My Inquiry
My Account
Analog Devices Inc. LT3909IMSE#TRPBF
- Part No.:
- LT3909IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 12-TSSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3909IMSE#TRPBF.pdf
- Description:
- IC LED DRV RGLTR PWM 50MA 12MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,934
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3909IMSE#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 and ±2% current matching. It regulates LED current up to 36V total forward voltage per string, features internal 400mΩ/40V/1A switch and Schottky diode, and supports analog dimming (10:1) and PWM dimming (up to 40,000:1 at 100Hz). It is used in automotive instrument clusters requiring precise dual-string brightness control.
For engineers reviewing the LT3909IMSE#TRPBF datasheet, LT3909IMSE#TRPBF pinout, LT3909IMSE#TRPBF application, or LT3909IMSE#TRPBF equivalent, key selection criteria include its fixed 2MHz switching frequency, programmable LED current via single ISET resistor (10–60mA), ±0.3% typical current matching, fault flag for open-LED/short-to-GND detection, and thermal regulation loop for junction temperature control.
Technical Context
The LT3909IMSE#TRPBF integrates a peak-current-mode boost controller with two independent high-side current sources, each regulated by a dedicated feedback path monitoring VOUT–LEDx differential voltage (target 1.3V). Its GM1 loop dynamically adjusts VOUT to the minimum required for LED string regulation-ensuring optimal efficiency across varying VF and input voltage (2.9V–40V).
It employs internal slope compensation for stability above 50% duty cycle, features cycle-by-cycle 1.1A switch current limiting, and uses an internal 3.0V INTVCC regulator (with UVLO at 2.75V/2.6V) to power gate drivers and control logic. Fault detection operates independently per string: open-LED triggers when VOUT–VLEDx < 0.4V; LED-short-to-GND triggers when VLEDx < 6.0V (≈25% of VOUT).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| LED Current per String | Programmable 10mA–60mA via single ISET resistor; enables precise dual-string brightness control without matched external components. |
| Current Matching Accuracy | ±2% max (±0.3% typ); ensures consistent luminance between strings in displays and instrumentation. |
| Switching Frequency | Fixed 2MHz (1.88–2.12MHz over temp); allows compact 3.3–10µH inductors and reduces EMI filtering requirements. |
| Input Voltage Range | 2.9V to 40V; supports wide automotive battery range (cold crank to load dump) and industrial 24V systems. |
| PWM Dimming Ratio | Up to 40,000:1 at 100Hz (250ns min on-time); enables ultra-fine brightness resolution in high-dynamic-range displays. |
| VOUT Regulation | Adaptive output voltage controlled by GM1 loop to maintain 1.3V across high-side current sources; minimizes power loss and heat generation. |
| Fault Protection | Dedicated FAULT pin asserts low on open-LED (VOUT–VLEDx < 0.4V) or LED-short-to-GND (VLEDx < 6.0V); unaffected string remains regulated. |
Pinout & Package
LT3909IMSE#TRPBF is housed in a 12-lead plastic MSOP package (3mm × 4.9mm) with exposed pad (Pin 13) soldered to PCB ground for thermal management (θJA = 40°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| INTVCC (1) | Internal 3.0V regulator output | Supplies gate driver and control circuits; must be bypassed with ≥1µF X7R ceramic capacitor; max 100µA external load. |
| VIN (2) | Main input supply | Accepts 2.9V–40V; powers internal regulator and switch; requires local ceramic bypass capacitor. |
| EN/UVLO (3) | Enable and undervoltage lockout input | Shuts down device below 0.4V; enables at 1.215V falling threshold; supports programmable UVLO with resistor divider. |
| ISET (4) | LED current programming input | Single resistor to GND sets identical current for both strings (10–60mA); ILEDx = 1000 / RISET (A). |
| CTRL (5) | Analog dimming and latch-off control | Voltage <1V scales LED current linearly; <80mV latches off both strings; supports NTC-based thermal derating. |
| FB (6) | Output voltage regulation feedback | Sets programmable OVP level (via RFB1/RFB2) and samples VOUT during PWM off-time to prevent droop. |
| PWM (7) | Digital dimming control | Active-low signal disables high-side current sources; enables 40,000:1 dimming ratio independent of VOUT leakage. |
| FAULT (8) | Open/short fault indicator | Open-drain active-low output; pulled low on per-string fault; updated only during PWM/CTRL high states. |
| LED1 (9), LED2 (10) | High-side LED current outputs | Each drives one LED string; can be paralleled for higher current; tolerate up to 40V relative to GND. |
| VOUT (11) | Boost converter output | Regulated node supplying both LED strings; connects to output capacitor and external Schottky (optional). |
| SW (12) | Internal switch drain | Connects to inductor and internal Schottky anode; requires minimized trace area to reduce EMI. |
| Exposed Pad (13) | Thermal ground | Must be soldered to continuous PCB ground plane; critical for thermal performance and reliability at full load. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 400mΩ, 40V, 1A power switch | Eliminates external MOSFET and reduces BOM count; rated for 40V input and 36V LED string operation. |
| On-chip Schottky diode | Reduces board space and component count; optional external Schottky (e.g., SBR1A40S3) improves efficiency at high current. |
| Independent per-string fault detection | Enables fail-operational behavior: one faulty string disables only itself while the other remains fully regulated. |
| Internal thermal regulation loop | Derates LED current to limit junction temperature ≤170°C; protects device during sustained overload or poor heatsinking. |
| Internal soft-start and compensation | Removes need for external compensation network or soft-start timing components; simplifies layout and validation. |
| Accurate EN/UVLO with hysteresis | 30mV hysteresis and 2.0µA pin current enable precise, stable system-level undervoltage lockout programming. |
Applications
| Automotive Instrument Clusters | High-Contrast Industrial Displays |
|---|---|
|
Use Scenario: Dual-color (e.g., red/green) segmented LCD backlight in vehicle dashboards with variable ambient light conditions. IC Role / Device Role / Timing Role: High-side LED driver providing matched current to two independent LED strings, dynamically adapting VOUT to minimize power dissipation. Use Value: ±0.3% typical current matching ensures uniform brightness across segments; 40,000:1 PWM dimming enables seamless transition from daylight to night mode. |
Use Scenario: Backlight for ruggedized HMI panels in factory automation equipment operating from 24V DC rails. IC Role / Device Role / Timing Role: Step-up LED driver with integrated switch and protection, delivering stable 60mA per string across 2.9V–40V input transients. Use Value: Built-in open-LED and short-to-GND fault detection maintains partial display functionality during field failures; thermal regulation prevents luminance drift at elevated ambient temperatures. |
| GPS Receivers with OLED UI | Portable Medical Diagnostic Devices |
|
Use Scenario: Compact GPS handheld with high-brightness OLED display requiring ultra-low quiescent current in battery-powered standby mode. IC Role / Device Role / Timing Role: Efficient 2MHz boost driver enabling small inductor size; shutdown current <2µA extends battery life. Use Value: 600µA typical VIN quiescent current (non-switching) and <2µA shutdown current preserve battery capacity during idle periods. |
Use Scenario: Portable ultrasound or blood glucose monitor with LED status indicators requiring precise, stable illumination under clinical lighting conditions. IC Role / Device Role / Timing Role: Dual-string LED driver with analog dimming (10:1) and accurate current setting for calibrated visual feedback. Use Value: Single ISET resistor programs identical current for redundant indicators; ±2% matching ensures consistent visual signaling across product variants. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3909EMSE#TRPBF | Same die, −40°C to 125°C extended temperature grade (E-grade vs I-grade); identical electrical specs and pinout. | Targeted at commercial/industrial environments where full automotive temp range not required. | Select LT3909EMSE#TRPBF for cost-sensitive non-automotive designs needing same performance at lower qualification cost. |
| LT3909IMSE#PBF | Same device in same MSOP package but supplied in cut-tape (not tape-and-reel); identical electrical and thermal characteristics. | Preferred for prototyping, low-volume production, or manual assembly where reel packaging is unnecessary. | Choose LT3909IMSE#PBF for engineering validation or small-batch builds where tape-and-reel handling is impractical. |
Compared with LT3909EMSE#TRPBF, the LT3909IMSE#TRPBF offers identical performance with guaranteed −40°C to 125°C operation, while LT3909IMSE#PBF provides identical functionality in cut-tape format-making the TRPBF variant optimal for high-volume automated SMT lines requiring reel-fed placement.
Availability
LT3909IMSE#TRPBF is available at Aetrix Electronics and suitable for automotive instrument clusters, high-contrast industrial HMIs, and portable medical diagnostics requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned reliability.
Supply support for LT3909IMSE#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 continues to develop and support its high-performance analog and power management portfolio.
The LT3909 belongs to Linear's precision LED driver product line, designed specifically for automotive and industrial displays demanding tight current matching, robust fault protection, and adaptive efficiency optimization across wide input voltage ranges.
FAQ
What is the maximum LED forward voltage supported by the LT3909IMSE#TRPBF?
The LT3909IMSE#TRPBF supports up to 36V total forward voltage across each LED string. This is enabled by its internal 40V-rated switch and Schottky diode, combined with adaptive VOUT regulation that dynamically adjusts to the minimum voltage required to sustain the programmed LED current-maximizing efficiency while maintaining safe operating margins.
Can the LT3909IMSE#TRPBF drive a single LED string at 120mA?
Yes-the LT3909IMSE#TRPBF allows paralleling of LED1 and LED2 pins to combine both high-side current sources. When configured this way and programmed for 60mA per string via the ISET resistor, the device delivers up to 120mA total to a single LED string while retaining ±2% matching accuracy and full fault protection on the combined output.
How does the LT3909IMSE#TRPBF achieve 40,000:1 PWM dimming without VOUT droop?
The LT3909IMSE#TRPBF samples the FB pin voltage at the PWM falling edge to capture the optimum VOUT level required for LED regulation, then actively regulates VOUT to that stored value during PWM off-time-even compensating for leakage through the internal Schottky diode. This closed-loop hold-and-regulate mechanism eliminates VOUT droop and enables fast LED current recovery at the next PWM rising edge.
What thermal protection mechanisms are implemented in the LT3909IMSE#TRPBF?
The LT3909IMSE#TRPBF includes an internal thermal regulation loop that monitors junction temperature and progressively derates LED current to maintain TJ ≤170°C. Unlike simple shutdown, this foldback behavior preserves partial functionality during transient overloads or inadequate heatsinking-critical for automotive and medical applications where graceful degradation is required.
Is the LT3909IMSE#TRPBF pin-compatible with other members of the LT3909 family?
Yes-LT3909IMSE#TRPBF shares identical pinout and footprint with all LT3909 variants in the 12-lead MSOP package, including LT3909EMSE#PBF, LT3909EMSE#TRPBF, and LT3909IMSE#PBF. This allows direct substitution within the same package family without PCB redesign, provided temperature grade and packaging format meet system requirements.
LT3909IMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-TSSOP (0.118", 3.00mm Width) 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-MSOP-EP
LT3909IMSE#TRPBF FAQ
1.How can I place an order for LT3909IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3909IMSE#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 LT3909IMSE#TRPBF reliable?
The price and inventory of LT3909IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3909IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3909IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3909IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3909IMSE#TRPBF?
LT3909IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3909IMSE#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 LT3909IMSE#TRPBF?
For technical support, including LT3909IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3909IMSE#TRPBF requirements.
6.How does Aetrix verify that LT3909IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3909IMSE#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 LT3909IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3909IMSE#TRPBF?
All LT3909IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3909IMSE#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 LT3909IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3909IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3909IMSE#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…
