50V 100mA quad analogue switch is unusually capable

Called TMUX7612 and made on a CMOS process, it will run on single rails between 4.5 and 50V, dual rails from ±4.5 to ±25V, and asymmetric rails – the company gave 37.5Vdd and -12.5Vss as an example, aimed at LCD production testing.

And at the same time, a beyond-the-rails 5V analogue switch – scroll down

Channels are rail-to-rail, fully bi-directional and on-resistance is typically 1.35Ω (+12V single-supply, 3 to 7.8V 10mA signal, 25°C). Max 25°C value is 1.65Ω (2.15Ω over -40 to +85°C, 2.45Ω over the IC’s full -40°C to +125°C).

Close to the rails, on-resistance climbs: only a little towards Vss, but with a significant step (~10Ω) very close to Vdd. “For the best linear performance, the signal range should be held within a 3V headroom below the positive and above the negative supplies,” said TI.

Current handling is high: between 65 and 470mA depending on temperature, how many channels are in use and package type – this appears to be valid with the signal anywhere within the power rails, except within 2.5V of Vdd.

25°C channel to channel matching is typically 0.1Ω, and on-resistance flatness is an impressive 0.01Ω – both of these numbers are with a 12V supply and with a 10mA signal between 3 and 7.8V. Off leakage is sub-nA except above +85°C.

Each switch has its own logic input, which are described as ‘1.8V compatible’ in the advance information version data sheet available at the time of writing. UPDATE: TI replied that Vhi and Vlow threshold voltages are 1.3V and 0.8V respectively relative to the GND pad, and therefore support 1.8V to 5.5V logic.

Up to +44V can be applied to the logic inputs, depending on voltage rails. A pull down on each biases the switches ‘off’ with no connection.

Turn on and off and in the low μs, and there is a minimum break-before-make of 125ns at all temperatures.

On-capacitance to ground is typically 37pF, or 43pF to ground from the switch ends when off. Charge injection is only 4pC.

Package choice is 4 x 4mm WQFN or 5 x 6mm TSSOP. For best performance, the exposed thermal pad should be tied to Vss.

Regarding the LCD testing application, TI said: “New generation LCD test equipment often requires simultaneous high-precision, high-voltage, multi-channel measurement capabilities and minimum channel-to-channel variation during measurement,” and explained that a 4-channel single-pole switch can be used in feedback and signal paths when measuring LCD driver current and voltage characteristics – an LCD tester circuit ins included in the data sheet.

The TMUX7612 advance information data sheet is well worth a look as TI has gone the extra mile with detailed advice on decoupling (avoid vias) and PCB layout (round track corners) amongst other morsels. It does not include logic input specs at the time of writing. The product page is here.

Diagram note: the GND pad is missing.

At the same time TI introduced TMUX2889, a double pole double throw analogue switch that handles ±5.5V signals despite running from single-rail 1.8 to 5.5V, and it can happily sit with ±5.5V on its signal inputs when powered down as well. The logic inputs can also be asserted when no power is applied without damage.

On resistance is a few hundred mΩ, and with 1mΩ on-resistance flatness, and 0.001% THD+N, it is designed for passing audio and precision analogue signals. As it can switch hundreds of mA – over 1A in certain circumstances – it can be used to switch audio outputs between speakers and headphones, for example. Automatic over-temperature protection opens the switch if over-heating occurs.

3dB bandwidth is 72MHz, broadening applications well beyond audio.