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Analog Devices Inc. LT8355IUFDM-1#WTRPBF
- Part No.:
- LT8355IUFDM-1#WTRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8355IUFDM-1#WTRPBF.pdf
- Description:
- IC LED DRV DC DC CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,460
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Product details
Overview
LT8355IUFDM-1#WTRPBF from Analog Devices is a dual-channel 60V input / 120V output DC/DC LED controller for high-current automotive and industrial boost LED drivers. It delivers ±2% LED current regulation, supports 100kHz–2MHz adjustable switching frequency, provides rail-to-rail LED current sensing (0V to 120V), and enables 20,000:1 external PWM dimming at 100Hz - used in adaptive automotive headlamps and precision lighting systems.
For engineers reviewing the LT8355IUFDM-1#WTRPBF datasheet, LT8355IUFDM-1#WTRPBF pinout, LT8355IUFDM-1#WTRPBF application, or LT8355IUFDM-1#WTRPBF equivalent, key selection criteria include dual-channel independent dimming control, AEC-Q100 qualification, high-side PMOS disconnect via PWMTG pins, scalable analog dimming (CTRL/IADJ2), and fault-per-channel open/short LED detection with FAULT1/FAULT2 outputs.
Technical Context
The LT8355IUFDM-1#WTRPBF implements fixed-frequency current-mode control per channel with independent error amplifiers (VC1/VC2), internal exponential PWM generator (128-step, 0.78%–100%), and dual-path protection logic. Each channel features separate ISP/ISN Kelvin sense inputs, FB-based overvoltage/undervoltage thresholds (1.26V/0.3V), and dedicated soft-start reset on fault.
It integrates two independent gate drivers: GATE1/GATE2 for external NMOS switches (5Ω pull-up, 3Ω pull-down) and PWMTG1/PWMTG2 for high-side PMOS load disconnect (8.5V below ISP, 150ns turn-on). Switching frequency is set by RT resistor (9.09kΩ → 1.95MHz; 51.1kΩ → 400kHz), with spread-spectrum modulation enabled.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5V to 60V - supports wide-range automotive battery and industrial DC bus operation. |
| Max Output Voltage | 120V - enables series-connected high-brightness LED strings without cascading stages. |
| LED Current Regulation | ±2% - ensures consistent luminance across temperature and unit variation in lighting modules. |
| Switching Frequency | 100kHz to 2MHz - selectable via RT resistor; higher frequencies reduce inductor size, lower frequencies improve efficiency at high power. |
| PWM Dimming Ratio | 20,000:1 (external) / 128:1 (internal exponential) - meets stringent contrast requirements in automotive DLP and matrix beam systems. |
| Operating Temp Range | –40°C to +125°C - qualified per AEC-Q100 Grade 1 for under-hood automotive applications. |
| Package | 28-lead 4mm × 5mm side-solderable QFN - enables automated optical inspection and thermal reliability in compact PCB layouts. |
Pinout & Package
LT8355IUFDM-1#WTRPBF uses a 28-lead, 4mm × 5mm side-solderable plastic QFN package (UFDM) with exposed GND pad (Pin 29) requiring PCB soldering for thermal and electrical integrity. θJA = 43°C/W, θJC = 3.4°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMTG1 (Pin 1) | High-side PMOS gate driver output | Drives external PMOS switch to disconnect LED load during PWM off or fault; voltage limited to ISP1 – 8.5V (typ). |
| ISN1 (Pin 2) | Low-side LED current sense input | Kelvin connection to RILED1 bottom; enables accurate current regulation down to 0V common-mode. |
| ISP1 (Pin 3) | High-side LED current sense input | Kelvin connection to RILED1 top; supports up to 120V common-mode voltage with ±1V differential limit. |
| FB1 (Pin 4) | Channel 1 output voltage feedback | Regulates output voltage at 1.2V threshold; triggers PWMTG1 high on overvoltage (>1.26V) or open LED (<0.3V). |
| CTRL1 (Pin 6) | Channel 1 analog dimming control | Sets LED current linearly: (CTRL1 − 0.5V)/(4 × RILED1) - enables precise analog brightness scaling. |
| FAULT1 (Pin 7) | Channel 1 open-drain fault indicator | Pulled low on LED open, short, overcurrent, or overvoltage; independent of Channel 2 for diagnostics. |
| PWM1 (Pin 10) | Channel 1 PWM dimming input | Accepts external digital PWM (0.4V/1.6V thresholds) or analog voltage (0.5–1.5V) for exponential dimming. |
| RT (Pin 12) | Frequency programming input | Resistor-to-ground sets fSW (100kHz–2MHz) and internal PWM clock (fSW/1000); no capacitors allowed. |
| VREF (Pin 14) | 2.0V reference output | Stable 2V source (±2mV) for biasing CTRL/IADJ2/PWM; max 2.5mA drive capability. |
| EN/UVLO (Pin 15) | Enable and input undervoltage lockout | Shuts down at 1.25V falling threshold with 60mV hysteresis; supports programmable VIN UVLO via resistor divider. |
| GATE1 (Pin 28) | Channel 1 NMOS gate driver output | Drives external NMOS switch with 5Ω pull-up / 3Ω pull-down; rise/fall times <45ns with 3.3nF load. |
| SENSEN1 (Pin 26) | Channel 1 switch current sense negative | Kelvin connection to low side of RSENSE1; used for peak-current-mode control loop stability. |
| SENSEP1 (Pin 27) | Channel 1 switch current sense positive | Kelvin connection to high side of RSENSE1; enables accurate inductor current measurement. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent PWM dimming | Each channel supports simultaneous external digital PWM (20,000:1) and internal exponential analog PWM (128 steps), enabling asymmetric beam shaping in automotive matrix headlamps. |
| Rail-to-rail LED current sensing | 0V to 120V common-mode range on ISP/ISN pins allows direct sensing at LED anode/cathode regardless of output voltage level - eliminates level-shifting circuitry. |
| AEC-Q100 Grade 1 qualification | Validated for –40°C to +125°C junction operation with automotive-grade reliability testing - suitable for front-end lighting modules without derating. |
| Independent per-channel fault reporting | Separate FAULT1/FAULT2 open-drain outputs signal LED open, short, overvoltage, or overcurrent events - enables real-time diagnostics and fail-safe system response. |
| Two-pin multiplying analog dimming (CH2) | CTRL2 × IADJ2 product sets CH2 current with multiplicative scaling - simplifies closed-loop brightness calibration using DACs or potentiometers. |
Applications
| Automotive Adaptive Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Matrix beam LED module with individually addressable segments for glare-free high-beam assist. IC Role / Device Role / Timing Role: Dual-channel CC/CV controller driving two independent LED strings; each channel manages segment current and PWM timing for dynamic beam shaping. Use Value: Enables 20,000:1 dimming ratio per segment and ±2% current matching across temperature - critical for ECE R149 compliance and pixel-level light control. | Use Scenario: 150W high-bay fixture with redundant LED strings for warehouse illumination. IC Role / Device Role / Timing Role: Dual boost controller delivering constant current to parallel LED arrays while monitoring open/short faults per string. Use Value: Rail-to-rail 0V–120V ISP/ISN sensing allows direct high-side current measurement without shunt relocation - reduces BOM and improves thermal layout. |
| Commercial Signage Backlight | Medical Surgical Lighting |
Use Scenario: Edge-lit LED signage requiring uniform brightness and flicker-free dimming across large panels. IC Role / Device Role / Timing Role: Dual-channel controller managing top/bottom edge LED strings with synchronized exponential PWM dimming. Use Value: Internal 128-step exponential dimming eliminates visible stepping at low intensities - meets IEC 62471 photobiological safety requirements. | Use Scenario: Sterile-field surgical lamp with color-tunable white LEDs and instant-on dimming. IC Role / Device Role / Timing Role: Dual-channel constant-current source with fast fault response (PWMTG disconnect within 150ns) for patient safety-critical illumination. Use Value: Independent FAULT1/FAULT2 outputs enable immediate channel isolation on LED failure - prevents total light loss during procedures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Single-channel, no integrated PWM generator; requires external microcontroller for dimming sequencing. | Lacks dual-channel independence and internal exponential PWM - unsuitable for asymmetric beam control. | Select only if single-string design suffices and external PWM timing logic is acceptable. |
| MAX20051ATP/V+T | Automotive-qualified dual-channel buck LED controller; max 65V output, no high-side PMOS disconnect (PWMTG). | Cannot support >65V LED strings or active load disconnect during PWM off - limits use in high-voltage boost topologies. | Prefer for low-output-voltage (<65V), space-constrained buck designs where PWMTG functionality is unnecessary. |
Compared with LTC3783EFE#PBF and MAX20051ATP/V+T, the LT8355IUFDM-1#WTRPBF uniquely combines dual-channel 120V boost capability, integrated exponential PWM, and high-side PMOS disconnect - making it the only option for AEC-Q100-compliant adaptive headlamp systems requiring independent per-string 20,000:1 dimming and fault-isolated operation.
Availability
LT8355IUFDM-1#WTRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, and medical surgical lighting requiring stable component supply, AEC-Q100 compliance, and long-term production continuity.
Supply support for LT8355IUFDM-1#WTRPBF 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets.
The LT8355-1 product line delivers dual-channel, high-voltage LED controllers optimized for AEC-Q100 automotive lighting systems - emphasizing precision current regulation, fault resilience, and scalable dimming for adaptive beam architectures.
FAQ
What is the maximum LED string voltage supported by the LT8355IUFDM-1#WTRPBF?
The LT8355IUFDM-1#WTRPBF supports up to 120V output voltage per channel, verified by absolute maximum ratings (ISP/ISN differential ≤ ±1V, common-mode up to 120V) and typical application circuits operating at 120V. This enables driving long series-connected LED strings in automotive headlamps and industrial fixtures without intermediate conversion stages.
Does the LT8355IUFDM-1#WTRPBF support independent dimming for each channel?
Yes, the LT8355IUFDM-1#WTRPBF provides fully independent dimming control per channel via separate PWM1/PWM2 inputs and CTRL1/CTRL2 + IADJ2 analog inputs. Each channel has its own exponential PWM generator, fault detection, and PWMTG driver - enabling asymmetric dimming profiles required in matrix beam headlamps.
How does the LT8355IUFDM-1#WTRPBF handle LED open-circuit faults?
On LED open-circuit detection, the LT8355IUFDM-1#WTRPBF pulls the corresponding FAULT pin low and drives the PWMTG pin high to disconnect the load. The FB pin voltage falls below 0.3V (typical), triggering soft-start reset and switching halt. After a cooldown period, the part re-enters soft-start - all actions occur independently per channel without affecting the other channel's operation.
What is the purpose of the PWMTG pins on the LT8355IUFDM-1#WTRPBF?
The PWMTG1 and PWMTG2 pins on the LT8355IUFDM-1#WTRPBF drive external high-side PMOS switches to actively disconnect the LED load during PWM off periods or fault conditions. This prevents residual charge leakage from output capacitors and eliminates long transient recovery times - ensuring clean, flicker-free dimming and rapid fault isolation in safety-critical lighting.
Is the LT8355IUFDM-1#WTRPBF qualified for automotive applications?
Yes, the LT8355IUFDM-1#WTRPBF is AEC-Q100 Grade 1 qualified (–40°C to +125°C junction temperature) and designated with the #W suffix per Analog Devices' automotive product definition. It undergoes automotive-specific reliability testing and is approved for use in front-end lighting modules, including adaptive driving beam (ADB) systems.
LT8355IUFDM-1#WTRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- SEPIC, Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 2
- Voltage - Supply (Min):
- 5V
- Voltage - Supply (Max):
- 60V
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 96kHz ~ 2.1MHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 28-QFN (4x5)
LT8355IUFDM-1#WTRPBF FAQ
1.How can I place an order for LT8355IUFDM-1#WTRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8355IUFDM-1#WTRPBF 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 LT8355IUFDM-1#WTRPBF reliable?
The price and inventory of LT8355IUFDM-1#WTRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8355IUFDM-1#WTRPBF is usually 5 days.
3.What payment methods are accepted for LT8355IUFDM-1#WTRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8355IUFDM-1#WTRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8355IUFDM-1#WTRPBF?
LT8355IUFDM-1#WTRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8355IUFDM-1#WTRPBF 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 LT8355IUFDM-1#WTRPBF?
For technical support, including LT8355IUFDM-1#WTRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8355IUFDM-1#WTRPBF requirements.
6.How does Aetrix verify that LT8355IUFDM-1#WTRPBF is sourced from the original manufacturer or authorized distributors?
All LT8355IUFDM-1#WTRPBF 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 LT8355IUFDM-1#WTRPBF meets industry standards.
7.What is the process for return or replacement of LT8355IUFDM-1#WTRPBF?
All LT8355IUFDM-1#WTRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8355IUFDM-1#WTRPBF, 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 LT8355IUFDM-1#WTRPBF part is unused and in its original packaging.
Return procedure for LT8355IUFDM-1#WTRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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