Analog Devices Inc./Maxim Integrated MAX860ESA+T

Overview

MAX860ESA+T from Maxim Integrated is a frequency-selectable, 50mA switched-capacitor voltage converter that inverts +1.5V to +5.5V inputs to negative outputs or doubles +2.5V to +5.5V inputs to positive outputs. It operates at selectable switching frequencies of 6kHz, 50kHz, or 130kHz, delivers 87% efficiency at 50mA load, and features 12Ω output resistance and 200µA quiescent current - ideal for portable medical instruments requiring compact, inductorless dual-rail power.

For engineers reviewing the MAX860ESA+T datasheet, MAX860ESA+T pinout, MAX860ESA+T application, or MAX860ESA+T equivalent, key selection criteria include its -40°C to +85°C operating range, SO-8 package compatibility with legacy ICL7660 sockets (with SHDN pin tied to VDD), three-frequency optimization for capacitor size vs. EMI trade-offs, and verified 600mV voltage drop at full 50mA load in inverter mode.

Technical Context

The MAX860ESA+T implements a BiCMOS charge-pump architecture with direct oscillator-to-switch coupling (no frequency division), enabling precise control of switching frequency via the FC pin (VDD/GND/OUT). Its LV pin configures operation mode: grounded for inversion, connected to OUT for doubling - unlike the MAX660, it lacks an OSC pin but retains pin-compatible SO-8 footprint with modified pin 7 (SHDN instead of OSC).

Internal switch resistance (~8Ω) combines with external capacitor ESR to define total output resistance (ROUT = RO + 4×ESR_C1 + ESR_C2 + 1/(f_S×C₁)), resulting in typical 12Ω performance with 10µF/0.2Ω capacitors at 50kHz. Shutdown reduces supply current to <1µA, and startup requires input supply capable of delivering 90mA transient surge beyond steady-state load.

Key Specifications

Pinout & Package

MAX860ESA+T is housed in an 8-pin SO package (package code S8-4, outline 21-0041), RoHS-compliant, with 1.27mm pitch and 5.0mm × 4.0mm body size.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switched-capacitor voltage converter applications.

Compared with MAX861ESA+T, MAX860ESA+T offers lower minimum switching frequency (6kHz vs. 13kHz) for reduced quiescent current in battery-critical apps; compared with MAX660CPA+, it provides pin-compatible upgrade path with enhanced EMI control via FC pin - no layout change needed beyond SHDN tie-high.

Availability

MAX860ESA+T is available at Aetrix Electronics and suitable for portable medical instruments, handheld test equipment, interface power supplies, and operational-amplifier power supplies requiring stable component supply across extended temperature ranges.

Supply support for MAX860ESA+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 is a semiconductor company specializing in analog and mixed-signal ICs for power management, sensing, and communication applications.

The MAX860/MAX861 product line was designed to replace legacy charge-pump ICs like the ICL7660 with higher efficiency, wider input range, and programmable frequency - specifically targeting space-constrained, battery-powered systems needing clean dual-rail power.

FAQ

What is the maximum continuous output current specification for MAX860ESA+T?

The MAX860ESA+T is rated for 50mA continuous output current in both inverter and doubler configurations. Absolute maximum ratings allow 60mA, but sustained operation above 50mA may exceed thermal limits in SO-8 package. Performance data shows 87% efficiency and 600mV dropout at exactly 50mA load with VDD=5V, confirming this as the validated design limit for reliable operation.

How does the FC pin configure switching frequency on MAX860ESA+T?

The FC pin on MAX860ESA+T selects one of three discrete switching frequencies: connecting FC to VDD sets 6kHz, to GND sets 50kHz, and to OUT sets 130kHz. These values are device-specific (MAX861 uses 13/100/250kHz) and directly drive the internal oscillator without division. The frequency determines capacitor sizing trade-offs - e.g., 68µF caps required at 6kHz versus 4.7µF at 130kHz - and places the fundamental noise spectrum for EMI mitigation.

Can MAX860ESA+T replace ICL7660 in existing designs without PCB changes?

MAX860ESA+T is pin-compatible with ICL7660 in SO-8 package but requires one wiring change: pin 7 (SHDN) must be tied to VDD to enable operation, whereas ICL7660 pin 7 (OSC) floats by default. All other pins match functionally (VDD, GND, C1+, C1-, OUT, LV, FC). No trace modifications are needed beyond this jumper, making MAX860ESA+T a drop-in upgrade for improved efficiency and frequency flexibility.

What is the recommended capacitor ESR for optimal performance with MAX860ESA+T?

Maxim specifies low-ESR capacitors (<0.2Ω) for both C1 (flying) and C2 (output) to achieve the 12Ω typical output resistance and 87% efficiency. Aluminum electrolytics, tantalum, or ceramic types meeting this ESR target are acceptable; higher ESR increases ROUT and reduces efficiency. The datasheet notes capacitor ESR directly adds to output resistance (ROUT = RO + 4×ESR_C1 + ESR_C2), so exceeding 0.2Ω ESR degrades regulation and ripple performance.

Does MAX860ESA+T require external components beyond capacitors?

MAX860ESA+T requires only two external capacitors (C1 and C2) for basic operation - no inductors, diodes, or resistors are needed. A 0.1µF ceramic bypass capacitor on VDD is strongly recommended to suppress switching noise. In high-EMI applications, additional filtering may be added at OUT, but the core charge-pump functionality is fully self-contained with just C1 and C2, making MAX860ESA+T a true two-component solution.