SPDT analog switch for signal routing and mux applications
The MAX4544ESA+T from Analog Devices is a single-pole double-throw (SPDT) analog switch configured as a 2:1 multiplexer/demultiplexer. It routes one of two inputs to a common output, or splits a common signal to one of two outputs. Key specs include a maximum on-resistance of 60 Ohm, channel-to-channel matching of 800 mOhm, and crosstalk of -90 dB at 1 MHz. The switch operates from a single supply of 2.7 V to 12 V. It is housed in an 8-SOIC surface-mount package and rated for the industrial temperature range of -40 °C to 85 °C. Typical applications include audio signal routing, analog multiplexing, relay replacement, and data acquisition front-ends in factory automation, telecom infrastructure, and instrumentation.
On-resistance and signal integrity
The 60 Ohm max on-resistance is moderate for a general-purpose analog switch. It introduces insertion loss that must be budgeted in the signal path, particularly for low-impedance loads. The 800 mOhm channel-to-channel matching ensures consistent attenuation when switching between two sources, which matters for gain-matched or differential signals. The -90 dB crosstalk at 1 MHz is strong — this switch will not bleed a 1 MHz signal from one channel into the other, making it suitable for audio or low-frequency precision analog multiplexing where isolation is critical.
Switching speed and charge injection
Turn-on time is 100 ns max, turn-off 75 ns max. That is fast enough for audio muting, relay replacement, and low-frequency analog muxing, but not for video or high-speed data switching. Charge injection is 1 pC — low enough that the switch will not glitch a sample-and-hold or precision ADC input beyond a few millivolts, depending on the hold capacitance. Off-leakage is 100 pA max, which is negligible for most signal-chain designs.
Supply voltage and temperature range
Single-supply operation from 2.7 V to 12 V covers 12 V industrial analog supplies. The industrial temperature grade of -40 °C to 85 °C suits outdoor telecom cabinets, factory-floor controllers, and engine-bay-adjacent electronics. The 8-SOIC package is a standard footprint, easily hand-solderable or machine-placed.