Analog Devices Inc./Maxim Integrated MAX14778ATP+T

Overview

MAX14778ATP+T from Maxim Integrated is a dual ±25V above- and below-the-rails 4:1 analog multiplexer IC designed for high-voltage signal routing in multi-protocol connector sharing systems. It operates from a single 3.0V to 5.5V supply, delivers ≤1.5Ω max on-resistance, supports ±300mA bidirectional current per channel, and enables RS-485 (20Mbps) and USB 1.1 (12Mbps) signal switching in industrial communication interfaces.

For engineers reviewing the MAX14778ATP+T datasheet, MAX14778ATP+T pinout, MAX14778ATP+T application, or MAX14778ATP+T equivalent, key selection criteria include its ±25V rail-to-rail analog range, break-before-make timing (840µs), 75MHz large-signal bandwidth, and integrated ±6kV HBM ESD protection on A_/B_ pins - critical for rugged cable-interfaced designs.

Technical Context

The MAX14778ATP+T integrates three charge pumps (5V regulated, +35V, and -27V) to generate bias voltages enabling ±25V analog signal handling from a single low-voltage supply. Its dual independent 4:1 mux architecture features separate enable (ENA/ENB) and 2-bit select (SA0/SA1, SB0/SB1) inputs with break-before-make switching logic.

Each channel supports bidirectional current flow up to ±300mA, exhibits 3mΩ typical R_ON flatness over -25V to +25V common-mode range, and maintains 78pF input capacitance and -103dB crosstalk at 100kHz - ensuring minimal signal degradation during protocol-agnostic multiplexing.

Key Specifications

Pinout & Package

MAX14778ATP+T uses a 20-pin thermally enhanced TQFN package (5mm × 5mm) with exposed pad connected to VN. The package supports high-power dissipation (θ_JA = 30°C/W on 4-layer board) and industrial temperature operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog multiplexer applications.

Compared with MAX14777ATP+T and ADG1419BRUZ, the MAX14778ATP+T uniquely delivers dual independent ±25V 4:1 mux functionality from a single 3.0–5.5V supply - making it the only option capable of true multi-protocol connector sharing without external voltage translation or additional power domains.

Availability

MAX14778ATP+T is available at Aetrix Electronics and suitable for RS-485/USB connector sharing, POS peripheral arbitration, and handheld industrial data loggers requiring stable component supply across extended temperature and high-reliability environments.

Supply support for MAX14778ATP+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) designs high-performance analog and mixed-signal ICs for industrial, automotive, and communications markets, with expertise in power management, interface, and signal conditioning.

The MAX14778ATP+T belongs to Maxim's high-voltage analog switch product line, engineered specifically to simplify multi-standard interface consolidation in space- and power-constrained embedded systems.

FAQ

What is the maximum continuous current rating for each channel of the MAX14778ATP+T?

The MAX14778ATP+T supports ±300mA continuous bidirectional current per channel (A0–A3 and B0–B3). This rating applies across the full -40°C to +125°C operating temperature range and enables robust routing of RS-485 differential pairs and USB 1.1 D+/D- lines without derating. Exceeding ±300mA risks thermal shutdown activation at 145°C junction temperature.

Does the MAX14778ATP+T require external capacitors, and if so, what values and locations?

Yes, the MAX14778ATP+T requires three external capacitors: a 1µF ceramic capacitor from VDD to GND (pin 13), and 100nF 50V ceramic capacitors from VP to GND (pin 2) and VN to GND (pin 4). These are mandatory for stable charge-pump operation, full ±25V analog range, and guaranteed ±6kV HBM ESD protection on A_/B_ pins per the datasheet Applications Information section.

Can the MAX14778ATP+T operate with VDD = 0V while analog signals are present?

Yes, the MAX14778ATP+T tolerates ±25V on A_, B_, ACOM, and BCOM pins with VDD = 0V. Input leakage remains typically <1µA, though transient charging currents may occur due to VP/VN capacitor charging. To avoid exceeding the ±500mA absolute maximum rating, dv/dt on analog inputs must be limited to ≤3V/µs once VP/VN capacitors reach steady state.

What is the break-before-make timing specification for the MAX14778ATP+T, and why is it critical?

The MAX14778ATP+T guarantees an 840µs minimum break-before-make interval between channel transitions. This prevents momentary short circuits during reconfiguration - essential when multiplexing incompatible protocols (e.g., RS-232 and RS-485) on shared pins. Violating this timing risks bus contention, transceiver damage, or data corruption in live communication links.

How does the MAX14778ATP+T achieve ±25V signal handling from a single 3.0V–5.5V supply?

The MAX14778ATP+T integrates three on-chip charge pumps: a 5V regulated pump, a +35V high-voltage pump, and a -27V high-voltage pump. When VDD > 4.7V, the 5V pump is bypassed and VDD directly powers the high-voltage pumps - generating internal bias rails that extend the analog switch's conduction range to ±25V without external supplies.