Analog Devices Inc./Maxim Integrated MAX6979AUG+

Overview

MAX6979AUG+ from Maxim Integrated is a 16-channel, constant-current-sinking LED driver IC with open-drain outputs rated to 5.5V, 3% output current matching, integrated open-LED fault detection, and a 1s watchdog timeout for fail-safe display blanking. It operates from 3V–5.5V logic supply and supports 25Mbps 4-wire serial interface in industrial signage applications.

For engineers reviewing the MAX6979AUG+ datasheet, MAX6979AUG+ pinout, MAX6979AUG+ application, or MAX6979AUG+ equivalent, key selection criteria include its 16-bit shift-register-plus-latch interface, single-resistor current programming (360Ω → 50mA), TSSOP-24 package thermal performance, and fault-reporting via DOUT bits D14/D13.

Technical Context

The MAX6979AUG+ implements a synchronous 4-wire serial interface with DIN/CLK/LE/OE control and DOUT cascading capability. Its internal architecture separates a 16-bit shift register from a transparent 16-bit output latch, enabling independent data loading and display update timing.

Each of the 16 OUTx pins integrates a precision current-sink circuit with feedback-based regulation-not simple mirroring-ensuring stable 37–61mA output across VOUT = 0.5V–2.5V and V+ = 3V–5.5V. Fault detection activates post-OE falling edge and reports open-circuit conditions on next LE-triggered DOUT shift-out cycle.

Key Specifications

Pinout & Package

MAX6979AUG+ is housed in a 24-pin Thin Shrink Small Outline Package (TSSOP) with exposed pad for thermal enhancement. The package measures 7.8mm × 4.4mm × 1.2mm and supports reflow soldering per JEDEC J-STD-020 (lead-free, 260°C peak).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant-current LED driver applications.

Compared with MAX6979AUG+, MAX6978AUG+ reduces channel count while preserving all safety and timing features in identical packaging, whereas MAX6983AUG+ extends voltage capability at the cost of compatibility with existing 5.5V LED layouts - neither is pin-compatible, but both share identical serial protocol and register mapping.

Availability

MAX6979AUG+ is available at Aetrix Electronics and suitable for traffic signage, variable message displays, and architectural lighting requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6979AUG+ 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

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for industrial, automotive, and communications systems.

The MAX6979AUG+ belongs to Maxim's shift-register-plus-latch LED driver family, engineered specifically for high-reliability, fault-aware outdoor and safety-critical signage applications demanding consistent brightness and autonomous failure response.

FAQ

What is the maximum LED supply voltage compatible with MAX6979AUG+?

The MAX6979AUG+ outputs are rated to 5.5V, meaning the anode of any LED or LED string connected to OUT0–OUT15 must not exceed 5.5V above GND. This allows direct use with standard 3.3V or 5V LED supplies, but prohibits connection to higher-voltage rails without external level-shifting or series limiting. The 5.5V rating is absolute - exceeding it risks permanent damage per Absolute Maximum Ratings.

How does the MAX6979AUG+ report open-LED faults?

The MAX6979AUG+ detects open circuits when an enabled output sinks less than ~50% of its programmed current. Fault status is captured after the OE pin falls and latched on the next LE rising edge. During the subsequent serial data transmission, bits D14 and D13 of DOUT output high to indicate fault presence - while D0–D12 and D15 retain original data for link integrity verification. No external circuitry is required.

Can MAX6979AUG+ be used with a 3.3V microcontroller SPI interface?

Yes - the MAX6979AUG+ accepts logic inputs (DIN, CLK, LE, OE) with VIH = 0.7×V+ and VIL = 0.3×V+, and operates with V+ = 3V–5.5V. When powered at 3.3V, its input thresholds become VIH ≈ 2.31V and VIL ≈ 0.99V, fully compatible with standard 3.3V CMOS outputs. No level translation is needed, and timing parameters (e.g., 52ns min CLK period) remain valid across the full supply range.

What is the role of the SET pin on MAX6979AUG+ and how is RSET calculated?

The SET pin on MAX6979AUG+ connects to GND through an external resistor RSET to establish the reference current for all 16 outputs. Output current is calculated as IOUT = 18,000 / RSET (in mA), where RSET is in ohms. For example, RSET = 360Ω yields 50mA per channel. Minimum RSET is 327.3Ω (55mA), maximum is 1.5kΩ (12mA). Precision metal-film resistors are recommended for stable brightness.

Does MAX6979AUG+ support daisy-chaining, and how is it implemented?

Yes - MAX6979AUG+ supports seamless daisy-chaining via its DOUT pin. Data shifted into DIN propagates through the internal 16-bit shift register and appears at DOUT exactly 16 clock cycles later. To cascade N devices, connect DIN of Device 1 to controller, DOUT of Device 1 to DIN of Device 2, and so on. LE must be wired in parallel to update all latches simultaneously, preserving synchronized display updates across the chain.