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Analog Devices Inc. LT3796HFE#TRPBF
- Part No.:
- LT3796HFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3796HFE#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,362
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Product details
Overview
LT3796HFE#TRPBF 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), programmable switching frequency (100kHz–1MHz), and operates across –40°C to +150°C junction temperature.
For engineers reviewing the LT3796HFE#TRPBF datasheet, LT3796HFE#TRPBF pinout, LT3796HFE#TRPBF application, or LT3796HFE#TRPBF equivalent, key selection criteria include its dual-loop regulation architecture (primary LED current + secondary voltage/current via FB2/TG), high-side PMOS disconnect control, C/10 battery charging detection, and thermal-rated H-grade packaging for automotive and industrial lighting systems.
Technical Context
The LT3796HFE#TRPBF 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), NMOS gate driver (GATE), PMOS top-gate driver (TG), and fault management logic with VMODE/FAULT open-collector outputs. The H-grade variant guarantees full electrical performance over –40°C to +150°C junction temperature, with thermal shutdown and soft-start restart timer for robust operation in high-ambient environments.
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 operation. |
| Operating Junction Temp | –40°C to +150°C - H-grade qualification enables use in under-hood automotive lighting and high-temperature industrial fixtures. |
| Switching Frequency | 100kHz to 1MHz - adjustable via RT resistor; allows optimization of efficiency vs. size for high-power LED drivers. |
| Current Sense Threshold | Programmable 16mV to 257mV (via CTRL pin) - enables precise analog dimming and C/10 battery charge termination. |
| ISP/ISN Common-Mode Range | 0V to 100V - permits high-side or low-side current sensing in boost, buck-boost, and SEPIC LED topologies. |
| VMODE/FAULT Outputs | Open-collector, 0.3V max low-level - provides direct interface to microcontroller GPIOs for fault reporting without level-shifting. |
| INTVCC Regulation | 7.7V ±0.3V, 85mA max - powers internal logic, gate drivers, and external bias networks reliably across input range. |
Pinout & Package
LT3796HFE#TRPBF is housed in a 28-lead plastic TSSOP package (FE) with exposed pad (Pin 29) soldered to PCB ground for thermal dissipation. Package dimensions: 4.4mm × 9.7mm × 1.1mm, pitch 0.65mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP (1) | Positive current sense input / TG driver rail | Serves as high-side reference for LED string current sensing and supplies gate drive for external PMOS disconnect switch. |
| ISN (2) | Negative current sense input | Kelvin-connected to low side of RLED; forms differential pair with ISP for accurate current regulation up to 100V common-mode. |
| TG (3) | Top gate driver output | Drives external PMOS between ISP and (ISP – 7V); internal clamp prevents VGS overstress on high-voltage MOSFETs. |
| GND (4,17,21,22,29) | Ground reference / thermal pad | Multiple GND pins reduce noise coupling; exposed pad (29) must be soldered to PCB ground plane for thermal management. |
| ISMON (5) | Current monitor output | Provides scaled replica of LED current (VISMON = ILED × RLED × 4) for system telemetry or closed-loop feedback. |
| FB2 (6) | Voltage loop feedback 2 | Regulates secondary output to 1.25V; on LT3796 (not -1), drives TG high if >1.3V to force PMOS off and protect LEDs. |
| FB1 (7) | Voltage loop feedback 1 | Enables CV mode or open-LED protection; asserts VMODE if VFB1 >1.19V and VISP-ISN <25mV (e.g., open circuit). |
| VC (8) | Error amplifier output | High-impedance during PWM low; stores demand state for seamless dimming transitions and loop stability with RC compensation. |
| CTRL (9) | Current threshold adjustment | Linearly scales full-scale current sense threshold from 25mV to 250mV (0.2V–1.2V input); default 250mV when tied to VREF. |
| VREF (10) | 2.015V precision reference | Stable 2.015V output (±15mV) with 100µA drive capability; used to bias CTRL for analog dimming or temperature compensation. |
| SS (11) | Soft-start / fault timer | 28µA pull-up charges external capacitor; fault conditions enable 2.8µA pull-down to discharge SS and initiate restart after fault clearance. |
| RT (12) | Frequency programming | Resistor to GND sets oscillator frequency (e.g., 82.5kΩ = ~105kHz); supports synchronization on LT3796 (SYNC) or TGEN on LT3796-1. |
| PWM (14) | Digital dimming input | Active-low signal enables 3000:1 PWM dimming; forces GATE low, TG high, and VC high-Z during idle for zero-current standby. |
| FAULT (15) | Fault status indicator | Asserts low on FB1 overvoltage (>1.3V), INTVCC UVLO (<4V), LED overcurrent (>375mV), or thermal shutdown. |
| VMODE (16) | Open-LED detection flag | Asserts low when FB1 >1.19V and VISP-ISN <25mV - signals open-circuit condition while preserving PWM dimming functionality. |
| SENSE (18) | Switch current sense input | Kelvin-connected to high side of RSENSE in NMOS source; monitors peak inductor current for cycle-by-cycle limiting (113mV typ). |
| GATE (19) | NMOS gate driver output | Swings between INTVCC and GND; drives external N-channel MOSFET with 20ns rise/18ns fall time into 3300pF load. |
| INTVCC (20) | Internal LDO supply | 7.7V regulated output (85mA max) powers gate drivers and logic; bypass with ≥4.7µF ceramic capacitor near pin. |
| VIN (23) | Main input supply | Accepts 6V–100V; requires local 0.22µF+ ceramic bypass; internal LDO derives INTVCC, eliminating need for external bias rail. |
| EN/UVLO (24) | Enable / undervoltage lockout | 1.22V falling threshold with programmable hysteresis; sub-µA quiescent current when disabled below 0.4V. |
| VS (25) | Current sense amplifier supply | 3V–100V supply for ISP/ISN amplifier; enables high-side sensing without level shifters in buck-boost or SEPIC configurations. |
| CSN (26) | Negative current sense amp input | Reference terminal for CSP amplifier; typically tied to VS and CSP in servo configuration per Figure 9 of datasheet. |
| CSP (27) | Positive current sense amp input | High-impedance input; sinks current proportional to VISP-ISN to generate CSOUT current for external monitoring. |
| CSOUT (28) | Current sense amplifier output | Sources current proportional to VISP-ISN; used for remote current reporting or secondary regulation loops. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent regulation loops | Simultaneous constant-current (ISP/ISN) and constant-voltage (FB1/FB2) control enables hybrid LED + battery charging applications. |
| Rail-to-rail ISP/ISN sensing | 0V–100V common-mode range allows flexible placement of current sense resistor - high-side, low-side, or floating - without external op-amps. |
| True Color PWM™ dimming | 3000:1 dimming ratio with minimal color shift achieved via precise current regulation and fast gate drivers (20ns/18ns). |
| C/10 battery charge termination | Integrated comparator triggers at VISP-ISN = 25mV (typical) when FB1 = 1.25V - enables accurate lead-acid or supercapacitor charging without external ICs. |
| H-grade thermal qualification | Guaranteed operation from –40°C to +150°C junction temperature - suitable for under-hood automotive lighting and high-ambient industrial enclosures. |
| PMOS high-side disconnect control | TG output drives external PMOS with built-in 7V VGS clamp - eliminates need for gate Zener or level shifter in high-voltage LED string isolation. |
Applications
| Automotive Headlamp Drivers | Industrial High-Bay LED Fixtures |
|---|---|
|
Use Scenario: Driving high-brightness LED arrays in vehicle headlamps with adaptive beam shaping and diagnostics. IC Role / Device Role / Timing Role: Constant-current controller regulating multiple parallel LED strings; VMODE reports open-circuit faults; FAULT flags overtemperature or overcurrent events. Use Value: Enables ASIL-B compliant diagnostics via VMODE/FAULT flags and supports 100V transients common in 24V truck/bus systems. |
Use Scenario: Powering 100W–300W LED modules in warehouse lighting with surge immunity and thermal derating. IC Role / Device Role / Timing Role: Primary DC/DC controller in buck-boost topology; ISP/ISN senses string current; INTVCC powers auxiliary sensors and MCU interface. Use Value: 150°C junction rating ensures reliability in enclosed fixtures; programmable frequency avoids audible noise in large inductors. |
| Battery & Supercapacitor Chargers | UV-C Sterilization Systems |
|
Use Scenario: Charging 12V/24V lead-acid batteries or 48V supercapacitor banks from variable solar or DC bus sources. IC Role / Device Role / Timing Role: Constant-voltage regulator (FB1) with C/10 termination (VISP-ISN = 25mV) and current limiting (SENSE = 113mV). Use Value: Eliminates need for dedicated charger IC; dual-loop architecture supports both CC/CV phases in single controller. |
Use Scenario: Driving high-voltage UV-C LED arrays (30–100V forward drop) requiring precise current control and rapid on/off cycling. IC Role / Device Role / Timing Role: Constant-current driver with 3000:1 PWM dimming; TG isolates UV-C array during standby; SENSE limits inrush. Use Value: Fast gate drivers and low propagation delay ensure nanosecond-level timing accuracy for germicidal pulse protocols. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current LED driver controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#TRPBF | Single-loop controller; no dual current sense; max 60V VIN; no VMODE/FAULT flags; 125°C max junction temp. | Lacks open-LED detection and secondary regulation; unsuitable for automotive diagnostics or hybrid LED/battery systems. | Select only for cost-sensitive, lower-voltage (<60V), single-string LED applications without fault reporting requirements. |
| LT3762EFE#TRPBF | 100V controller with single ISP/ISN sense; no CSP/CSN amplifier; no C/10 detection; no TGEN/SYNC; 125°C max junction temp. | Supports basic high-voltage LED driving but lacks auxiliary monitoring, battery charging, and H-grade thermal margin. | Choose when only primary LED current regulation is needed and ambient temperature remains below 125°C. |
Compared with LTC3783EFE#TRPBF and LT3762EFE#TRPBF, the LT3796HFE#TRPBF uniquely combines 100V operation, dual current sense paths, C/10 battery termination, and H-grade thermal rating - making it the only option qualified for automotive headlamp and high-ambient industrial LED systems requiring integrated diagnostics and hybrid power management.
Availability
LT3796HFE#TRPBF is available at Aetrix Electronics and suitable for automotive lighting, industrial high-bay fixtures, and battery/supercapacitor charging systems requiring stable component supply, long-term lifecycle support, and guaranteed high-temperature performance.
Supply support for LT3796HFE#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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for all Linear parts, including the LT3796 family.
The LT3796 series was designed as a high-voltage, dual-loop LED controller targeting automotive, industrial, and battery-powered lighting systems where reliability, diagnostics, and thermal robustness are critical.
FAQ
What is the maximum operating junction temperature for the LT3796HFE#TRPBF?
The LT3796HFE#TRPBF is rated for continuous operation from –40°C to +150°C junction temperature. This H-grade qualification is verified per datasheet Note 4 and distinguishes it from E/I-grade variants (max 125°C). Thermal derating above 125°C applies per lifetime degradation curves in the datasheet.
Does the LT3796HFE#TRPBF support synchronization of its switching frequency?
Yes - the LT3796HFE#TRPBF supports frequency synchronization via the SYNC pin (Pin 13), which accepts an external logic-level clock. The internal oscillator locks to the SYNC signal when RT is configured for a frequency ~20% slower than the SYNC input. This feature reduces EMI in multi-controller systems and is documented in the "SYNC Pin" section of the datasheet.
How does the LT3796HFE#TRPBF implement open-LED detection?
The LT3796HFE#TRPBF uses VMODE flag assertion: when FB1 voltage exceeds 1.19V (typical) *and* VISP-ISN falls below 25mV (typical), the open-collector VMODE pin pulls low. This dual-condition logic prevents false triggers during PWM dimming and is latched during PWM low periods for reliable fault reporting in the LT3796HFE#TRPBF.
Can the LT3796HFE#TRPBF drive both high-side and low-side current sense configurations?
Yes - the LT3796HFE#TRPBF supports both configurations. Its ISP/ISN inputs have 0V–100V rail-to-rail common-mode range, enabling direct high-side sensing without level shifters. For low-side sensing, ISN connects to ground and ISP to the sense resistor's load side. The CSP/CSN amplifier further extends flexibility for auxiliary monitoring.
What is the purpose of the TGEN pin on the LT3796HFE#TRPBF?
The LT3796HFE#TRPBF does not include a TGEN pin - that function is exclusive to the LT3796-1 variant (e.g., LT3796HFE-1#TRPBF). The LT3796HFE#TRPBF uses SYNC (Pin 13) for synchronization. Confusion arises because the datasheet covers both families; always verify suffix: "-1" denotes TGEN, non-"-1" denotes SYNC.
LT3796HFE#TRPBF 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:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3796HFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3796HFE#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 LT3796HFE#TRPBF reliable?
The price and inventory of LT3796HFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3796HFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3796HFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3796HFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3796HFE#TRPBF?
LT3796HFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3796HFE#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 LT3796HFE#TRPBF?
For technical support, including LT3796HFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3796HFE#TRPBF requirements.
6.How does Aetrix verify that LT3796HFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3796HFE#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 LT3796HFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3796HFE#TRPBF?
All LT3796HFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3796HFE#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 LT3796HFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3796HFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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