Analog Devices Inc./Maxim Integrated MAX2235EUP+T

Overview

MAX2235EUP+T from Analog Devices is a silicon RF power amplifier optimized for 800–1000MHz constant-envelope systems, delivering +30dBm (1W) output at +3.6V with 47% power-added efficiency and 37dB gain-control range. It integrates autoramping, shutdown mode (<1μA), and direct OOK capability-designed for battery-powered 900MHz ISM-band transmitters in pagers and analog cellular handsets.

For engineers reviewing the MAX2235EUP+T datasheet, MAX2235EUP+T pinout, MAX2235EUP+T application, or MAX2235EUP+T equivalent, key selection criteria include its thermally enhanced 20-pin TSSOP-EP package, 836MHz-optimized matching, ramp capacitor-controlled turn-on/turn-off timing, and dual-mode bias control (SHDN/GC) enabling precise battery-life management in portable RF front-ends.

Technical Context

The MAX2235EUP+T implements a three-stage architecture: Class-A variable-gain input stage (37dB control range), Class-C driver stage, and Class-E power stage delivering 30dBm into 50Ω. Gain is monotonic with GC voltage (0.6V–2.3V), and bias sequencing is managed via SHDN and GC pins to support standby, active, and shutdown modes.

Its autoramping function uses an external capacitor between RAMP and REF (internally biased at 1.9V) to shape RF envelope rise/fall as a raised cosine-enabling clean OOK modulation without VCO pulling or intersymbol interference. Input and interstage matching networks are integrated on-die to maintain performance across 800–1000MHz.

Key Specifications

Pinout & Package

The MAX2235EUP+T is housed in a thermally enhanced 20-pin TSSOP-EP (exposed pad) package. The underside metal slug must be soldered directly to the PCB ground plane for optimal thermal dissipation and RF performance. Pin 13, 14, 17, 18, and the slug are all GND connections dedicated to the power stage.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF power amplifier applications.

Compared with SX1231IMLTRT and RFM22BP, the MAX2235EUP+T provides higher output power (+30dBm vs. ≤+20dBm), true analog gain control (not digital register-based), and hardware-ramped OOK-making it uniquely suited for legacy 900MHz constant-envelope systems where spectral purity and battery efficiency are co-critical.

Availability

MAX2235EUP+T is available at Aetrix Electronics and suitable for two-way pagers, analog cellular handsets, 900MHz ISM-band data links, and microcellular GSM power-class applications requiring stable component supply across extended product lifecycles.

Supply support for MAX2235EUP+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

Analog Devices is a global leader in high-performance analog, mixed-signal, and RF ICs, serving industrial, communications, automotive, and aerospace markets with precision signal processing solutions.

The MAX2235EUP+T belongs to Analog Devices' RF power amplifier product line, engineered specifically for battery-efficient, spectrally clean transmission in 800–1000MHz constant-envelope communication systems.

FAQ

What is the maximum output power of the MAX2235EUP+T and at what supply voltage is it achieved?

The MAX2235EUP+T delivers +30dBm (1W) typical output power at +3.6V supply voltage, as verified under standard test conditions (fRFIN = 836MHz, TA = +25°C). At +2.7V, output drops to +28dBm-enabling compatibility with single-cell Li-Ion batteries while maintaining usable RF output. This performance is specified in the AC Electrical Characteristics table of the official MAX2235EUP+T datasheet.

How does the autoramping feature of the MAX2235EUP+T reduce spectral splatter in OOK applications?

The MAX2235EUP+T's autoramping shapes the RF envelope during turn-on and turn-off using a raised cosine profile, controlled by an external capacitor between RAMP and REF pins. This minimizes transient noise and harmonic distortion-reducing spectral splatter that would otherwise interfere with adjacent channels. Measured nonharmonic spurious output remains below -60dBc even under 6:1 load mismatch, confirming its suitability for strict OOK modulation standards.

What thermal management requirements apply to the MAX2235EUP+T package?

The MAX2235EUP+T uses a 20-pin TSSOP-EP package with an exposed metal slug that must be soldered directly to the PCB ground plane. All vias under the slug should be filled, and pins 13, 14, 17, and 18 must be connected to the slug via short traces. This configuration enables 6.4W continuous power dissipation at +70°C ambient and ensures junction temperature stays below +150°C under full +30dBm operation.

Can the MAX2235EUP+T operate from a 2.7V supply, and what performance trade-offs occur?

Yes, the MAX2235EUP+T operates over +2.7V to +5.5V. At +2.7V, output power is +28dBm (630mW) with 47% PAE maintained, but supply current increases to ~610mA at +30dBm-equivalent drive level. The device remains fully functional across the full -40°C to +85°C temperature range, making it viable for low-voltage battery systems-though peak output is reduced versus +3.6V operation.

What is the function of the GC pin on the MAX2235EUP+T, and how is it used in closed-loop power control?

The GC (Gain-Control) pin on the MAX2235EUP+T accepts an analog voltage (0.6V–2.3V) to set output power with monotonic dB/V response-verified across temperature. In closed-loop systems, a feedback detector monitors RFOUT and adjusts GC voltage via DAC or op-amp to maintain constant output despite supply or temperature drift. This replaces external attenuators and enables real-time power adaptation in dynamic RF environments.