CST3640 Summary:
CST3640 multi point capacitive touch chip, supporting single-layer, multi-layer modules and multiple patterns, using multiple high-voltage drives above 7V to achieve high-performance, high sensitivity, and realistic multi finger touch effects. Compared to traditional single channel low-voltage drives, it can provide higher signal-to-noise ratio and anti-interference ability. At the same time, the chip integrates a self integrating capacitive sensing module, combined with intelligent scanning algorithms, to achieve fast response while also exhibiting excellent noise resistance, waterproofing, and low power consumption performance.
CST3640 Features:
* High performance capacitance detection circuit and DSP module
-Self integrating capacitance detection module;
-Multiple high-voltage simultaneous driving, achieving high sensitivity and high signal-to-noise ratio sampling;
-Dynamic wide range frequency hopping technology, hardware filtering module, stronger common mode and LCD anti-interference ability;
-Built in 32Bit MCU, with a maximum clock of 100MHz;
-Built in Flash storage, supporting online programming;
-Support various gestures for touchpad mice;
* Performance indicators
-Support reporting rate to 160Hz;
-Supports up to 10 real touch points;
-Typical power consumption in dynamic mode (140Hz): 9mA;
-Typical power consumption in monitoring mode (10Hz): 500uA;
-Typical power consumption in sleep mode: 30uA;
-Water carrying operation, thumb recognition, and palm suppression.
* Capacitive screen support
-Supports 40 drive/sensing channels and flexible interchangeability;
-Channel suspension/pull-down design support;
-Support various graphic sensors for traditional DITO, SITO, and touch soft and hard board circuits;
-Support factory testing toolchain for sensors and ribbon cables, including short circuits, open circuits, micro breaks, and consistency;
-Automatic tuning of module parameters, supporting a maximum impedance of 40K;
-Cover Lens thickness support, glass<=2mm, acrylic<=1mm.
* Communication interface
-IIC master/slave communication interface, with a speed of 10k~400kbps software configurable;
-Support PS2 interface communication;
-Support touchpad protocols such as PTP and HID-IIC;
-GPIO support, multiple working modes can be matched, with built-in 2.5k pull-up resistor mode;
-Built in 1.8V LDO, compatible with 1.8V/VDDA interface level adjustable.
* Power supply
-Single power supply 2.7-5.5V, please refer to the circuit design;
-A small amount of peripheral devices.
* Package type: QFN52 6mm * 6mm 0.4mm Pitch.
CST3640 application:
Touchpad, mobile phone, tablet, etc.
CST3640 Pin arrangement:
CST3640 Pin Description:
CST3640 Typical application circuit diagram:
C1：2.2uF/6.3V C2: 1uF/6.3V
C3：1uF/10V C4: 1uF/6.3V
R3: 560 ohm
D1: Optional, TVS tube (ESD5Z3.3/5.0V corresponds to VDDA), enhancing ESD capability;
R1/R2: optional, IIC bus pull-up resistor, can be configured to replace 2.5K pull-up inside the chip.
VDDIO: VDDA (3.6V) or suspended, suspended IIC bus voltage defaults to 1.8V.
DP and INT: Universal digital I/O that can be used as an INT, as well as a SensorID suspended or connected to GND.
CST3640 Ordering information:
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Part number
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package
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Surface printing
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Packaging
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CST3640
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QFN6*6-52L(P0.40 T0.55)
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CST3640
XXXXX
（Production tracking code）
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4000/plate, bundled for shipment
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CST3640 Function Description:
The CST3640 series multi point capacitive touch chip adopts 7V high-voltage multi-channel drive, which can provide higher signal-to-noise ratio and noise resistance compared to traditional low-voltage drive, achieving ultra sensitive touch. At the same time, the internal self capacitive induction module of the chip, combined with intelligent scanning algorithms, has extremely excellent noise resistance, waterproofing, and low power consumption performance while achieving rapid response.
The overall system diagram is as follows：
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