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Allegro MicroSystems A6278ELW-T
- Part No.:
- A6278ELW-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- LED Drivers
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
A6278ELW-T.pdf
- Description:
- IC LED DRVR LINEAR 75.5MA 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,567
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Product details
Overview
A6278ELW-T from Allegro MicroSystems is an 8-channel serial-input constant-current LED sink driver with open-LED detection, CMOS shift register and latches, and Schmitt-trigger inputs for noise immunity. It operates from 3.0–5.5 V logic supply, delivers up to 90 mA per output, supports 25 MHz serial data rates, and is used in multiplexed LED signage and industrial panel displays.
For engineers reviewing the A6278ELW-T datasheet, A6278ELW-T pinout, A6278ELW-T application, or A6278ELW-T equivalent, key selection criteria include its 16-pin SOIC-W package, REXT-based current programming, staggered 20 ns output timing, thermal shutdown at 165°C, and integrated open-circuit diagnostics via SERIAL DATA OUT.
Technical Context
The A6278ELW-T integrates a serial-to-parallel shift register with independent latching control, enabling microprocessor-driven LED column/segment driving without external timing logic. Its constant-current sink outputs are set by a single external resistor (REXT), maintaining stable LED current across VLED variations from –0.5 V to 17 V and ambient temperatures from –40°C to +85°C.
Open-LED detection operates in dedicated test mode: after initialization via OUTPUT ENABLE and LATCH ENABLE sequencing, error bits (0 = open/TSD, 1 = normal) are latched and shifted out via SERIAL DATA OUT. Internal UVLO (2.15–2.85 V threshold) and thermal shutdown (165°C TJ, 15°C hysteresis) ensure robust operation under fault conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output channels | 8 independent constant-current sink drivers |
| Max output current | 90 mA per channel (set by REXT; e.g., 75.5 mA typ. at REXT = 470 Ω) |
| Logic supply range | 3.0–5.5 V - compatible with 3.3 V and 5 V microcontrollers |
| Serial data rate | Up to 25 MHz - enables high-speed LED refresh in dynamic displays |
| Staggering delay | 20 ns typical between consecutive outputs - reduces simultaneous switching noise and EMI |
| Open-LED detection | VCE(OCD) = 0.30 V threshold - identifies open circuits during active drive |
| Thermal shutdown | 165°C junction temperature (15°C hysteresis) - protects against sustained overload |
Pinout & Package
Package: 16-pin SOIC-W (suffix LW), lead-free with 100% matte tin plating, 0.65 mm pitch, 10.30 × 7.50 mm body size, exposed thermal pad not present (SOIC-W variant).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 16 | GND / LOGIC SUPPLY (VDD) | Common ground reference and 3.0–5.5 V logic power input |
| 2 | SERIAL DATA IN | CMOS-level serial data input to shift register (Schmitt-triggered) |
| 3 | CLOCK | Rising-edge clock for serial data shifting; min. pulse width 20 ns |
| 4 | LATCH ENABLE | Active-high strobe to transfer shift register contents to output latches |
| 5–12 | OUT0–OUT7 | Constant-current sink outputs; each drives one LED cathode |
| 13 | OUTPUT ENABLE | Active-low global enable/disable of all 8 output drivers |
| 14 | SERIAL DATA OUT | CMOS-level serial output for cascading or OCD bit readout |
| 15 | REXT | Connection point for external current-setting resistor (determines IO per channel) |
Key Features
| Feature | Design Value |
|---|---|
| Single-resistor current programming | One REXT sets identical 8-channel current; eliminates per-channel trimming |
| Integrated open-LED diagnostics | Detects open circuits during active drive and reports via serial shift-out |
| Output staggering | 20 ns inter-output delay reduces peak ground current and improves EMC |
| Power-on reset & UVLO | Resets internal registers on power-up and disables outputs below 2.15–2.85 V VDD |
| Wide load voltage support | VLED range –0.5 V to 17 V enables use with high-VF LEDs or series strings |
Applications
| LED Signage Panels | Industrial HMI Displays |
|---|---|
Use Scenario: Driving 8-segment alphanumeric modules in outdoor digital signage with variable ambient temperature and EMI exposure. IC Role / Device Role / Timing Role: Constant-current sink driver with serial interface and open-circuit reporting for remote fault identification. Use Value: Eliminates need for discrete current-limiting resistors and enables automated LED health monitoring without additional sensors. | Use Scenario: Controlling status indicator LEDs on programmable logic controller (PLC) I/O modules operating in factory environments. IC Role / Device Role / Timing Role: Serial-input latched LED driver with thermal shutdown and UVLO for reliable operation under brownout or overtemperature conditions. Use Value: Ensures consistent LED brightness across supply voltage fluctuations and prevents false status indication during power transients. |
| Automated Test Equipment | Medical Device Status Indicators |
Use Scenario: Driving multi-color LED arrays in benchtop test instruments requiring precise timing and fault logging. IC Role / Device Role / Timing Role: Shift-register-based LED controller with staggered outputs to minimize ground bounce during rapid pattern changes. Use Value: Reduces PCB-level noise coupling into sensitive analog measurement circuitry during LED state transitions. | Use Scenario: Illuminating critical status LEDs on patient-monitor front panels where reliability and diagnostic capability are mandated. IC Role / Device Role / Timing Role: Safety-relevant LED driver with built-in open-circuit detection and thermal protection. Use Value: Enables self-test functionality to verify LED integrity before clinical use, supporting IEC 62304 compliance. |
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 |
|---|---|---|---|
| TB62786AFTG | 16-channel, no open-LED detection, higher max IO (120 mA), requires external clock generator | Designed for larger LED matrices; lacks diagnostic capability and integrated shift register latch control | Select when scaling to 16 outputs and diagnostics are unnecessary |
| MAX7219CWG+ | 8-channel, SPI interface, on-chip BCD decode, no REXT current setting, 40 mA max IO | Optimized for 7-segment numeric displays; includes display memory and scan control | Select for embedded numeric readouts with minimal MCU overhead |
Compared with TB62786AFTG and MAX7219CWG+, the A6278ELW-T uniquely balances 8-channel precision current sinking, integrated open-circuit diagnostics, and microcontroller-friendly serial+strobe interface - making it optimal for industrial LED arrays requiring field-serviceability and fault transparency.
Availability
A6278ELW-T is available at Aetrix Electronics and suitable for LED signage panels, industrial HMI displays, automated test equipment, and medical device status indicators requiring stable component supply and long-term production continuity.
Supply support for A6278ELW-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 sensing and power IC solutions, founded in 1989 and headquartered in Worcester, Massachusetts.
The A6278 family is part of Allegro's LED driver product line, engineered specifically for high-reliability, low-noise, serially controlled LED display systems in industrial and commercial applications.
FAQ
What is the maximum recommended output current per channel for the A6278ELW-T?
The A6278ELW-T supports up to 90 mA per output channel when configured with appropriate REXT and thermal management. At REXT = 470 Ω and VCE = 0.7 V, typical current is 40.0 mA; at REXT = 225 Ω, it rises to 75.5 mA. Absolute maximum rating is 90 mA, but sustained operation above 64 mA requires derating based on ambient temperature and PCB copper area per the allowable current vs. duty cycle curves in the datasheet.
How does the A6278ELW-T implement open-LED detection?
The A6278ELW-T performs open-LED detection in a dedicated test mode initiated by specific OUTPUT ENABLE and LATCH ENABLE timing sequences. When enabled, it compares each output's VCE against a 0.30 V threshold; if VCE < 0.30 V while the output is active, an error bit (0) is generated and shifted out via SERIAL DATA OUT. This occurs without interrupting normal display operation and requires no external components.
Can the A6278ELW-T be used with both 3.3 V and 5 V microcontrollers?
Yes, the A6278ELW-T accepts logic supply voltages from 3.0 V to 5.5 V and features Schmitt-trigger inputs with 200–400 mV hysteresis, ensuring reliable signal reception from both 3.3 V and 5 V MCUs. Input thresholds scale with VDD (VIH = 0.7×VDD, VIL = 0.3×VDD), and serial data rates up to 25 MHz are supported across the full voltage range.
What package type is used by the A6278ELW-T, and does it include a thermal pad?
The A6278ELW-T uses a 16-pin SOIC-W (wide-body) package (suffix LW) with 0.65 mm lead pitch and dimensions 10.30 × 7.50 mm. Unlike the LP (TSSOP with exposed pad) or ET (QFN) variants, the LW package has no exposed thermal pad - thermal dissipation relies on standard SOIC copper land patterns and internal leadframe conduction. RθJA is 48°C/W (16-pin) on a 4-layer JEDEC board.
Does the A6278ELW-T require external components to operate, and what are they?
The A6278ELW-T requires only two external components for basic operation: a single resistor (REXT) connected between pin 15 and GND to set output current, and a 0.1 µF bypass capacitor between VDD (pin 16) and GND (pin 1). No external clock generator, level shifters, or current-limiting resistors per LED are needed - all timing, latching, and current regulation are integrated.
A6278ELW-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- 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-SOIC
A6278ELW-T FAQ
1.How can I place an order for A6278ELW-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A6278ELW-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 A6278ELW-T reliable?
The price and inventory of A6278ELW-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6278ELW-T is usually 5 days.
3.What payment methods are accepted for A6278ELW-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6278ELW-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A6278ELW-T?
A6278ELW-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A6278ELW-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 A6278ELW-T?
For technical support, including A6278ELW-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6278ELW-T requirements.
6.How does Aetrix verify that A6278ELW-T is sourced from the original manufacturer or authorized distributors?
All A6278ELW-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 A6278ELW-T meets industry standards.
7.What is the process for return or replacement of A6278ELW-T?
All A6278ELW-T units undergo pre-shipment inspection (PSI). If there is an issue with A6278ELW-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 A6278ELW-T part is unused and in its original packaging.
Return procedure for A6278ELW-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
A6278ELW-T Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
Infineon Technologies
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BCR420UE6327HTSA1
Infineon Technologies
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BCR421UE6327HTSA1
Infineon Technologies
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LYT1604D-TL
Power Integrations
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HV9910CLG-G
Microchip Technology
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CL2N8-G
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BCR420UW6-7
Diodes Incorporated
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BCR421UW6-7
Diodes Incorporated
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BCR420UFD-7
Diodes Incorporated
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BCR421UFD-7
Diodes Incorporated
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