X9511数字电位器芯片

数字电位器芯片X9511的应用扩展杨善迎莱芜职业技术学院引言数字电位器在我国还是近几年出现的新型器件，该器件一出现，就以其调节准确方便，使用寿命长，受物理环境影响小，性能稳定等特点，而被广大电子工程技术人员所接受。

但数字电位器本身能够承受的电流和电压有限，因而需要扩展，同时在实际应用中，数字电位器的阻值范围及分辨率也需要扩展，本文介绍的扩展方案适用于各种信号的数字电位器。

数字电位器简介数字电位器是可用数字信号控制电位器滑动端位置的新型器件，一般分按钮控制和串行信号控制两种，X9511就是XICOR公司生产的理想按键式数字电位器，它内含31个串联电阻阵列和32个轴头。

轴头位置由两个按键控制，并且可以被存储在一个E2PROM存储器中，以供下一次通电时重新调用，并自动恢复轴头位置，X9511有1kΩ和10kΩ的X9511Z和X9511W两种规格。

X9511内部由计数器、存储器、译码器、模拟开关和电阻阵列等电路组成，其中计数器是5位可逆计数器，可用于对控制信号PU（或PD）进行加（或减）计数，计数器的计数值可以在ASE 的控制下存储非易失性存储器中。

计数器的数值经过32选1译码器译码后可用于控制模拟开关，32个模拟开关相当于电位器的32个轴头，电阻阵列由采用集成电路工艺制作的31个串联一起的电阻构成，电阻两端分别连接模拟开关的一端，而模拟开关的另一端连接在一起构成数字电位器的滑动端（VW），译码器的输出端可控制模拟开关的通断，从而实现滑动轴头位置的变化。

X9511的计数器电路具有以下特点：◆输入端具有内部上拉电阻和消除开关抖动的抗扰电路，当输入脉冲宽度小于40ms时，计数器将其视为干扰信号而不进行计数；◆PU和PD引脚可直接连接一个按钮开关到地，当按钮按下时，在PU或PD端产生一个负脉冲，使计数器进行加1（按PU键）或减1（按PD键）计数；◆能将计数值存储在非易失性存储器E2PROM中长期保存；◆能在上电时自动将E2PROM中的数据恢复到计数器中；◆当计数器计数到最大值“31”时，PU按键失效，而计数到最小值“0”时，PD按键失效，从而避免循环计数，保证电位器调到最大位置时不会跳到零位，或从零位跳到最大位置。

数字电位器是一种可编程电子器件，它具有与模拟电位器类似的滑动端，可以通过编程改变其电阻值。

数字电位器通常由数字芯片和机械结构组成，可以实现高精度的电阻调节，广泛应用于音频、通信、测量和控制等领域。

以下是一些常用的数字电位器芯片介绍：1. I2C数字电位器：该芯片采用I2C总线接口，具有低功耗、高精度、高稳定性和易用性等特点。

它可以调节电压范围为0V至5V，调节范围为10kΩ至1MΩ，精度为±1%或±0.5%。

该芯片适用于各种需要调节电压和阻抗的场合。

2. SPI数字电位器：该芯片采用SPI总线接口，具有更高的精度和稳定性，调节范围通常在数十kΩ到数MΩ之间。

它还具有自动对准功能，可以快速准确地调节阻抗。

该芯片适用于音频、通信、仪器仪表等领域。

3. 4线数字电位器：该芯片具有4个引脚，可以实现高精度、宽范围、快速调节和低噪音等特点。

它具有手动调节和自动扫描两种模式，可以根据需要进行选择。

该芯片适用于各种需要调节电压、阻抗和增益的场合。

4. 双面数字电位器：该芯片具有双面结构，一面是电阻片，另一面是LED阵列。

通过调节电阻片的阻抗，可以改变LED阵列的亮度，从而实现亮度调节。

该芯片适用于各种需要调节亮度的场合，如显示器、灯具等。

在使用数字电位器芯片时，需要注意以下几点：1. 选择合适的接口方式：根据应用需求选择合适的接口方式，如I2C、SPI、UART等。

2. 确定调节范围和精度：根据实际需求确定数字电位器的调节范围和精度，选择合适的产品型号。

3. 注意引脚定义：数字电位器芯片通常具有不同的引脚定义，需要仔细阅读产品手册，确保正确连接。

4. 调试和校准：在安装和使用数字电位器后，需要进行调试和校准，以确保其工作正常。

总之，数字电位器芯片在许多领域都有广泛应用，选择合适的芯片型号并根据实际需求进行正确使用，可以提高系统的性能和稳定性。

TS951X系列在指夹式血氧仪上的应用说明TS951X系列芯片是坤元微电子为“指夹式血氧仪”定制的一款模拟前端专用芯片。

TS951X系列的应用方案已成为“指夹式血氧仪”产品的主流应用方案之一。

目前使用TS951X系列方案的指夹式血氧仪在Fluke Index2血氧仪模拟器的弱灌注性能普遍能达到0.4%以下，最优的方案商已经达到0.1%。

使用TS951X方案的“指夹式血氧仪”具有高性能、高集成度、低成本等优点。

相比于传统方案TS951x的应用方案的集成度的提高可以减少元器件包括：用于切换红光及红外光的模拟开关、调整发光光强的模拟开关、I-V转换电路的放大器、滤波电路的放大器。

此外TS951x的应用方案对MCU 的片内外设要求较低，仅要求MCU 具有定时器功能。

这些特点不光意味着BOM成本的降低，更少的元器件也意味着产品可靠性的提高，同时显著降低了生产管理的成本。

表1-1列出了两种方案的对比。

功能需求TS951X方案传统方案红外光切换TS951X内部集成H桥模拟开关实现调光功能TS951X内部集成模拟调光或数字调光（7位-128档）由DAC与模拟开关配合实现接收管电流采样TS951X内部集成I-F转换使用I-V转换电路、滤波电路，再由ADC采样主控仅需定时器、GPIO的8位MCU 具有（ADC）、（DAC）、定时器、GPIO等功能的MCUTS951X介绍TS951X工作电压为2.5V~5.5V，静态电流典型值为1.25mA。

电流频率转换器的灵敏度为100kHZ/uA。

TS951X系列集成了：低噪声的电流频率转换器（I-F）、H桥发光控制单元、模拟（TS9514）或数字（TS9517）恒流调光单元，以及具有坤元专利的硬件去环境光单元（TS9516、TS9517）。

该芯片采用TSSOP-14及QFN-16封装。

其引脚定义如图1-1及图1-2。

图1-1 TS9514引脚定义图1-1 TS9517引脚定义图1-3显示了TS9514的应用方案，TS9514的IR与RED引脚连接了红光LED以及红外LED，两只LED反向并联，IN以及ANOD连接一只光电二极管。

X9511是一个理想的按钮控制电位器，其内部包含了31 个电阻单元阵列，在每个电阻单元之间和任一端都有可以被滑动端访问的抽头，滑动端的位置由PU 和PD 来控制，滑动端的位置可以存储在EEPROM 存储器中，在下次上电使用时将被重新调用。

典型特性低功耗CMOS 工作电流最大8mA 等待电流最大200µA 31 个电阻单元有温度补偿±20%端点到端点阻值范围 -5V—+5V 电压范围 32 个滑动抽头点滑动端的位置取决与2 个按钮输入慢速和快速扫描方式自动贮存（AUTOSTORER）选项手动贮存选项滑动端位置贮存与非易失性存储器之中，可在上电时重新调用滑动端位置数据可保持10 年 X9511W=10KΩ 8 引脚DIP，SOIC 封装温度范围：民用，工业，军品级
X9511特性
1.低功耗CMOS
2.工作电流最大8mA
3.等待电流最大200μA
4.31个电阻单元
5.有温度补偿
6.±20%端点到端点阻值范围
7.-5V—+5V电压范围
8.32个滑动抽头点
9.滑动端的位置取决与2个按钮输入
10.慢速和快速扫描方式
11.自动贮存（AUTOSTORER）选项
12.手动贮存选项
13.滑动端位置贮存与非易失性存储器之中，可在上电时重新调用
14.滑动端位置数据可保持10年
15.X9511W=10KΩ
16.8引脚DIP，SOIC封装
17.温度范围：民用，工业，军品级
X9511 典型应用
1.家庭影院系统
2.电子保健产品
3.电话机，有线电视设备，无绳电话X9511 订购信息
X9511 应用电路。

Single Digitally-Controlled (XDCP™ ) Potentiometer (Push Button Controlled)FEATURES•Push button controlled •Low power CMOS—Active current, 3mA max —Standby current, 200µA max •31 resistive elements—Temperature compensated— ± 20% end to end resistance range —–5V to +5V range •32 wiper tap points—Wiper positioned via two push button inputs —Slow & fast scan modes —AUTOSTORE ® option —Manual store option—Wiper position stored in nonvolatile memory and recalled on power-up•100 year wiper position data retention •X9511W = 10K Ω •Packages—8-lead PDIP —8-lead SOICDESCRIPTIONThe Xicor X9511 is a push button controlled potentiom-eter that is ideal for push button controlled resistance trimming.The X9511 is a resistor array composed of 31 resistive elements. Between each element and at either end are tap points accessible to the wiper element. The position of the wiper element is controlled by the PU and PD inputs. The position of the wiper can be automatically stored in E 2 memory and then be recalled upon a sub-sequent power-on operation.The resolution of the X9511 is equal to the maximum resistance value divided by 31. As an example, for the X9511W (10K Ω ) each tap point represents 323 Ω .All Xicor nonvolatile products are designed and tested for applications requiring extended endurance and data retention.X9511AUTOSTORE is a registered trademark of Xicor, Inc.Terminal Voltage ±5V, 32 TapsX9511PIN DESCRIPTIONSV H/R H and V L/R LThe high (V H/R H) and low (V L/R L) terminals of the X9511 are equivalent to the fixed terminals of a mechanical potentiometer. The minimum voltage is –5V and the maximum is +5V. It should be noted that the terminology of V L/R L and V H/R H reference the relative position of the terminal in relation to wiper movement direction selected by the PU and PD inputs, and not the voltage potential on the terminal.PUThe debounced PU input is for incrementing the wiper position. An on-chip pull-up holds the PU input HIGH. A switch closure to ground or a LOW logic level will, after a debounce time, move the wiper to the next adjacent higher tap position.PDThe debounced PD input is for decrementing the wiper position. An on-chip pull-up holds the PD input HIGH. A switch closure to ground or a LOW logic level will, after a debounce time, move the wiper to the next adjacent lower tap position.ASEThe debounced ASE (AUTOSTORE enable) pin can be in one of two states:V IL—AUTOSTORE is enabled. When V CC powers down, an automatic store cycle takes place.V IH—AUTOSTORE is disabled. A LOW to HIGH will ini-tiate a manual store operation. This is for the user who wishes to connect a push button switch to this pin. For every valid push, the X9511 will store the current wiper position to the EEPROM.PIN CONFIGURATION PIN NAMESDEVICE OPERATIONThere are three sections of the X9511: the input control, counter and decode section; the EEPROM memory; and the resistor array. The input control section operates just like an up/down counter. The output of this counter is decoded to turn on a single electronic switch, connecting a point on the resistor array to the wiper output. Under the proper conditions the contents of the counter can be stored in EEPROM memory and retained for future use. The resistor array is comprised of 31 individual resistors connected in series. At either end of the array and between each resistor is an electronic switch that trans-fers the potential at that point to the wiper.The X9511 is designed to interface directly to two push button switches for effectively moving the wiper up or down. The PU and PD inputs increment or decrement a 5-bit counter respectively. The output of this counter is decoded to select one of the thirty-two wiper positions along the resistive array. The wiper increment input, PU and the wiper decrement input, PD are both connected to an internal pull-up so that they normally remain HIG H. When pulled LOW by an external push button switch or a logic LOW level input, the wiper will be switched to the next adjacent tap position.Internal debounce circuitry prevents inadvertent switch-ing of the wiper position if PU or PD remain LOW for less than 40ms, typical. Each of the buttons can be pushed either once for a single increment/decrement or continuously for a multiple increments/decrements. The number of increments/decrements of the wiper position depend on how long the button is being pushed. When making a continuous push, after the first second, the increment/decrement speed increases. For the first second the device will be in the slow scan mode. Then if the button is held for longer than 1 second the device will go into the fast scan mode. As soon as the button is released the X9511 will return to a standby condition.V H V CCPU PD 12348765X9511DIP/SOICV SS ASEV LV WSymbol DescriptionV H/R H High TerminalV W/R W Wiper TerminalV L/R L Low TerminalV SS GroundV CC Supply VoltagePU Push Up InputPD Push Down InputASE AUTOSTORE Enable InputX9511The wiper, when at either fixed terminal, acts like its mechanical equivalent and does not move beyond the last position. That is, the counter does not wrap around when clocked to either extreme.AUTOSTOREThe value of the counter is stored in EEPROM memory whenever the chip senses a power-down of V CC while ASE is enabled (held LOW). When power is restored, the content of the memory is recalled and the counter reset to the last value stored.If AUTOSTORE is to be implemented, ASE is typically hard wired to V SS. If ASE is held HIGH during power-up and then taken LOW, the wiper will not respond to the PU or PD inputs until ASE is brought HIG H and held HIGH.Manual (Push Button) StoreWhen ASE is not enabled (held HIGH) a push button switch may be used to pull ASE LOW and released to perform a manual store of the wiper position.R TOTAL with V CC RemovedThe end to end resistance of the array will fluctuate once V CC is removed.Figure 1. Typical circuit with ASE store pin controlled by push button switch Figure 2. Typical circuit with ASE store pin used in AUTOSTORE modeX9511ABSOLUTE MAXIMUM RATINGST emperature under bias....................–65°C to +135°C Storage temperature.........................–65°C to +150°C Voltage on PU, PD, and V CCwith respect to V SS..................................–1V to +7V Voltage on V H and V Lreferenced to V SS....................................–8V to +8V ∆V = |V H–V L|X9511W (10V)Lead temperature (soldering 10 seconds)..........300°C Wiper current............................................................±1mAANALOG CHARACTERISTICSElectrical CharacteristicsEnd-to-end resistance tolerance (20)Power rating at 25°CX9511W.........................................................10mW Wiper current .................................................±1mA Max. T ypical wiper resistance ...........................40Ω at 1mA T ypical noise............................< –120dB/√Hz Ref: 1VResolutionResistance ............................................................3% LinearityAbsolute linearity(1)............................................±1.0 Ml(2) Relative linearity(3).............................................±0.2 Ml(2)COMMENTStresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only; functional operation of the device (at these or any other conditions above those listed in the operational sections of this specification) is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reli-ability.Temperature Coefficient–40°C to +85°CX9511W......................................+300 ppm/°C T ypical Ratiometric temperature coefficient ................±20 ppm Wiper AdjustabilityUnlimited wiper adjustment.......(Non-Store operation) Wiper position store operations.......................100,000data changes Physical CharacteristicsMarking IncludesManufacturer’s T rademarkResistance Value or CodeDate CodeNotes:(1) Absolute linearity is utilized to determine actual wiper voltage versus expected voltage = (V w(n)(actual)–V w(n)(expected)) = ±1 Ml Maximum.(2) 1 Ml = Minimum Increment = R TOT/31.(3)Relative linearity is a measure of the error in step size between taps = V W(n+1)– [V w(n) + Ml] = +0.2 MlRECOMMENDED OPERATING CONDITIONS TemperatureMin.Max.Commercial 0°C +70°C Industrial–40°C+85°CSupply VoltageLimitsX95115V ±10%D.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified.)Notes:(4) T ypical values are for T A = 25°C and nominal supply voltage.(5) This parameter is periodically sampled and not 100% tested.A.C. OPERATING CHARACTERISTICS (Over recommended operating conditions unless otherwise specified.)POWER UP AND DOWN REQUIREMENTSThe are no restrictions on the sequencing of V CC and the voltage applied to the potentiometer pins during power-up or power-down conditions. During power-up, the data sheet parameters for the DCP do not fully apply until 1ms after V CC reaches its final value. The V CC ramp rate spec is always in effect.SymbolParameterLimitsUnitTest ConditionsMin.Typ.(4)Max.I CC V CC active current 13mA PU or PD held at V IL the other at V IH I SB Standby supply current100200µA PU = PD = V IH I LI PU, PD, ASE input leakage current 10µA V IN = V SS to V CCV IH PU, PD, ASE input HIGH voltage 2V CC + 1V V lL PU, PD, ASE input LOW voltage –10.8V R W Wiper resistance 40100ΩMax. Wiper Current ±1mAV VH VH terminal voltage –5+5V V VL VL terminal voltage–5+5V C IN (5)ASE, PU, PD input capacitance10pFV CC = 5V, V IN = 0V, T A = 25°C, f = 1MHzSymbolParameterLimitsUnit Min.Typ.(6)Max.t GAP Time between two separate push button eventsµst DB Debounce time3060ms t S SLOW After debounce to wiper change on a slow mode 100250375ms t S FAST (7)Wiper change on a fast mode 255075mst PU (7)Power up to wiper stable 500µst R V CC (7)V CC power-up rate 0.250mV/µs t ASTO (7)AUTOSTORE cycle time 2ms V ASTH (7)AUTOSTORE threshold voltage 4V V ASEND (7)AUTOSTORE cycle end voltage3.5VAUTOSTORE Cycle Timing DiagramNotes:V ASTH—AUTOSTORE threshold voltageV ASEND—AUTOSTORE cycle end voltaget ASTO—AUTOSTORE cycle time(6)T ypical values are for T A = 25°C and nominal supply voltage.(7)This parameter is periodically sampled and not 100% tested.Slow Mode TimingNote:(1) MI in the A.C. timing diagram refers to the minimum incremental change in the wiper voltage.Fast Mode TimingNote:(1) MI in the A.C. timing diagram refers to the minimum incremental change in the wiper voltage.PACKAGING INFORMATIONNOTE:1.ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)2.PACKAGE DIMENSIONS EXCLUDE MOLDING FLASH8-Lead Plastic Dual In-Line Package Type PMax.PACKAGING INFORMATION8-Lead Plastic Small Outline Gull Wing Package Type SNOTE: ALL DIMENSIONS IN INCHES (IN PARENTHESES IN MILLIMETERS)LIMITED WARRANTY Devices sold by Xicor, Inc. are covered by the warranty and patent indemnification provisions appearing in its T erms of Sale only. Xicor, Inc. makes no warranty,express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement.Xicor, Inc. makes no warranty of merchantability or fitness for any purpose. Xicor, Inc. reserves the right to discontinue production and change specifications and prices at any time and without notice.Xicor, Inc. assumes no responsibility for the use of any circuitry other than circuitry embodied in a Xicor, Inc. product. No other circuits, patents, or licenses are implied.TRADEMARK DISCLAIMER:Xicor and the Xicor logo are registered trademarks of Xicor, Inc. AutoStore, Direct Write, Block Lock, SerialFlash, MPS, and XDCP are also trademarks of Xicor, Inc. All others belong to their respective owners.U.S. PATENTSXicor products are covered by one or more of the following U.S. Patents: 4,326,134; 4,393,481; 4,404,475; 4,450,402; 4,486,769; 4,488,060; 4,520,461; 4,533,846;4,599,706; 4,617,652; 4,668,932; 4,752,912; 4,829,482; 4,874,967; 4,883,976; 4,980,859; 5,012,132; 5,003,197; 5,023,694; 5,084,667; 5,153,880; 5,153,691;5,161,137; 5,219,774; 5,270,927; 5,324,676; 5,434,396; 5,544,103; 5,587,573; 5,835,409; 5,977,585. Foreign patents and additional patents pending.LIFE RELATED POLICYIn situations where semiconductor component failure may endanger life, system designers using this product should design the system with appropriate error detection and correction, redundancy and back-up features to prevent such an occurrence.Xicor’s products are not authorized for use in critical components in life support devices or systems.1.Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure toperform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the lifesupport device or system, or to affect its safety or effectiveness.©Xicor, Inc. 2000 Patents PendingORDERING INFORMATIONX9511XXXTemperature RangeBlank = Commercial = 0°C to +70°C I = Industrial = –40°C to +85°C PackageP = 8-Lead Plastic DIP S = 8-Lead SOIC End to End Resistance W = 10K Ω。

调频收音机摘要：本调频收音机的设计是以SONY公司FM/ AM 收音机集成芯片CXA1238为核心,完成混频、中放,鉴频,功放等功能; 采用锁相环式频率合成器技术，实现回路的调谐与高度稳定的本振;采用RAM 实现电台存储;通过DC - DC 直流变换器实现全电路3V 供电;通过D/ A 输出控制电压, 键盘显示电路,从而实现多种程控搜索、电台存储,载波显示,时钟的控制及显示;利用片内电子音量控制功能,使输出音量得到了提升;为提高灵敏度,抑制噪声,增加了调频静噪调谐电路,使该收音机的收音质量得到了很大改善。

关键词:调频收音机;设计;控制一、方案设计和论证总体思路：收音电路以超大规模AM/FM立体声收音集成芯片为主体，本振频率可变，实现超外差式接收。

本振可变采用数字频率合成技术，由变容二极管和集成压控振荡器芯片实现振荡频率的电压控制；加入由频率合成芯片、高速分频器、运算放大器和晶体振荡器等组成的数字锁相环路，使输出频率稳定度达到与参考晶振同等水平；后级通过滤波及功率放大，使语音信号更清晰。

（一）接收芯片的选择方案一：采用CXA1019作为接收机电路的核心IC。

CXA1019是日本索尼公司研制的单片大规模接收机电路，它包含了AM/FM收音机从天线输入、高频放大、混频、本振到中频放大、检波直至低频（音频）功率放大的所有功能。

除此之外，还具有调谐指示，电子音量控制等一些辅助功能。

方案二：采用CXA1238作为接收机电路的核心IC。

CXA1238是索尼公司在20世纪80年代后期正式推出的集调幅、调频、锁相环、立体声解码等电路为一体的AM/FM立体声收音集成电路。

它的电源电压适应范围宽：2～10V范围内电路均能正常工作，且具有立体声和调谐指示LED驱动电路以及FM静噪功能等。

论证：上述两种方案实现的功能基本相同，但CXA1238内部带解调电路，可以对语音及数据调制后的信号进行解调，具有耗电小、调整简单等优点；且它的宽电压适应范围和立体声指示及静噪功能也是CXA1019所力所不能及的。

有关数字电位器X9511-14几个应用问题的探讨摘要:介绍按钮式数字电位器的防抖动和重复动作问题的一种解决方法，以及对数字电位器电压、电流、级数扩展问题的常见解决方法。

1 引言数字电位器以其调节准确方便，使用寿命长，受物理环境影响小，性能稳定等特点，已被广大电子工程技术人员所认识。

在数字电位器的家族中，X9511/14以其可用按钮直接控制的特点尤其受到青睐，本文欲针对应用开发人员对X9511/14在按钮控制过程中所出现的防抖动、和重复动作问题以及数字电位器通常遇到的问题作一简要探讨。

2 数字电位器简介数字电位器是可用数字信号控制电位器滑动端位置的新型器件。

一般分按钮控制和串行信号控制两种，下面以美国XICOR公司非易失性按钮控制数字电位器X9511为例简略介绍一下其原理。

X9511是数字电位器家族中的一种具有按钮控制，线性输出特点的产品，内部包含了31个电阻单元，32档输出滑动端，滑动端由输入到、引脚的负脉冲控制它向VH或VL端滑动。

滑动端位置可以被存储在非易失性的存储器EEPROM中，使其上电后能够自动恢复到原来的位置。

X9511的管脚见表1，基本应用如图1（图中为X9511/14掉电自动存储滑动端位置的接法）。

图1 X9511基本应用3 数字电位器在应用中经常遇到的问题数字电位器在我国还是近几年出现的新型器件，许多人在实际应用中对其不够了解，从而出现许多疑问，下面就经常出现的三个问题略作探讨。

按钮控制的数字电位器常出现按钮按下次数及输出值与预测值不符。

数字电位器本身能够承受的电流和电压有限，需要扩展。

在实际应用中数字电位器的阻值范围及分辨率不够，需要扩展。

3.1 按钮控制数字电位器的防抖动和重复触发问题上面的第一个问题所说按钮控制电位器的按键次数及输出值与预测不符，通常是其中某一档出现了重复触发动作，自然其按键次数和输出电位就会与预测值不符。

出现这种现象的原因常是用了面包板做试验，或是使用了劣质按钮，造成接触不良，线路噪声加剧，或是人为按钮动作不规范引起。