Analog Devices Inc./Maxim Integrated MAX8790AETP+T

Overview

MAX8790AETP+T from Maxim Integrated is a high-efficiency, six-string white LED driver IC for LCD backlighting in large-panel displays. It integrates a current-mode step-up controller, six matched ±1.5% accurate current sinks (up to 27mA per string), selectable 500kHz/750kHz/1MHz switching frequency, and dual dimming modes (direct DPWM and PLL-based analog). It operates from 4.5V–26V input and delivers regulated LED current with 450mV feedback voltage for high efficiency in notebook, tablet, and industrial display systems.

For engineers reviewing the MAX8790AETP+T datasheet, MAX8790AETP+T pinout, MAX8790AETP+T application, or MAX8790AETP+T equivalent, this page provides verified technical context, real-world dimming behavior, fault protection thresholds, thermal shutdown at 170°C, and validated alternative drivers for LCD backlight design-without generic claims or unsupported performance assertions.

Technical Context

The MAX8790AETP+T employs a fixed-frequency, current-mode boost architecture that regulates output voltage just above the highest active FB_ string voltage using LVC feedback, while HVC monitors overvoltage across current sources. Its internal 5V LDO powers control logic and gate drive, and supports external VCC override when VIN ≤ 5.5V.

Dimming is implemented via two distinct paths: direct DPWM toggles the step-up switch and current sinks synchronously, while analog mode uses an integrated PLL (tuned by FSET) to convert BRT PWM into linear DAC-controlled current down to 12.5%, extended to 1% via hybrid digital-analog blending. Fault protection includes per-string open/short detection, OV pin-based output clamping (1.23V threshold), and thermal shutdown at 170°C.

Key Specifications

Pinout & Package

MAX8790AETP+T is housed in a thermally enhanced, lead-free, 20-pin, 4mm × 4mm thin QFN package with exposed pad (EP) for PCB ground connection and thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar six-string LED driver applications.

Compared with LM3409QMH/NOPB and TPS68400RHDR, the MAX8790AETP+T uniquely integrates a six-string current-balanced boost controller in one QFN package, eliminating external matching components and secondary power stages while delivering verified ±1.5% regulation and 100:1 dimming without firmware or I²C overhead.

Availability

MAX8790AETP+T is available at Aetrix Electronics and suitable for notebook display backlighting, tablet computer panels, industrial HMI interfaces, medical imaging monitors, and handheld terminal displays requiring stable component supply and long-term production continuity.

Supply support for MAX8790AETP+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

Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for demanding industrial, automotive, and computing applications.

The MAX8790AETP+T belongs to Maxim's LCD backlight driver product line, designed specifically for high-accuracy, multi-string white LED current regulation in space-constrained, thermally sensitive display systems requiring flicker-free dimming and robust fault protection.

FAQ

What is the maximum LED string voltage supported by the MAX8790AETP+T?

The MAX8790AETP+T does not specify a fixed maximum string voltage; instead, its step-up controller regulates output just above the highest active FB_ string voltage. With OV pin set for 1.23V threshold and typical R1/R2 divider, VOUT can reach up to 35V in standard configurations. Absolute maximum ratings limit FB_ pins to +28V, defining practical upper bound for string compliance.

How does the MAX8790AETP+T achieve ±1.5% current matching between six LED strings?

The MAX8790AETP+T achieves ±1.5% current matching through laser-trimmed, matched current-sink transistors fabricated on the same die. Each FB_ output uses identical reference and amplifier topology, and regulation is performed independently per string with shared biasing-verified across temperature and process corners in production testing.

Can the MAX8790AETP+T operate with input voltage below 5.5V?

Yes - the MAX8790AETP+T supports input voltages as low as 4.5V. When VIN ≤ 5.5V, the internal 5V LDO is disabled by connecting VCC to IN, and an external 5V supply powers the IC. This configuration is documented in Figure 3 of the datasheet and maintains full functionality including dimming and protection features.

What happens when one LED string opens during operation of the MAX8790AETP+T?

When one string opens, its FB_ pin is pulled near ground, causing the step-up controller to raise VOUT until clamped by the OV feedback loop (1.23V threshold). Simultaneously, HVC monitoring detects excessive voltage across remaining strings; if V_HVC > VCC + 0.6V for >65ms, the device latches off to prevent damage - confirmed in Typical Operating Characteristics figure toc16.

Is the MAX8790AETP+T pin-compatible with earlier MAX8790 variants like MAX8790ETP+?

No - the MAX8790AETP+T is not pin-compatible with the legacy MAX8790ETP+. The 'A' suffix denotes a revised version with updated internal PLL architecture, tighter current matching (±1.5% vs. ±2%), improved thermal shutdown threshold (170°C vs. 150°C), and modified FSET/CPLL behavior. Pin functions and layout are identical, but electrical behavior differs in dimming and fault timing.