ADG731BSUZ is a single-pole eight-throw (SP8T) analog switch by ADI

The ADG731BSUZ is a high-performance, single-pole, eight-throw (SP8T) analog switch manufactured by Analog Devices (ADI). It belongs to ADI’s family of low-voltage, low-on-resistance (Rₒₙ) analog switches, designed to route analog or digital signals between a common input/output (I/O) port and one of eight selectable channels. Its compact size, low power consumption, and robust signal integrity make it ideal for signal routing in space-constrained, precision electronics.

The ADG731BSUZ is engineered to address key challenges in signal routing, including low insertion loss, minimal signal distortion, and flexible control. Its key functional features are detailed below:

• Switch Topology: Operates as a single-pole, eight-throw (SP8T) switch, meaning it connects one common terminal (COM) to any of eight independent channel terminals (CH0–CH7). It supports bidirectional signal flow, allowing signals to be routed from COM to a channel or from a channel to COM.
• Dual Signal Compatibility: Seamlessly handles both analog signals (e.g., sensor outputs, audio signals) and digital signals (e.g., control signals, data streams), making it versatile across mixed-signal systems.

• Ultra-Low Rₒₙ: Features a typical on-resistance of 0.8 Ω (at 3.3 V supply) and a maximum of 1.5 Ω. Low Rₒₙ minimizes insertion loss (signal attenuation) when routing signals, critical for preserving signal integrity in precision applications (e.g., sensor data acquisition).
• Flat Rₒₙ Profile: The on-resistance remains stable across the entire signal voltage range (from near ground to the supply voltage). This flatness eliminates signal distortion caused by variable resistance, ensuring linear signal transmission—especially important for high-amplitude analog signals.

• Supply Voltage Flexibility: Operates from a single low supply voltage of 1.8 V to 5.5 V, compatible with modern low-power systems (e.g., battery-powered IoT devices) and standard 3.3 V/5 V industrial systems.
• Signal Voltage Range: Supports signal voltages from -0.3 V to VDD + 0.3 V (with VDD being the supply voltage). This wide range allows it to handle signals slightly beyond the supply rails, adding robustness to system design.

• Minimal Quiescent Current: Draws a typical quiescent current of 0.1 µA (at 3.3 V), making it ideal for power-constrained applications such as portable sensors, wearables, or battery-operated test equipment. Even in active switching mode, power consumption remains negligible.

• Serial Control Interface: Uses a 3-bit serial select input (S0, S1, S2) to choose the active channel (CH0–CH7). A separate chip enable (EN) pin allows the switch to be disabled (all channels disconnected) for power-saving or system safety.
• Built-In Protection: Includes electrostatic discharge (ESD) protection (up to ±2 kV per IEC 61000-4-2) on all pins, preventing damage from static during handling or operation. It also features break-before-make switching behavior—disconnecting the previously active channel before connecting the new one—to avoid signal shorting between channels.

The ADG731BSUZ’s combination of low Rₒₙ, wide voltage compatibility, and compact size makes it a critical component in systems requiring efficient, high-integrity signal routing. Below are its primary application areas:

• Use Cases: Precision sensor multiplexing (e.g., temperature, pressure, or strain sensors), multi-channel ADC/DAC signal routing.
• Role: Enables a single ADC to sample signals from up to eight different sensors, reducing the number of ADCs needed and lowering system cost. For example, in a industrial DAS monitoring multiple machine sensors, the ADG731BSUZ routes each sensor’s analog output to a shared ADC, ensuring minimal signal loss thanks to its low Rₒₙ.

• Use Cases: Multi-channel oscilloscopes, signal generators, digital multimeters (DMMs), and automated test equipment (ATE).
• Role: Switches test signals between different measurement points or instruments. For instance, a DMM uses the ADG731BSUZ to alternate between measuring voltages from eight different test points, maintaining accuracy via the switch’s flat Rₒₙ profile.

• Use Cases: PLC (Programmable Logic Controller) I/O expansion, industrial sensor networks, process control systems.
• Role: Expands the number of analog/digital inputs a PLC can handle by multiplexing signals from multiple sensors (e.g., flow meters, level sensors) to a limited number of PLC input ports. Its wide supply voltage range (1.8 V–5.5 V) ensures compatibility with industrial 24 V systems via level-shifted control signals.

• Use Cases: Patient monitoring devices (e.g., ECG machines, blood pressure monitors), diagnostic equipment (e.g., glucose meters with multi-sample testing).
• Role: Routes low-amplitude biological signals (e.g., ECG waveforms) between multiple sensors and a signal conditioning circuit. The switch’s low noise and low Rₒₙ prevent distortion of sensitive medical signals, ensuring accurate readings.

• Use Cases: Portable audio devices (e.g., headphone jack signal switching), IoT sensors (e.g., multi-sensor modules for environmental monitoring), wearables (e.g., fitness trackers with heart rate, temperature, and motion sensors).
• Role: Multiplexes signals from multiple on-board sensors to a single microcontroller (MCU) or ADC, saving board space and power. For example, a smart thermostat uses the ADG731BSUZ to switch between temperature, humidity, and occupancy sensor signals, optimizing power use with its low quiescent current.

• Use Cases: In-vehicle sensor networks (e.g., tire pressure monitoring systems, engine temperature sensors), infotainment systems (e.g., audio signal routing).
• Role: Routes signals from distributed automotive sensors to the ECU (Engine Control Unit) or infotainment MCU. Its ESD protection and wide operating temperature range (-40°C to +85°C) ensure reliability in harsh automotive environments.

The table below highlights critical electrical and mechanical specifications of the ADG731BSUZ, contextualizing its performance:

In summary, the ADG731BSUZ is a versatile, high-performance SP8T analog switch that excels in low-resistance signal routing, low power consumption, and wide compatibility. Its design makes it a go-to solution for multiplexing in data acquisition, test equipment, industrial, medical, and consumer electronics—where space, power, and signal integrity are critical.