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QT140-D Datasheet(PDF) 2 Page - Quantum Research Group |
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QT140-D Datasheet(HTML) 2 Page - Quantum Research Group |
2 / 14 page 1 - OVERVIEW QT140/150 devices are burst mode digital charge-transfer (QT) sensor ICs designed specifically for touch controls; they include all hardware and signal processing functions necessary to provide stable sensing under a wide variety of conditions. Only a single low cost capacitor per channel is required for operation. Figures 1-6 and 1-7 show basic circuits for these devices. See Table 1-1 for device pin listings. The DIP and SOIC pinouts are not the same and serious damage can occur if a part is miswired. 1.1 BASIC OPERATION The devices employ bursts of charge-transfer cycles to acquire signals. Burst mode permits low power operation, dramatically reduces RF emissions, lowers susceptibility to RF fields, and yet permits excellent speed. Internally, signals are digitally processed to reject impulse noise using a 'consensus' filter that requires three consecutive confirmations of detection. Each channel is measured in sequence starting with Channel 1. The QT switches and charge measurement hardware functions are all internal to the device. A single-slope switched capacitor ADC includes the QT charge and transfer switches in a configuration that provides direct ADC conversion; an external Cs capacitor accumulates the charge from sense-plate Cx, which is then measured. Larger values of Cx cause the charge transferred into Cs to rise more rapidly, reducing available resolution; as a minimum resolution is required for proper operation, this can result in dramatically reduced gain. Conversely, larger values of Cs reduce the rise of differential voltage across it, increasing available resolution by permitting longer QT bursts. The value of Cs can thus be increased to allow larger values of Cx to be tolerated. The IC is responsive to both Cx and Cs, and changes in Cs can result in substantial changes in sensor gain. lQ 2 QT140/150 1.01/1102 /RST OSC_I OSC_O OPT2 OPT1 SYNC NC OUT4 OUT3 OUT1 AKS OC NC Vss Vdd Vdd SNS1A SNS1B SNS2A SNS2B Vss OUT2 SNS3A SNS3B SNS4A SNS4B NC Vss SSOP /RST OSC_I OSC_O OPT2 OPT1 SYNC NC OUT4 OUT3 OUT1 AKS OC NC Vdd Vss Vss Vss SNS1A SNS1B SNS2A Vdd OUT2 SNS2B SNS3A SNS3B SNS4A SNS4B NC DIP Reset pin (active low input) /RST 28 Reset pin (active low input) /RST 28 Oscillator input OSC_I 27 Oscillator input OSC_I 27 Oscillator output OSC_O 26 Oscillator output OSC_O 26 Option Mode (Input pin - see Table 2-1) OPT2 25 Option Mode (Input pin - see Table 2-1) OPT2 25 Option Mode (Input pin - see Table 2-1) OPT1 24 Option Mode (Input pin - see Table 2-1) OPT1 24 Synchronization pin (I/O pin - pull high with 10K) SYNC 23 Synchronization pin (I/O pin - pull high with 10K) SYNC 23 Channel 5 output, o-d or p-p (n/c on QT140) NC/OUT5 22 Channel 5 output, o-d or p-p (n/c on QT140) NC/OUT5 22 Channel 4 output, o-d or p-p OUT4 21 Channel 4 output, o-d or p-p OUT4 21 Channel 3 output, o-d or p-p OUT3 20 Channel 3 output, o-d or p-p OUT3 20 Channel 2 output, o-d or p-p OUT2 19 Channel 2 output, o-d or p-p OUT2 19 Channel 1 output, o-d or p-p OUT1 18 Channel 1 output, o-d or p-p OUT1 18 Adjacent Key Suppression Opt. (input ; 1=AKS) AKS 17 Adjacent Key Suppression Opt. (input; 1=AKS) AKS 17 Output Option (input pin; 1= open drain) OC 16 Output Option (input pin; 1= open drain) OC 16 Sense pin (to Cs5) n/c on QT140 NC/SNS5B 15 Sense pin (to Cs5) n/c on QT140 NC/SNS5B 15 Sense pin (to Cs5, electrode) n/c on QT140 NC/SNS5A 14 Supply negative rail (ground) Vss 14 Sense pin (to Cs4) SNS4B 13 Sense pin (to Cs5, electrode) n/c on QT140 NC/SNS5A 13 Sense pin (to Cs4, electrode) SNS4A 12 Sense pin (to Cs4) SNS4B 12 Sense pin (to Cs3) SNS3B 11 Sense pin (to Cs4, electrode) SNS4A 11 Sense pin (to Cs3, electrode) SNS3A 10 Sense pin (to Cs3) SNS3B 10 Sense pin (to Cs2) SNS2B 9 Sense pin (to Cs3, electrode) SNS3A 9 Sense pin (to Cs2, electrode) SNS2A 8 Sense pin (to Cs2) SNS2B 8 Sense pin (to Cs1) SNS1B 7 Sense pin (to Cs2, electrode) SNS2A 7 Sense pin (to Cs1, electrode) SNS1A 6 Sense pin (to Cs1) SNS1B 6 Negative power (Ground) Vss 5 Sense pin (to Cs1, electrode) SNS1A 5 Negative power (Ground) Vss 4 Positive power Vdd 4 Negative power (Ground) Vss 3 Positive power Vdd 3 Positive power Vdd 2 Negative power (Ground) Vss 2 Positive power Vdd 1 Negative power (Ground) Vss 1 Description Name Pin Description Name Pin QT140 / QT150 DIP-28 QT140 / QT150 SSOP-28 Table 1-1 Pin Listing Fig 1-1 QT140 Pinouts NOTE: SSOP / DIP Pinouts are not the same! |
Similar Part No. - QT140-D |
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Similar Description - QT140-D |
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