Electronics Weekly Electronics Design & Components Tech News
It has logic-level (1.8 to 5V) control inputs, with thresholds set by the separate 1.7 to 5.5V logic supply, and needs at least 40V across its switch supply pins (0V and +40V, or ±20V, for example) to operate. Absolute max for the controlled signal is 240Vp-p.
“Many high voltage transmitters are designed to transmit up to ±100V,” according to TI. “The extra headroom above ±100 V that TMUX9616 provides is critical for operating the high voltage transmitters in systems up to ±100 V for a few reasons.”
It went on to explain that, when ‘on’, the resistance of analogue switches typically rises as the signal voltage approaches the supply voltage. By allowing the IC to be powered by 10V outside of a ±100V signal, the switch’s resistance is almost constant, removing that source of signal distortion.
A second reason is that it gives the IC some protection against voltages on top of the 100V signal caused by stray system inductance.
Further protection against over-voltage comes from the silicon-on-insulator process from which the device is built, with an oxide layer added between pmos and nmos transistors in each switch, preventing the formation of parasitic structures that can destructively latch.
The bi-directional switches turn on in a maximum of 3μs and offer 12Ω resistance. When they turn off, isolation is -70dB at 5MHz.
Both ends of each switch are connected to ~35kΩ bleed resistors to drain the charged capacitance of external piezoelectric transducers. All 32 of them are commoned to a single package leg, intended to be connected to system 0V.
Control is via a shift register that can be clocked at up to 72MHz, and both input and output connections of the register are bought out so that multiple ICs can be daisy-chained into one long shift register – one of the use-cases is for multiple copies of this IC to be integrated with a piezo-electric transducer array in a scanning head, connected via a cable to a separate control unit, with the shift register reducing connections down the cable to a minimum.
A common ‘load’ connection means that all switches can be updated from the shift register simultaeniously, via a latch.
Operation is over -40 to 125°C and packaging is 9 x9mm LQFP.
Applications are foreseen with piezoelectric transducers in medical ultrasound imaging, non-destructive metal flaw detection, ultrasonic flow transmitters, printers and optical mems modules.
The TMUX9616 product page can be found here
TI is clearly going through a creative patch, as this is just one of a string of unique ICs that it has revealed over the last few months. Other are: its opto-free ‘opto-isolator‘, an accurate isolated Hall-based current sensor, and two more analogue switches which are nothing like each other nor today’s …9616.
