My Inquiry
My Account
Allegro MicroSystems A6277ELW
- Part No.:
- A6277ELW
- Manufacturer:
- Allegro MicroSystems
- Category:
- LED Drivers
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
A6277ELW.pdf
- Description:
- IC LED DRVR LINEAR 120MA 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,243
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
A6277ELW from Allegro MicroSystems is an 8-bit serial-input constant-current latched LED driver with NPN sink outputs, designed for multiplexed LED display systems. It integrates a CMOS shift register, data latches, and eight 150 mA-rated constant-current drivers, supporting 5 V logic supply and up to 20 MHz serial data input. Its HIGH/LOW pin enables dynamic current scaling (100% or 50%), and ENABLE input provides inter-digit blanking - used in industrial panel meters and segmented LED signage.
For engineers reviewing the A6277ELW datasheet, A6277ELW pinout, A6277ELW application, or A6277ELW equivalent, key selection criteria include output current programmability via REXT, thermal derating behavior in SOICW package, cascade-capable dual serial outputs (SDO1/SDO2), and undervoltage lockout protection at 4.3 V.
Technical Context
The A6277ELW implements a serial-to-parallel architecture where rising-edge clock shifts data into an 8-bit shift register, and a high-level LATCH ENABLE transfers contents to independent output latches. Output drivers are NPN transistors with user-defined current set by a single external resistor connected to pin 19 (REXT), enabling precise per-bit current control across temperature.
It features dual CMOS serial outputs: SDO1 (rising-edge synchronized) and SDO2 (falling-edge synchronized), allowing daisy-chained expansion without external logic. The OUTPUT ENABLE (active-low, pin 16) disables all sinks simultaneously for blanking, while HIGH/LOW (pin 5) toggles full or half current per output - critical for digital dimming in time-multiplexed displays.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Type | NPN constant-current sink drivers (8-channel) |
| Max Output Current | 150 mA per channel at VCE = 1.0 V, TA = 85°C (SOICW package) |
| Logic Supply Voltage | 4.5–5.5 V - supports standard 5 V microcontroller interfaces |
| Serial Data Rate | Up to 20 MHz - enables fast refresh in high-segment-count LED arrays |
| Undervoltage Lockout | Triggers below 4.3 V - prevents erratic operation during power ramp-up |
| Thermal Resistance | RθJA = 90°C/W (SOICW on 1-layer PCB) - requires thermal-aware layout above 80 mA average per output |
| Current Matching | ±6.0% between any two outputs at same VCE - ensures uniform LED brightness across digits |
Pinout & Package
Package: 20-pin SOICW (suffix LW), surface-mount, lead-free with 100% matte-tin plating. Dimensions per JEDEC MS-013 AC; 7.50 mm × 12.80 mm body, 1.27 mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | LOGIC GROUND | Reference for all control inputs; must be isolated from power ground to avoid noise coupling |
| 2 | SERIAL DATA IN | CMOS-compatible serial data input to shift register (rising-edge sampled) |
| 3 | CLOCK | Rising-edge clock synchronizes data shift; min pulse width 50 ns |
| 4 | LATCH ENABLE | High-level strobe transfers shift register contents to output latches |
| 5 | HIGH/LOW (CURRENT) | Logic low = 100% programmed current; logic high = 50% - enables software-controlled dimming |
| 6, 15 | POWER GROUND | Return path for all output currents; separate from logic ground to minimize voltage offset |
| 7–14 | OUT0–OUT7 | Eight NPN open-collector sink outputs; each drives one LED segment or digit cathode |
| 16 | OUTPUT ENABLE | Active-low global blanking control - disables all outputs without affecting latch state |
| 17 | SERIAL OUT2 | Falling-edge synchronized serial output for cascading to next device |
| 18 | SERIAL OUT1 | Rising-edge synchronized serial output - supports dual-chain topologies |
| 19 | REXT | Connection point for external current-setting resistor (e.g., 160 Ω → ~120 mA) |
| 20 | LOGIC SUPPLY (VDD) | 5 V CMOS logic supply; powers shift register, latches, and interface circuitry |
Key Features
| Feature | Design Value |
|---|---|
| Programmable constant-current sink | Single REXT sets identical current for all 8 outputs - simplifies BOM and calibration |
| Dual-edge serial outputs | SDO1 (rising) and SDO2 (falling) enable flexible daisy-chaining without external clock inversion |
| Inter-digit blanking | Active-high ENABLE input blanks all outputs simultaneously - essential for multiplexed display timing |
| Digital current scaling | HIGH/LOW pin selects 100% or 50% of REXT-set current - enables 1-bit brightness control per frame |
| Undervoltage lockout | Prevents partial register updates below 4.3 V - avoids ghosting or flicker during brownout conditions |
Applications
| Industrial Panel Meters | LED Segment Displays |
|---|---|
|
Use Scenario: Driving 4–6 digit 7-segment displays in factory-floor instrumentation with ambient temperatures up to 85°C. IC Role / Device Role / Timing Role: Constant-current sink driver managing segment current and digit blanking via OUTPUT ENABLE and LATCH ENABLE timing. Use Value: Eliminates per-segment resistors; maintains consistent brightness across digits using single REXT and thermal derating curves for SOICW package. |
Use Scenario: Controlling alphanumeric LED modules in vending machines and point-of-sale terminals with microcontroller-based serial control. IC Role / Device Role / Timing Role: Serial-to-parallel converter with latch retention, enabling static display hold while new data loads. Use Value: Reduces GPIO count from 14+ to 4 (DATA, CLOCK, LATCH, OE); supports daisy-chained multi-module configurations. |
| Automotive Dashboard Indicators | Appliance Status Displays |
|
Use Scenario: Illuminating warning icons and gear-position indicators in automotive instrument clusters operating over –40°C to +85°C. IC Role / Device Role / Timing Role: High-reliability current sink with UVLO and robust ESD protection (Class 2), synchronized to vehicle MCU SPI-like interface. Use Value: Ensures fail-safe dimming (via HIGH/LOW) and blanking (via ENABLE) during ignition transients or low-battery conditions. |
Use Scenario: Powering LED status bars and function indicators in microwave ovens, washing machines, and HVAC controllers. IC Role / Device Role / Timing Role: Low-power (≤22 mA IDD at 5 V) LED driver interfacing directly with 5 V microcontrollers without level shifting. Use Value: Minimizes system power draw while delivering stable 100–150 mA sink capability per segment under varying load supply voltages. |
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 |
|---|---|---|---|
| Toshiba TD62715FN | Pin-compatible 20-pin SOIC; identical functional block diagram and REXT-based current setting, but lacks HIGH/LOW current scaling pin | No built-in 50% current mode - requires external PWM or resistor switching for dimming | Choose TD62715FN only if digital dimming is unnecessary and legacy footprint reuse is mandatory |
| ON Semiconductor CAT4016 | 16-pin SOIC; I²C interface instead of serial shift register; fixed 100 mA max per channel; no cascade outputs | Requires I²C host controller and separate address configuration; not suitable for long daisy chains | Select CAT4016 when system uses I²C infrastructure and needs fewer pins, but accept loss of serial expandability and lower current headroom |
Compared with TD62715FN and CAT4016, the A6277ELW uniquely combines daisy-chain capability, hardware-based 2-level current scaling, and SOICW thermal performance - making it optimal for cost-sensitive, high-channel-count LED display systems requiring minimal firmware overhead.
Availability
A6277ELW is available at Aetrix Electronics and suitable for industrial panel meters, LED segment displays, and appliance status indicators requiring stable component supply and long-term production continuity.
Supply support for A6277ELW 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, headquartered in Worcester, Massachusetts.
The A6277ELW belongs to Allegro's LED driver product line, engineered specifically for reliable, low-cost, constant-current driving of multiplexed LED displays in industrial and consumer equipment.
FAQ
What is the maximum continuous output current per channel for A6277ELW at 85°C ambient?
The A6277ELW delivers up to 150 mA per output continuously at TA = 85°C when VCE = 1.0 V, as specified in the Absolute Maximum Ratings table. This assumes proper PCB thermal design with RθJA ≤ 90°C/W for the SOICW package. Derating is required above 85°C ambient or with higher VCE.
How does the HIGH/LOW pin affect current regulation in A6277ELW?
In the A6277ELW, the HIGH/LOW pin (pin 5) directly scales the programmed current: a logic low enables 100% of the REXT-set current, while a logic high reduces it to 50%. This is implemented internally via analog current mirror scaling - no external components or timing changes are needed to switch between levels.
Can A6277ELW be used in daisy-chain configurations, and how many devices can be cascaded?
Yes, the A6277ELW supports daisy chaining via two dedicated serial outputs: SDO1 (rising-edge) and SDO2 (falling-edge). There is no hard limit on cascade length; practical limits depend on signal integrity, clock rise/fall times (<10 ns recommended), and total propagation delay accumulation across devices - typically >10 devices are feasible with proper layout.
What is the purpose of separating LOGIC GROUND (pin 1) and POWER GROUND (pins 6 & 15) in A6277ELW?
The A6277ELW separates logic and power grounds to prevent switching noise from high-current outputs (up to 150 mA × 8) from corrupting sensitive CMOS inputs. If shared, voltage spikes >2.5 V on pins like CLOCK or LATCH ENABLE relative to logic ground may cause metastability or incorrect latching - verified in Allegro's pattern layout guidelines.
Does A6277ELW include built-in protection against overtemperature or overcurrent faults?
The A6277ELW includes undervoltage lockout (UVLO) that disables operation below 4.3 V, but it does not feature thermal shutdown or overcurrent foldback. Protection relies on external design: proper REXT selection, thermal PCB layout, and limiting VLED to keep VCE ≤ 1.0 V - as detailed in the Applications Information section of the A6277ELW datasheet.
A6277ELW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 20-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):
- 4.5V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 4V
- Current - Output / Channel:
- 120mA
- Frequency:
- 20MHz
- Dimming:
- -
- Applications:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
A6277ELW FAQ
1.How can I place an order for A6277ELW through Aetrix?
Please submit a Request for Quotation (RFQ) for A6277ELW 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 A6277ELW reliable?
The price and inventory of A6277ELW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A6277ELW is usually 5 days.
3.What payment methods are accepted for A6277ELW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A6277ELW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A6277ELW?
A6277ELW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A6277ELW 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 A6277ELW?
For technical support, including A6277ELW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A6277ELW requirements.
6.How does Aetrix verify that A6277ELW is sourced from the original manufacturer or authorized distributors?
All A6277ELW 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 A6277ELW meets industry standards.
7.What is the process for return or replacement of A6277ELW?
All A6277ELW units undergo pre-shipment inspection (PSI). If there is an issue with A6277ELW, 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 A6277ELW part is unused and in its original packaging.
Return procedure for A6277ELW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
A6277ELW Tags
-
BCR402RE6327HTSA1
Infineon Technologies
-
BCR430UXTSA2
Infineon Technologies
-
BCR420UE6433HTMA1
Infineon Technologies
-
BCR420UE6327HTSA1
Infineon Technologies
-
BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
-
BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
Tech Hub
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
