APPLICATION NOTE
Multiplexers and Signal Switches Glossary
1 About This Multiplexers and Signal Switches Glossary
This glossary provides a brief overview and introduction to the terminology, features, and parameters for TI'smultiplexers and signal switches for analog signal chain applications. The entire signal switches and multiplexers portfolio can be found at www.ti.com/switches.
For components used to manage power rails and for applications that require a switch current of greater than 500mA, TI offers a power switch and power multiplexer portfolio which can each be found at www.ti.com/powerswitch.
2 Introduction to Multiplexers and Signal Switches
| Signal switch — An integrated circuit (IC) used for connecting and disconnecting an electrical circuit. For more information, see the Switches and muxes: What are switches & multiplexers? training video from TI Precision Labs. |  Figure 2-1 Ideal 1:1 SPST Switch |
| Multiplexer (Mux) — An integrated circuit that connects a selected signal path to a single line. |  Figure 2-2 Ideal 4:1 Mux |
Analog switches and multiplexers — These devices are used for switching and multiplexing analog and digital signals up to 500 mA in applications such as:
| |
| Protocol-specific switches and multiplexers — These devices are defined to support specific protocol applications such as USB, HDMI, LAN, MIPI, audio, memory and so forth. | |
| Precision — These devices minimize offset error and signal distortion in a high-accuracy measurement system. | |
| Protection — These devices isolate I/O signal paths and protect the system using powered-off, overvoltage and undershoot protection. | |
| Low voltage — These devices support I/O signals ≤ ±25 V | |
| Mid voltage — These devices support I/O signals > ±25 V | |
| Configuration — Defines the number of signals that can be selected. Table 2-1 shows the typical configurations. | |
| Channel — Defines the number of configurations (circuits) in a single device. Table 2-1 shows the 1- and 2- channel configurations, but the number of channels may exceed 2. | |
Table 2-1 Configurations and Channels
| 1-Channel | 2-Channel | ||
|---|---|---|---|
| Configuration | 1:1 |  |  |
| 2:1 |  |  | |
| 3:1 |  | ||
| 4:1 |  |  | |
| Configuration | 8:1 |  |  |
| Configuration | 16:1 | N/A |
3 Operation of Multiplexers and Signal Switches
| Absolute maximum ratings — These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under the Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Stresses beyond those listed under the Absolute Maximum Rating may cause permanent damage to the device. | |
| Recommended operating conditions — The operating conditions for which the device has been characterized. | |
| Single power supply — Device with only positive power supply pins with reference to ground. The voltage applied is labeled as VDD, VCC, V+ and so forth. Dual power supply — Device with positive and negative supply pins with reference to ground. Voltage applied at the positive pin is labeled as VDD, VCC, V+, and so forth, and at the negative pin is labeled as VSS, VEE, V-, and so forth. |  Figure 3-1 Single and Dual Supply |
Switch control signal levels (VIH, VIL) — Voltage levels required on the control pins (EN, SEL, IN, and so forth) required for the switch to change the internal signal path.
|  Figure 3-2 Switch Control Signal Levels |
| Rail-to-rail — A common term meaning that a device will support VI/O voltage range between the most positive and most negative power supply rails. |  Figure 3-3 Rail-to-Rail |
| Input/Output voltage beyond supply – The switch can support voltage range beyond the supply rail to VI/O(MAX)as indicated by the recommended operating conditions. |  Figure 3-4 I/O Voltage Beyond Supply |
| Bidirectional signal path – The switch conducts equally well from source (S) to drain (D) or from drain (D) to source (S). Each channel has very similar characteristics in both directions and supports both analog and digital signals. TI analog switches and multiplexers are typically bidirectional. See the Switches and muxes: Are switches & multiplexers bidirectional? training video from TI Precision Labs. |  Figure 3-5 Bidirectional Signal Path |
4 Additional Features
| 1.8-V Control Logic – Switches with this feature have a built-in voltage translator to prevent voltage mismatch between the supply rail and the control logic. VIH and VIL levels are compatible with the 1.8-V logic levels at any voltage supply. See the Simplifying Design With 1.8 V logic MUXes and Switches Tech Note for more information. | |
| Fail-Safe Logic – Ensures the switch stays off and the voltage on the logic pin (VSEL) does not back-power VDD when VSEL is greater than VDD. See the Switches and muxes: What is fail-safe logic? training video from TI Precision Labs. |  Figure 4-1 Fail-Safe Logic |
| Injection Current Control — Devices with Injection Current Control shunt injected current on disabled (high-Z) signal pathways to ground. This mitigates error on the active signal pathway as the injected current is going into the ground rail and not the power rail. See the Switches and muxes: Prevent crosstalk with injection current control training video from TI Precision Labs. |  Figure 4-2 Injection Current Control |
| Integrated Pulldown Resistor on Logic Pin – Internal weak pulldown resistors to GND to ensure the logic pins are not floating. |  Figure 4-3 Integrated Pulldown Resistor on Logic Pin |
| Latch-Up Immunity – Devices that are latch-up immune can use various methods to achieve latch up immunity such as being built in a Silicon On Insulator (SOI) process, employing the use of guard rings, or a mix between different methods. When these measures are taken Electrical Overstress, Electrically Fast Transients, and Injected Currents will not cause latch up in these devices. See the Switches and muxes: What is latch-up immunity? training video from TI Precision Labs. |  Figure 4-4 Latch-Up Immunity With SOI Process |
Overvoltage Protection – When the input voltage VI/O exceeds the defined threshold voltage, VTH or VT, the switch enters the high impedance state, isolates signal path, and protects downstream components. Depending on device the threshold can determined in 1 of 3 ways.
| Figure 4-5 Overvoltage Protection |
Undervoltage Protection – When the input voltage VI/O falls below the defined threshold voltage, VTH, the switch enters the high impedance state, isolates signal path, and protects downstream components. Depending on device the threshold can determined in 1 of 2 ways.
| Figure 4-6 Undervoltage Protection |
| Fault Flag Indicators – On some devices there is a fault flag pin that will change states (typically from high to low) when a fault is present on the device and will return to its default state when the fault is cleared. | Figure 4-7 Fault Flag Indicators |
Drain Response Output – On some protection switches/multiplexers the output response of a device during a fault condition can be set to either clamp to supply or open circuit the output. | Figure 4-8 Drain Response Output |
| Powered-Off Protection – Protects switch and isolates signal path when signals are present at the I/O pins and VDD = 0 V. See the Switches and muxes: Simplify power sequencing with powered-off protection training video from TI Precision Labsand the Eliminate Power Sequencing With Powered-off Protection Signal Switches Tech Note for more information. |  Figure 4-9 Powered-Off Protection |
