Input Multiplexer

Within an ADC Array, the Input Multiplexer is a critical switching component that manages multiple analog input channels. It sequentially or selectively connects different input sources to a single analog-to-digital converter (ADC) or a specific ADC within an array, enabling efficient signal acquisition from multiple sensors or sources while minimizing hardware requirements. The multiplexer uses solid-state switches (typically MOSFET-based) or relay-based switching controlled by digital selection signals. When a specific channel is selected, the corresponding switch closes, connecting that analog input to the common output line that feeds into the ADC. Channel selection is controlled by address lines or serial communication protocols, allowing precise timing and sequencing of signal acquisition across multiple inputs. Typical parameters include 8–16 channels, input voltage range 0–5 V, on-resistance 50–100 Ω, leakage current 0.1–1 nA, bandwidth 100–500 MHz, switching time 50–200 ns, supply voltage 2.7–5.5 V, operating temperature range -40–85 °C, ESD protection 2–4 kV (IEC 61000-4-2), package types SOIC-16 and TSSOP-16, surface mount (SMD), and RoHS compliance (2011/65/EU). Materials typically include silicon for integrated circuits, copper for traces and contacts, and plastic or ceramic for packaging. These values are reference ranges; verify model-specific specifications with the manufacturer. The multiplexer is essential in multi-sensor data acquisition systems, test equipment, and industrial monitoring. It reduces the number of ADCs needed, lowering cost and board space. However, it introduces on-resistance and leakage that can affect signal integrity, so careful selection is required. The device operates within specified voltage and temperature limits; exceeding them may cause damage. Proper ESD protection is necessary during handling and installation. The multiplexer is not a standalone measurement device; it must be integrated with an ADC and control logic. It does not provide amplification or filtering; these functions are external. The switching time limits the maximum sampling rate. The on-resistance varies with input voltage and temperature, so it must be considered in precision applications. The leakage current is critical for high-impedance sources. The bandwidth determines the maximum frequency of the input signal that can be switched without significant attenuation. The supply voltage must be within the specified range for reliable operation. The package type and mounting are important for PCB design. RoHS compliance indicates lead-free and hazardous substance-free construction. Always consult the datasheet and confirm compliance with applicable standards.

The Input Multiplexer operates using solid-state switches (typically MOSFET-based) or relay-based switching controlled by digital selection signals. When a specific channel is selected, the corresponding switch closes, connecting that analog input to the common output line that feeds into the ADC. Channel selection is controlled by address lines or serial communication protocols, allowing precise timing and sequencing of signal acquisition across multiple inputs. The switching action is fast, with typical switching times of 50–200 ns, enabling high-speed sampling. The on-resistance of the switches (50–100 Ω) introduces some signal attenuation, which must be accounted for in the system design. The multiplexer is designed to handle input voltages within 0–5 V and operates from a supply voltage of 2.7–5.5 V. It is essential to stay within these limits to avoid damage. The device also features ESD protection up to 4 kV (HBM) to withstand electrostatic discharges during handling.