Datasheet

ManualsBrandsMicrochip ManualsIntegrated Circuits (ICs)Touch Sensor IC SOT-23-6 Digital Output

AT42QT1012

AT42QT1012 Data Sheet

Introduction

The AT42QT1012 (QT1012) is a single key device featuring a touch on/touch off (toggle) output with a

programmable auto switch-off capability. The device is One-channel Toggle-mode QTouch

Touch

Sensor IC with Power Management Functions.

The QT1012 features a digital burst mode charge-transfer sensor designed specifically for touch controls

and a unique “green” feature - the timeout function, which can turn off power after a time delay.

Features

• Number of Keys:

– One, toggle mode (touch-on / touch-off), plus programmable auto-off delay and external

cancel

– Configurable as either a single key or a proximity sensor

• Technology:

– Patented spread-s

6 mm x 6 mm or larger (panel thickness dependent); widely different sizes and shapes

possible

• Electrode design:

– Solid or ring electrode shapes

• PCB Layers required:

– One

• Electrode materials:

– Etched copper, silver, carbon, Indium Tin Oxide (ITO)

• Electrode substrates:

– PCB, FPCB, plastic films, glass

• Panel materials:

– Plastic, glass, composites, painted surfaces (low particle density metallic paints possible)

• Panel thickness:

– Up to 12 mm glass, 6 mm plastic (electrode size and Cs dependent)

• Key sensitivity:

• Settable via external capacitor (Cs)

• Interface:

– Digital output, active high or active low (hardware configurable)

• Moisture tolerance:

– Increased moisture tolerance based on hardware design and firmware tuning

• Power:

Datasheet

DS40001948A-page 1

Summary of content (35 pages)

PAGE 1
AT42QT1012 AT42QT1012 Data Sheet Introduction The AT42QT1012 (QT1012) is a single key device featuring a touch on/touch off (toggle) output with a programmable auto switch-off capability. The device is One-channel Toggle-mode QTouch® Touch Sensor IC with Power Management Functions. The QT1012 features a digital burst mode charge-transfer sensor designed specifically for touch controls and a unique “green” feature - the timeout function, which can turn off power after a time delay.
PAGE 2
AT42QT1012 • • – 1.8 V – 5.5 V; 32 µA at 1.8 V Package: – 6-pin SOT23-6 (3 x 3 mm) RoHS compliant – 8-pin UDFN/USON (2 x 2 mm) RoHS compliant Signal processing: – Self-calibration, auto drift compensation, noise filtering © 2017 Microchip Technology Inc.
PAGE 3
Table of Contents Introduction......................................................................................................................1 Features.......................................................................................................................... 1 1. Pinout and Schematic................................................................................................5 1.1. 1.2. 1.3. Pinout Configurations.......................................................................
PAGE 4
AT42QT1012 5.8. 5.9. Part Number............................................................................................................................... 28 Moisture Sensitivity Level (MSL)................................................................................................ 29 6. Associated Documents............................................................................................30 7. Revision History..............................................................................
PAGE 5
1. Pinout and Schematic 1.1 Pinout Configurations 1.1.1 6-pin SOT23-6 1.1.2 OUT 1 VSS 2 SNSK 3 QT1012 AT42QT1012 6 TIME 5 VDD 4 SNS 8-pin UDFN/USON Pin 1 ID 1.2 8 SNS 7 VDD 3 6 TIME 4 5 OUT SNSK 1 N/C 2 N/C VSS QT1012 Pin Descriptions Table 1-1. Pin Listing 6-Pin 8-Pin Name Type Description If Unused, Connect To... 1 5 OUT O(1) Output state. To switched circuit and output polarity selection resistor (Rop) 2 4 VSS P Ground 3 1 SNSK I/O Sense pin.
PAGE 6
AT42QT1012 (1) I/O briefly on power-up I Input only O Output only, push-pull I/O Input/output P Ground or power 1.3 Schematics 1.3.1 6-pin SOT23-6 Figure 1-1. Basic Circuit Configuration (active high output, toggle on/off, no auto switch off) Note: bypass capacitor to be tightly wired between VDD and VSS and kept close to pin 5. VDD SENSE ELECTRODE Cby Rs 5 3 VDD SNSK OUT 1 Cs 4 SNS Rop Rm TIME 6 VSS 2 1.3.2 8-pin UDFN/USON Figure 1-2.
PAGE 7
AT42QT1012 2. Overview of the AT42QT1012 2.1 Introduction The AT42QT1012 (QT1012) is a single key device featuring a touch on/touch off (toggle) output with a programmable auto switch-off capability. The QT1012 is a digital burst mode charge-transfer sensor designed specifically for touch controls. It includes all hardware and signal processing functions necessary to provide stable sensing under a wide variety of changing conditions; only low cost, noncritical components are required for operation.
PAGE 8
AT42QT1012 Figure 2-1. Sense Connections VDD SENSE ELECTRODE Cby 5 Rs 3 VDD SNSK OUT 1 Cs 4 SNS Cx TIME 6 VSS 2 2.4 Sensitivity 2.4.1 Introduction The sensitivity on the QT1012 is a function of things like the value of Cs, electrode size and capacitance, electrode shape and orientation, the composition and aspect of the object to be sensed, the thickness and composition of any overlaying panel material, and the degree of ground coupling of both sensor and object. 2.4.
PAGE 9
AT42QT1012 recommendations in the application note Atmel AVR3002: Moisture Tolerant QTouch Design (downloadable from www.microchip.com). © 2017 Microchip Technology Inc.
PAGE 10
AT42QT1012 3. Operation Specifics 3.1 Acquisition Modes 3.1.1 Introduction The OUT pin of the QT1012 can be configured to be active high or active low. • • 3.1.2 If active high then: – “on” is high – “off” is low If active low then: – “on” is low – “off” is high OUT Pin The QT1012 runs in Low Power (LP) mode. In this mode it sleeps for approximately 80 ms at the end of each burst, saving power but slowing response.
PAGE 11
AT42QT1012 3.3 Detect Integrator It is desirable to suppress detections generated by electrical noise or from quick brushes with an object. To accomplish this, the QT1012 incorporates a detect integration (DI) counter that increments with each detection until a limit is reached, after which the output is activated. If no detection is sensed prior to the final count, the counter is reset immediately to zero. In the QT1012, the required count is four.
PAGE 12
AT42QT1012 increasing signals. Increasing signals should not be compensated for quickly, since an approaching finger could be compensated for partially or entirely before even approaching the sense electrode. However, an obstruction over the sense pad, for which the sensor has already made full allowance, could suddenly be removed leaving the sensor with an artificially elevated reference level and thus become insensitive to touch.
PAGE 13
AT42QT1012 Table 3-1. Output Configuration Name (Vop) Function (Output Polarity) Vss Active high Vdd Active low Note: Some devices, such as Digital Transistors, have an internal biasing network that will naturally pull the OUT pin to its inactive state. If these are being used then the resistor Rop is not required (see Figure 3-5). Figure 3-5. Output Connected to Digital Transistor (6-pin SOT23) SENSE ELECTRODE VDD Cby 100 nF 5 Rs VDD Load 3 SNSK Cs 4 SNS OUT 1 TIME 6 Rm VSS 2 3.
PAGE 14
AT42QT1012 The TIME and SNS pins are used to configure the Auto-off delay and must always be connected in one of the ways described in Section 3.11.2. 3.11.2 Auto-off – Predefined Delay To configure the predefined delay the TIME pin is hard wired to Vss, Vdd or OUT as shown in Table 3-2 and Table 3-3. This provides nominal values of 15 minutes, 60 minutes or infinity (remains on until toggled off).
PAGE 15
AT42QT1012 Table 3-3. Predefined Auto-off Delay (Active Low Output) Vt Auto-off Delay (to) Vss 15 minutes Vdd Infinity (remain on until toggled to off) OUT 60 minutes Table 3-4. Auto-off Delay Multiplier 3.11.3 Vm Auto-off Delay Multiplier Vss to × 1 Vdd to × 24 Auto-off – User-programmed Delay If a user-programmed delay is required, a RC network (resistor and capacitor) can be used to set the auto-off delay (see Table 3-5 and Figure 3-7).
PAGE 16
AT42QT1012 and Rt × Ct = Delay × � 15 Note: Rt is in kΩ, Ct is in nF, Delay is in seconds. K values are obtained from Figure 3-8. To ensure correct operation it is recommended that the value of Rt × Ct is between 4 and 240. � Values outside this range may be interpreted as the hard wired options TIME linked to OUT and TIME linked to “off” respectively, causing the QT1012 to use the relevant predefined auto-off delays. Table 3-5.
PAGE 17
AT42QT1012 As an alternative to calculation, Figure 3-9 and Figure 3-10 show charts of typical curves of auto-off delay against resistor and capacitor values for active high and active low outputs at various values of VDD (delay multiplier = x1). Figure 3-9. Auto-off Delay, Active High Output Vm = Vss (delay multiplier = x1) © 2017 Microchip Technology Inc.
PAGE 18
AT42QT1012 Figure 3-10. Auto-off Delay, Active Low Output Vm = Vss (delay multiplier = x1) Example using a chart to calculate Rt and Ct Requirements: • • • Active low output (Vop connected to VSS) Auto-off delay 25 minutes VDD = 4 V 1. Calculate Auto-off delay in seconds 25 × 60 = 1500. 1500 Find = 1500 on the 4 V chart in Figure 3-10. 1 2. 3. 3.11.
PAGE 19
AT42QT1012 To ensure the pulse is detected it must be present for typical times as shown in Table 3-6. Table 3-6. Time Delay Pulse Pulse Duration Action tp – series of short pulses, typically 65 ms “Sustain”/retrigger (reload auto-off delay counter) tp – long pulse, typically 250 ms “Cancel”/switch output to off state and inhibit further touch detection until Vm returns to original state While Vm is held in the override state the QT1012 inhibits bursts and waits for Vm to return to its original state.
PAGE 20
AT42QT1012 Figure 3-12. Override Pulse (Delay Multiplier x24) SENSE ELECTRODE VDD Cby 100 nF 5 Rs VDD 3 SNSK Cs 4 SNS Rm Vdd Vss 1 OUT TIME 6 VSS Rop 2 Vm Tp Figure 3-13 shows override pulses being applied to a QT1012 with delay multiplier set to x1. Figure 3-13. Overriding Auto-off O OUT P P P toff Vm Bursts SNSK C C C C P - override (reload auto off delay) O - switch output off (toff burst time + 50ms) C - sensor recalibration © 2017 Microchip Technology Inc.
PAGE 21
AT42QT1012 3.12 Examples of Typical Applications Figure 3-14. Application 1: Active low, driving PNP transistor, auto-off time 375 s x 24 = 9000 s = 2.5 hours +3V 100nF Rm 1M SENSE ELECTRODE DTA143 5 RS 3 CS 4 VDD OUT 1 SNSK Rt SNS 10k TIME 6 2.2k Ct VSS Load 47nF 2 Auto-off time obtained from 3 V chart in Figure 3-10 on page 16 Auto-off time obtained from 3 V chart in Figure 3-10 Figure 3-15. Application 2: Active high, driving high impedance, auto-off time 315 s x 1 = 5.
PAGE 22
AT42QT1012 4. Circuit Guidelines 4.1 More Information Refer to Application Note QTAN0002, Secrets of a Successful QTouch Design and the Touch Sensors Design Guide (both downloadable from the Microchip website), for more information on construction and design methods. 4.2 Sample Capacitor Cs is the charge sensing sample capacitor. The required Cs value depends on the thickness of the panel and its dielectric constant. Thicker panels require larger values of Cs. Typical values are 2.
PAGE 23
AT42QT1012 For best EMC performance the circuit should be made entirely with SMT components. Electrode trace routing: Keep the electrode trace (and the electrode itself) away from other signal, power, and ground traces including over or next to ground planes. Adjacent switching signals can induce noise onto the sensing signal; any adjacent trace or ground plane next to, or under, the electrode trace will cause an increase in Cx load and desensitize the device.
PAGE 24
AT42QT1012 5. Specifications 5.1 Absolute Maximum Specifications Operating temperature –40°C to +85°C Storage temperature –55°C to +125°C Vdd 0 to +6.5 V Max continuous pin current, any control or drive pin ±20 mA Short circuit duration to Vss, any pin Infinite Short circuit duration to Vdd, any pin Infinite Voltage forced onto any pin –0.6 V to (Vdd + 0.6) V CAUTION: Stresses beyond those listed under Absolute Maximum Specifications may cause permanent damage to the device.
PAGE 25
AT42QT1012 5.4 Parameter Description Min Typ Max Units Notes Tbl Burst length – 1.86 – Tr Response time – – ms Vdd, Cs and Cx dependent. See Section 4.2 for capacitor selection. 100 ms Signal Processing Table 5-2. Vdd = 3.0V, Cs = 10 nF, Cx = 5 pF, Ta = recommended range, unless otherwise noted 5.5 Description Min Typ Max Units Threshold differential 10 counts Hysteresis 2 counts Consensus filter length 4 samples Notes DC Specifications Table 5-3. Vdd = 3.0V, Cs = 4.
PAGE 26
AT42QT1012 5.6 Mechanical Dimensions 5.6.1 6-pin SOT23-6 D 5 6 E E1 A 4 A2 Pin #1 ID 1 b 0.10 C SEATING PLANE A 3 2 A A1 C Side View e Top View A2 A 0.10 C SEATING PLANE c 0.25 O L C View A-A SEATING PLANE C A1 SEE VIEW B View B COMMON DIMENSIONS (Unit of Measure = mm) Notes: 1. This package is compliant with JEDEC specification MO-178 Variation AB. 2. Dimension D does not include mold Flash, protrusions or gate burrs.
PAGE 27
AT42QT1012 5.6.2 8-pin UDFN/USON Top view 8 7 6 Side view Bottom view A D2 e 5 5 8 k E C0.2 E2 PIN 1 ID L 1 2 3 4 4 D 0.05 C f A 8X d 1 b A1 0.05 C C Side view COMMON DIMENSIONS (Unit of Measure = mm) A1 MIN NOM MAX A - - 0.60 A1 0.00 - 0.05 b 0.20 - 0.30 D 1.95 2.00 2.05 D2 1.40 1.50 1.60 1.95 2.00 0.90 1.00 SYMBOL NOTES: 1. All dimensions are in mm. Angles in degrees. 2. Coplanarity applies to the exposed pad as well as the terminals.
PAGE 28
AT42QT1012 5.7 Part Marking 5.7.1 AT42QT1012– 6-pin SOT23-6 Abbreviated Part Number: AT42QT Pin 1 ID Note: Samples of the AT42QT1012 may also be marked T10E. 5.7.2 AT42QT1012 – 8-pin UDFN/USON Abbreviated Part Number: AT42QT1012 Die Revision (Example: “E” shown) Class code (H = Industrial, green NiPdAu) Assembly Location Code (Example: “C” shown) Pin 1 ID Lot Number Trace code (Variable text) Pin 1 Last Digit of Year (Variable text) Note: Samples of the AT42QT1012 may also be marked T10 5.
PAGE 29
AT42QT1012 5.9 Moisture Sensitivity Level (MSL) MSL Rating Peak Body Temperature Specifications MSL1 260oC IPC/JEDEC J-STD-020 © 2017 Microchip Technology Inc.
PAGE 30
AT42QT1012 6. Associated Documents For additional information, refer to the following document (downloadable from the Touch Technology area of the Microchip website, www.microchip.com): • • Touch Sensors Design Guide ® QTAN0002 – Secrets of a Successful QTouch Design © 2017 Microchip Technology Inc.
PAGE 31
AT42QT1012 7. Revision History Revision No. History Revision A – May 2009 Initial release Revision B – August 2009 Update for chip revision 2.2 Revision C – August 2009 Minor update for clarity Revision D – January 2010 Power specifications updated for revision 2.4.1 Revision E – January 2010 Part markings updated Revision F – February 2010 MSL specification revised Other minor updates Revision G – March 2010 Update for chip revision 2.
PAGE 32
AT42QT1012 The Microchip Web Site Microchip provides online support via our web site at http://www.microchip.com/. This web site is used as a means to make files and information easily available to customers.
PAGE 33
AT42QT1012 • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act.
PAGE 34
AT42QT1012 ISBN: 978-1-5224-2071-2 Quality Management System Certified by DNV ISO/TS 16949 Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California ® ® and India. The Company’s quality system processes and procedures are for its PIC MCUs and dsPIC ® DSCs, KEELOQ code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products.
PAGE 35
Worldwide Sales and Service AMERICAS ASIA/PACIFIC ASIA/PACIFIC EUROPE Corporate Office 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http://www.microchip.com/ support Web Address: www.microchip.