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Analog Devices Inc. LT3796HFE#PBF
- Part No.:
- LT3796HFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3796HFE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:170
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Product details
Overview
LT3796HFE#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 supports 6V–100V input, delivers up to 3000:1 true-color PWM dimming, features rail-to-rail ISP/ISN common-mode range (0–100V), and operates across –40°C to +150°C junction temperature. Used in automotive exterior lighting and industrial high-voltage LED arrays.
For engineers reviewing the LT3796HFE#PBF datasheet, LT3796HFE#PBF pinout, LT3796HFE#PBF application, or LT3796HFE#PBF equivalent, key selection criteria include its dual-loop regulation architecture (primary LED current + secondary voltage or current), programmable open-LED protection via VMODE flag, C/10 battery charging detection, and high-side PMOS disconnect driver with 7V gate clamp - all in a thermally enhanced 28-lead TSSOP package with exposed pad.
Technical Context
The LT3796HFE#PBF implements fixed-frequency current-mode control with two independent transconductance amplifiers (FB1/FB2), enabling simultaneous constant-current (via ISP/ISN) and constant-voltage (via FB1 or FB2) regulation. Its dual current sense path includes a primary rail-to-rail amplifier (ISP/ISN) and a separate high-side configurable amplifier (CSP/CSN) for auxiliary monitoring or second-string control.
It integrates a 7.7V LDO (INTVCC) with 85mA current limit, NMOS gate driver (GATE) with 20ns rise/fall times, and top-gate PMOS driver (TG) with 7V VGS clamp and 50ns rise/100ns fall times. The device supports frequency synchronization (LT3796 variant) or independent top-gate enable (LT3796-1 variant); LT3796HFE#PBF is the high-temp (–40°C to +150°C) version of the LT3796 family, not the -1 variant.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 100V - supports wide-range industrial and automotive inputs, including transient-tolerant 100V systems. |
| Operating Junction Temp | –40°C to +150°C - qualified for under-hood automotive and high-ambient industrial environments. |
| Switching Frequency | 100kHz to 1MHz - adjustable via RT resistor; enables optimization of efficiency vs. size in high-power designs. |
| SENSE Current Limit | 113mV typical - sets peak switch current threshold; ensures robust overcurrent protection without external scaling. |
| VREF Output | 2.015V ±25mV - precision reference for CTRL biasing and analog dimming; stable over full temperature range. |
| Fault Detection | Open-LED (VMODE), overvoltage (FB1/FB2), thermal shutdown, INTVCC UVLO - latched fault reporting with SS-based restart timer. |
| Dimming Ratio | 3000:1 true-color PWM - preserves color consistency across full brightness range in RGB and tunable-white LED systems. |
Pinout & Package
LT3796HFE#PBF is housed in a 28-lead plastic TSSOP (FE package) with exposed thermal pad (Pin 29 = GND), optimized for high-power dissipation in compact layouts. The package supports θJA = 30°C/W and θJC = 10°C/W when properly soldered to PCB ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP / ISN (Pins 1, 2) | Primary LED current sense differential input | Rail-to-rail 0–100V common-mode range; directly senses LED string current with 243–257mV full-scale threshold. |
| TG (Pin 3) | Top-gate PMOS driver output | Drives external high-side PMOS disconnect switch; clamped to VISP–7V to protect gate oxide; active-low during PWM high. |
| GATE (Pin 19) | NMOS power switch driver | Drives low-side N-channel MOSFET gate between INTVCC and GND; 20ns rise/18ns fall time into 3300pF load. |
| FB1 / FB2 (Pins 7, 6) | Voltage loop feedback inputs | Regulate to 1.25V nominal; FB1 enables open-LED detection and overvoltage protection; FB2 supports secondary CV loop or PMOS disable. |
| CTRL (Pin 9) | Analog dimming and current threshold control | Sets VISP–ISN threshold from 16mV to 250mV linearly (0.2V–1.0V) or fixed full-scale (≥1.2V); enables precise current scaling. |
| VMODE / FAULT (Pins 16, 15) | Open-LED and system fault flags | Open-collector outputs; VMODE asserts when FB1 >1.19V and VISP–ISN<25mV; FAULT asserts on OV, UV, OC, or thermal events. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent current sense paths | Primary ISP/ISN (0–100V CM) + auxiliary CSP/CSN (3–100V supply) enable simultaneous LED current regulation and input current monitoring or second-string control. |
| Programmable C/10 battery charging detection | Uses VMODE flag and FB1 comparator to detect end-of-charge at 10% of set current - critical for supercapacitor and LiFePO4 charging applications. |
| High-side PMOS disconnect with integrated clamp | TG output limits VGS to ≤7V regardless of ISP voltage up to 100V - eliminates need for external Zener clamp in high-voltage LED disconnect circuits. |
| True-color 3000:1 PWM dimming | Preserves chromaticity across full intensity range by maintaining constant LED forward voltage during dimming - essential for architectural and display lighting. |
| Thermally rugged high-temp grade | Guaranteed operation to +150°C junction temperature with full electrical specs - enables placement near heat sources in enclosed LED drivers. |
Applications
| Automotive Headlamp Driver | Industrial High-Voltage LED Array |
|---|---|
|
Use Scenario: Driving 80W+ LED headlamps in vehicles with 12V/24V battery systems subject to load-dump transients up to 100V. IC Role / Device Role / Timing Role: Constant-current controller regulating LED string current while providing open-circuit protection and thermal foldback. Use Value: Enables single-chip solution for AHB (Adaptive Driving Beam) systems with fast PWM dimming and fault-safe shutdown during lamp failure. |
Use Scenario: Powering multi-string 48V–85V LED arrays in factory floor lighting, where ambient temperatures exceed 85°C. IC Role / Device Role / Timing Role: Dual-loop regulator maintaining precise current per string while monitoring total input current for system-level protection. Use Value: Eliminates need for external current monitors and discrete protection ICs - reduces BOM count and improves long-term reliability in harsh environments. |
| Battery & Supercapacitor Charger | UV-C LED Disinfection System |
|
Use Scenario: Charging 24V LiFePO4 batteries or 30V supercapacitors from variable-input solar or DC bus sources. IC Role / Device Role / Timing Role: Accurate constant-current/constant-voltage charger with C/10 termination detection and input current limiting. Use Value: Achieves <±2% charge current accuracy across temperature using internal VREF and CTRL-based threshold programming - no external DAC required. |
Use Scenario: Driving high-threshold UV-C LEDs (forward voltage >35V) requiring precise current control and rapid on/off cycling for germicidal exposure. IC Role / Device Role / Timing Role: High-speed PWM-controlled current source with <200ns fault response and 3000:1 dimming for dose control. Use Value: Ensures consistent UV irradiance by eliminating current droop during pulse bursts - critical for medical-grade disinfection validation. |
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 path; no CSP/CSN monitor; max 60V VIN; no VMODE flag; 125°C max junction temp. | Lacks dual-loop capability and open-LED flag - suitable only for simpler single-string, lower-voltage LED systems. | Select when cost sensitivity outweighs need for high-voltage resilience, dual monitoring, or automotive-grade temperature range. |
| MAX16834ATI+T | Fixed 200kHz switching; no RT adjustment; no high-side TG driver; 40V max VIN; no C/10 detection. | Designed for AC-powered indoor lighting - lacks transient tolerance, thermal rating, and auxiliary sensing needed for industrial/automotive use. | Choose only for cost-constrained, non-automotive, low-input-voltage (<40V) LED drivers where dimming ratio <1000:1 is acceptable. |
Compared with LTC3783EFE#PBF and MAX16834ATI+T, the LT3796HFE#PBF uniquely combines 100V operation, dual current sense, programmable open-LED detection, and +150°C qualification - making it the only option for thermally demanding, high-reliability LED and charging applications requiring full functional redundancy.
Availability
LT3796HFE#PBF is available at Aetrix Electronics and suitable for automotive lighting, industrial LED arrays, and battery/supercapacitor charging systems requiring stable component supply, extended temperature performance, and long-term lifecycle support.
Supply support for LT3796HFE#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-reliability, high-voltage LED current regulation with dual-loop flexibility - targeting automotive, industrial, and energy storage applications where precision, fault resilience, and thermal robustness are mandatory.
FAQ
What is the maximum input voltage rating for the LT3796HFE#PBF?
The LT3796HFE#PBF has an absolute maximum input voltage (VIN) rating of 100V, and its ISP, ISN, CSP, and CSN pins also tolerate up to 100V common-mode voltage. This allows direct interfacing with high-voltage LED strings and industrial DC buses without external level-shifting circuitry. The LT3796HFE#PBF is rated for continuous operation across its full –40°C to +150°C junction temperature range at these voltages.
Does the LT3796HFE#PBF support dual independent current regulation loops?
The LT3796HFE#PBF supports one primary constant-current loop via ISP/ISN and a secondary regulation path using CSP/CSN with configurable gain. While it does not implement two fully independent current regulation loops like the LT3796-1 variant, it enables combined current + voltage regulation or current + input monitoring. The LT3796HFE#PBF belongs to the base LT3796 family (not LT3796-1), so it uses SYNC (Pin 13), not TGEN, and lacks the dedicated second current loop enable/disable logic.
How does the VMODE pin function in the LT3796HFE#PBF?
In the LT3796HFE#PBF, the VMODE pin is an open-collector output that asserts (pulls low) when FB1 exceeds ~1.19V *and* V(ISP–ISN) falls below ~25mV - indicating an open LED condition. It updates only during PWM high time and latches during PWM low. An external pull-up resistor is required. This signal can trigger system-level fault handling or drive indicator LEDs without additional logic, simplifying open-circuit protection in high-reliability lighting systems.
What is the purpose of the TG pin on the LT3796HFE#PBF?
The TG (Top Gate) pin on the LT3796HFE#PBF drives an external high-side PMOS disconnect switch. It provides an inverted PWM signal with built-in 7V gate-source clamp - ensuring safe VGS even when ISP is at 100V. During normal operation, TG goes low to turn on the PMOS; during PWM low or fault, it pulls high to disconnect the LED string. This enables fail-safe open-circuit protection and hot-swap capability in mission-critical LED systems.
Can the LT3796HFE#PBF be used for battery charging applications?
Yes - the LT3796HFE#PBF includes dedicated C/10 detection circuitry that compares V(ISP–ISN) against a 25mV threshold when VMODE is active and FB1 = 1.25V. This enables accurate end-of-charge detection for lithium iron phosphate and supercapacitor charging without external comparators. Combined with its 6V–100V input range and ±2% current regulation accuracy, the LT3796HFE#PBF serves as a highly integrated, thermally robust charger controller for energy storage systems.
LT3796HFE#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LT3796HFE#PBF FAQ
1.How can I place an order for LT3796HFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3796HFE#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 LT3796HFE#PBF reliable?
The price and inventory of LT3796HFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3796HFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3796HFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3796HFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3796HFE#PBF?
LT3796HFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3796HFE#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 LT3796HFE#PBF?
For technical support, including LT3796HFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3796HFE#PBF requirements.
6.How does Aetrix verify that LT3796HFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3796HFE#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 LT3796HFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3796HFE#PBF?
All LT3796HFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3796HFE#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 LT3796HFE#PBF part is unused and in its original packaging.
Return procedure for LT3796HFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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