/UVLO (24) | Enable and UVLO input | 1.22V falling threshold with programmable hysteresis; sub-µA bias current below threshold |
| VS (25) | Current sense amplifier supply | 3–100V supply for ISP/ISN amplifier; decoupled internally; enables high-voltage sensing |
| CSN (26) | Current sense amplifier negative input | Reference terminal for CSP amplifier; tied to VS in typical configurations |
| CSP (27) | Current sense amplifier positive input | Sinks current proportional to V(ISP–ISN); used with external resistor for ISMON scaling |
| CSOUT (28) | Current sense amplifier output | Sources current proportional to ISP–ISN voltage; drives external resistor for analog monitoring |
Key Features
| Feature | Design Value |
|---|---|
| Dual current sense amplifiers | Primary ISP/ISN (0–100V CMR, ±3mV offset) + secondary CSP/CSN (programmable gain) enable independent regulation of two LED strings or current+voltage loops |
| Programmable top-gate driver | TG pin drives external PMOS with 7V gate clamp and 50ns rise time, enabling safe high-voltage LED string disconnect without layout compromises |
| True-color PWM dimming | 3000:1 ratio achieved via synchronized PWM input and internal latch timing, preserving LED chromaticity at low duty cycles |
| C/10 battery charging detection | Integrated comparator triggers at V(ISP–ISN) = 25mV with 200mV hysteresis, supporting accurate termination for Li-ion and supercapacitor charging |
| Adjustable frequency synchronization | RT pin sets 100kHz–1MHz range; LT3796 variant supports external SYNC input for EMI reduction in multi-rail systems |
| Comprehensive fault reporting | Separate VMODE (open-LED) and FAULT (overcurrent/UVLO/thermal) open-collector outputs simplify system-level diagnostics and safety interlocks |
Applications
| High-Power LED Lighting | Battery & Supercapacitor Charging |
|---|---|
Use Scenario: Driving 80W+ LED arrays in streetlights or industrial high-bay fixtures using boost topology with 48V–96V input. IC Role / Device Role / Timing Role: Constant-current controller regulating LED string current via ISP/ISN; TG pin isolates string during fault or dimming off-cycle. Use Value: 3000:1 PWM dimming preserves color fidelity; 100V rating eliminates need for input pre-regulators; dual FB pins support auxiliary voltage rails. | Use Scenario: Precision charging of 48V LiFePO₄ battery packs or 50V supercapacitor banks from variable solar or DC bus sources. IC Role / Device Role / Timing Role: Accurate current-limited voltage regulator using FB1 for CV stage and C/10 detection on ISP/ISN for CC termination. Use Value: ±1% current regulation ensures cell balancing; programmable UVLO prevents deep discharge; ISMON provides real-time charge current telemetry. |
| Industrial Power Supplies | Automotive Exterior Lighting |
Use Scenario: Programmable 24V–72V output power supply for factory automation controllers requiring stable current-limited operation. IC Role / Device Role / Timing Role: Constant-voltage regulator with current limiting via SENSE pin; FB2 configures auxiliary 5V rail for logic; FAULT signals overcurrent to PLC. Use Value: Dual-loop regulation meets IEC 61000-4-5 surge immunity requirements; 100V input withstand accommodates 75V transients per ISO 7637-2. | Use Scenario: Adaptive front-lighting system (AFS) headlamp module with separate high-beam and low-beam LED strings. IC Role / Device Role / Timing Role: Dual-string controller using ISP/ISN for main beam and CSP/CSN for auxiliary beam; TGEN enables independent beam activation. Use Value: Independent top-gate control allows fast beam switching (<10ms); VMODE detects open-circuit filaments for fail-safe reporting per UNECE R149. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current/constant-voltage controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Single current sense input; no TG driver; 60V max input; no C/10 detection | Lacks dual-string capability and high-voltage disconnect; suited for lower-power, single-LED applications | Select when cost sensitivity outweighs need for 100V operation or PMOS isolation |
| LM34927QMH/NOPB | Fixed 600kHz frequency; no programmable dimming; 65V max input; no VMODE/FAULT flags | Designed for automotive LED headlamps but lacks open-LED reporting and flexible topology support | Choose for AEC-Q100-compliant designs where qualification priority exceeds feature set |
Compared with LTC3783EFE#PBF and LM34927QMH/NOPB, the LT3796IFE#PBF offers unique 100V operation, dual current sensing, integrated TG driver, and C/10 charging detection - making it the only option capable of single-chip 80W+ LED driving with battery charging functionality.
Availability
LT3796IFE#PBF is available at Aetrix Electronics and suitable for high-power LED lighting, battery charging systems, and industrial power supplies requiring stable component supply, extended temperature operation (–40°C to 125°C), and long-term lifecycle support.
Supply support for LT3796IFE#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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for the LT3796 family.
The LT3796 product line was designed specifically for high-voltage, high-power LED driver and precision current-limited power supply applications - emphasizing robust fault handling, dual-loop regulation, and seamless integration with PMOS/NMOS power stages.
FAQ
What is the maximum input voltage rating for the LT3796IFE#PBF?
The LT3796IFE#PBF has an absolute maximum input voltage rating of 100V on VIN, EN/UVLO, ISP, ISN, CSP, and CSN pins. This allows direct operation from 48V, 60V, or 72V industrial and automotive buses without external pre-regulation. The device is specified to operate continuously from 6V to 100V input, with transient tolerance up to 100V as confirmed in the Typical Application schematic.
Does the LT3796IFE#PBF support dual LED string regulation?
Yes, the LT3796IFE#PBF supports dual LED string regulation through its dual current sense architecture: the primary ISP/ISN inputs regulate the main string, while the secondary CSP/CSN amplifier - combined with FB2 - enables independent regulation of a second string or auxiliary voltage rail. The TGEN pin (LT3796-1 variant) allows software-controlled enable/disable of the second loop without disrupting the primary PWM dimming.
How does the VMODE flag function on the LT3796IFE#PBF?
The VMODE flag on the LT3796IFE#PBF is an open-collector output that pulls low when FB1 exceeds 1.19V (typical) and V(ISP–ISN) falls below 25mV (typical), indicating an open-LED condition. It updates only during PWM high time and latches during PWM low, providing reliable fault reporting even during dimming intervals. An external pull-up resistor is required for proper operation.
Can the LT3796IFE#PBF be used for battery charging applications?
Yes, the LT3796IFE#PBF includes integrated C/10 charging termination detection, with a comparator threshold of 25mV on V(ISP–ISN) and 200mV hysteresis. This enables precise end-of-charge detection for Li-ion, LiFePO₄, and supercapacitor systems. Combined with ±1% current regulation and programmable UVLO, it functions as a complete current-limited voltage regulator for charging circuits.
What is the purpose of the TG pin on the LT3796IFE#PBF?
The TG pin on the LT3796IFE#PBF is a top-gate driver output designed to control an external high-side PMOS transistor for LED string disconnect. It provides an inverted PWM signal with internal 7V gate clamp to protect the PMOS, enabling safe isolation of the LED load during fault conditions, dimming off-cycles, or system standby - a critical feature for safety-critical lighting and charging applications.
LT3796IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- True Color PWM™
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- SEPIC, Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 6V
- Voltage - Supply (Max):
- 100V
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 100kHz ~ 1MHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LT3796IFE#PBF FAQ
1.How can I place an order for LT3796IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3796IFE#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 LT3796IFE#PBF reliable?
The price and inventory of LT3796IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3796IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3796IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3796IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3796IFE#PBF?
LT3796IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3796IFE#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 LT3796IFE#PBF?
For technical support, including LT3796IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3796IFE#PBF requirements.
6.How does Aetrix verify that LT3796IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3796IFE#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 LT3796IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3796IFE#PBF?
All LT3796IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3796IFE#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 LT3796IFE#PBF part is unused and in its original packaging.
Return procedure for LT3796IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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