TMUX821x SPST Four-Channel Switches Texas Instruments TMUX821x SPST Four-Channel Switches are modern high voltage capable analog switches with latch-up immunity. Each device has four independently controllable 1:1, single-pole single-throw (SPST) switch channels. The devices work well with dual supplies, a single supply, or asymmetric supplies up to a maximum supply voltage of 100V. The TMUX821x devices provide consistent analog parametric performance across the entire supply voltage range. The TMUX821x family supports bidirectional analog and digital signals on the source (Sx) and drain (Dx) pins.