Analog Devices Inc./Maxim Integrated MAX861ESA/V+T

Overview

MAX861ESA/V+T from Maxim Integrated is a frequency-selectable, 50mA switched-capacitor voltage converter that inverts +1.5V to +5.5V inputs or doubles +2.5V to +5.5V inputs. It operates at three user-selectable switching frequencies (13/100/250 kHz), delivers ≥87% efficiency at 50mA load, and features 12Ω output resistance and 1µA shutdown current. It serves as a compact, inductorless power solution for portable medical instruments and handheld test equipment.

For engineers reviewing the MAX861ESA/V+T datasheet, MAX861ESA/V+T pinout, MAX861ESA/V+T application, or MAX861ESA/V+T equivalent, key selection criteria include its -40°C to +85°C operating range, SO-8 package compatibility, selectable high-frequency operation to minimize external capacitor size, and direct functional replacement capability for legacy ICL7660 and MAX660 designs requiring higher output current and faster switching.

Technical Context

The MAX861ESA/V+T implements a BiCMOS charge-pump architecture with integrated switches and oscillator, supporting both inverting and doubling topologies via LV pin configuration. Its FC pin selects one of three discrete switching frequencies without internal division - 13kHz (FC = VDD), 100kHz (FC = GND), or 250kHz (FC = OUT) - each directly setting the pump rate and defining trade-offs between capacitor size, quiescent current, and noise spectrum.

It uses no magnetic components: two external flying/output capacitors suffice. Output regulation is unregulated but highly predictable - output voltage droop is governed by 12Ω effective source resistance and load current, enabling stable bias generation for op-amps and interface ICs without feedback loops or LDO post-regulation.

Key Specifications

Pinout & Package

MAX861ESA/V+T is housed in an 8-pin SO (Small Outline) package, 3.9mm × 4.9mm, with standard 1.27mm pitch and RoHS-compliant lead finish. The package supports automated assembly and provides thermal performance suitable for continuous 50mA operation at +85°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX861ISA, the MAX861ESA/V+T guarantees operation down to −40°C and tighter parametric limits over temperature; versus MAX660CPA+, it trades 50mA peak current for 250kHz switching, 4× lower noise floor, and 20% higher efficiency at typical portable loads (10–30mA), making it optimal for modern battery-sensitive designs.

Availability

MAX861ESA/V+T is available at Aetrix Electronics and suitable for portable medical diagnostics, handheld test equipment, interface power supplies, and operational-amplifier power supplies requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX861ESA/V+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, medical, and communications applications.

The MAX860/MAX861 product line was designed specifically to replace aging ICL7660-based solutions with higher efficiency, wider input range, and selectable frequency - targeting portable, battery-operated systems where size, noise, and power efficiency are critical.

FAQ

What is the maximum continuous output current of the MAX861ESA/V+T?

The MAX861ESA/V+T delivers 50mA continuous output current under specified conditions (VDD = +5V, TA ≤ +85°C, C1/C2 = 10µF low-ESR). Absolute maximum rating is 60mA, but sustained operation above 50mA may exceed thermal limits in SO-8 package. Derating is recommended above +70°C ambient per the 5.88mW/°C power dissipation curve.

How does the FC pin select switching frequency on the MAX861ESA/V+T?

The FC pin on the MAX861ESA/V+T selects one of three discrete frequencies: 13kHz (FC tied to VDD or left open), 100kHz (FC tied to GND), or 250kHz (FC tied to OUT). No external resistor or clock source is needed - the device reads FC logic level at power-up and locks the oscillator frequency accordingly, as confirmed in Table 1 of the datasheet.

Can the MAX861ESA/V+T replace an ICL7660 in an existing design?

Yes, the MAX861ESA/V+T can replace an ICL7660 with minimal changes: connect SHDN to VDD (not floating), retain same C1/C2 values initially, and verify LV pin connection (GND for inverter). It delivers 5× higher output current (50mA vs. 10mA), 25× higher switching frequency, and 17% better efficiency - improving size, noise, and battery life without PCB rework.

What is the output voltage accuracy of the MAX861ESA/V+T in inverter mode?

The MAX861ESA/V+T has no output voltage regulation - output follows −VIN × (1 − ILOAD × ROUT / VIN). With ROUT = 12Ω and VIN = +5V, output is −5.0V at no load and −4.4V at 50mA. Accuracy depends entirely on input rail stability and load current; for precision rails, pair with a low-dropout linear regulator downstream of MAX861ESA/V+T.

Does the MAX861ESA/V+T require external diodes or inductors?

No, the MAX861ESA/V+T requires only two external capacitors (C1 flying, C2 output) and optionally a 0.1µF VDD bypass capacitor. It integrates all switching elements, oscillator, and control logic - eliminating external diodes, inductors, and feedback resistors required by inductive DC/DC converters or older charge pumps like the ICL7660.