My Inquiry
My Account
Analog Devices Inc. LT3909IDD#TRPBF
- Part No.:
- LT3909IDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LT3909IDD#TRPBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 50MA 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,338
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3909IDD#TRPBF from Analog Devices (formerly Linear Technology) is a 2-string, 60mA high-side LED driver IC with integrated 2MHz step-up DC/DC converter, ±2% current matching, and programmable output voltage regulation up to 36V. It delivers precise constant-current drive for automotive instrument clusters and high-contrast displays requiring stable brightness across temperature and supply variation.
For engineers reviewing the LT3909IDD#TRPBF datasheet, LT3909IDD#TRPBF pinout, LT3909IDD#TRPBF application, or LT3909IDD#TRPBF equivalent, key selection criteria include its 2MHz fixed-frequency boost architecture, ±0.3% typical current matching at 20mA, 40,000:1 PWM dimming capability at 100Hz, internal 400mΩ/40V/1A switch, and thermal regulation loop for junction temperature control.
Technical Context
The LT3909IDD#TRPBF integrates a peak-current-mode 2MHz boost controller with two independent high-side current sources, each regulated via dedicated sensing of VOUT–LEDx differential voltage (target 1.3V). Its GM1 feedback loop dynamically adjusts VOUT to the minimum required for LED string compliance, optimizing efficiency across VF variations.
Fault protection includes open-LED detection (VOUT–VLEDx < 0.4V), LED-short-to-GND detection (VLEDx < 6.0V), and active low FAULT flag with latching during PWM/CTRL low states. Internal compensation, soft-start, and thermal foldback ensure robust startup and thermal safety without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.9V to 40V - supports wide automotive battery range including cold-crank and load-dump conditions. |
| Switching Frequency | Fixed 2MHz (±6%) - enables compact magnetics and reduces EMI filtering requirements. |
| Max LED Current per String | 60mA (±3% at 60mA) - set by single ISET resistor; supports dual 10-LED white LED strings. |
| Current Matching Accuracy | ±0.3% typical (±2% max) - ensures uniform brightness in dual-string display backlighting. |
| PWM Dimming Ratio | 40,000:1 at 100Hz (250ns min on-time) - enables ultra-fine grayscale control in automotive HUDs. |
| Integrated Switch | 400mΩ, 40V, 1.1A rated - eliminates external MOSFET and reduces BOM count in space-constrained designs. |
| Thermal Regulation | Junction temperature foldback above 170°C - maintains safe operation without external thermal sensors. |
Pinout & Package
LT3909IDD#TRPBF is housed in a thermally enhanced 12-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 13) soldered to PCB ground for optimal thermal dissipation (θJC = 5.5°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 INTVCC | Internal 3.0V regulator output | Bypass with ≥1µF ceramic capacitor; powers gate driver and control circuits; max 100µA external load. |
| 2 VIN | Main input supply | Accepts 2.9V–40V; requires local ceramic bypass capacitor to GND. |
| 3 EN/UVLO | Enable and undervoltage lockout input | 0.4V shutdown / 1.215V enable threshold; supports programmable UVLO with resistor divider. |
| 4 ISET | LED current programming input | Single resistor to GND sets both strings' current (10–60mA); accuracy depends on resistor tolerance. |
| 5 CTRL | Analog dimming and latch-off control | Voltage <80mV disables LED current; 0.1V–1.0V enables 10:1 analog dimming. |
| 6 FB | Output voltage regulation feedback | Resistor divider from VOUT to GND programs OVP level (1.215V reference) for fault protection. |
| 7 PWM | Digital dimming control | Active-high signal; controls high-side current sources; supports 40,000:1 PWM ratio. |
| 8 FAULT | Open-LED/short-to-GND fault flag | Active-low open-drain output; requires external pull-up; updates only during PWM/CTRL high state. |
| 9 LED1 10 LED2 |
High-side LED current outputs | Each drives one LED string; can be paralleled for >60mA total; no external sense resistors needed. |
| 11 VOUT | Boost converter output | Connects to output capacitor; regulated to minimum required for LED string compliance. |
| 12 SW | Internal switch drain node | Connects to inductor and internal Schottky anode; minimize trace area to reduce EMI. |
| 13 (Exposed Pad) | Power ground | Mandatory solder connection to PCB ground plane for thermal and electrical performance. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Schottky diode | Eliminates external diode, reducing footprint and component count in space-constrained automotive modules. |
| Dynamic VOUT regulation | Adapts output voltage to lowest level needed for LED string compliance, improving efficiency by up to 15% vs fixed-VOUT boost. |
| Independent fault handling | One LED string failure (open or short) does not affect regulation of the other string - critical for safety-critical displays. |
| VOUT regulation during PWM off-time | Maintains stable VOUT using stored optimum level, preventing droop from Schottky leakage and enabling fast LED current recovery. |
| Accurate EN/UVLO threshold | 1.215V falling threshold with 30mV hysteresis allows precise system-level undervoltage lockout programming. |
Applications
| Automotive Instrument Clusters | High-Contrast Automotive Displays |
|---|---|
|
Use Scenario: Driving dual 10-LED white strings behind TFT LCD gauges in vehicle dashboards under 12V battery supply with load-dump transients. IC Role / Device Role / Timing Role: Dual high-side constant-current source with adaptive VOUT regulation and 2MHz switching for minimal EMI in EMC-sensitive cockpit environments. Use Value: ±0.3% current matching ensures pixel-perfect brightness uniformity; 40,000:1 PWM dimming enables seamless day/night transition without visible stepping. |
Use Scenario: Backlighting for 7-inch automotive infotainment displays requiring 1000+ nits brightness and dynamic contrast control. IC Role / Device Role / Timing Role: Fixed-frequency boost LED driver with thermal foldback and fault latching to maintain display integrity during extended high-temperature operation. Use Value: Internal 1.1A switch and 400mΩ RDS(on) eliminate external FET, reducing board area by 35%; programmable OVP protects LEDs during hot-plug events. |
| GPS Navigation Receivers | PDA & Handheld Computers |
|
Use Scenario: Powering dual LED strings for outdoor-readable GPS map displays operating from 3.3V–40V input (e.g., vehicle power + USB battery backup). IC Role / Device Role / Timing Role: Wide-input boost driver with analog + PWM dimming support for automatic ambient light adaptation and user brightness control. Use Value: 10:1 analog dimming (CTRL pin) plus 40,000:1 PWM enables smooth 5-decade brightness range; 2.9V min VIN supports USB-powered operation. |
Use Scenario: Compact backlight solution for legacy PDA displays where PCB real estate is constrained and thermal management is limited. IC Role / Device Role / Timing Role: Thermally optimized DFN-packaged LED driver with integrated Schottky and internal compensation to minimize external components. Use Value: Exposed-pad DFN package achieves θJA = 43°C/W - 22% lower junction rise than MSOP variant; eliminates need for heatsinks in handheld form factors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3909EDD#TRPBF | Same die, –40°C to 125°C temp grade but E-grade screening (0°C to 125°C guaranteed performance) | Suitable for commercial/handheld use; not qualified for full automotive temperature range | Select when cost sensitivity outweighs need for full industrial/automotive qualification. |
| LT3909IMSE#TRPBF | Same functionality in 12-lead MSOP package; θJA = 40°C/W, no exposed pad | Lower thermal performance; preferred where DFN reflow process is unavailable | Choose for legacy assembly lines lacking DFN-compatible reflow profiles or where manual inspection is required. |
Compared with LT3909EDD#TRPBF, the LT3909IDD#TRPBF guarantees full –40°C to 125°C operation with tighter parametric limits; versus LT3909IMSE#TRPBF, it delivers superior thermal performance via exposed-pad DFN packaging-critical for sustained 60mA dual-string operation in sealed enclosures.
Availability
LT3909IDD#TRPBF is available at Aetrix Electronics and suitable for automotive instrument clusters, high-contrast displays, and portable navigation systems requiring stable component supply with long lifecycle assurance.
Supply support for LT3909IDD#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 its precision analog and power management portfolio with rigorous automotive qualification standards.
The LT3909 series was designed specifically for dual-string LED backlighting in automotive and industrial displays, emphasizing current matching accuracy, fault resilience, and wide-input operation under harsh electrical environments.
FAQ
What is the maximum LED forward voltage supported by the LT3909IDD#TRPBF?
The LT3909IDD#TRPBF supports up to 36V total LED forward voltage across both strings, with VOUT regulated adaptively to the minimum required for string compliance. Its internal 40V-rated switch and 40V absolute maximum ratings on LED1/LED2 pins ensure safe operation even with transient overvoltage conditions.
Can the LT3909IDD#TRPBF drive a single LED string at 120mA?
Yes - the LT3909IDD#TRPBF allows paralleling of LED1 and LED2 pins to deliver up to 120mA total current. When configured this way, the ISET resistor must be halved (e.g., 8.35kΩ for 120mA) and thermal design must account for doubled power dissipation in the DFN package.
How does the LT3909IDD#TRPBF achieve 40,000:1 PWM dimming without VOUT droop?
The LT3909IDD#TRPBF samples the FB pin voltage at the PWM falling edge to store the optimum VOUT level, then actively regulates VOUT to that level during PWM off-time - compensating for leakage from the internal Schottky diode and enabling consistent LED current recovery within 250ns.
What is the purpose of the INTVCC pin on the LT3909IDD#TRPBF?
The INTVCC pin on the LT3909IDD#TRPBF provides a regulated 3.0V supply (2.9V–3.1V) for internal gate drivers and control circuits. It must be bypassed with ≥1µF low-ESR ceramic capacitor and supports ≤100µA external loading - e.g., for PWM pull-up or CTRL resistor dividers - but is not intended for powering external circuitry.
Does the LT3909IDD#TRPBF require external compensation components?
No - the LT3909IDD#TRPBF features fully internal compensation, eliminating external RC networks. This simplifies layout, improves reliability, and ensures stable operation across all valid input voltages, output loads, and temperature ranges without tuning.
LT3909IDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 2
- Voltage - Supply (Min):
- 2.9V
- Voltage - Supply (Max):
- 40V
- Voltage - Output:
- 40V
- Current - Output / Channel:
- 50mA
- Frequency:
- 2MHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-DFN (3x3)
LT3909IDD#TRPBF FAQ
1.How can I place an order for LT3909IDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3909IDD#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 LT3909IDD#TRPBF reliable?
The price and inventory of LT3909IDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3909IDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3909IDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3909IDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3909IDD#TRPBF?
LT3909IDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3909IDD#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 LT3909IDD#TRPBF?
For technical support, including LT3909IDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3909IDD#TRPBF requirements.
6.How does Aetrix verify that LT3909IDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3909IDD#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 LT3909IDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3909IDD#TRPBF?
All LT3909IDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3909IDD#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 LT3909IDD#TRPBF part is unused and in its original packaging.
Return procedure for LT3909IDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3909IDD#TRPBF Tags
-
BCR402RE6327HTSA1
Infineon Technologies
-
BCR430UXTSA2
Infineon Technologies
-
BCR420UE6433HTMA1
Infineon Technologies
-
BCR420UE6327HTSA1
Infineon Technologies
-
BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
-
BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
