Analog Devices Inc./Maxim Integrated MAX8805ZEWEAE+T

Overview

MAX8805ZEWEAE+T from Maxim Integrated is a 4MHz, 2V/V gain, 600mA high-frequency step-down converter with integrated 60mΩ bypass FET and dual 200mA low-noise LDOs, designed specifically to dynamically power WCDMA/NCDMA power amplifiers in mobile handsets. It supports analog voltage control via REFIN input (0.4V–2.2V), delivers 7.5µs settling time for 0.8V→3.4V output transitions, and operates from 2.7V–5.5V input.

For engineers reviewing the MAX8805ZEWEAE+T datasheet, MAX8805ZEWEAE+T pinout, MAX8805ZEWEAE+T application, or MAX8805ZEWEAE+T equivalent, key selection considerations include its 4MHz switching frequency for minimal external component count, 2V/V REFIN-to-PA gain, automatic/forced bypass mode operation, dual independent LDO enable control, and 2mm × 2mm UCSP package with 0.7mm height.

Technical Context

The MAX8805ZEWEAE+T implements a hysteretic PWM control scheme enabling fast transient response and stable regulation with small ceramic capacitors (2.2µF input/output). Its feedback network samples LX directly-eliminating phase lag from output capacitance-to support voltage-positioning load regulation that compensates for inductor DCR-induced droop.

Bypass mode is triggered either automatically when VREFIN exceeds 0.465 × VIN2 (enabling seamless transition during high-power PA transmission) or forcibly via HP logic input. The integrated 60mΩ p-channel bypass FET ensures low dropout (<100mV at 90mA) and supports up to 2.9A total bypass current (1.1A step-down + 1.8A bypass path).

Key Specifications

Pinout & Package

The MAX8805ZEWEAE+T is housed in a 16-bump, 2mm × 2mm × 0.7mm UCSP (Ultra Compact Silicon Package) with 4×4 bump grid layout and 0.4mm pitch. This lead-free, RoHS-compliant package supports reflow per JEDEC J-STD-020A and requires preheating; hand/wave soldering is prohibited.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX8805YEREXX+T, the MAX8805ZEWEAE+T offers superior high-frequency transient response and smaller passive footprint, while differing from MAX8805XEREXX+T in gain ratio and maximum output current-making it optimal for 0.4V–2.2V-controlled, 600mA-class WCDMA PA systems prioritizing compactness and noise performance.

Availability

MAX8805ZEWEAE+T is available at Aetrix Electronics and suitable for WCDMA handset design, smartphone RF front-end development, and portable wireless PDA power management requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for MAX8805ZEWEAE+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 precision analog, mixed-signal, and power management ICs for demanding applications in communications, computing, consumer, and industrial markets.

The MAX8805 family targets RF power amplifier supply in cellular handsets, combining high-efficiency step-down conversion, low-noise LDOs, and intelligent bypass control to extend battery life while meeting stringent 3G/CDMA spectral and linearity requirements.

FAQ

What is the switching frequency of the MAX8805ZEWEAE+T and why does it matter?

The MAX8805ZEWEAE+T operates at 4MHz. This high frequency allows the use of small 2.2µF ceramic input and output capacitors-reducing solution size, cost, and PCB area versus lower-frequency alternatives. It also improves transient response and enables tighter output voltage regulation during rapid PA power adjustments in WCDMA transmission bursts.

How does the MAX8805ZEWEAE+T achieve low output noise for sensitive RF bias applications?

The MAX8805ZEWEAE+T integrates two independent 200mA LDOs with 35µV_RMS typical output noise and 70dB PSRR at 1kHz. Each LDO features dedicated AGND and bypass pins (REFBP, LDO1/LDO2 caps), and the REFBP node must be decoupled with a 0.22µF ceramic capacitor to suppress reference noise-ensuring clean bias for PA drivers and LNAs without external filtering.

What triggers bypass mode on the MAX8805ZEWEAE+T and how does it improve efficiency?

Bypass mode activates automatically when VREFIN exceeds 0.465 × VIN2, or forcibly via the HP pin. In this mode, the internal 60mΩ p-channel FET connects IN1A/B directly to PAA/PAB, eliminating switching losses. This delivers near-zero dropout voltage and extends battery life during high-power transmission-achieving >95% efficiency at 2A load versus ~88% in PWM mode.

Can the MAX8805ZEWEAE+T support independent control of its dual LDOs?

Yes. The MAX8805ZEWEAE+T provides separate enable inputs EN1 and EN2 for LDO1 and LDO2, allowing independent power-up sequencing, dynamic power gating, and fault isolation. Each LDO maintains 1kΩ shutdown impedance and draws only 0.1µA quiescent current when disabled-critical for low-power sleep modes in handheld devices.

What package type and mounting requirements apply to the MAX8805ZEWEAE+T?

The MAX8805ZEWEAE+T uses a 16-bump UCSP (2mm × 2mm × 0.7mm) with 0.4mm pitch. It requires JEDEC J-STD-020A-compliant reflow profiling with mandatory preheating; hand soldering and wave soldering are prohibited. Thermal relief pads and strict AGND/PGND separation are essential to maintain noise performance and thermal reliability.