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Analog Devices Inc. LT8500ETJ#PBF
- Part No.:
- LT8500ETJ#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 56-VTLA Exposed Pad
- Datasheet:
-
LT8500ETJ#PBF.pdf
- Description:
- IC PWM GENERATOR 56-TLAQFN
- Quantity:
- Payment:
- Shipping:
Inventory:223
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Product details
Overview
LT8500ETJ#PBF from Analog Devices is a 48-channel LED PWM generator IC with 12-bit (4096-step) resolution, 6-bit ±50% per-channel correction, and a 50MHz cascadable 5-wire serial interface. It operates from 3.0V to 5.5V, supports phase-shifted 16-channel banks for noise reduction, and delivers up to 6.1kHz PWM frequency at 25MHz PWMCK - enabling precise dynamic backlighting for large-screen LCDs and full-color LED displays.
For engineers reviewing the LT8500ETJ#PBF datasheet, LT8500ETJ#PBF pinout, LT8500ETJ#PBF application, or LT8500ETJ#PBF equivalent, key selection considerations include its 56-pin TLA QFN package, diagnostic open-LED/sync-error flags, direct control capability for three LT3595A LED drivers, and cascaded timing integrity across multi-chip systems.
Technical Context
The LT8500ETJ#PBF implements a fully synchronous, frame-based serial architecture with a 584-bit shift register, independent 6-bit correction multiplier per channel, and dual-clock domain operation: SCKI (up to 50MHz) for command/status framing and PWMCK (up to 25MHz) for output timing generation. All 48 PWM outputs are derived from comparison between a free-running PWMCK counter and programmable 12-bit PWMRSYNC registers.
It supports two distinct operational modes: synchronous update (latched on LDIBLANK edge, then applied at next PWM period start) and asynchronous update (immediate transfer to PWMRSYNC), plus optional 120° phase shifting across three 16-channel banks to reduce peak current and EMI. Diagnostic reporting includes real-time OPENLED fault detection and synchronization error flagging via status frames.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Channels | 48 independent PWM outputs with individual 12-bit resolution (0–4095 cycles) |
| PWM Frequency | Up to 6.1kHz (at 25MHz PWMCK input; 4096-cycle period) |
| Serial Interface | 50MHz TTL/CMOS-compatible 5-wire interface (SDI/SCKI/LDIBLANK/SDO/SCKO) with skew-balanced buffering |
| Correction Range | 6-bit per-channel correction register (±50% of programmed PWM width, 0–63 steps) |
| Supply Voltage | 3.0V to 5.5V - compatible with standard logic I/O and LED driver bias rails |
| Operating Temp | –40°C to +125°C junction temperature - qualified for industrial and automotive display subsystems |
| Package | 56-lead TLA QFN (6mm × 6mm × 0.78mm) with exposed GND pad for thermal management |
Pinout & Package
LT8500ETJ#PBF uses a 56-lead plastic TLA QFN package (6mm × 6mm, 0.78mm height) with exposed GND pad (Pin 57) requiring PCB soldering for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWM[48:1] | 48-channel PWM output terminals | Open-drain capable; each driven by comparison of PWMRSYNC[n] vs PWMCK counter; logic-high when counter < register value |
| OPENLED (B11) | Diagnostic status input | Wired-OR open-collector input with internal 100kΩ pull-up; captures LED string fault state on PWMCK edges for per-channel self-test |
| SDO (A25) | Serial data output | Shift-register output; returns status frame (COR registers, fault flags, command bits) synchronized to SCKO |
| SCKI (B12) | Serial clock input | Master clock for SDI frame ingestion and status frame egress; independent of PWMCK; max 50MHz |
| VCC (A26) | Power supply | 3.0V–5.5V analog/digital supply; requires local bypass capacitor to GND |
| SCKO (B13) | Serial clock output | Buffered, skew-compensated replica of SCKI; enables daisy-chain clock distribution without global routing |
| PWMCK (A27) | PWM timing clock input | Free-running clock source for all 48 PWM generators; determines fundamental PWM frequency and period alignment |
| SDI (B14) | Serial data input | Command/data input for update/correction/enable frames; MSB-first, 584-bit frame length |
| LDIBLANK (A28) | Dual-function control input | Rising edge latches command frame; high pulse >50µs triggers global blank/reset; high pulse <5µs avoids unintended reset |
| GND (Pin 57) | Ground reference | Exposed thermal pad; must be soldered to PCB ground plane for thermal dissipation and signal integrity |
Key Features
| Feature | Design Value |
|---|---|
| 48-channel 12-bit PWM generation | Enables fine-grained brightness control across large LED arrays without external DACs or microcontroller overhead |
| Per-channel 6-bit correction | Compensates for LED forward-voltage variation and driver mismatch - improves uniformity in multi-string displays |
| 120° phase-shifted bank operation | Reduces peak input current and conducted EMI by staggering turn-on of 16-channel groups within one PWM period |
| Integrated diagnostic reporting | Real-time sync-error and open-LED flags delivered via status frame - eliminates need for external monitoring circuitry |
| Cascadable 5-wire serial interface | Eliminates global clock routing; SCKO/SDO skew balancing allows >10-chip chains at 50MHz without buffer insertion |
| Direct LT3595A driver compatibility | Native timing and control protocol support for three 16-channel LED drivers - simplifies system-level design and BOM |
Applications
| Large-Screen LCD Backlighting | Mono-/Full-Color LED Displays |
|---|---|
|
Use Scenario: Dynamic local dimming in 55"+ commercial LCD panels using 48-zone LED backlight array. IC Role / Device Role / Timing Role: Primary PWM controller generating synchronized, phase-shifted dimming signals for multiple LED driver ICs. Use Value: Enables 12-bit grayscale depth and flicker-free dimming down to 0.02% brightness while reducing peak current by 67% via 120° bank phasing. |
Use Scenario: High-fidelity RGB pixel control in outdoor LED billboards with >100,000 pixels per panel. IC Role / Device Role / Timing Role: Centralized PWM engine driving three LT3595A drivers to manage 48 independent color channels per tile. Use Value: Delivers consistent color point accuracy across temperature via per-channel 6-bit correction and open-LED fault isolation. |
| LED Signage & Billboards | Industrial HMI Lighting Control |
|
Use Scenario: Modular LED sign cabinets requiring scalable, daisy-chained PWM control across dozens of LT8500ETJ#PBF units. IC Role / Device Role / Timing Role: Cascaded node in high-speed 5-wire topology - receives SCKO/SDO from upstream, forwards to downstream with <2.75ns hold margin. Use Value: Supports >15-chip chains at 50MHz SCKI with no external buffers - reduces PCB layer count and layout complexity. |
Use Scenario: Programmable status lighting on factory HMIs with variable intensity, color mixing, and fault indication. IC Role / Device Role / Timing Role: Standalone PWM generator interfaced to FPGA or ARM Cortex-M host via SPI-like 5-wire interface. Use Value: Provides deterministic 6.1kHz PWM with diagnostic feedback (sync error, open LED) for safety-critical visual alerts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLC5947 (Texas Instruments) | 24-channel, 12-bit PWM; 30MHz SPI interface; no built-in phase shifting or OPENLED diagnostics | Limited to smaller LED arrays; requires external logic for multi-chip synchronization and fault reporting | Select when channel count and diagnostic depth are secondary to cost and footprint in compact designs |
| IS31FL3731 (Lumissil) | 28-channel, 8-bit PWM; I²C interface; integrated auto-breathing and dot correction; no cascading support | Targeted at small-format RGB indicators and wearables; lacks high-speed serial throughput and multi-chip scalability | Prefer for low-pin-count, I²C-based systems where per-pixel animation features outweigh raw channel density |
Compared with TLC5947 and IS31FL3731, the LT8500ETJ#PBF uniquely combines 48-channel density, 50MHz cascadable interface, hardware-accelerated phase shifting, and integrated open-LED diagnostics - making it the only solution qualified for large-scale, high-reliability LED video walls and industrial backlighting.
Availability
LT8500ETJ#PBF is available at Aetrix Electronics and suitable for large-screen LCD backlighting, LED video wall control, industrial HMI lighting, and automated test equipment requiring stable component supply and long-term production continuity.
Supply support for LT8500ETJ#PBF 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and communications markets.
The LT8500ETJ#PBF belongs to Analog Devices' LED lighting control product line, engineered specifically for high-channel-count, high-speed, and fault-aware PWM applications in professional displays and industrial signage.
FAQ
What is the maximum PWM frequency supported by the LT8500ETJ#PBF?
The LT8500ETJ#PBF achieves a maximum PWM frequency of 6.1kHz when driven by a 25MHz PWMCK input signal, corresponding to a 4096-cycle period. This frequency is fixed by the 12-bit counter depth and PWMCK rate - no software or register configuration alters the fundamental period length. The LT8500ETJ#PBF maintains this timing accuracy across its full –40°C to +125°C operating range.
How does the LT8500ETJ#PBF handle open-LED fault detection?
The LT8500ETJ#PBF monitors the OPENLED pin (B11) on every rising edge of PWMCK and reports its state in the status frame. During diagnostic self-test mode (CMD = 0x5X), it sequentially pulses each PWM[1]–PWM[48] output high for 64 cycles and captures OPENLED state per channel - enabling precise identification of failed LED strings. The LT8500ETJ#PBF integrates this function without external comparators or microcontroller polling.
Can the LT8500ETJ#PBF be used without the LT3595A LED drivers?
Yes - the LT8500ETJ#PBF is a standalone 48-channel PWM generator with open-drain outputs capable of directly driving logic-level loads or interfacing with any LED driver IC accepting PWM enable inputs. Its phase-shifting, correction registers, and diagnostic features remain fully functional regardless of whether LT3595A drivers are present. The LT8500ETJ#PBF datasheet confirms compatibility but does not require LT3595A for basic operation.
What is the purpose of the LDIBLANK pin's dual functionality?
The LDIBLANK pin (A28) serves two distinct roles: a short high pulse (<5µs) acts as Latch Data In (LDI), capturing the command field and triggering frame execution; a longer high pulse (>50µs) asserts BLANK, disabling all PWM outputs and resetting internal registers. The LT8500ETJ#PBF internally distinguishes these modes by pulse duration - eliminating need for separate control lines and simplifying host interface design.
Does the LT8500ETJ#PBF require external components for stable operation?
The LT8500ETJ#PBF requires only a local 0.1µF ceramic bypass capacitor between VCC (A26) and GND (Pin 57), as specified in the Absolute Maximum Ratings and Layout Guidelines. No external resistors, pull-ups, or timing crystals are needed - the 50MHz serial interface and 25MHz PWM timing are fully internal to the LT8500ETJ#PBF and driven by host-provided clocks. The exposed GND pad must be soldered to the PCB ground plane for thermal and electrical performance.
LT8500ETJ#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 56-VTLA Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- -
- Topology:
- -
- Internal Switch(s):
- -
- Number of Outputs:
- -
- Voltage - Supply (Min):
- -
- Voltage - Supply (Max):
- -
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- -
- Dimming:
- -
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 56-TLAQFN (6x6)
LT8500ETJ#PBF FAQ
1.How can I place an order for LT8500ETJ#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8500ETJ#PBF 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 LT8500ETJ#PBF reliable?
The price and inventory of LT8500ETJ#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8500ETJ#PBF is usually 5 days.
3.What payment methods are accepted for LT8500ETJ#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8500ETJ#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8500ETJ#PBF?
LT8500ETJ#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8500ETJ#PBF 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 LT8500ETJ#PBF?
For technical support, including LT8500ETJ#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8500ETJ#PBF requirements.
6.How does Aetrix verify that LT8500ETJ#PBF is sourced from the original manufacturer or authorized distributors?
All LT8500ETJ#PBF 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 LT8500ETJ#PBF meets industry standards.
7.What is the process for return or replacement of LT8500ETJ#PBF?
All LT8500ETJ#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8500ETJ#PBF, 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 LT8500ETJ#PBF part is unused and in its original packaging.
Return procedure for LT8500ETJ#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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