CXTC8964LQ is manufactured by CMOS technology, with built-in voltage stabilization and dejitter circuit. The operating voltage range is 2.4V to 5.5V, which is suitable for various power supply scenarios. Its ultra-low power consumption (fast mode is only 3.5 μA) makes it especially suitable for battery-powered devices, such as TWS headphones, smart bracelets, remote control, portable lamps, etc. At the same time, the chip supports the Surface touch of glass, ceramics, plastics, acrylic and other media, providing greater freedom for product appearance design.
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[ CXTC8964LQ ]"
CXTC8964LQ: capacitive single-key touch sensing chip designed for TWS and DC applications
With the rapid development of consumer electronics products such as smart wear, TWS headphones and portable devices, users have put forward higher requirements for interaction methods-simpler, more beautiful and more intelligent. As a control chip specially designed for capacitive single-key touch and proximity sensing, CXTC8964LQ is becoming an ideal choice to replace traditional mechanical button due to its ultra-low power consumption, fast response, high integration and strong anti-interference capability. This article will systematically introduce the core features, working modes, design points and typical applications of CXTC8964LQ to help engineers build more competitive intelligent products.
I. Product positioning and application scenarios
CXTC8964LQ is manufactured by CMOS technology, with built-in voltage stabilization and dejitter circuit. The operating voltage range is 2.4V to 5.5V, which is suitable for various power supply scenarios. Its ultra-low power consumption (fast mode is only 3.5 μA) makes it especially suitable for battery-powered devices, such as TWS headphones, smart bracelets, remote control, portable lamps, etc. At the same time, the chip supports the Surface touch of glass, ceramics, plastics, acrylic and other media, providing greater freedom for product appearance design.
Typical application areas include:
·TWS headset: Touch Play/Pause, volume adjustment, wake-up voice assistant;
·Portable devices: mobile power supply, USB fan, LED light touch control;
·Home appliances and smart home: touch panel, Smart Switch, small home appliance control;
·Industrial and medical equipment: Instrument Control Panel, portable detection equipment.
II. Analysis of core functions and advantages
2.1. Ultra-low power consumption and fast response
CXTC8964LQ in fast mode, the work current is only 3.5 μA(VDD = 3.0V), and the response time is about 45ms, which takes into account energy saving and real-time, and is especially suitable for wearable devices sensitive to power consumption.
2.2. Intelligent automatic calibration
The chip has the ability to adapt to the environment. The reference value is refreshed every 1 second within 8 seconds of power-on, and then calibrated every 4 seconds to ensure stable detection performance under different temperature and humidity, surface pollution and other environments.
2.3. Flexible output mode configuration
It can be realized through HLD and OLH pins.Direct outputAndLatch outputThe two modes support high-level or low-level effective output and adapt to different system logic and power architectures.
2.4. Built-in voltage stabilization and anti-interference design
The chip has built-in LDO voltage stabilizing circuit, which provides a stable voltage for Touch Detection. At the same time, it integrates a dejitter circuit, which can effectively suppress external noise interference and prevent false triggering.
2.5. Long press protection and esysreset
When the touch duration exceeds about 16 seconds (± 25%), the chip automatically resets and stops output to avoid system locking caused by long-term coverage of objects and improve the use safety.
3. Output mode details and Configuration Guide
3.1. Direct output mode (HLD = 0)
The output signal is synchronized with the touch action, and the output is valid when touching. After Releasing, the initial state is restored. It is suitable for touch operations that require immediate feedback, such as headphone song cutting and device wake-up.
3.2. Latch output mode (HLD = 1)
The output status remains after the touch and does not switch until the next touch. It is suitable for switch applications, such as power switch and mode switching.
3.3. Output polarity selection (OLH pin)
·OLH = 0: The output high level is valid.
·OLH = 1: The output low level is valid.
You can flexibly configure the logic based on the input logic of subsequent circuits (such as MCU, MOS tube, and indicator lights).
IV. Sensitivity adjustment and PCB design best practices
4.1 Selection of medium thickness
It is recommended that the thickness of the touch panel is between 0.5mm and 1.2mm, which will reduce the sensitivity if it is too thick.
4.2. Selection of external cscapacitor
·Capacity range: 0 ~ 75pF, the larger the capacity, the lower the sensitivity;
·We recommend that you use NPO or X7R materials with good temperature stability;
·We recommend that you use a 0402-package 10pF capacitor for initial debugging, and reserve the capacitor bit on the PCB for adjustment.
4.3. Touch PAD design specifications
·The minimum size is recommended to be 3 × 5mm, and the maximum size cannot exceed 8 × 8mm;
·If FPC soft board is used, the Mirror layer and bottom layer of PAD should not be covered with copper;
·Keep the periphery of the route clear to avoid the influence of parasitic capacitance.
4.4 PCB layout and routing suggestions
·The TCH pin is as short as possible, and the recommended length is less than 35mm;
·In the multi-layer board, touch around the routing for clearance treatment;
·Keep away from interference sources such as high frequency and RF to avoid parallel or cross routing;
·Do not arrange other signal lines within 1mm outside the Touch PAD.
V. Typical application circuit and principle description
5.1. The following figure shows the typical application circuit of CXTC8964LQ, which is suitable for most single-key touch scenarios:
VDD → Cv(0.1μF) → GND
TCH → R2(1K) → Touch PAD
TCH → Cf(10pF) → GND
HLD & rarr; VDD/GND (mode selection)
OLH & rarr; VDD/GND (output polarity selection)
OUT & rarr; R1(1K) & rarr; V-out (to load or MCU)
5.2. Circuit description:
·Cv is the power supply filter capacitor, we recommend that you use 0.1 μF;
·R2 is a current limiting resistor to enhance ESD protection;
·Cf is the sensitivity adjustment capacitor, and 10pF is initially recommended;
·R1 is a pull-up or pull-down resistor, which is configured according to the output polarity.
5.3. Typical application circuit schematic diagram
VI. Electrical characteristics and reliability data
6.1. Absolute maximum (TA = 25℃)
·Supply Voltage:-0.3V to VDD 5.5V
·Operating temperature:-20 ℃ to 85 ℃
·Storage Temperature:-40℃ ~ 125℃
·ESD protection (HBM):6KV
6.2. DC/AC characteristics (VDD = 3.0V)
·Operating voltage range: 2.4V to 5.5V
·Internal regulated output: 2.3V (typical)
·Work current: fast mode 3.5 μA, low power mode 1.5 μA
·Output drive capability: irrigation current 8mA, source current 4mA
·Response time: fast mode ≤ 45ms
VII. Encapsulation information
CXTC8964LQ adoptedSOT23-6LPackage, small size, convenient welding, clear pin definition:
·OUT-CMOS output
·GND-power ground
·TCH-touch signal input
·OLH-effective selection of output high/low
·VDD-power positive
·HLD-output mode selection (direct/latch)
VIII. Design attention and FAQ
8.1. Power-on initialization time
The initialization is completed within about 0.5 seconds after the power supply is stable. All functions are disabled during this period. This delay should be considered when designing.
8.2. Environmental adaptability debugging
We recommend that you perform sensitivity debugging under actual shell and medium conditions. You can adjust the CS capacitor value or PAD size to optimize the experience.
8.3. Power supply stability
Although the chip has built-in LDOs, it is recommended to arrange 0.1 μF filter capacitor near VDD, especially in battery-powered scenarios.
8.4. Touch feedback design
It can be combined with OUT signal to drive LED, vibration motor or sound prompt to improve interactive experience.
IX. Conclusion
With its advantages of ultra-low power consumption, high reliability and flexible configuration, CXTC8964LQ provides high-performance touch interaction solutions for TWS headphones, portable devices, smart home and other products. Its automatic calibration, long press protection, anti-interference and other intelligent functions significantly improve the practicability and user experience of the product. Whether it is the pursuit of light and beautiful consumer electronics or the focus on stable and reliable industrial equipment, CXTC8964LQ can help developers achieve more intelligent and humanized touch control.
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