Analog Devices Inc./Maxim Integrated MAX881REUB-TG075

Overview

MAX881REUB-TG075 from Maxim Integrated is a low-noise, inverting charge-pump power supply with integrated negative linear regulator, designed specifically to bias GaAsFET power amplifiers in portable wireless transceivers. It accepts 2.5V–5.5V input, delivers up to 4mA at preset −2.0V or adjustable −0.5V to (−VIN + 0.6V), and achieves 1mV_p-p output ripple/noise. Its POK output enables controlled GaAsFET drain switching.

For engineers reviewing the MAX881REUB-TG075 datasheet, MAX881REUB-TG075 pinout, MAX881REUB-TG075 application, or MAX881REUB-TG075 equivalent, this device is selected for ultra-low-noise GaAsFET biasing where startup timing, shutdown current (<1µA), and precise power-OK sequencing are critical in space-constrained RF front ends.

Technical Context

The MAX881REUB-TG075 integrates a capacitive charge pump followed by an N-channel pass transistor-based linear regulator. The charge pump generates unregulated negative voltage at NEGOUT; the linear stage regulates OUT with 2mV/mA load regulation and filters switching noise to ≤1mV_p-p. Oscillation occurs at 80–120kHz, determined internally without external timing components.

Its POK output is open-drain and active-low, asserting when OUT reaches 92.5% of its setpoint-enabling safe GaAsFET gate/drain power sequencing. Shutdown is logic-controlled (SHDN active-low), forcing OUT and NEGOUT to GND while drawing only 0.05µA typical supply current.

Key Specifications

Pinout & Package

MAX881REUB-TG075 is housed in a 10-pin µMAX package (3.0mm × 3.0mm × 0.8mm, 0.5mm pitch), optimized for RF-sensitive portable layouts with exposed pad for thermal and ground integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar GaAsFET bias supply applications.

Compared with MAX882REUB+, MAX881REUB-TG075 trades output current headroom for tighter integration and lower BOM count in 4mA-limited designs; versus LT1931IS5#TRMPBF, it eliminates external regulation and sequencing components but occupies more board area due to µMAX size.

Availability

MAX881REUB-TG075 is available at Aetrix Electronics and suitable for cellular handsets, wireless modems, and two-way pagers requiring stable component supply, low-noise bias generation, and reliable power-sequencing capability.

Supply support for MAX881REUB-TG075 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 communications, computing, and industrial markets.

The MAX881R product line delivers integrated, low-noise negative bias supplies for GaAsFET power amplifiers in portable wireless infrastructure-designed to replace discrete charge-pump + LDO solutions with single-chip reliability and reduced layout complexity.

FAQ

What is the function of the POK pin on the MAX881REUB-TG075?

The POK (Power-OK) pin on the MAX881REUB-TG075 is an active-low, open-drain output that signals when the regulated negative output (OUT) reaches 92.5% of its setpoint. It is used to safely enable the GaAsFET drain switch-ensuring the FET is not powered until proper gate bias is established. For MAX881REUB-TG075, this prevents latch-up and improves RF module reliability in handheld transceivers.

Can the MAX881REUB-TG075 generate output voltages other than −2.0V?

Yes, the MAX881REUB-TG075 supports adjustable output from −0.5V to (−VIN + 0.6V) using the FB pin. When FB is grounded, the output is fixed at −2.0V. To adjust, connect FB to a resistor divider between OUT and GND-R1 (100kΩ–400kΩ) and R2 calculated as R2 = R1 × (2 × |V_OUT| − 1). This flexibility allows MAX881REUB-TG075 to match varying GaAsFET V_GS requirements across bands and processes.

What capacitor values are required for minimum noise operation of the MAX881REUB-TG075?

For minimum output noise (1mV_p-p), the MAX881REUB-TG075 requires C1, C2, and C3 = 1µF ceramic capacitors (ESR < 0.4Ω) and C4 = 10µF low-ESR (≤0.1Ω) ceramic or chip tantalum. These values are specified in Figure 3b of the MAX881REUB-TG075 datasheet. Using smaller 0.22µF caps (Figure 3a) reduces cost and footprint but increases noise slightly-still within spec at 1mV_p-p.

How does the MAX881REUB-TG075 achieve such low output noise?

The MAX881REUB-TG075 achieves 1mV_p-p output noise through cascaded architecture: a charge pump generates inverted voltage at NEGOUT, then an internal N-channel linear regulator filters switching artifacts at OUT. The linear stage provides high PSRR and low output impedance (~2Ω), suppressing both charge-pump ripple and input supply noise. This dual-stage design is why MAX881REUB-TG075 is preferred over standalone charge pumps in GaAsFET bias applications.

Is the MAX881REUB-TG075 pin-compatible with other members of the MAX881R family?

Yes, all MAX881R variants-including MAX881REUB-TG075, MAX881REUB+, and MAX881REUB-T-share identical 10-pin µMAX package, pinout, and electrical interface. Differences lie in temperature grade (−40°C to +85°C for MAX881REUB-TG075), tape-and-reel packaging (TG075 = 750-piece reel), and minor parametric tolerances-not pin function or layout. Thus, MAX881REUB-TG075 can be substituted without PCB changes where temperature and reel size align.