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Allegro MicroSystems A6278ELPTR-T
- Part No.:
- A6278ELPTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- LED Drivers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
A6278ELPTR-T.pdf
- Description:
- IC LED DRVR LIN 75.5MA 16ETSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,892
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Product details
Overview
A6278ELPTR-T from Allegro MicroSystems is an 8-channel serial-input constant-current latched LED driver with open-LED detection, designed for multiplexed LED display systems. It features Schmitt-trigger inputs, 3.0–5.5 V logic supply, up to 90 mA per output, 20 ns output staggering delay, and CMOS serial data output for cascading. Used in industrial panel meters and signage where reliable LED current control and fault reporting are required.
For engineers reviewing the A6278ELPTR-T datasheet, A6278ELPTR-T pinout, A6278ELPTR-T application, or A6278ELPTR-T equivalent, key selection criteria include constant-current sink capability, open-circuit detection via SERIAL DATA OUT, thermal shutdown (165°C), UVLO (2.4–2.85 V), and compatibility with microprocessor-based serial interfaces operating at ≤25 MHz.
Technical Context
The A6278ELPTR-T integrates a BiCMOS shift register, parallel latches, and eight NPN constant-current sink drivers in a single TSSOP-16 package with exposed thermal pad. Its architecture supports serial-to-parallel conversion via LATCH ENABLE and enables real-time LED fault monitoring through dedicated OCD mode sequencing using OUTPUT ENABLE and CLOCK.
Internal circuitry includes undervoltage lockout (UVLO), thermal shutdown (TSD), and a user-configurable current-setting resistor (REXT) that determines output current across all channels. Output staggering (20 ns typical between consecutive outputs) reduces simultaneous switching noise and EMI during full-line updates.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Channels | 8 independent constant-current sink outputs for LED anode-side common displays |
| Max Output Current | 90 mA per channel (typical at REXT = 225 Ω, VCE = 0.7 V) |
| Logic Supply Range | 3.0–5.5 V - compatible with both 3.3 V and 5 V microcontrollers |
| Serial Data Rate | Up to 25 MHz - supports high-speed display refresh in dynamic signage |
| Open LED Detection | Detects open-circuit faults per channel and reports error bits via SERIAL DATA OUT |
| Thermal Shutdown | Triggers at TJ = 165°C typical; recovers after 15°C hysteresis - protects against sustained overloads |
| Staggering Delay | 20 ns typical between adjacent outputs - reduces peak ground current and EMI |
Pinout & Package
Package: 16-pin TSSOP with exposed thermal pad (LP suffix), RoHS-compliant, 100% matte tin leadframe, 0.65 mm pitch, 5.00 mm × 4.40 mm footprint, 1.20 mm max height.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND | Ground reference | Common logic and power ground; must connect to exposed pad (EP) for thermal performance |
| SERIAL DATA IN | Shift register input | CMOS-level serial data input synchronized on rising CLOCK edge |
| CLOCK | Timing control | Rising-edge-triggered clock for shifting data into internal 8-bit register |
| LATCH ENABLE | Data strobe | High-level signal transfers shift register contents to output latches (serial-to-parallel) |
| OUT0–OUT7 | Current sinks | Eight NPN open-collector outputs; each sinks up to 90 mA with user-set current via REXT |
| OUTPUT ENABLE | Global output control | Active-low enable; disables all outputs when high, enters OCD test mode when sequenced with CLOCK |
| SERIAL DATA OUT | Cascade & fault readout | CMOS-level serial output for daisy-chaining devices or reading 8-bit OCD error code |
| REXT | Current calibration | Connects external resistor to set identical constant current for all 8 outputs |
| LOGIC SUPPLY | VDD rail | 3.0–5.5 V supply powering logic, latches, and internal regulators - not used for LED load |
Key Features
| Feature | Design Value |
|---|---|
| Open LED detection | Reports per-output open-circuit status as 8-bit error code via SERIAL DATA OUT without external sensing components |
| User-adjustable current | Single REXT resistor sets precise, matched current (±6% matching) across all 8 outputs - eliminates per-LED resistors |
| Noise-immune inputs | Schmitt-trigger inputs on CLOCK, LATCH ENABLE, and OUTPUT ENABLE tolerate slow-rising or noisy signals in industrial environments |
| Power-on reset | Ensures all latches and shift registers initialize to zero state at power-up or after UVLO recovery - prevents spurious LED activation |
| Thermal protection | Internal TSD shuts down outputs at 165°C while preserving latch data - allows safe recovery without MCU reinitialization |
Applications
| Industrial Panel Meters | LED Signage Modules |
|---|---|
Use Scenario: Driving 7-segment or dot-matrix displays in factory HMIs with ambient temperature swings from –40°C to +85°C. IC Role / Device Role / Timing Role: Constant-current sink driver with serial interface and open-circuit reporting for fault-tolerant display operation. Use Value: Eliminates need for individual current-limiting resistors and enables automated LED health diagnostics via microcontroller-read SERIAL DATA OUT. | Use Scenario: Cascaded control of multi-line alphanumeric signs in outdoor advertising cabinets with high reliability requirements. IC Role / Device Role / Timing Role: Serial-input latched driver enabling synchronized update of multiple display segments using shared CLOCK and LATCH ENABLE lines. Use Value: 20 ns output staggering reduces ground bounce and EMI during full-line refresh, improving EMC compliance in dense PCB layouts. |
| Automated Test Equipment Displays | Medical Device Status Indicators |
Use Scenario: Driving high-brightness LED arrays in benchtop test instruments requiring visual status feedback under variable load conditions. IC Role / Device Role / Timing Role: Fault-aware LED driver supporting real-time open-circuit verification during self-test sequences. Use Value: Built-in OCD mode allows host MCU to verify LED continuity without external ADC or sense circuitry - reducing BOM count and board area. | Use Scenario: Controlling status LEDs in Class II medical devices where consistent brightness and failure reporting are critical for regulatory compliance. IC Role / Device Role / Timing Role: Precision current-regulated sink driver with thermal shutdown and UVLO ensuring safe, predictable LED behavior during power transients. Use Value: 90 mA per channel supports high-luminance LEDs while internal TSD (165°C) and UVLO (2.4 V) prevent unsafe operation during brownouts or overheating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLC59283DBQR | 16-channel, no open-LED detection, requires external current-setting resistors per channel | Lacks integrated OCD and single-REXT current setting - higher BOM cost and reduced diagnostic capability | Choose only if higher channel count is needed and OCD is unnecessary |
| MAX6966ATL+ | 16-channel, I²C interface, built-in PWM dimming, no OCD, 40 mA max per channel | I²C protocol adds software overhead; lower current rating limits high-brightness LED use | Select when I²C bus integration and programmable dimming outweigh need for open-circuit reporting |
Compared with TLC59283DBQR and MAX6966ATL+, the A6278ELPTR-T provides unique value in applications requiring per-channel open-LED fault detection, single-resistor current programming, and robust industrial-grade thermal/UVLO protection - all in a compact TSSOP-16 package with exposed thermal pad.
Availability
A6278ELPTR-T is available at Aetrix Electronics and suitable for industrial HMIs, LED signage modules, automated test equipment displays, and medical device status indicators requiring stable component supply and long-term production support.
Supply support for A6278ELPTR-T 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
Allegro MicroSystems is a U.S.-based designer and manufacturer of high-performance magnetic sensors, motor drivers, and power ICs, headquartered in Worcester, Massachusetts.
The A6278 product line delivers serial-input constant-current LED drivers optimized for reliability-critical display applications, combining integrated diagnostics, thermal safety, and microcontroller-friendly timing.
FAQ
What is the maximum recommended output current per channel for A6278ELPTR-T?
The A6278ELPTR-T supports up to 90 mA per output channel when configured with REXT = 225 Ω and VCE = 0.7 V. At higher ambient temperatures or duty cycles, derating is required - for example, at TA = 85°C and 100% DC, maximum usable current drops to ~45 mA. Always consult the "Allowable Output Current versus Duty Cycle" curves on page 11 of the A6278 datasheet to ensure safe operation for your specific thermal design.
How does open-LED detection work on the A6278ELPTR-T?
The A6278ELPTR-T performs open-LED detection by measuring VCE voltage on each enabled output during OCD test mode. If VCE falls below 0.30 V (VCE(OCD)), the corresponding bit in the shift register is set to 0, indicating an open circuit. These 8-bit error codes are then clocked out via SERIAL DATA OUT. The process requires specific OE/LE/CLOCK sequencing per the timing diagram on page 7 - it is not automatic in normal operation.
Can A6278ELPTR-T be used with a 3.3 V microcontroller?
Yes, the A6278ELPTR-T operates with a logic supply (VDD) from 3.0 V to 5.5 V, making it fully compatible with 3.3 V microcontrollers. Its Schmitt-trigger inputs provide noise immunity, and VIH/VIL thresholds scale with VDD (VIH ≥ 0.7×VDD, VIL ≤ 0.3×VDD). No level-shifting is required for interfacing with standard 3.3 V GPIOs driving CLOCK, LATCH ENABLE, or OUTPUT ENABLE.
What is the purpose of the exposed thermal pad on the A6278ELPTR-T package?
The exposed thermal pad (EP) on the A6278ELPTR-T's TSSOP-16 package serves as the primary thermal path to the PCB. It must be soldered to a solid copper ground plane - ideally with ≥4 thermal vias - to achieve the specified RθJA of 34°C/W (16-pin LP). Failure to connect EP results in excessive junction temperature rise, triggering thermal shutdown at lower output currents and compromising reliability in continuous operation.
Does A6278ELPTR-T support daisy-chaining with other A6278 or A6279 devices?
Yes, the A6278ELPTR-T supports seamless daisy-chaining via its CMOS SERIAL DATA OUT pin, which connects directly to the SERIAL DATA IN of the next device. This enables expansion beyond 8 outputs - for example, two A6278ELPTR-T devices provide 16 channels, while one A6278ELPTR-T and one A6279ELPTR-T support mixed 8+16 configurations. All devices share the same CLOCK and LATCH ENABLE lines for synchronized updates.
A6278ELPTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Linear
- Topology:
- Shift Register
- Internal Switch(s):
- Yes
- Number of Outputs:
- 8
- Voltage - Supply (Min):
- 3V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- -
- Current - Output / Channel:
- 75.5mA
- Frequency:
- 25MHz
- Dimming:
- -
- Applications:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-eTSSOP-EP
A6278ELPTR-T FAQ
1.How can I place an order for A6278ELPTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A6278ELPTR-T 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 A6278ELPTR-T reliable?
The price and inventory of A6278ELPTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6278ELPTR-T is usually 5 days.
3.What payment methods are accepted for A6278ELPTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6278ELPTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A6278ELPTR-T?
A6278ELPTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A6278ELPTR-T 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 A6278ELPTR-T?
For technical support, including A6278ELPTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6278ELPTR-T requirements.
6.How does Aetrix verify that A6278ELPTR-T is sourced from the original manufacturer or authorized distributors?
All A6278ELPTR-T 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 A6278ELPTR-T meets industry standards.
7.What is the process for return or replacement of A6278ELPTR-T?
All A6278ELPTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A6278ELPTR-T, 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 A6278ELPTR-T part is unused and in its original packaging.
Return procedure for A6278ELPTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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