**ADG711BRU: Key Specifications, Application Circuits, and Design Considerations for the 8 V to 5 V, Single SPDT Analog Switch**

The ADG711BRU from Analog Devices is a monolithic, CMOS-based single-pole/double-throw (SPDT) analog switch designed for precision signal routing in a wide range of applications. Engineered to operate from a single **+2.7 V to +5.5 V supply**, this switch is a cornerstone component for portable, battery-operated, and space-constrained systems where low power consumption and high performance are paramount.

**Key Specifications**

The ADG711BRU distinguishes itself through a combination of critical electrical characteristics. It features an extremely **low on-resistance (Ron) of 2.5 Ω typical**, which remains flat across the specified signal range, ensuring minimal signal attenuation and distortion. The device boasts a **fast switching time of 20 ns**, enabling its use in high-speed data acquisition and multiplexing circuits. Power consumption is exceptionally low, with a typical supply current of less than 1 µA, making it ideal for always-on or battery-sensitive designs.

A significant advantage is its **break-before-make switching action**, which prevents momentary shorting between the two signal paths during switching transitions, a crucial feature for protecting source and destination circuits. Furthermore, the ADG711BRU is TTL/CMOS compatible, allowing for direct interfacing with modern microcontrollers and logic families without requiring level-shifting circuitry.

**Application Circuits**

The versatility of the SPDT configuration allows the ADG711BRU to be deployed in numerous circuit topologies.

1. **Multiplexing/Demultiplexing:** A primary use case is routing one input signal to one of two outputs (demux) or selecting one of two input signals to a common output (mux). This is fundamental in data acquisition systems where a single analog-to-digital converter (ADC) must sample multiple sensor inputs.

2. **Programmable Gain Amplifier (PGA):** The switch can be used to select different feedback resistors in an op-amp circuit, dynamically altering the amplifier's gain. This allows a single amplifier stage to handle a wide dynamic range of input signals.

3. **Signal Gating:** The ADG711BRU can effectively connect or disconnect a signal path from a circuit block. When the switch is off, it provides **excellent isolation**, blocking the signal from passing through.

4. **Battery-Powered Systems:** In portable devices, it is used to power down unused subsystems by switching their power rails or signal lines, contributing to extended battery life.

**Critical Design Considerations**

Successful implementation of the ADG711BRU requires attention to several key factors:

* **Power Supply Sequencing:** Although the ADG711BRU is designed to be hot-swappable, it is good practice to ensure the logic control inputs do not exceed the supply voltage (Vdd). This prevents forward-biasing internal parasitic diodes, which can latch the device or cause unexpected operation.

* **Signal Range Management:** The analog signal voltage on any pin must never exceed the power supply rails (Vss and Vdd). Exceeding these limits can cause latch-up or damage the part. For bipolar signals, the device requires a dual supply or level-shifting circuitry.

* **Charge Injection:** This is a phenomenon where a small amount of charge is injected onto the analog signal path during switching, causing a voltage glitch. While the ADG711BRU has low charge injection, its effect must be evaluated in high-impedance or high-precision applications. A smaller load resistance can help minimize the resulting voltage error.

* **Layout and Bypassing:** To maintain signal integrity, especially at higher frequencies, use a compact PCB layout with short, direct traces. A **0.1 µF decoupling capacitor** placed as close as possible between the Vdd and GND pins is essential to suppress noise on the power supply line.

**ICGOOODFIND**

The ADG711BRU stands out as an **exceptional solution for low-voltage, precision switching needs**. Its robust combination of low on-resistance, fast switching speed, minuscule power consumption, and small package form factor makes it an indispensable component for designers tackling the challenges of modern portable and high-performance electronic systems.

**Keywords:** Analog Switch, SPDT, Low On-Resistance, Low Power Consumption, CMOS