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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > LED Drivers

Analog Devices Inc. LT8355IUFDM-1#WPBF

Name: LT8355IUFDM-1#WPBF
Brand: Analog Devices Inc.
SKU: LT8355IUFDM-1#WPBF
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LT8355IUFDM-1#WPBF

Manufacturer:: Analog Devices Inc.

Category:: LED Drivers

Package:: 28-WFQFN Exposed Pad

Datasheet:: LT8355IUFDM-1#WPBF.pdf

Description:: IC LED DRVR DC DC CTRL PWM 28QFN

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Product details

Overview

LT8355IUFDM-1#WPBF from Analog Devices is a dual-channel 60V input / 120V output boost LED controller supporting independent constant-current and constant-voltage regulation per channel, ±2% LED current accuracy, 100kHz–2MHz programmable switching frequency, and 20,000:1 external PWM dimming at 100Hz - deployed in automotive headlamp systems requiring high-voltage, high-reliability LED drive.

For engineers reviewing the LT8355IUFDM-1#WPBF datasheet, LT8355IUFDM-1#WPBF pinout, LT8355IUFDM-1#WPBF application, or LT8355IUFDM-1#WPBF equivalent, key selection considerations include dual-channel rail-to-rail LED current sensing (0V to 120V), AEC-Q100 qualification, side-solderable 28-lead 4mm × 5mm QFN package, and independent OPEN/SHORT LED fault detection per channel.

Technical Context

The LT8355IUFDM-1#WPBF implements fixed-frequency current-mode control with dual independent error amplifiers (VC1/VC2) and dedicated feedback paths (FB1/FB2) enabling simultaneous CC/CV regulation. Each channel features separate ISP/ISN Kelvin sense inputs, programmable soft-start, and internal overvoltage (1.26V FB threshold), overcurrent (670mV ISP–ISN), and open/short LED protection logic.

It integrates two high-side PMOS drivers (PWMTG1/PWMTG2) for load disconnect during PWM dimming or faults, plus dual NMOS gate drivers (GATE1/GATE2) with 5Ω pull-up / 3Ω pull-down on-resistance. The internal exponential PWM generator accepts analog voltage inputs (0.5V–1.5V) to produce 128 precision dimming steps from 0.78% to 100% duty ratio.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	5V to 60V - supports wide automotive battery range including cold-crank and load-dump transients.
Max Output Voltage	120V - enables driving long series-connected LED strings without cascading stages.
LED Current Accuracy	±2% - ensures consistent luminance across channels and temperature (–40°C to 125°C).
Switching Frequency	100kHz to 2MHz - adjustable via RT resistor; higher frequencies reduce inductor size, lower frequencies improve efficiency at high power.
PWM Dimming Ratio	20,000:1 at 100Hz - enables ultra-fine brightness control for adaptive driving beam (ADB) systems.
Package	28-lead 4mm × 5mm side-solderable QFN - supports automated optical inspection (AOI) and high-density PCB layouts.
AEC-Q100 Grade	Grade I (–40°C to +125°C) - qualified for under-hood automotive lighting applications.

Pinout & Package

LT8355IUFDM-1#WPBF uses a 28-lead, 4mm × 5mm side-solderable plastic QFN package with exposed GND pad (Pin 29) requiring soldering to PCB thermal plane. θ_JA = 43°C/W, θ_JC = 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-time or fault; clamped to ISP1 – 8.5V.
ISN1 (Pin 2)	Low-side LED current sense input	Kelvin connection to R_ILED1 low side; enables accurate current regulation down to 0V common-mode voltage.
ISP1 (Pin 3)	High-side LED current sense input	Kelvin connection to R_ILED1 high side; supports up to 120V common-mode voltage with ±1V differential limit.
FB1 (Pin 4)	Channel 1 output voltage feedback	Regulates output voltage to 1.2V reference; triggers PWMTG1 high and soft-start reset on open/short LED events.
VC1 (Pin 5)	Error amplifier compensation node	Connect RC network to ground to stabilize current loop; sets phase margin and transient response.
CTRL1 (Pin 6)	Channel 1 analog dimming input	Linearly programs LED current: (CTRL1 − 0.5V)/(4 × R_ILED1) - enables smooth analog dimming without PWM artifacts.
FAULT1 (Pin 7)	Channel 1 open-drain fault indicator	Pulled low on LED open, short, overvoltage, or overcurrent; requires external 100kΩ pull-up to INTVCC or ≤15V supply.
CTRL2 (Pin 8)	Channel 2 analog dimming input	Part of two-pin multiplying interface with IADJ2; sets R_ILED2 current as [(CTRL2 − 0.48V) × (IADJ2 − 0.5V) − 0.02V]/(4 × R_ILED2).
IADJ2 (Pin 9)	Channel 2 analog dimming scaling input	Adjusts gain of CTRL2 path; enables independent dimming range tuning for asymmetric LED strings.
PWM1 (Pin 10)	Channel 1 exponential PWM input	Accepts 0.5V–1.5V analog voltage for 128-step exponential dimming or digital PWM signal (ON >1.6V, OFF <0.4V).
PWM2 (Pin 11)	Channel 2 exponential PWM input	Functionally identical to PWM1; enables independent dimming profiles per channel for matrix lighting.
RT (Pin 12)	Frequency programming input	Resistor to GND sets f_SW (100kHz–2MHz); also determines internal PWM clock (f_SW/1000).
FAULT2 (Pin 13)	Channel 2 open-drain fault indicator	Independent fault reporting; allows diagnostics without cross-channel interference.
VREF (Pin 14)	2.0V internal reference output	Stable 2V source (±2.5mV) for biasing CTRL/PWM/IADJ pins; max 2.5mA load capability.
EN/UVLO (Pin 15)	Enable and input undervoltage lockout	Shuts down converter when <1.15V (falling); 60mV hysteresis prevents chatter during brownout.
VIN (Pin 16)	Main input supply	Accepts 5V–60V; powers internal circuitry and gate drivers; requires local ceramic bypass capacitor.
VC2 (Pin 17)	Channel 2 error amplifier compensation node	Independent compensation for second channel; enables optimized loop response for mismatched LED loads.
FB2 (Pin 18)	Channel 2 output voltage feedback	Dual independent voltage regulation; supports different output voltages per channel in multi-string designs.
ISP2 (Pin 19)	High-side LED current sense input (CH2)	Identical function to ISP1; supports independent 0V–120V common-mode sensing for CH2.
ISN2 (Pin 20)	Low-side LED current sense input (CH2)	Identical function to ISN1; enables true Kelvin sensing for both channels simultaneously.
PWMTG2 (Pin 21)	High-side PMOS gate driver output (CH2)	Independent load disconnect for CH2; critical for pixel-level control in adaptive front lighting systems (AFS).
INTVCC (Pin 22)	Internal LDO output	7.5V regulated supply (±150mV) for internal circuits; requires ≥4.7µF ceramic capacitor to GND.
GATE2 (Pin 23)	CH2 NMOS gate driver output	Drives external NMOS switch; 5Ω pull-up / 3Ω pull-down ensures fast turn-on/turn-off for high-efficiency operation.
SENSEP2 (Pin 24)	CH2 switch current sense positive	Kelvin connection to high side of R_SENSE2; minimizes PCB trace resistance impact on current limit accuracy.
SENSEN2 (Pin 25)	CH2 switch current sense negative	Kelvin connection to low side of R_SENSE2; completes accurate inductor current measurement.
SENSEN1 (Pin 26)	CH1 switch current sense negative	Enables precise peak-current-mode control; used with SENSEP1 to set current limit threshold (95–120mV).
SENSEP1 (Pin 27)	CH1 switch current sense positive	Paired with SENSEN1; supports accurate cycle-by-cycle current limiting and slope compensation.
GATE1 (Pin 28)	CH1 NMOS gate driver output	Drives CH1 external NMOS; matched timing with GATE2 enables synchronized dual-channel operation.
GND (Pin 29)	Power and signal ground	Exposed thermal pad - must be soldered to PCB ground plane for thermal management and noise immunity.

Key Features

Feature	Design Value
Dual independent CC/CV regulation	Each channel maintains ±2% LED current and ±2% output voltage accuracy across temperature and line/load variations.
128-step exponential PWM dimming	Internally generated dimming curve matches human eye perception - eliminates need for external microcontroller lookup tables.
Rail-to-rail LED current sensing	0V to 120V common-mode range enables direct sensing at LED anode/cathode regardless of string voltage or topology (boost/SEPIC).
Spread spectrum frequency modulation	Reduces EMI peak emissions by ±10% around nominal f_SW, easing compliance with CISPR 25 Class 5 automotive EMC requirements.
Independent OPEN/SHORT LED fault per channel	Dedicated fault logic isolates failures - prevents single-point failure from disabling entire lighting system in safety-critical AFS applications.
Side-solderable QFN package	Eliminates shadowing during reflow; enables AOI verification of all solder joints - critical for zero-defect automotive manufacturing.

Applications

Automotive Adaptive Headlamps	Commercial Vehicle Running Lamps
Use Scenario: Matrix-style LED headlamps dynamically mask portions of beam to avoid glare while illuminating road signs and pedestrians. IC Role / Device Role / Timing Role: LT8355IUFDM-1#WPBF independently controls up to 256 LEDs across two channels using PWM1/PWM2 and PWMTG1/PWMTG2 for pixel-level on/off switching. Use Value: 20,000:1 dimming ratio and 120V output capability enable precise photometric control of high-lumen LED arrays without secondary DC-DC stages.	Use Scenario: Heavy-duty truck running lamps require robust, thermally stable LED drive under extreme ambient temperatures (–40°C to +85°C). IC Role / Device Role / Timing Role: LT8355IUFDM-1#WPBF operates as constant-current source for dual parallel LED strings, leveraging ±2% current accuracy and AEC-Q100 qualification. Use Value: Side-solderable QFN package and integrated fault reporting (FAULT1/FAULT2) simplify board-level diagnostics and meet ISO 16750-4 vibration and thermal shock requirements.
Industrial High-Bay Lighting	Aviation Exterior Signage
Use Scenario: Warehouse high-bay fixtures use long LED strings powered from 48V DC microgrids with minimal voltage drop. IC Role / Device Role / Timing Role: LT8355IUFDM-1#WPBF configures as dual boost converter delivering up to 120V per channel to drive 40–60V LED strings in series. Use Value: 60V input rating and 100kHz–2MHz frequency adjustment allow optimization for efficiency (low f_SW) or compact magnetics (high f_SW) in space-constrained fixtures.	Use Scenario: Aircraft wingtip and tail lights require EMI-quiet, fail-safe LED drive compliant with DO-160 Section 20 radiated emissions. IC Role / Device Role / Timing Role: LT8355IUFDM-1#WPBF implements spread-spectrum switching and independent fault monitoring for redundant lighting channels. Use Value: Integrated spread spectrum and rail-to-rail sensing eliminate external EMI filters and high-voltage op-amps - reducing BOM count and certification risk.

Automotive Adaptive Headlamps

Commercial Vehicle Running Lamps

Use Scenario: Matrix-style LED headlamps dynamically mask portions of beam to avoid glare while illuminating road signs and pedestrians.

IC Role / Device Role / Timing Role: LT8355IUFDM-1#WPBF independently controls up to 256 LEDs across two channels using PWM1/PWM2 and PWMTG1/PWMTG2 for pixel-level on/off switching.

Use Value: 20,000:1 dimming ratio and 120V output capability enable precise photometric control of high-lumen LED arrays without secondary DC-DC stages.

Use Scenario: Heavy-duty truck running lamps require robust, thermally stable LED drive under extreme ambient temperatures (–40°C to +85°C).

IC Role / Device Role / Timing Role: LT8355IUFDM-1#WPBF operates as constant-current source for dual parallel LED strings, leveraging ±2% current accuracy and AEC-Q100 qualification.

Use Value: Side-solderable QFN package and integrated fault reporting (FAULT1/FAULT2) simplify board-level diagnostics and meet ISO 16750-4 vibration and thermal shock requirements.

Industrial High-Bay Lighting

Aviation Exterior Signage

Use Scenario: Warehouse high-bay fixtures use long LED strings powered from 48V DC microgrids with minimal voltage drop.

IC Role / Device Role / Timing Role: LT8355IUFDM-1#WPBF configures as dual boost converter delivering up to 120V per channel to drive 40–60V LED strings in series.

Use Value: 60V input rating and 100kHz–2MHz frequency adjustment allow optimization for efficiency (low f_SW) or compact magnetics (high f_SW) in space-constrained fixtures.

Use Scenario: Aircraft wingtip and tail lights require EMI-quiet, fail-safe LED drive compliant with DO-160 Section 20 radiated emissions.

IC Role / Device Role / Timing Role: LT8355IUFDM-1#WPBF implements spread-spectrum switching and independent fault monitoring for redundant lighting channels.

Use Value: Integrated spread spectrum and rail-to-rail sensing eliminate external EMI filters and high-voltage op-amps - reducing BOM count and certification risk.

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
LT3965EFE#PBF	Single-channel, 60V input, 60V output; no internal exponential PWM; requires external MCU for dimming sequencing.	Suitable for simpler, lower-voltage LED arrays where independent dual-channel control is unnecessary.	Select LT3965EFE#PBF only when cost sensitivity outweighs need for dual-channel integration and analog dimming flexibility.
MAX20050ATP/V+T	Automotive-grade dual-channel buck LED controller; max 65V input; no high-side PMOS driver; limited to 45V output.	Optimized for low-output-voltage interior lighting; lacks 120V capability and rail-to-rail sensing required for headlamp boost topologies.	Choose MAX20050ATP/V+T for cabin lighting where VIN <40V and VOUT <45V; not viable for adaptive headlamps.

Compared with LT3965EFE#PBF and MAX20050ATP/V+T, the LT8355IUFDM-1#WPBF uniquely delivers dual-channel 120V boost capability with integrated exponential PWM, rail-to-rail sensing, and AEC-Q100 qualification - making it the only option for automotive adaptive front lighting systems requiring pixel-level control and high-voltage string drive.

Availability

LT8355IUFDM-1#WPBF is available at Aetrix Electronics and suitable for automotive headlamps, commercial vehicle running lamps, and industrial high-bay lighting requiring stable component supply, AEC-Q100 compliance, and long-term production continuity.

Supply support for LT8355IUFDM-1#WPBF 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 product line was designed specifically for high-reliability, high-voltage automotive LED lighting - integrating dual-channel control, fault resilience, and AEC-Q100 qualification into a single side-solderable package.

FAQ

What is the maximum LED string voltage supported by the LT8355IUFDM-1#WPBF?

The LT8355IUFDM-1#WPBF supports up to 120V output per channel, verified by absolute maximum ratings (ISP/ISN pins rated to 120V common-mode) and typical application circuits driving 100V LED strings. This enables direct drive of long series-connected LED arrays without cascaded converters, reducing system complexity and improving efficiency in automotive headlamp designs.

Does the LT8355IUFDM-1#WPBF support both analog and PWM dimming on the same channel?

Yes, the LT8355IUFDM-1#WPBF supports concurrent analog and PWM dimming: CTRL1/CTRL2 and IADJ2 provide two-pin multiplying analog dimming for coarse adjustment, while PWM1/PWM2 accept either analog voltage inputs (0.5V–1.5V) for exponential dimming or digital signals (ON >1.6V, OFF <0.4V) for high-ratio PWM. Both methods operate independently per channel without conflict.

How does the LT8355IUFDM-1#WPBF handle LED open-circuit faults?

On LED open-circuit detection, the LT8355IUFDM-1#WPBF pulls the corresponding FAULT pin (FAULT1 or FAULT2) low, disables switching, drives PWMTG high to disconnect the load, and resets soft-start. Recovery occurs automatically after a cooldown period. This behavior is confirmed in the Electrical Characteristics table (FB Open Threshold = 1.116V–1.164V) and Pin Functions description for FB1/FB2.

What is the purpose of the PWMTG pins on the LT8355IUFDM-1#WPBF?

The PWMTG1 and PWMTG2 pins on the LT8355IUFDM-1#WPBF drive external high-side PMOS switches to physically 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 - a critical feature for adaptive driving beam systems requiring microsecond-level pixel control. PWMTG voltage is clamped to ISP – 8.5V (typical) to protect the PMOS gate oxide.

Is the LT8355IUFDM-1#WPBF pin-compatible with other devices in the LT8355 family?

No, the LT8355IUFDM-1#WPBF is not pin-compatible with non–"-1" variants such as LT8355IUFD#PBF. The "-1" suffix denotes specific internal configuration differences including enhanced PWM dimming architecture, updated fault thresholds, and revised internal oscillator calibration - confirmed by distinct part markings, ordering codes, and Rev. C datasheet revision history.

LT8355IUFDM-1#WPBF Specifications

Product attributes: Attribute value

Manufacturer:: Analog Devices Inc.

Series:: -

Package/Case:: 28-WFQFN Exposed Pad

Packaging:: Tube

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#WPBF FAQ

1.How can I place an order for LT8355IUFDM-1#WPBF through Aetrix?

Please submit a Request for Quotation (RFQ) for LT8355IUFDM-1#WPBF 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#WPBF reliable?

The price and inventory of LT8355IUFDM-1#WPBF 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#WPBF is usually 5 days.

3.What payment methods are accepted for LT8355IUFDM-1#WPBF?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8355IUFDM-1#WPBF transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LT8355IUFDM-1#WPBF?

LT8355IUFDM-1#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LT8355IUFDM-1#WPBF 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#WPBF?

For technical support, including LT8355IUFDM-1#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8355IUFDM-1#WPBF requirements.

6.How does Aetrix verify that LT8355IUFDM-1#WPBF is sourced from the original manufacturer or authorized distributors?

All LT8355IUFDM-1#WPBF 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#WPBF meets industry standards.

7.What is the process for return or replacement of LT8355IUFDM-1#WPBF?

All LT8355IUFDM-1#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8355IUFDM-1#WPBF, 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#WPBF part is unused and in its original packaging.

Return procedure for LT8355IUFDM-1#WPBF:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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