Analog Devices Inc./Maxim Integrated MAX865EUA+T

Overview

MAX865EUA+T from Maxim Integrated is a CMOS dual-output charge-pump DC-DC converter in an 8-pin µMAX package. It generates +2×VIN and −2×VIN outputs from a single +1.5V to +6.0V input, requires only four external capacitors, delivers up to 20mA per output, and operates with a guaranteed 20kHz–38kHz oscillator frequency. It is used in GaAsFET biasing and split-supply analog circuitry.

For engineers reviewing the MAX865EUA+T datasheet, MAX865EUA+T pinout, MAX865EUA+T application, or MAX865EUA+T equivalent, key selection criteria include input voltage range (+1.5V to +6.0V), dual-rail output capability (±2×VIN), output impedance (75Ω typical), temperature range (−40°C to +85°C), and µMAX footprint compatibility for space-constrained portable designs.

Technical Context

The MAX865EUA+T implements a two-stage switched-capacitor topology: first a voltage-doubling stage (IN → V+), then an inverting stage referenced to V+ (V+ → V−). Its internal oscillator drives complementary CMOS power switches-four P-channel and four N-channel MOSFETs-with fixed 50% duty cycle, eliminating need for external timing components.

It is not regulated: output voltages droop linearly with load current due to inherent source resistance (~75Ω for V+, ~140Ω for V− at +25°C). Output ripple is capacitor-dependent (e.g., 10mV_p-p at 5mA with 3.3µF reservoir caps), and efficiency peaks at ~95% (VIN = 5V, light load).

Key Specifications

Pinout & Package

The MAX865EUA+T is housed in an 8-pin µMAX package (3.05mm × 3.05mm × 1.11mm), occupying 50% of the board area of a standard SOIC-8. Its lead pitch is 0.65mm, and substrate is connected to V+.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-output charge-pump applications.

Compared with MAX864EUA+ and TPS60403DBVR, the MAX865EUA+T offers the highest voltage gain (±2×VIN) and lowest quiescent current in its class, making it optimal for battery-critical, high-rail-voltage portable analog systems where simplicity and size are paramount.

Availability

MAX865EUA+T is available at Aetrix Electronics and suitable for low-voltage GaAsFET biasing, split-supply data-acquisition systems, and LCD panel biasing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX865EUA+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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and consumer applications.

The MAX865EUA+T belongs to Maxim's legacy charge-pump DC-DC converter family, designed specifically for compact, low-noise, dual-rail generation in battery-powered RF and analog subsystems where inductor-free solutions are mandatory.

FAQ

What is the maximum continuous output current supported by the MAX865EUA+T?

The MAX865EUA+T supports up to 20mA per output under typical conditions (VIN = 5V, TA = +25°C). The V+ output can deliver this current with ~1.5V droop (75Ω × 20mA), while V− exhibits greater droop (~2.8V at 20mA) due to its higher 140Ω output impedance. Absolute maximum ratings allow 100mA on V−, but sustained operation above 20mA degrades regulation and efficiency significantly.

Can the MAX865EUA+T generate outputs beyond ±2×VIN?

No, the MAX865EUA+T is a fixed-ratio charge pump with no programmable gain. Its architecture strictly produces V+ ≈ +2×VIN and V− ≈ −2×VIN under no-load conditions. Load-dependent droop reduces actual output magnitudes linearly with current draw, but the conversion ratio itself is hardwired and cannot be adjusted via external components or control pins.

What capacitor types and values are recommended for stable operation of the MAX865EUA+T?

Maxim specifies 3.3µF polarized electrolytic or ceramic capacitors for all four external components (C1–C4). Low-ESR capacitors are mandatory-especially for C1 and C2 (flying caps)-to minimize output impedance and ripple. For 5mA loads, 3.3µF yields ~10mV_p-p ripple; 1µF is acceptable only for ≤1mA loads and requires careful layout to avoid instability.

Does the MAX865EUA+T include built-in overcurrent or thermal protection?

No, the MAX865EUA+T has no internal overcurrent, overtemperature, or short-circuit protection circuitry. Its absolute maximum ratings specify indefinite V− short-circuit to GND and 100mA V− output current, but sustained overload will cause thermal runaway. External current limiting (e.g., series resistors or Schottky clamps) is required in high-reliability designs, especially when V+ supplies current to V− loads.

How does the MAX865EUA+T compare to inductor-based DC-DC converters in terms of efficiency and noise?

The MAX865EUA+T achieves up to 95% peak efficiency at light loads (VIN = 5V), but efficiency drops faster with increasing current than inductor-based regulators due to fixed switching losses and output resistance. Its 20kHz–38kHz fundamental frequency avoids audible noise but generates stronger low-frequency harmonics than MHz-range inductor converters-making it less suitable for ultra-low-noise analog rails unless filtered with LC networks.