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Analog Devices Inc. LT3796EFE#PBF
- Part No.:
- LT3796EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3796EFE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,241
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Product details
Overview
LT3796EFE#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 sense capability. It delivers up to 3000:1 true-color PWM dimming, supports input voltages from 6V to 100V, regulates LED current via ISP/ISN with programmable 250mV full-scale threshold, and integrates a rail-to-rail common-mode range current sense amplifier for accurate high-side sensing - deployed in automotive exterior lighting and industrial high-voltage LED arrays.
For engineers reviewing the LT3796EFE#PBF datasheet, LT3796EFE#PBF pinout, LT3796EFE#PBF application, or LT3796EFE#PBF equivalent, key selection criteria include its dual-loop regulation architecture (current + voltage), 28-lead TSSOP package with exposed thermal pad, 100kHz–1MHz adjustable switching frequency, integrated top-gate PMOS driver with 7V clamp, and C/10 battery charging detection capability.
Technical Context
The LT3796EFE#PBF implements fixed-frequency current-mode control with two independent feedback paths: FB1 enables open-LED protection and constant-voltage regulation at 1.25V, while FB2 provides secondary voltage loop control and overvoltage shutdown of TG/GATE when driven above 1.3V. Its dual current sense architecture includes a primary ISP/ISN amplifier (0–100V common mode, ±3mV offset) and a separate high-side CSOUT reporting channel scaled at ×4.
Control logic integrates synchronized soft-start with fault-restart timer, programmable undervoltage lockout on EN/UVLO (1.22V threshold, 20mV hysteresis), and PWM-driven idle state that disables switching, pulls TG high, and places VC in high-impedance storage mode. The device supports frequency synchronization (via SYNC pin) and features independent top-gate enable (TGEN) only on LT3796-1 variants - LT3796EFE#PBF is the standard LT3796 version without TGEN functionality.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports wide-range industrial and automotive inputs including transient 100V surges. |
| Switching Frequency | 100kHz to 1MHz - adjustable via RT resistor; enables optimization of efficiency vs. size in boost/buck-boost LED drivers. |
| Current Sense Threshold | 250mV full-scale (typical) - linearly programmable from 16mV to 250mV via CTRL pin for precise analog dimming and current scaling. |
| FB Regulation Voltage | 1.25V (FB1/FB2) - enables stable constant-voltage regulation and open-LED fault detection with ±10mV tolerance. |
| VREF Output | 2.015V (typical) - precision internal reference used to bias CTRL and external dividers; ±0.045V over temperature. |
| Operating Temperature | –40°C to +125°C junction - qualified for automotive under-hood and industrial ambient environments. |
| Package | 28-Lead TSSOP with exposed pad - thermally enhanced for high-power dissipation; requires soldering exposed pad to PCB ground plane. |
Pinout & Package
LT3796EFE#PBF is housed in a 28-lead plastic TSSOP (FE package) with exposed thermal pad (Pin 29 = GND). The exposed pad must be soldered to the PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP (1) | Positive current sense input / PMOS gate supply rail | Serves as high-side current sense node and power source for TG driver; operates up to 100V. |
| ISN (2) | Negative current sense input | Completes ISP/ISN differential pair; referenced to VS; supports rail-to-rail common-mode sensing. |
| TG (3) | Top-gate PMOS driver output | Drives external high-side PMOS disconnect switch; clamped to ISP – 7V to protect gate oxide. |
| GND (4,17,21,22,29) | Ground reference / current sense return | Multiple GND pins provide low-impedance return path for sense resistors and thermal conduction via exposed pad. |
| ISMON (5) | Current monitor output | Reports LED current as VISMON = ILED × RLED × 4; used for system-level monitoring or closed-loop feedback. |
| FB2 (6) | Secondary voltage feedback input | Regulates secondary output to 1.25V; asserts TG high and GATE low if driven >1.3V for overvoltage protection. |
| FB1 (7) | Primary voltage feedback / open-LED detection | Regulates CV mode or detects open circuit; VMODE flag pulled low when V(ISP-ISN) <25mV and FB1 >1.19V. |
| VC (8) | Error amplifier output | Integrates difference between sensed current and CTRL-set threshold; high-Z during PWM low for state retention. |
| CTRL (9) | Analog dimming / current threshold control | Sets full-scale current sense threshold from 16mV to 250mV; connect to VREF for default 250mV operation. |
| VREF (10) | 2.015V precision reference output | Stable reference for CTRL biasing and external circuits; capable of sourcing 100µA. |
| SS (11) | Soft-start / fault timer | Charged by 28µA current source; discharges via 2.8µA sink during faults; must fall below 0.2V to restart. |
| RT (12) | Frequency programming | Resistor-to-GND sets oscillator frequency; 82.5k yields ~105kHz, 19.6k yields ~400kHz, 6.65k yields ~1MHz. |
| SYNC (13) | External clock synchronization input | Accepts logic-level signal to synchronize switching; RT must be set 20% slower than SYNC frequency. |
| PWM (14) | Digital dimming control | Active-low input enabling 3000:1 PWM dimming; forces idle state, disables switching, and stores VC state. |
| FAULT (15) | Open-collector fault indicator | Pulled low on FB1 overvoltage, INTVCC UVLO, LED overcurrent (>375mV), or thermal shutdown. |
| VMODE (16) | Open-LED status flag | Open-collector output asserted when FB1 >1.19V and V(ISP-ISN) <25mV; requires external pull-up resistor. |
| SENSE (18) | Low-side current sense input | Kelvin-connected to positive terminal of RSENSE in NMOS source; monitors switch current for peak-current limiting. |
| GATE (19) | NMOS gate driver output | Drives external N-channel MOSFET gate between INTVCC and GND; pulled low during fault/idle states. |
| INTVCC (20) | Internal LDO regulator output | 7.7V regulated supply for gate drivers and internal circuitry; bypass with ≥4.7µF capacitor near pin. |
| VIN (23) | Main input supply | Primary power input; must be bypassed with ≥0.22µF ceramic capacitor close to IC. |
| EN/UVLO (24) | Enable and undervoltage lockout | 1.22V falling threshold with user-programmable hysteresis; draws <1µA when disabled. |
| VS (25) | Current sense amplifier supply | Power rail for ISP/ISN amplifier; operates from 3V to 100V; decoupled internally. |
| CSN (26) | Negative current sense amplifier input | High-voltage input tied to VS in typical configurations; supports up to 100V common-mode range. |
| CSP (27) | Positive current sense amplifier input | Sinks current from CSP to match CSN potential; used with RIN1 to generate CSOUT proportional to V(ISP-ISN). |
| CSOUT (28) | Current sense amplifier output | Sources current proportional to V(ISP-ISN); typically connected to resistor-to-GND for voltage output scaling. |
Key Features
| Feature | Design Value |
|---|---|
| Dual current sense amplifiers | Primary ISP/ISN path (0–100V CMR, ±3mV offset) + secondary CSOUT reporting (×4 gain) enable redundant current monitoring and system diagnostics. |
| Programmable analog dimming | CTRL pin scales full-scale current threshold from 16mV to 250mV linearly, allowing precise analog dimming without PWM artifacts. |
| Integrated top-gate PMOS driver | TG output drives high-side PMOS with built-in 7V VGS clamp, eliminating need for external level-shifting or gate protection components. |
| C/10 battery charging detection | Internal comparator triggers at V(ISP-ISN) = 25mV with 200mV hysteresis, enabling accurate end-of-charge detection for Li-ion and supercapacitor systems. |
| True-color PWM dimming | 3000:1 dimming ratio achieved via synchronous PWM control with minimal color shift, critical for architectural and medical LED applications. |
| Robust fault protection suite | Includes open-LED (VMODE), overcurrent (ISP/ISN >375mV), INTVCC UVLO (<4V), thermal shutdown, and FB overvoltage (FB1/FB2 >1.3V). |
Applications
| Automotive Headlamp Driver | Industrial High-Voltage LED Array |
|---|---|
|
Use Scenario: Driving 80V LED strings in adaptive front-lighting systems (AFS) with dynamic beam shaping and diagnostics. IC Role / Device Role / Timing Role: Constant-current controller regulating LED current via ISP/ISN; uses VMODE for open-circuit detection and FAULT for thermal/overcurrent shutdown. Use Value: Enables fail-safe illumination with real-time fault reporting, meeting ISO 26262 ASIL-B functional safety requirements through hardware-based protections. |
Use Scenario: Powering 100V industrial signage LEDs requiring stable brightness across wide input voltage fluctuations (e.g., 24V–72V DC bus). IC Role / Device Role / Timing Role: Dual-loop regulator maintaining constant current (via ISP/ISN) and constant voltage (via FB1) to prevent LED overvoltage during transients. Use Value: Eliminates need for external OVP clamps and reduces BOM count by integrating 100V-rated sensing and 7.7V internal LDO. |
| Battery & Supercapacitor Charger | Medical Surgical Lighting |
|
Use Scenario: Charging 48V LiFePO₄ battery packs or 50V supercapacitors with C/10 termination and input current limiting. IC Role / Device Role / Timing Role: Constant-current/constant-voltage charger using ISP/ISN for charge current regulation and C/10 comparator for end-of-charge detection. Use Value: Achieves ±3% charge current accuracy over temperature and line, with automatic transition to CV mode and precise cutoff at 25mV sense voltage. |
Use Scenario: Driving high-CRI surgical LEDs requiring flicker-free, color-stable illumination during 100–1000Hz PWM dimming cycles. IC Role / Device Role / Timing Role: Precision current controller with 3000:1 True Color PWM™ dimming and fast transient response (<1µs ISP/ISN step response). Use Value: Maintains consistent chromaticity across dimming range, satisfying IEC 60601-2-57 requirements for photobiological safety and visual stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Single current sense input (no ISP/ISN dual-path), no C/10 detection, lower max input voltage (60V), no VMODE flag. | Lacks open-LED diagnostics and high-voltage capability; suitable only for ≤60V LED strings without battery charging functions. | Select when cost sensitivity outweighs need for dual-sense redundancy, 100V operation, or battery charging features. |
| LT3762EFE#PBF | Higher peak gate drive current (2.5A vs 1.5A), no CSOUT reporting, no TGEN/SYNC, different FB architecture (single FB pin). | Optimized for high-current boost converters but lacks secondary voltage loop (FB2) and ISP/ISN reporting - limited to single-loop CC operation. | Choose for high-efficiency boost-only LED drivers where dual-loop regulation and diagnostic reporting are unnecessary. |
Compared with LTC3783EFE#PBF and LT3762EFE#PBF, the LT3796EFE#PBF uniquely combines 100V ISP/ISN sensing, dual FB loops, C/10 detection, and VMODE/FAULT flags - making it the only option among the three supporting automotive headlamps, industrial HV arrays, and battery charging in a single IC.
Availability
LT3796EFE#PBF is available at Aetrix Electronics and suitable for automotive lighting, industrial LED arrays, and battery/supercapacitor charging applications requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant lead-free packaging.
Supply support for LT3796EFE#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 all Linear ICs including the LT3796 series.
The LT3796 product line was designed specifically for high-reliability, high-voltage LED driver and battery charging applications - emphasizing integrated protection, wide input range, and dual-loop regulation without external op-amps or comparators.
FAQ
What is the maximum input voltage rating for the LT3796EFE#PBF?
The LT3796EFE#PBF has an absolute maximum input voltage rating of 100V on VIN, ISP, ISN, CSP, CSN, and VS pins. This allows direct operation from 48V, 60V, and 72V industrial or automotive DC buses with margin for transients. Operation above 100V risks permanent damage per Absolute Maximum Ratings.
Does the LT3796EFE#PBF support synchronization to an external clock?
Yes, the LT3796EFE#PBF supports external clock synchronization via the SYNC pin (Pin 13). When used, the internal RT-resistor-programmed frequency must be set at least 20% slower than the external SYNC frequency to ensure reliable locking. The LT3796EFE#PBF does not support TGEN functionality - that is exclusive to LT3796-1 variants.
How does the VMODE flag function on the LT3796EFE#PBF?
The VMODE flag on the LT3796EFE#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, requiring an external pull-up resistor to operate correctly.
Can the LT3796EFE#PBF be used for battery charging applications?
Yes, the LT3796EFE#PBF includes a dedicated C/10 comparator that triggers at V(ISP-ISN) = 25mV with 200mV hysteresis, enabling precise end-of-charge detection for lithium-ion, LiFePO₄, and supercapacitor systems. Its constant-current/constant-voltage regulation and 100V input capability make it suitable for 48V–72V battery charging topologies.
What thermal management requirements apply to the LT3796EFE#PBF package?
The LT3796EFE#PBF uses a 28-lead TSSOP with exposed thermal pad (Pin 29). This pad must be soldered directly to a large PCB copper area connected to GND for effective heat dissipation. Thermal resistance is θJC = 10°C/W and θJA = 30°C/W - insufficient copper area will cause junction temperature to exceed the 125°C maximum rating under sustained load.
LT3796EFE#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
LT3796EFE#PBF FAQ
1.How can I place an order for LT3796EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3796EFE#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 LT3796EFE#PBF reliable?
The price and inventory of LT3796EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3796EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3796EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3796EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3796EFE#PBF?
LT3796EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3796EFE#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 LT3796EFE#PBF?
For technical support, including LT3796EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3796EFE#PBF requirements.
6.How does Aetrix verify that LT3796EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3796EFE#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 LT3796EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3796EFE#PBF?
All LT3796EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3796EFE#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 LT3796EFE#PBF part is unused and in its original packaging.
Return procedure for LT3796EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3796EFE#PBF Tags
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