Analog Devices Inc./Maxim Integrated MAX8805YEWEAE+T

Overview

MAX8805YEWEAE+T from Maxim Integrated is a 2MHz, 600mA high-frequency step-down converter with integrated 60mΩ bypass FET and dual 200mA low-noise LDOs, designed specifically to dynamically power the power amplifier (PA) in WCDMA handsets. It supports analog voltage control via REFIN (2V/V gain), delivers 7.5µs settling time for 0.8V–3.4V output transitions, and operates from 2.7V–5.5V input.

For engineers reviewing the MAX8805YEWEAE+T datasheet, MAX8805YEWEAE+T pinout, MAX8805YEWEAE+T application, or MAX8805YEWEAE+T equivalent, key selection criteria include PA supply dynamic response, bypass-mode dropout performance, REFIN-controlled output linearity, LDO PSRR/noise specs, and UCSP package thermal behavior in compact handset layouts.

Technical Context

The MAX8805YEWEAE+T implements a hysteretic PWM control scheme enabling fast transient response and stable operation with only 2.2µF ceramic input/output capacitors. Its Dual Mode™ architecture automatically switches between PWM step-down and direct battery bypass based on REFIN voltage thresholds (0.465 × VIN2), eliminating external mode control logic.

It integrates two independent LDOs with 35µVRMS noise and 70dB PSRR (10Hz–10kHz), each individually enabled via EN1/EN2. The PA step-down section features internal synchronous rectification, no external Schottky diode required, and uses LX-node DC feedback to remove phase lag-enabling ultra-stable regulation with minimal output capacitance.

Key Specifications

Pinout & Package

MAX8805YEWEAE+T is housed in a 16-bump, 2mm × 2mm × 0.7mm UCSP (Ultra Compact Silicon Package) - a wafer-level chip-scale package optimized for ultra-thin mobile handset PCBs with tight thermal and space constraints.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PA power management applications.

Compared with MAX8805WERExy+T, MAX8805YEWEAE+T offers lower REFIN gain for finer low-voltage PA control but reduced max current; versus MAX8805ZERExy+T, it trades 4MHz switching for better heavy-load efficiency and simpler EMI filtering-making it optimal for mainstream WCDMA handset PA supply where 2MHz balance is preferred.

Availability

MAX8805YEWEAE+T is available at Aetrix Electronics and suitable for WCDMA handset design, RF transceiver power systems, and portable cellular baseband applications requiring stable component supply, consistent UCSP packaging, and guaranteed -40°C to +85°C operation.

Supply support for MAX8805YEWEAE+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 semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX8805 family was engineered specifically for dynamic PA power delivery in 3G cellular handsets, combining high-efficiency step-down conversion, low-noise bias generation, and intelligent bypass control in a single ultra-compact package.

FAQ

What is the REFIN-to-PA output voltage gain for MAX8805YEWEAE+T?

The MAX8805YEWEAE+T has a fixed REFIN-to-PA output gain of 2V/V. When a 0.9V analog voltage is applied to REFIN, the PA output regulates to approximately 1.8V (accounting for small voltage-positioning offset). This linear relationship holds across the full 0.4V–2.0V REFIN range, enabling precise closed-loop PA power control in WCDMA systems.

Does MAX8805YEWEAE+T support automatic bypass mode, and what triggers it?

Yes, MAX8805YEWEAE+T supports automatic bypass mode triggered when the REFIN voltage exceeds 0.465 × VIN2. For example, with VIN2 = 3.6V, bypass engages when REFIN rises above ~1.67V. This threshold prevents premature switching and ensures smooth transition from PWM to low-dropout FET conduction during high-power transmission bursts.

What are the recommended external components for MAX8805YEWEAE+T?

MAX8805YEWEAE+T requires a 2.2µF ceramic capacitor on each of IN1A/IN1B and IN2 (to AGND/PGND), a 2.2µF ceramic capacitor on PAA/PAB (to PGND), 1µF ceramics on LDO1/LDO2 (to AGND), and a 0.22µF ceramic on REFBP (to AGND). An external inductor (typically 1.0–2.2µH) connects LX to PAA/PAB. No external compensation or Schottky diode is needed.

How does the MAX8805YEWEAE+T handle thermal protection?

MAX8805YEWEAE+T incorporates thermal shutdown that activates at +160°C junction temperature with ~20°C hysteresis. When triggered, the device disables the PA step-down converter, LDOs, and bypass FET until temperature falls below ~140°C. This protects against sustained overload or poor PCB thermal design while maintaining safe operation in compact handset enclosures.

Can the two LDOs in MAX8805YEWEAE+T be powered independently?

Yes, the two LDOs in MAX8805YEWEAE+T are fully independent: LDO1 is controlled by EN1 and LDO2 by EN2. Each can be enabled or disabled separately using logic-level signals, allowing flexible power sequencing-for example, enabling LDO2 only during active RF transmission while keeping LDO1 active for always-on bias circuits. Both outputs are pulled down via internal 1kΩ resistors when disabled.