What is an elevator call button?
Elevator Controls and Indicators - Archtoolbox Call Buttons are used to request an elevator. They are mounted 42" above the finished floor and consist of an up button and a down button that illuminate to indicate the request has been received and an elevator is on the way.
Elevator calling button operating panels are adding new features and capabilities including capacitive touch human machine interface (HMI), people counting and wireless communication.
Design requirements
Modern elevator calling button operating panel designs require:
Noise-tolerant capacitive touch HMI.
Wireless communication.
Faster, more robust wired communication solutions, such as CAN.
As shown in the picture, this is a design drawing of Calling button operating panel, it contains several parts such as Display interface、Non-isolated DC/DC power supply、User interface signal input/output protection、Input user interface、Digital processing、Signal isolation、Wired interface、Wired interface signal input/output protection、Output user interface、Self-diagnostics/monitoring、Wireless interface、Audio interface. What are them? What products are needed to design them?
Display interface is an LED or LCD/TFT display may be included to display the floor location or provide additional information such as weather, date, time and advertisements. An LCD driver and a backlight LED driver may be used in systems that use displays. This part of the design requires the use of Shift registers, which include the following products:
1. Features
• Wide operating voltage range: 2 V to 6 V
• Schmitt-trigger inputs allow for slow or noisy inputsignals
• Low power consumption
– Typical ICC of 100 nA
– Typical input leakage current of ±100 nA
• ±7.8-mA output drive at 6 V
• Extended ambient temperature range: –40°C to
+125°C, TA
2. Applications
• Output expansion
• LED matrix control
• 7-segment display control
• 8-bit data storage
3. Description
The SN74HCS595 device contains an 8-bit, serialin, parallel-out shift register that feeds an 8-bit D-type storage register. All inputs include Schmitttrigger architecture, eliminating any erroneous data outputs due to slow-edged or noisy input signals. The storage register has parallel 3-state outputs. Separate clocks are provided for both the shift and storage register. The shift register has a direct overriding clear (SRCLR) input, serial (SER) input, and a serial output (QH') for cascading. When the output-enable (OE) input is high, the storage register outputs are in a high-impedance state. Internal register data and serial output (QH') are not impacted by the operation of the OE input.
1.Features
• 8-Bit serial-in, parallel-out shift
• Wide operating voltage range of 2 V to 6 V
• High-current 3-state outputs can drive up to 15 LSTTL loads
• Low power consumption, 80-µA max ICC
• Typical tPD = 14 ns
• ±6-mA output drive at 5 V
• Low input current of 1 µA max
• Shift register has direct clear
2. Description
The CD74HC595 is an 8-bit serial-input paralleloutput shift register with output registers and 3-state outputs.
Non-isolated DC/DC power supply
The operating panel is typically powered from a 24V DC wired power source. Buck converters may be used to step down the input voltage. Linear regulators (LDOs) are a good option for simple designs. LDOs also enable added functionalities including EMI filtering. This part of the design requires the use of Shift registers, which include two parts: Power management and Switches & multiplexers.
Power management include: Buck converters (integrated switch)、Linear & low-dropout (LDO) regulators、Multi-channel ICs (PMICs)、Boost converters (integrated switch)、N-channel MOSFETs
Multiplexers include: Analog switches & muxes
The corresponding products are TPS54231、TPS7A24、CSD17483F4、SN74AHC4066
TPS54231 2-A, 28-V Input, Step-Down DC-DC Converter With Eco-mode™
1. Features
• 3.5- to 28-V Input Voltage RangeAdjustable Output Voltage Down to 0.8 V
• Integrated 80-mΩ High-Side MOSFET Supportsup to 2 A Continuous Output Current
• High Efficiency at Light Loads with a Pulse Skipping Eco-mode™
• Fixed 570-kHz Switching FrequencyTypical 1-yA Shutdown Quiescent Current
• Adjustable Slow-Start Limits inrush Currents
• Programmable UVLO Threshold
• Overvoltage Transient Protection
• Cycle-by-Cycle Current Limit, Frequency Fold Back and Thermal Shutdown Protection
• Available in Easy-to-Use SOlC8 PackageSupported by WEBENCH® Software Tool
2. Applications
Consumer Applications such as Set-Top Boxes,CPE Equipment, LCD Displays, Peripherals, andBattery Chargers、Industrial and Car Audio Power Supplies5-V,12-V and 24-V Distributed Power Systems
3. Description
The TPS54231 device is a 2-V,2-A non-synchronousbuck converter that integrates a low Rps(on) high-sideMOSFET. To increase efficiency at light loads, apulse skipping Eco-modem feature is automaticallyactivated.Furthermore,the 1-uA shutdown supplycurrent allows the device to be usedin batterypowered applications.Current mode control withinternal slope compensation simplifies the externacompensation calculations and reduces componentcount while allowing the use of ceramic outputcapacitors.A resistor divider programs the hysteresisof the input undervoltage lockout. An overvoltagetransient protection circuit limits voltage overshootsduring startup and transient conditions. A cycle-by-cycle current limit scheme, frequency fold back andthermal shutdown protect the device and the load inthe event of an overload condition. The TPS54231device is available in an 8-pin SOlC package that hasbeen intemallyoptimized to improve thermalperformance.
TPS7A24 200-mA, 18-V, Ultra-Low IQ, Low-Dropout Voltage Regulator
1. Features
• Ultra-low IQ: 2.0 μA
• Input voltage: 2.4 V to 18 V
• Output voltage options available:
– Fixed: 1.25 V to 5.5 V
– Adjustable: 1.24 V to 17.75 V
• 1.25% accuracy over temperature
• Low dropout: 250 mV (max) at 200 mA
• Active overshoot pulldown protection
• Thermal shutdown and overcurrent protection
• Operating junction temperature: –40°C to +125°C
• Stable with 1-µF output capacitors
• Package: 5-pin SOT-23
2. Applications
• Smoke and heat detectors
• Thermostats
• Motion detectors (PIR, uWave, and so forth)
• Cordless power tools
• Appliance battery packs
• Electricity meters
• Water meters
3. Description
The TPS7A24 low-dropout(LDO)linear voltageregulator supports a 2.4-V to 18-V input voltage rangewith ultra-low quiescent current (lo). These featureshelp modern appliances meet increasingly stringentenergy requirements and help extend battery life inportable-power solutions.
The TPS7A24isavailable in both fixed andadjustable versions.The fixed-voltage versioneliminates external resistors and minimizes printedcircuit board(PCB)area. For more fexibility orhigher output voltages, the adjustable version usesfeedback resistors to set the output voltage from1.24 V to 17.75 V Both versions have 1.25% outputregulation accuracy that provides precision regulationfor microcontroller (MCU)references.
The TPS7A24 LDO operates more efficiently thanstandard linear regulators because the maximumdropout voltage is less than 250 mV at 200 mA ofcurrent. This maximum dropout voltage allows for92.8% efficiency from a 3.55-V input voltage (Vin) to a3.3-V output voltage (VouT).
CSD17483F4 30-V N-Channel FemtoFET™ MOSFET
1. Features
• Low on-resistance
• Low Qg and Qgd
• Low-threshold voltage
• Ultra-small footprint (0402 case Size)
– 1.0 mm × 0.6 mm
• Ultra-low profile
– 0.36-mm height
• Integrated ESD protection diode
– Rated > 4-kV HBM
– Rated > 2-kV CDM
• Lead and halogen free
• RoHS compliant
2. Applications
• Optimized for load switch applications
• Optimized for general purpose switching applications
• Single-cell battery applications
• Handheld and mobile applications
3. Description
This 200-mΩ, 30-V N-Channel FemtoFET™ MOSFET technology is designed and optimized to minimize the footprint in many handheld and mobile applications. This technology is capable of replacing standard small signal MOSFETs while providing at least a 60% reduction in footprint size.
SN74AHC4066 Quadruple Bilateral Analog Switch
1. Features
• 1V to 5.5V VCC operation
• Supports mixed-mode voltage operation on all ports
• High on-off output-voltage ratio
• Low crosstalk between switches
• Individual switch controls
• Extremely low input current
• ESD protection exceeds JESD 22:
– 2000V Human-Body Model (A114-A)
– 200V Machine Model (A115-A)
– 1000V Charged-Device Model (C101)
2. Applications
• Analog signal switching or multiplexing:
– Signal gating, modulator, squelch control, demodulator, chopper, commutating switch
• Digital signal switching and multiplexing
– Audio and video signal routing
• Transmission-gate logic implementation
• Analog-to-digital and digital-to-analog conversion
• Digital control of frequency, impedance, phase, and analog-signal gain
• Motor speed control
• Battery chargers
• DC-DC converter
3. Description
This quadruple silicon-gate COS analog switch isdesigned for 1V to 5.5v CC operation.The switch is designed to handle both analog anddigital signals. Each switch permits signals withamplitudes of up to 5.5V(peak)to be transmitted ineither direction.
Each switch section has its own enable input control(C).A high-level voltage applied to C turns on theassociated switch section. Applications includesignalgating，chopping,modulation or demodulation(modem),and signamultiplexing for analog-to-digital and digitalto-analogconversion systems.
User interface signal input/output protection is an ESD protection device may be required on user buttons. This part of the design requires the use of ESD protection diodes, which include the following products: TPD2EUSB30、TPD6F003、TPD1E1B04
Digital processing is a microprocessor monitors the user buttons and updates the LCD and system LEDs. This part of the design requires the use of Microcontrollers (MCUs) & processors、Wireless connectivity, which include the following products: MSPM0G1106、MSPM0L1346、MSP430FR2633、TMS320C5517、CC2651R3、CC2642R
Signal isolation is a digital isolator may be used to isolate the wired interfaces. This part of the design requires the use of Digital isolators and Isolated RS-485 transceivers which include the following products: ISO7221A、ISO6721、ISO7842、ISO3082、ISO3088
Hopen Our reference designs and integrated circuits help you understand and integrate these technologies into your design.
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