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Analog Devices Inc. LT8356IUDCM-1#WTRPBF
- Part No.:
- LT8356IUDCM-1#WTRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LT8356IUDCM-1#WTRPBF.pdf
- Description:
- 110V LED DRIVER INTERNAL PWM DIM
- Quantity:
- Payment:
- Shipping:
Inventory:1,262
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Product details
Overview
LT8356IUDCM-1#WTRPBF from Analog Devices is a 100V input, 120V output constant-current/constant-voltage DC/DC LED controller in a 20-lead 3mm × 4mm side-solderable QFN package. It supports boost, SEPIC, buck-mode, and flyback topologies with ±2% LED current regulation, 20,000:1 external PWM dimming at 100Hz, and rail-to-rail LED current sensing (0V to 120V). It is AEC-Q100 qualified for automotive headlamp and running lamp applications.
For engineers reviewing the LT8356IUDCM-1#WTRPBF datasheet, LT8356IUDCM-1#WTRPBF pinout, LT8356IUDCM-1#WTRPBF application, or LT8356IUDCM-1#WTRPBF equivalent, key selection considerations include its dual analog dimming (CTRL/IADJ), internal exponential PWM generator (128-step, 0.78–100% duty), high-side PMOS driver (PWMTG), 5V–100V input range, and integrated fault protection (LED open/short, overvoltage, overcurrent).
Technical Context
The LT8356IUDCM-1#WTRPBF employs a fixed-frequency current-mode control architecture with an internal error amplifier (VC node) and dual feedback paths: one for LED current regulation via ISP/ISN sense differential voltage, and another for output voltage regulation via FB. Its PWM dimming engine operates at fSW/1000, enabling precise time-based dimming without external timing components.
It integrates two independent gate drivers: a low-side NMOS driver (GATE) with 5Ω pull-up/3Ω pull-down resistance and fast rise/fall times (<50ns), and a high-side PMOS driver (PWMTG) that swings from ISP–8.5V to ISP to ensure robust load disconnect during dimming or fault events. The device uses a programmable RT resistor to set switching frequency from 185kHz to 2.15MHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5V to 100V - supports wide-range automotive battery systems including cold-crank (6V) and load-dump (80V transient) conditions. |
| Output Voltage Capability | Up to 120V - enables driving long LED strings in high-brightness automotive lighting. |
| LED Current Regulation Accuracy | ±2% - ensures consistent luminance across temperature and unit-to-unit variation in production. |
| External PWM Dimming Ratio | 20,000:1 at 100Hz - delivers ultra-fine brightness control for adaptive driving beam (ADB) systems. |
| Internal Exponential PWM Steps | 128 discrete dimming levels (0.78% to 100%) - provides smooth, perceptually linear dimming without microcontroller firmware interpolation. |
| Switching Frequency Range | 185kHz to 2.15MHz - allows EMI optimization and compact magnetics design via RT resistor selection. |
| Operating Junction Temperature | –40°C to +125°C - meets automotive under-hood thermal requirements per AEC-Q100 Grade I. |
Pinout & Package
LT8356IUDCM-1#WTRPBF is housed in a 20-lead, 3mm × 4mm side-solderable plastic QFN (UDCM) package with exposed thermal pad (Pin 21 = GND). The package features θJA = 34°C/W and θJC = 3.4°C/W, requiring direct soldering of the exposed pad to PCB ground plane for thermal integrity and electrical stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (1) | Enable / Input Undervoltage Lockout | Shuts down converter when VIN drops below 1.25V (typ); 60mV hysteresis prevents chatter during brownout. |
| GND (2, 21) | Power Ground / Thermal Pad | Pin 21 is exposed pad - must be soldered to PCB ground plane; Pin 2 alone is insufficient for thermal or current return. |
| INTVCC (3) | Internal Bias Supply | 7.5V regulated supply (±2.5%) for internal circuits; requires ≥4.7µF ceramic bypass capacitor to GND. |
| VC (4) | Error Amplifier Compensation Node | Connect RC network between VC and GND to stabilize current/voltage control loop; critical for transient response. |
| CTRL (5) | Analog Dimming Input (Multiplier Factor) | Together with IADJ, sets LED current threshold; 0.3V–1.5V range enables fine-grained analog scaling of full-scale current. |
| FB (6) | Output Voltage Feedback | Regulates output voltage at 1.2V (±1.0%); triggers overvoltage (1.26V) or short-LED (0.3V) fault if thresholds exceeded. |
| ISN (7) | Low-Side LED Sense Input | Kelvin connection to low side of RILED; used with ISP to measure VISP–VISN for current regulation up to 120V common-mode. |
| ISP (8) | High-Side LED Sense Input | Kelvin connection to high side of RILED; supports rail-to-rail sensing (0V–120V) and fast overcurrent detection (>670mV). |
| SENSE (10) | Switch Current Sense Input | Monitors NMOS switch current via grounded sense resistor; negative terminal connects to exposed pad (GND). |
| GATE (11) | Low-Side NMOS Gate Driver | Drives external NMOS switch with 5Ω pull-up / 3Ω pull-down; 45ns rise / 40ns fall time into 3.3nF load. |
| FAULT (14) | Open-Drain Fault Indicator | Pulls low on LED open, short, overvoltage, or overcurrent; requires external pull-up to ≤40V supply. |
| PWM (16) | Dimming Control Input | Accepts analog voltage (0.5–1.5V) for internal exponential PWM or digital signal (0.4V/1.6V thresholds) for external PWM. |
| VREF (17) | 2.0V Precision Reference | Stable 2.0V (±1.5%) reference for biasing CTRL/IADJ/PWM; supplies up to 2.5mA; bypass with 1µF if noisy. |
| RT (18) | Frequency Programming Input | Resistor to GND sets fSW (185kHz–2.15MHz) and internal PWM clock (fSW/1000); no capacitors allowed. |
| VIN (20) | Main Input Supply | 5V–100V input; requires local ceramic bypass (≥2.2µF) close to pin; withstands 80V transients. |
Key Features
| Feature | Design Value |
|---|---|
| Two-pin multiplying analog dimming (CTRL/IADJ) | Enables continuous, noise-immune current scaling without DAC or microcontroller-ideal for analog sensor-driven dimming. |
| Internal exponential PWM generator (128 steps) | Eliminates need for external PWM generator IC or MCU firmware; achieves perceptually linear dimming with single analog ramp. |
| Rail-to-rail LED current sensing (0V to 120V) | Supports high-side or low-side sensing in any topology (boost, SEPIC, flyback), simplifying layout and improving accuracy. |
| Integrated high-side PMOS driver (PWMTG) | Provides active load disconnect during PWM off-time, preventing output capacitor recharging transients and enabling true zero-current off-state. |
| AEC-Q100 Grade I qualification (–40°C to +125°C) | Validated for automotive front-end lighting systems with full reliability testing (HTOL, TC, UHAST, ESD). |
| Spread spectrum frequency modulation | Reduces peak EMI by ±12.5% frequency dithering-critical for meeting CISPR-25 Class 5 radiated emissions limits. |
Applications
| Automotive Head Lamps | Adaptive Driving Beam (ADB) |
|---|---|
Use Scenario: High-intensity LED arrays in projector-based headlamps requiring precise current control and dynamic dimming. IC Role / Device Role / Timing Role: Constant-current LED controller with integrated PWM dimming engine and fault protection. Use Value: ±2% current regulation ensures uniform beam intensity; 20,000:1 external PWM enables pixel-level ADB zone control without flicker. |
Use Scenario: Matrix LED modules where individual segments are switched on/off based on camera input and vehicle speed. IC Role / Device Role / Timing Role: High-voltage LED driver with fast PWMTG load disconnect and internal exponential dimming for smooth transitions. Use Value: PWMTG's <180ns turn-off prevents residual glow between zones; 128-step internal PWM eliminates MCU timing jitter in real-time dimming. |
| Commercial Vehicle Running Lamps | Industrial High-Bay LED Lighting |
Use Scenario: 24V/48V truck/bus tail/brake lamps operating across wide input (9V–36V) and ambient (–40°C–+85°C) ranges. IC Role / Device Role / Timing Role: Wide-input boost LED controller with UVLO hysteresis and thermal derating support. Use Value: Programmable EN/UVLO (1.15–1.35V) enables custom brownout recovery; AEC-Q100 qualification ensures field reliability. |
Use Scenario: 100–277VAC-fed industrial LED fixtures using offline boost PFC + LT8356-1 secondary stage. IC Role / Device Role / Timing Role: Secondary-side CC/CV LED controller accepting 100V DC bus from PFC stage. Use Value: 120V output capability drives >60-LED strings; spread spectrum reduces conducted EMI coupling into sensitive factory sensors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3762EFE#TRPBF | Higher max input (60V vs 100V), no internal exponential PWM, only external PWM dimming (1000:1), no PWMTG driver. | Lacks integrated high-side disconnect and 128-step dimming-requires external PMOS driver and MCU for fine dimming. | Choose LT3762 for cost-sensitive non-automotive designs where 60V input suffices and external PWM control is acceptable. |
| LM3423MH/NOPB | Lower input (75V), no internal PWM generator, no PWMTG, only analog dimming via ISET, no spread spectrum. | Requires external PWM generator IC and PMOS driver; lacks AEC-Q100 qualification and rail-to-rail sensing. | Choose LM3423 for legacy industrial LED drivers where 75V input and basic analog dimming meet requirements. |
Compared with LT3762EFE#TRPBF and LM3423MH/NOPB, the LT8356IUDCM-1#WTRPBF uniquely integrates exponential PWM generation, high-side PMOS drive (PWMTG), and AEC-Q100 qualification-enabling single-chip ADB solutions without external timing or load-switch circuitry.
Availability
LT8356IUDCM-1#WTRPBF is available at Aetrix Electronics and suitable for automotive headlamps, adaptive driving beam systems, and industrial high-voltage LED lighting requiring stable component supply, AEC-Q100 compliance, and high-reliability thermal performance.
Supply support for LT8356IUDCM-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 LT8356-1 belongs to Analog Devices' Power by Linear™ LED controller family, designed specifically for high-voltage, high-reliability automotive lighting with integrated dimming, protection, and AEC-Q100 qualification.
FAQ
What is the maximum LED string voltage supported by the LT8356IUDCM-1#WTRPBF?
The LT8356IUDCM-1#WTRPBF supports up to 120V output voltage, verified by absolute maximum ratings (ISP/ISN pins rated to 120V common-mode) and typical application circuits delivering 40W into high-voltage LED strings. This enables driving 30–40 white LEDs in series at standard forward voltage (3.2–3.6V per LED) under automotive thermal conditions.
Does the LT8356IUDCM-1#WTRPBF require an external microcontroller to achieve 128-step dimming?
No. The LT8356IUDCM-1#WTRPBF includes a fully integrated exponential PWM generator that selects one of 128 precise dimming ratios (0.78% to 100%) based solely on the analog voltage applied to the PWM pin-no microcontroller, timer, or external logic is required to realize this feature in the LT8356IUDCM-1#WTRPBF.
How does the PWMTG pin function during LED overcurrent fault events in the LT8356IUDCM-1#WTRPBF?
During an overcurrent event-detected when VISP–VISN exceeds 670mV-the LT8356IUDCM-1#WTRPBF immediately disables switching, asserts PWMTG high (to ISP–8.5V), and resets soft-start. This actively disconnects the LED load via external PMOS, preventing thermal runaway while enabling automatic recovery after cooldown-without external intervention.
Can the LT8356IUDCM-1#WTRPBF operate in buck mode, and what are the key design constraints?
Yes, the LT8356IUDCM-1#WTRPBF supports buck-mode LED driver configurations as confirmed in the Applications section and block diagram. Key constraints include ensuring ISP/ISN sense inputs remain within 0–120V common-mode range, using the GATE pin to drive a low-side NMOS, and configuring FB for output voltage regulation-while maintaining AEC-Q100 thermal derating margins.
What is the purpose of the SENSE pin in the LT8356IUDCM-1#WTRPBF, and how does it differ from ISP/ISN?
The SENSE pin in the LT8356IUDCM-1#WTRPBF monitors switch current (via a grounded sense resistor) for current-mode control and cycle-by-cycle limiting, whereas ISP/ISN measures LED string current for final output regulation. SENSE enables stable operation across topologies; ISP/ISN provides precision ±2% LED current accuracy independent of inductor or MOSFET variations-both are essential for robust LT8356IUDCM-1#WTRPBF operation.
LT8356IUDCM-1#WTRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- Flyback, SEPIC, Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 5V
- Voltage - Supply (Max):
- 100V
- Voltage - Output:
- 0V ~ 120V
- Current - Output / Channel:
- -
- Frequency:
- 185kHz ~ 2.1MHz
- Dimming:
- Analog, PWM
- Applications:
- Automotive
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x4)
LT8356IUDCM-1#WTRPBF FAQ
1.How can I place an order for LT8356IUDCM-1#WTRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8356IUDCM-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 LT8356IUDCM-1#WTRPBF reliable?
The price and inventory of LT8356IUDCM-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 LT8356IUDCM-1#WTRPBF is usually 5 days.
3.What payment methods are accepted for LT8356IUDCM-1#WTRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8356IUDCM-1#WTRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8356IUDCM-1#WTRPBF?
LT8356IUDCM-1#WTRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8356IUDCM-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 LT8356IUDCM-1#WTRPBF?
For technical support, including LT8356IUDCM-1#WTRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8356IUDCM-1#WTRPBF requirements.
6.How does Aetrix verify that LT8356IUDCM-1#WTRPBF is sourced from the original manufacturer or authorized distributors?
All LT8356IUDCM-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 LT8356IUDCM-1#WTRPBF meets industry standards.
7.What is the process for return or replacement of LT8356IUDCM-1#WTRPBF?
All LT8356IUDCM-1#WTRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8356IUDCM-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 LT8356IUDCM-1#WTRPBF part is unused and in its original packaging.
Return procedure for LT8356IUDCM-1#WTRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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