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Allegro MicroSystems A6275SA
- Part No.:
- A6275SA
- Manufacturer:
- Allegro MicroSystems
- Category:
- LED Drivers
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
A6275SA.pdf
- Description:
- IC LED DRVR LINEAR 75.5MA 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,423
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Product details
Overview
A6275SA from Allegro MicroSystems is an 8-bit serial-input constant-current latched LED driver with eight NPN sink outputs, 90 mA max per channel, undervoltage lockout (UVLO), and CMOS-compatible 5 V logic interface - designed for multiplexed LED displays requiring precise current regulation and microprocessor-controlled blanking.
For engineers reviewing the A6275SA datasheet, A6275SA pinout, A6275SA application, or A6275SA equivalent, this device supports high-speed serial data rates up to 20 MHz, enables cascade chaining via SERIAL DATA OUT, and provides inter-digit blanking through active-low OUTPUT ENABLE - critical for low-noise, high-reliability LED signage and industrial panel displays.
Technical Context
The A6275SA integrates a 8-bit CMOS shift register, parallel latches, and eight matched BiCMOS constant-current sink drivers - all sharing a single external REXT resistor to set output current. Its UVLO circuit disables operation below 3.4 V to prevent erratic behavior during power ramp-up.
It features active-low OUTPUT ENABLE for global output blanking and LATCH ENABLE for synchronous serial-to-parallel data transfer on rising clock edges. The CMOS serial data output allows daisy-chaining multiple A6275SA devices without additional logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Type | NPN constant-current sink (8 channels) |
| Max Output Current | 90 mA per channel at VCE = 0.7 V, TA = 85°C - ensures stable LED brightness across temperature |
| Supply Voltage | 4.5–5.5 V - compatible with standard 5 V logic rails and tolerant of ±10% variation |
| UVLO Threshold | 3.4–4.0 V - prevents partial activation during brown-out conditions |
| Serial Data Rate | Up to 20 MHz - supports fast refresh in high-resolution LED matrices |
| Logic Interface | CMOS-compatible inputs (VIH ≥ 0.7VDD, VIL ≤ 0.3VDD) - ensures robust noise margin with microcontrollers |
| Thermal Resistance | RθJA = 38 °C/W (DIP-A package) - enables full 90 mA per channel at 85°C ambient with minimal derating |
Pinout & Package
Package: 16-pin through-hole DIP (suffix A), lead-free with 100% matte tin plating, JEDEC MS-001 BB compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 GND | Logic ground reference | Shared ground for control logic; must be low-impedance to avoid latch enable/clock noise coupling |
| 2 SERIAL DATA IN | Shift register serial input | Accepts 5 V CMOS-level data; sampled on rising edge of CLOCK |
| 3 CLOCK | Shift register clock input | Rising-edge triggered; min pulse width 50 ns; max frequency 20 MHz |
| 4 LATCH ENABLE | Parallel load strobe | High level transfers shift register contents to output latches; enables synchronized display updates |
| 5–12 OUT0–OUT7 | Constant-current sink outputs | Each sinks up to 90 mA; current set by REXT; VCE(sat) ≤ 0.9 V at rated current |
| 13 OUTPUT ENABLE | Global output disable | Active-low; when high, all outputs forced OFF - used for inter-digit blanking |
| 14 SERIAL DATA OUT | Cascaded serial output | CMOS-level output; enables daisy-chaining of multiple A6275SA devices |
| 15 REXT | Current-setting resistor node | Connects external resistor to set identical current for all 8 outputs (e.g., 250 Ω → ~75 mA) |
| 16 VDD | Logic supply input | 5 V nominal; powers internal CMOS logic and bias circuits; decoupling capacitor required |
Key Features
| Feature | Design Value |
|---|---|
| 8-channel constant-current sink | Matched ±6.0% output current across channels (REXT = 250 Ω) - ensures uniform LED brightness in multi-segment displays |
| Undervoltage lockout (UVLO) | Disables output drivers below 3.4 V - eliminates flicker or ghosting during power-up/down transitions |
| 20 MHz serial data rate | Enables full 8-bit load in ≤400 ns - supports >2.5 kHz refresh in 8×8 LED arrays without timing bottlenecks |
| CMOS serial data output | Allows unlimited cascading without external buffers - reduces BOM count in large LED matrix controllers |
| Inter-digit blanking | Single active-low OUTPUT ENABLE pin blanks all outputs simultaneously - essential for time-multiplexed digit scanning |
Applications
| LED Segment Displays | Industrial Panel Meters |
|---|---|
|
Use Scenario: Driving 7-segment or 14-segment alphanumeric displays in HVAC controls and factory HMIs. IC Role / Device Role / Timing Role: Constant-current sink driver with synchronized latch and blanking for time-multiplexed digit scanning. Use Value: Eliminates external current-limiting resistors per segment and ensures consistent brightness across digits using single REXT. |
Use Scenario: Controlling status indicator LEDs and bar-graph displays in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Serially loaded, latched LED driver interfaced to RS-485 or CAN bus microcontrollers. Use Value: Reduces GPIO count by 8× and simplifies firmware with shift-and-latch protocol instead of parallel port management. |
| LED Signage Modules | Test Equipment Front Panels |
|
Use Scenario: Driving high-brightness red/green/blue LED modules in outdoor message signs. IC Role / Device Role / Timing Role: Cascadable constant-current sink enabling modular expansion of display rows/columns. Use Value: Supports daisy-chained configuration for >64 LEDs per controller with uniform current matching and thermal stability. |
Use Scenario: Illuminating status LEDs and signal indicators on benchtop oscilloscopes and power supplies. IC Role / Device Role / Timing Role: Low-noise, latch-based LED driver with UVLO protection against supply transients. Use Value: Prevents false LED activation during power cycling and maintains visual integrity under noisy industrial power conditions. |
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 |
|---|---|---|---|
| A6279 | Successor device with open-LED detection, dot correction, and enhanced ESD protection; same pinout and REXT-based current setting. | Required where LED fault monitoring or grayscale calibration is needed; not drop-in for legacy A6275SA designs lacking detection circuitry. | Select A6279 for new designs requiring reliability diagnostics; verify compatibility with existing REXT values and timing margins. |
| TB62705CP | Pin-compatible 8-bit constant-current LED driver from Toshiba; similar 90 mA rating but no UVLO and different timing specs (max 10 MHz clock). | Suitable for cost-sensitive, non-critical LED applications where UVLO and 20 MHz speed are not required. | Use TB62705CP only if system clock <10 MHz and brown-out immunity is handled externally; validate latch timing and output leakage. |
Compared with A6275SA, the A6279 adds diagnostic features without changing footprint or basic drive architecture, while TB62705CP offers lower-cost compatibility at reduced performance margins - making A6275SA optimal for legacy 5 V, high-speed, UVLO-dependent LED systems still in production.
Availability
A6275SA is available at Aetrix Electronics and suitable for LED segment displays, industrial panel meters, LED signage modules, and test equipment front panels requiring stable component supply despite its Last Time Buy status.
Supply support for A6275SA 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 and power ICs, founded in 1989 and headquartered in Worcester, Massachusetts.
The A6275SA belongs to Allegro's constant-current LED driver product line, engineered specifically for reliable, low-noise, microprocessor-controlled LED display systems in industrial and commercial environments.
FAQ
What is the maximum continuous output current per channel for the A6275SA?
The A6275SA delivers up to 90 mA per output channel continuously at 85°C ambient temperature with VCE ≤ 0.9 V. This rating assumes proper PCB thermal design (RθJA = 38 °C/W for DIP-A package) and use of the recommended external REXT resistor value (e.g., 250 Ω for ~75 mA typical). Derating applies above 85°C.
Does the A6275SA include undervoltage lockout, and what is its threshold?
Yes, the A6275SA includes built-in undervoltage lockout (UVLO) that disables all outputs when VDD falls below 3.4 V (typical) and re-enables them above 4.0 V (typical). This prevents erratic behavior during power-up or brown-out events and is confirmed in the Electrical Characteristics table on page 4 of the official Allegro datasheet for A6275SA.
Can multiple A6275SA devices be cascaded, and how is this implemented?
Yes, the A6275SA supports daisy-chain cascading via its SERIAL DATA OUT (pin 14) terminal. The serial output of one A6275SA connects directly to the SERIAL DATA IN (pin 2) of the next device. Clock and latch signals are shared across the chain, allowing a single microcontroller to drive dozens of outputs with minimal GPIO usage - a key feature verified in the functional block diagram and truth table of the A6275SA datasheet.
What is the purpose of the REXT pin (pin 15) on the A6275SA?
The REXT pin (pin 15) on the A6275SA connects to an external resistor that sets the constant-current value for all eight output channels simultaneously. For example, a 250 Ω resistor yields ~75 mA per output at VCE = 0.7 V. This single-resistor calibration simplifies design, ensures channel-to-channel matching (±6.0%), and eliminates per-channel resistors - a core specification confirmed in the Applications Information section of the A6275SA datasheet.
Is the A6275SA still in production, and what does "Last Time Buy" mean for this part?
The A6275SA is classified as Last Time Buy (LTB) with a final order deadline of April 30, 2011, as stated in the official Allegro status notice. It remains available for existing customer applications but is obsolete for new designs. Aetrix Electronics maintains traceable, tested inventory for ongoing production support, and recommends the A6279 as the documented successor for future designs requiring extended availability.
A6275SA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- Linear
- Topology:
- Shift Register
- Internal Switch(s):
- Yes
- Number of Outputs:
- 8
- Voltage - Supply (Min):
- 4.5V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 4V
- Current - Output / Channel:
- 75.5mA
- Frequency:
- 20MHz
- Dimming:
- -
- Applications:
- -
- Operating Temperature:
- -20°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-DIP
A6275SA FAQ
1.How can I place an order for A6275SA through Aetrix?
Please submit a Request for Quotation (RFQ) for A6275SA 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 A6275SA reliable?
The price and inventory of A6275SA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6275SA is usually 5 days.
3.What payment methods are accepted for A6275SA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6275SA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A6275SA?
A6275SA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A6275SA 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 A6275SA?
For technical support, including A6275SA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6275SA requirements.
6.How does Aetrix verify that A6275SA is sourced from the original manufacturer or authorized distributors?
All A6275SA 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 A6275SA meets industry standards.
7.What is the process for return or replacement of A6275SA?
All A6275SA units undergo pre-shipment inspection (PSI). If there is an issue with A6275SA, 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 A6275SA part is unused and in its original packaging.
Return procedure for A6275SA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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