Multitouch, TacTouch, Capacitive Touch-Screen Controllers
Capacitive Touch-Screen Controllers Allow 4-Finger Tracking with No Ghosting
DescriptionThe MAX11855/MAX11856 high-sensitivity, low-power, mutual-capacitance touch-screen controllers target power-sensitive applications such as handheld devices. The devices return sets of location (X, Y) and pressure metric (Z) data to support two-finger touches, up to four-finger touches for the MAX11855, with no ghosting.
The devices can operate stand-alone or in conjunction with Maxim’s haptic controllers for a near zero-latency touch and haptics solution. Background calibration allows for cancellation of environmental changes. Background calibration occurs continuously and does not affect user operation. The devices also feature a dedicated input for suppression of high noise events from cell phone transmit bursts and LCD switching events.
The MAX11855/MAX11856 support applications with two or three available power supplies for analog and digital blocks. The digital supply (DVDD) range is 1.7V to 1.9V, the analog supply (AVDD) range is 2.7V to 3.6V, and the digital I/O supply (DVDDIO) range is VDVDD to 1.9V.
Minimal external component count is needed to implement a complete touch solution. A typical single-chip solution consists of three bypass capacitors.
The MAX11856 is available in a 48-pin TQFN package and the MAX11855 is available in a 40-pin TQFN package. All devices are specified over the -40°C to +85°C extended temperature range.
- Superior Analog Front-End Provides High SNR (250:1)
- Supports 1.5 and 2-Layer Capacitance Touch Screens and Capacitive Buttons
- Two Touches, No Ghosting (MAX11856)
- Four Touches, No Ghosting (MAX11855)
- Touch-Screen Support (16:9 Aspect Ratios)
- 4.3in. with 5mm Grid Spacing (31 Sensors)
- 3.2in. with 5mm Grid Spacing (25 Sensors)
- Arbitrary Channel Assignment for Touch Screens and Buttons
- Scan Disable Input (Active-Low SDIS) Allows High-Frequency Noise Rejection
- Performs Self-Calibration, Automatic Drift Compensation
- Configurable Interrupt Output
- User-Programmable Modes
- Scan Rate, Sample Time, Number of Samples
- Adjustable Low-Power Mode Response Time
- TacTouch—Trigger to Haptic Controllers (Active-Low TRIG)
- MAX11835 Haptic Actuator Controller
- Integrated Memory
- Flash-Based Upgradeable Firmware and Parameter Storage
- Comprehensive Post-Processing
- Data Output Format: X, Y, Z (Pressure Metric)
- User-Defined Touch-Detect Thresholds
- Region Dependent Haptics Generation
- Automatic Power-Down Capable
- Low-Power Operation
- 3.8mW FPS (typ)
- 400kHz I²C (Fast Mode, No Clock Stretching)
- ±4kV HBM ESD Protection
- Mobile Communication Devices
- Netbooks, Tablet Computers
- Portable Instruments
- POS Terminals
- Smartphones, GPS, Media Players
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