Analog Devices Inc./Maxim Integrated MAX852ESA+T

Overview

MAX852ESA+T from Maxim Integrated is a low-noise, inverting, regulated charge-pump DC-DC converter optimized for GaAsFET biasing in cellular transmitter amplifiers. It delivers a fixed -4.1V output at up to 5mA with 2mV_p-p ripple, operates from 4.5V to 10V input, and features external clock synchronization via pin 4 (OSC). Its SO-8 package supports compact RF front-end integration.

For engineers reviewing the MAX852ESA+T datasheet, MAX852ESA+T pinout, MAX852ESA+T application, or MAX852ESA+T equivalent, key selection criteria include its synchronized 100kHz switching frequency, logic-level shutdown (<1µA), -40°C to +85°C industrial temperature range, and compatibility with GaAsFET V_GG bias networks requiring ultra-low noise and stable negative regulation.

Technical Context

The MAX852ESA+T implements a two-stage architecture: a capacitive charge pump inverts VIN to generate unregulated negative voltage at NEGOUT, followed by an internal N-channel linear regulator that stabilizes and filters the output at OUT. Its OSC pin accepts an external 80–120kHz square wave (50% duty cycle) to synchronize switching and avoid interference with sensitive RF bands.

Unlike the MAX850/MAX851, the MAX852ESA+T replaces SHDN with OSC functionality on pin 4; FB remains grounded for fixed -4.1V operation. The linear regulator provides >60dB AC rejection of supply noise and maintains load regulation of ±3mV/mA across 0–5mA output current.

Key Specifications

Pinout & Package

MAX852ESA+T is housed in an 8-pin SO (Small Outline) plastic package (3.9mm × 4.9mm, 1.75mm height), RoHS-compliant and rated for surface-mount reflow.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar negative charge-pump regulator applications.

Compared with MAX850ESA+T, the MAX852ESA+T trades pin-compatible shutdown for EMI-controllable synchronization-critical in dense RF layouts. Versus MAX853ESA+T, it sacrifices output flexibility and sub-mV ripple for deterministic fixed-voltage operation and simplified bias network design.

Availability

MAX852ESA+T is available at Aetrix Electronics and suitable for cellular phone RF modules, GaAsFET bias networks, and portable LCD contrast control requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX852ESA+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 high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and consumer applications.

The MAX850–MAX853 family was designed specifically to replace discrete charge-pump + LDO solutions in GaAsFET bias circuits, integrating inversion, regulation, and noise filtering into a single 8-pin SO package for cellular handset power amplifiers.

FAQ

What is the primary function of the MAX852ESA+T in RF power amplifier designs?

The MAX852ESA+T serves as a dedicated negative bias supply for GaAsFET gate terminals in cellular transmitter amplifiers. It generates a stable -4.1V output with 2mV_p-p ripple from a 4.5V–10V input, using an integrated charge pump and linear regulator. Its OSC pin enables external clock synchronization-critical for minimizing EMI in densely packed RF front-ends. The MAX852ESA+T ensures consistent FET transconductance and prevents AM-to-PM distortion during high-power transmit bursts.

Can the MAX852ESA+T be used with a 3.3V input supply?

No, the MAX852ESA+T requires a minimum input voltage of 4.5V to maintain regulation at its fixed -4.1V output. At inputs below 4.5V, the device may not sustain 5mA output current or specified ripple performance. This limitation arises from the combined voltage drop across the charge pump and linear regulator stages. For 3.3V systems, alternative solutions such as the MAX863 or MAX889 should be evaluated-not the MAX852ESA+T.

How does the OSC pin on the MAX852ESA+T improve system-level EMI performance?

The OSC pin on the MAX852ESA+T accepts an external 80–120kHz square wave to precisely control switching timing, preventing random beat frequencies between the charge pump and other system clocks (e.g., baseband processors or RF synthesizers). This deterministic synchronization reduces broadband conducted and radiated emissions by up to 15dB in typical handset layouts. Unlike free-running oscillators, the MAX852ESA+T's OSC input eliminates spectral spreading-making it essential for passing FCC/CE RF immunity tests.

What is the recommended capacitor configuration for optimal noise performance with the MAX852ESA+T?

For optimal noise performance, use 1µF, ≤0.8Ω ESR ceramic or tantalum capacitors for C1, C2, and C3, and a 10µF, ≤0.2Ω ESR capacitor for C4 (output filter). C1 and C2 form the flying capacitor pair; their low ESR minimizes charge-pump dropout and ripple injection. C4 directly filters the regulated OUT node-its low ESR and value suppress residual 100kHz harmonics. Avoid electrolytic capacitors; all must be surface-mount and placed within 3mm of the MAX852ESA+T pins.

Is the MAX852ESA+T pin-compatible with other members of the MAX850–MAX853 family?

No-the MAX852ESA+T is not pin-compatible with MAX850ESA+T or MAX851ESA+T due to functional reassignment of pin 4: MAX852ESA+T uses OSC, while MAX850/MAX851 use SHDN. Pin 4 on MAX852ESA+T must receive a clock signal, not a logic level. Swapping packages without redesigning the control interface will cause malfunction. Only MAX852 variants (e.g., MAX852ISA+T) share identical pinout and function mapping with the MAX852ESA+T.