The SMX-3276, 3U PXIe high-density multiplexer modules designed for scanning of multiple points to a common bus, in 1, 2, or 4-wire configurations. The SMX-3276 consists of two individual (1 x 76) 1-wire, or two (1x38) 2-wire multiplexers or one 1x76 2-wire mux, that can be interconnected under program control (via bussing relays) to configure larger multiplexers as required. This eliminates external wiring and helps reduce unterminated stubs.
The SMX-3276 has an internal residual voltage discharge relays which can be enabled to momentarily short out the measurement path when changing from one input channel to the next. This dissipates any voltage held by the wiring and instrument input capacitance and protects sensitive devices, such as CMOS circuits, from residual voltages caused by previous high-voltage measurements. This feature can also be disabled in low-voltage applications where maximum throughput speed is important.
The SMX-3276 incorporates extensive signal shielding and exposes shield pins on the front panel connector for tying to the cable shield. This preserves signal integrity throughout the signal path by maintaining the signals at the same reference level as the UUT. In addition, meticulous signal routing is done for impedance matching, signal shielding and cross talk reduction, allowing the SMX-3276 to achieve best in class switching performance with a bandwidth of > 30 MHz. This performance allows the card to be used with high frequency signals, and signals that have fast rise times and narrow pulse widths.