Analog Devices Inc./Maxim Integrated MAX1864UEEE

Overview

The MAX1864UEEE from Maxim Integrated is a triple-output, current-mode synchronous step-down power-supply controller with two integrated positive analog gain blocks. It generates a main 3.3V (preset) or adjustable 1.236V–0.8×VIN output at up to 3A, plus two auxiliary positive rails via external PNP pass transistors-used in xDSL/cable modem CPE power systems requiring cost-effective, multi-rail DC-DC conversion from unregulated 4.5V–28V inputs.

For engineers reviewing the MAX1864UEEE datasheet, MAX1864UEEE pinout, MAX1864UEEE application, or MAX1864UEEE equivalent, this device is selected for its valley-current-limit sensing (no sense resistor), 100kHz fixed-frequency PWM operation enabling low-cost aluminum electrolytic capacitors, soft-start for all regulators, and integrated 5V VL LDO powering gate drivers and bias circuitry.

Technical Context

The MAX1864UEEE implements a forced-PWM, current-mode control architecture with slope compensation to ensure stability across line/load transients. Its dual-mode feedback (preset/adjustable) uses a 1.236V internal reference at FB, while the COMP pin supports type-II/III compensation networks for loop tuning.

Current limiting operates via valley detection across the low-side MOSFET's R_DS(ON), eliminating external sense resistors. The ILIM pin enables adjustable threshold (106–530mV) or default 250mV mode, and the VL regulator (4.75–5.25V, 20mA max) powers internal circuitry, DL driver, and BST capacitor charging.

Key Specifications

Pinout & Package

MAX1864UEEE is housed in a 16-pin QSOP package (5.3mm × 10.2mm, 0.65mm pitch) with exposed pad for thermal enhancement. Pin functions are validated per Maxim's official datasheet Rev 0 (April 2001).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-output DC-DC controller applications.

Compared with MAX1864TEEE, the MAX1864UEEE trades higher inductor/capacitor size for lower EMI and relaxed layout constraints; versus TPS5430DDAR, it delivers integrated auxiliary regulation at the cost of less flexibility in rail assignment and sequencing.

Availability

MAX1864UEEE is available at Aetrix Electronics and suitable for xDSL modems, cable CPE, and set-top boxes requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for MAX1864UEEE 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 industrial, communications, and consumer applications.

The MAX1864UEEE belongs to Maxim's cost-optimized power-supply controller family targeting broadband CPE, designed to replace discrete buck + LDO combinations with integrated multi-rail solutions using minimal external components.

FAQ

What is the primary function of the MAX1864UEEE in a power system?

The MAX1864UEEE serves as a triple-output synchronous step-down controller that generates a main 3.3V (or adjustable) rail plus two auxiliary positive rails using external PNP transistors. It integrates current-mode PWM control, valley-current limiting, soft-start, and a 5V VL LDO - all within a single 16-pin QSOP package. This makes the MAX1864UEEE ideal for compact, cost-sensitive CPE power supplies where minimizing external components is critical.

Can the MAX1864UEEE generate negative output voltages?

No, the MAX1864UEEE cannot generate negative outputs. It contains two positive analog gain blocks (B2/FB2 and B3/FB3) for auxiliary positive rails only. Negative rail generation requires the MAX1865 series (e.g., MAX1865UEEP), which adds a dedicated B5/FB5 negative gain block and associated circuitry. Using the MAX1864UEEE for negative outputs is not supported by its pinout, internal architecture, or datasheet specifications.

How does the MAX1864UEEE achieve current limiting without a sense resistor?

The MAX1864UEEE senses the voltage drop across the low-side MOSFET's on-resistance (R_DS(ON)) during the valley of the inductor current waveform. This "valley current limit" technique amplifies the sensed voltage (gain = 5) and compares it to an internal threshold (default 250mV at ILIM). Because it leverages the MOSFET's intrinsic resistance, no external sense resistor is needed - reducing cost, power loss, and PCB area. This method is explicitly confirmed in the MAX1864UEEE's Electrical Characteristics table and Detailed Description section.

What is the role of the VL pin on the MAX1864UEEE?

The VL pin is the output of an internal 5V low-dropout linear regulator that powers the MAX1864UEEE's internal circuitry, DL low-side gate driver, BST capacitor charging circuit, and small external loads. It delivers up to 20mA with 4.75V–5.25V tolerance and must be bypassed with ≥1µF ceramic capacitor to GND. The VL regulator also enables thermal shutdown (disabled if VL is shorted to GND) and serves as the reference for POK pull-up and ILIM default threshold - making it central to both functionality and protection in the MAX1864UEEE.

Is the MAX1864UEEE pin-compatible with the MAX1864TEEE?

Yes, the MAX1864UEEE and MAX1864TEEE are pin-compatible 16-pin QSOP devices with identical pinout, package dimensions, and electrical interface. Their only functional difference is switching frequency: MAX1864UEEE operates at 100kHz, while MAX1864TEEE runs at 200kHz. This means PCB layouts, external components (except magnetics and output caps), and firmware can be reused - allowing frequency selection based on EMI requirements, component size, and efficiency trade-offs without redesigning the board for the MAX1864UEEE.