Low-Resistance Switch Design Analysis Solution

^{September 20, 2025 News — With increasing demands for signal switching reliability in automotive electronics and portable devices, high-precision analog switch chips are becoming critical components in signal chain design. The 74LVC4066BQ-Q100X quad single-pole single-throw (SPST) analog switch, with its wide voltage range of 1.4V to 4.5V and low on-resistance of 6Ω, provides a reliable solution for in-vehicle infotainment systems, sensor signal routing, and audio signal processing.}

I. Core Technical Features

^{The 74LVC4066BQ-Q100X is an AEC-Q100 certified automotive-grade quad single-pole single-throw (SPST) analog switch featuring 6Ω low on-resistance and a wide operating voltage range of 1.4V to 4.5V. The device adopts a break-before-make switching architecture, supports bidirectional signal transmission, and has an ultra-low static current of 0.1μA. Housed in a compact DHVQFN14 package, it meets the high-reliability signal switching requirements of automotive electronics and industrial applications.}

^{II. Functional Diagram Description}

 ^{Overall Structure}

^{The chip contains 4 independent bidirectional analog switches (SW1 to SW4).}

^{Each switch is controlled by a dedicated control input pin.}

^{Supports bidirectional signal transmission (input/output interchangeable).}

^{The 74LVC4066BQ-Q100X is an integrated circuit containing four independent analog switches. Each switch can bidirectionally transmit analog or digital signals and is controlled by a dedicated digital control pin (INx).}

^{Core Functional Description:
The chip's functionality can be understood as four independent single-pole single-throw (SPST) switches. Each switch has two bidirectional ports (e.g., IO1A and IO1B) that are interchangeable, and one control terminal (IN1).}

^{When the control pin (INx) is high: The corresponding switch closes, allowing signals to flow bidirectionally between its two ports (IOxA and IOxB).}

^{When the control pin (INx) is low: The corresponding switch opens, presenting a high-impedance state between the two ports, blocking signal transmission.}

^{Pin Function Brief Description:}

^{Power (VCC, Pin 14) and Ground (GND, Pin 7) supply power to the entire chip.}

^{The remaining pins are divided into four groups, each controlling one switch:}

^{IN1 (Pin 1) controls the switch connected to IO1A (Pin 2) and IO1B (Pin 3).}

^{IN2 (Pin 4) controls the switch connected to IO2A (Pin 5) and IO2B (Pin 6).}

^{IN3 (Pin 10) controls the switch connected to IO3A (Pin 9) and IO3B (Pin 8).}

^{IN4 (Pin 13) controls the switch connected to IO4A (Pin 12) and IO4B (Pin 11).}

III. Pinout Diagram Description

^{The title "Pinning information" indicates that the core purpose is to introduce the device's pin configuration, including pin numbers, functional definitions, and pin layout under different packages.}

^{Left Section (Logic Symbols):}

^{Function: The chip contains 4 independent analog switches.}

^{Pins: Each switch includes:}

^{1 control terminal (1E, 2E, etc.). The switch conducts when the control signal is high.}

^{2 bidirectional signal terminals (1Y/1Z, etc.), allowing bidirectional signal flow.}

^{Right Section (Physical Package):}

^{Appearance: The physical chip is in an SO14 package.}

^{Key Point: The notch in the diagram indicates the position of Pin 1, and pin numbers follow a counterclockwise sequence.}

^{Important Note: The text at the bottom clarifies that the thermal pad beneath the chip is not a ground connection and is not mandatory to solder (though it is generally recommended for better heat dissipation).}

^{Core Summary:
The left diagram explains what the chip does (4 switches), while the right diagram shows how to connect it (actual pin order). This serves as a bridge connecting the circuit schematic to the physical chip.}

^{IV. Test Circuit Diagram Analysis}

^{Test Circuit 1: OFF-state Leakage Current Measurement}

^{Purpose: Measure the tiny leakage current through the switch channel when the switch is off.}

^Description:

^{V_I is set to V_CC or GND}

^{V_O is set to GND or V_CC (creating a voltage difference with V_I)}

^{Control pin nE is set to low level to ensure the switch is in the off state}

^{The current measured through the ammeter at this time is the OFF-state leakage current (I_off)}

^{Test Circuit 2: ON-state Leakage Current Measurement
Purpose: Measure the tiny leakage current flowing from the signal channel to the power supply or ground when the switch is closed.}

IV. Test circuit for measuring ON resistance

1.Test Circuit Diagram

^{2.Components and Parameter Description}

^{DUT (Device Under Test): One switch in the 74LVC4066BQ-Q100X (e.g., nY-nZ)}

^{V_st: Control Voltage (typically V_CC, such as 3.3V or 5V), used to enable the switch (nE)}

^{V_i: Input Voltage (recommended to use an adjustable DC source, e.g., 0~5V)}

^{I_SW: Series Ammeter (or indirect measurement using a precision resistor + voltmeter)}

^{GND: Common Ground}

^{3.Test Steps}

^{Set V_CC = 5V (or required operating voltage)}

^{Set V_st = V_CC to enable the switch}

^{Gradually increase V_i from 0V to V_CC}

^{Measure the switch current (I_SW) and switch voltage drop (Switch Voltage = V_i - V_nZ)}

^{Calculate ON Resistance = Switch Voltage / Switch Current}

^{4.Precautions}

^{Use four-wire measurement (Kelvin connection) to reduce lead resistance errors}

^{Ensure current does not exceed the chip's maximum rating (refer to datasheet)}

^{When testing multiple switches, enable and measure each separately}

V. Charge Injection Test Circuit

^{Test Principle
Charge injection is a critical parameter for analog switches, referring to the amount of charge injected into the analog signal path due to parasitic capacitance within the switch when the control signal (nE) toggles.}

^{Calculation Formula:}

^{Qinj​=ΔVo​×Ct​}

^{Qinj​ =Injected Charge Amount (Coulombs)
ΔVo​ =Output Voltage Variation (Volts)}

^{Ct​ =Test Capacitor (0.1 nF)}

^{Circuit Schematic Diagram}

^{Test Steps}

^{Circuit Setup:}

^{Connect the test circuit as shown in the diagram above.}

^{Set Rgen ​to the specified value (according to datasheet requirements)}

^{Set Vgen to an appropriate voltage (typically half of the supply voltage)}

^{Test Procedure:}

^{Switch the logic input (nE) from the off state to the on state (or vice versa)}

^{Use an oscilloscope or high-precision voltmeter to measure the output voltage variation Vo​ of ΔVo}

^{Record the voltage difference before and after the switch toggles.}

^{Calculate Charge Injection:
Using the formula Qinj​=ΔVo​×Ct Calculate Charge Injection Amount}

^{Results are typically reported in picocoulombs (pC)}

^Precautions

^{Use low-noise and high-precision measurement equipment.
Ensure a stable test environment to reduce external interference.
Take the average of multiple measurements to improve accuracy.
Refer to the specific test conditions and limitations in the data sheet.}

^{Typical parameters (refer to the data sheet)Test capacitance}

^{ypical parameters (refer to the data sheet)Test capacitance Ct​：0.1 nF}

^{Load Resistance Rc​：1 MΩ}

^{Source Resistance Rgen​：Set according to specific test conditions}

^{For procurement or further product information, please contact:86-0775-13434437778,}

^{​Or visit the official website:https://mao.ecer.com/test/icsmodules.com/,Visit the ECER product page for details: [链接]}