Analog Devices Inc./Maxim Integrated MAX4936ACTO+T

Overview

MAX4936ACTO+T from Maxim Integrated is an octal high-voltage transmit/receive (T/R) switch IC for ultrasound imaging front-ends, featuring diode-bridge topology, 6Ω typical on-impedance, 100MHz typical -3dB bandwidth, <0.5nV/√Hz typical input voltage noise at 1.5mA bias, and integrated grass-clipping diodes. It operates in two independently enabled banks (channels 1–4 and 5–8) and supports high-voltage transmit isolation with low-voltage receive protection.

For engineers reviewing the MAX4936ACTO+T datasheet, MAX4936ACTO+T pinout, MAX4936ACTO+T application, or MAX4936ACTO+T equivalent, key selection considerations include its dual-bank enable control (EN1/EN2), programmable bias current via S0–S2, TQFN-42 package footprint, grass-clipping diode integration, and 0°C to +70°C commercial temperature range compliance.

Technical Context

The MAX4936ACTO+T implements eight independent T/R switches using diode-bridge architecture, where each channel's forward current is digitally programmed via three logic inputs (S0/S1/S2), enabling precise control of on-resistance and power dissipation. Two dedicated enable pins (EN1, EN2) provide per-bank activation for channels 1–4 and 5–8, supporting time-multiplexed beamforming.

Its receive path exhibits low-impedance during low-voltage signal acquisition and high-impedance during high-voltage transmit pulses-achieving inherent protection without external circuitry. The SWA_/SWB_/SWC_ terminal configuration enables flexible connection to LNAs and clamping networks, with internal anti-parallel diodes usable as grass clippers when SWC_ is grounded.

Key Specifications

Pinout & Package

MAX4936ACTO+T is housed in a 42-pin, 3.5mm × 9mm thin quad flat no-lead (TQFN) package with exposed thermal pad. Pin numbering follows standard TQFN convention, with pins grouped by functional bank and signal type (SWA_, SWB_, SWC_, EN1/EN2, S0–S2, VDD, GND).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transmit/receive switching applications.

Compared with MAX4936ACTO+T, MAX4937ACTO+T removes grass-clipping capability but retains identical switching performance and layout compatibility, while TX810IRHBT trades analog bias flexibility and integrated clamping for digital configurability and built-in diagnostics-making it better suited for automated test environments than clinical imaging.

Availability

MAX4936ACTO+T is available at Aetrix Electronics and suitable for medical ultrasound imaging, industrial non-destructive testing, and portable diagnostic equipment requiring stable component supply and long-term production continuity.

Supply support for MAX4936ACTO+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 industrial, medical, and communications applications.

The MAX4936ACTO+T belongs to Maxim's ultrasound front-end portfolio, engineered specifically for high-channel-count, low-noise, high-voltage T/R switching in diagnostic and therapeutic imaging systems.

FAQ

What is the function of the S0, S1, and S2 pins on the MAX4936ACTO+T?

The S0, S1, and S2 pins on the MAX4936ACTO+T are digital inputs that program the forward bias current through each diode bridge, selecting one of eight discrete current levels (1.5mA to 6.5mA). This adjustment directly controls on-impedance, power dissipation, and noise performance per channel. The MAX4936ACTO+T uses this 3-bit code to optimize trade-offs between bandwidth, linearity, and thermal load in real time.

How does the MAX4936ACTO+T protect the receive path during high-voltage transmit pulses?

The MAX4936ACTO+T protects the receive path by presenting high impedance at SWB_ terminals during high-voltage transmit events, isolating the LNA from damaging voltage transients. During low-voltage receive mode, it switches to low-impedance state with <0.5nV/√Hz noise and 100MHz bandwidth. This automatic impedance transition is inherent to the diode-bridge topology and requires no external control signals beyond EN1/EN2.

Can the MAX4936ACTO+T be used without external clamping diodes?

Yes-the MAX4936ACTO+T integrates anti-parallel diodes usable as grass-clipping diodes when SWC_ is driven with high-voltage signals or grounded. When SWC_ is tied to GND, these internal diodes act as clamps, limiting voltage swing at SWB_ to ±0.7V. This eliminates the need for external clamping components in most ultrasound probe designs, reducing layout complexity and parasitic capacitance.

What is the thermal performance of the MAX4936ACTO+T in full 8-channel operation?

In full 8-channel operation at 1.5mA bias, the MAX4936ACTO+T dissipates approximately 120mW total (15mW per channel), resulting in a junction-to-ambient temperature rise of ≤15°C with standard 2-layer FR4 PCB and the exposed thermal pad soldered to a 200mm² copper pour. The TQFN-42 package's thermal pad and low on-resistance enable reliable continuous operation in compact ultrasound modules.

Is the MAX4936ACTO+T pin-compatible with any other Maxim T/R switches?

Yes-the MAX4936ACTO+T shares identical pinout, package, and bias programming interface with the MAX4937ACTO+T. Both devices use the same 42-pin TQFN layout and support identical EN1/EN2 and S0–S2 control schemes. However, MAX4937ACTO+T omits the internal grass-clipping diodes, so SWC_ pins serve only as transmit return paths-not active clamping nodes.