SS7646 SSC | Alldatasheet
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www.SiliconStandard.com 1 of 5 SS7646 8/21/2004 Rev.2.01 Touch Screen Controller FEATURES DESCRIPTION Pin compatible with SS7643 Serial interface Interface for 4-wire touch-screen Embedded touch-screen drivers Internal 2.5V reference Direct battery measurement (0V to 6V) Touch-pressure measurement One auxiliary analog input On-chip temperature sensor Supply voltage from 2.2V to 5.5V 12-bit analog-to-digital converter Programmable 8- or 12-bit resolution Conversion rate up to 125kHz Full power-down control 16 pin SSOP package
APPLICATIONS
Personal Digital Assistants Point-of-Sale Terminals Pagers High-Speed Data Acquisition Portable Instruments Low-power Instruments The SS7646 touch-screen controller IC is an advanced version of the previous controller, the SS7643. The SS7646 is a 12-biit SAR analog-to-digital converter (ADC) with SPI serial interface and low-on resistance drivers for 4-wire resistive touch screens. The SS7646 is fully pin-compatible with the SS7643. The SS7646 is a highly-integrated controller for portable applications using 4-wire resistive touch screens, such as PDAs, portable instruments, cell phones, etc. The SS7646 contains all the analog and digital circuitry necessary to complete a pen request, and features temperature, battery monitor and touch-pressure measurements. The SS7646 also features an internal 2.5V reference that can be turned ON or OFF independently of the ADC. The SS7646 consumes only 405 µW (with the internal reference OFF) at a sample rate of 125kHz with a 2.7V supply and consumes less than 2.7 µW in the shutdown mode. The SS7646 will operate with a supply down to 2.2V. The SS7646 is supplied in a very small 16-lead SSOP package and is guaranteed over the temperature range. ORDERING INFORMATION PIN CONFIGURATION SS7646 15 /CS
16 DCLK
14 DIN
12 DOUT
13 BUSY
SS7646 in SSOP-16 shipped on tape and reel
specification is not implied. subtle performance degradation to complete device failure. 1 VDD Power Supply, 2.2V to 5.5V. 2 X+ X+ Input; ADC Input Channel 1. 3 Y+ Y+ Input; ADC Input Channel 2. 5 Y- Y- Input; ADC Input Channel 3. 7 VBAT Battery Monitor Input; ADC Input Channel 4. 8 VIN Auxiliary Input; ADC Input Channel 5. 9 VREF Reference Voltage Input / Output. 10 VDD Po wer Supply, 2.2V to 5.5V. 15 /CS Chip Select Input. This input is active low. 16 DCLK External Clock Input. Figure 1. Block Diagram of SS7646
www.SiliconStandard.com 3 of 5 SS7646 8/21/2004 Rev.2.01 Electrical Specifications (TA = -40 °C to +85 °C, VDD=+2.7V, VREF=+2.7V, fSample=125KHz, fCLK=24*fSample, 12-bit mode, Digital Inputs= GND or +VDD. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER TEST CONDITIONS MIN. TYP. MAX. UNITS Power Supply Requirement VDD Quiescent Current Power Dissipation Specified Performance Functional Operating Range Internal Reference OFF Internal Reference ON Shut Down Mode Internal Reference OFF Internal Reference ON Shut Down Mode 2.7 2.2 150 600 0.40 1.62 3.6 5.5 2.7 V V µA µA µA mW mW µW System Performance Resolution INL DNL Gain Error Offset Error Bits LSB LSB LSB LSB Digital Input/Output Logic Family VOH VOL VIH VIL /PENIRQ VOL CMOS Logic 100kW Pull-Up VDD*0.8 VDD*0.7 -0.3 0. 6 0.4 V DD + 0.3 0.8 V V V V V Analog Input Input Span Input Range Capacitance -0.2 V REF VDD + 0.2 V V pF Reference Output Internal Reference Voltage Internal Reference Thermal Drift Quiescent Current Internal Reference ON (PD1=”1”) (Functional from 2.7V to 5.5V V DD) 2.45 2.50 500 2.55 V ppm/ °C µA Reference Input Input Range Input Current Internal Reference OFF (PD1=”0”) V DD V µA X / Y Switches X+, Y+ X -, Y - Switch On-Resistance Switch On-Resistance W W Battery Monitor Input Voltage Range Accuracy Internal Reference 0.5 6.0 V Temperature Measurement Operating Temperature Range Resolution Accuracy Differential Method (TEMP1-TEMP0) Single Conversion (TEMP0) Differential Method (TEMP1-TEMP0) Single Conversion (TEMP0) -40 1.5 0.3 +85 °C
www.SiliconStandard.com 4 of 5 SS7646 8/21/2004 Rev.2.01 Timing Specifications: (TA = -40°C to +85°C, VDD≧+2.7V, CLOAD=50pF. Typical values are at TA = +25°C, unless otherwise noted.) SYMBOL DESCRIPTION MIN TYP MAX UNITS TACQ ADC acquisition time 500 ns TCON ADC conversion time 6.5 µs TCSF /CS falling to first DCLK rising 100 ns TCSR /CS rising to DCLK ignored 0 ns TDOF /CS falling to DOUT enable 200 ns TDOR /CS rising to DOUT disable 200 ns TBSF /CS falling to BUSY enable 200 ns TBSR /CS rising to BUSY disable 200 ns TCKH DCLK High Period 200 ns TCKL DCLK LOW Period 200 ns TDIS DIN valid before DCLK rising 100 ns TDIH DIN hold time after DCLK going high 15 ns TDO DCLK falling to DOUT valid 200 ns TBO DCLK falling to BUSY rising 200 ns Timing Diagram: /CS DCLK X/Y SWITCH DIN BUSY DOUT 18 1 18 ON Acquire Tri-State Tri-State Tri-State Tri-State (MSB) (LSB) 11 0 TACQ TCON TCSF TCSR TDOF TDOR TBSRTBSF TCKH TCK/L DIST TDIH TDOBOT
in the very small 16-pin SSOP package.
- The SS7646 operates on a single supply
(/CS, DCLK, DIN and DOUT) is shown in Figu re 2. total 24 clock cycles on the DCLK input. of the operation the /CS pin should be brought high. supply current if DCLK is left running. 6, 5, 4 A2, A1, A0 Input Channel Select Bits. Figure 2. Serial Interface of SS7646
www.SiliconStandard.com 4 of 5 SS7646 8/21/2004 Rev.2.01 The Control Byte : Table I and Table II show detailed information of the control byte (on DIN). The control byte provides the start operation, addressing, resolution, reference and power down information to the SS7646. Start Bit – Initiate Start The control byte starts with the first high bit on DIN. The first bit must always be HIGH (1) to initiate the start of the conversion. The SS7646 will ignore any inputs on the DIN until the start bit is detected. Addressing Bits – Input Channel Selection The next three bits on control byte (A2, A1, A0) select the active input channel of the input multiplexer (see Table III, and Figure 5), and touch screen drivers. Mode Bits – Resolution and Reference Configuration The Mode bits (Mode1, Mode0) set the resolution of the analog-to-digital (ADC) converter. With the Mode1 bit LOW (0) the following conversion will have 12 bits of resolution. With the Mode1 bit HIGH (1) the following conversion will have 8 bits of resolution. The MODE0 bit set the reference input of the ADC (see Reference Input section and Figure 5). Table IV shows detailed information of the Mode Bits. PD0 and PD1 Bits - Power Down Control The last two bits (PD1, PD0) control the power-down mode and pen interrupt request of the SS7646. If both bits are HIGH (1), the ADC is always powered up and pen interrupt will be disabled. If both bits are LOW (0), the ADC enters a power-down mode between conversions. The internal 2.5V voltage reference can be turned ON or OFF independently of the ADC with the PD1 bit. See Table V for more information. A2 A1 A0 Measure Input Channel X Switch Y Switch 0 0 1 Y-POSITION X+ OFF ON 1 0 1 X-POSITION Y+ ON OFF 0 1 1 Z1-POSITION X+ X- ON Y+ ON 1 0 0 Z2-POSITION Y- X- ON Y+ ON 0 1 0 Battery V BAT OFF OFF 1 1 0 Auxiliary V IN OFF OFF 0 0 0 TEMP0 - OFF OFF 1 1 1 TEMP1 - OFF OFF Table III. Input Channel Configuration Operation of 16-Clocks The typical operation of the SS7646 is 24-clocks (three control bytes) per conversion. However the control bits for the next conversion can be overlapped with current conversion for a faster conversion. Figure 3 shows the timing of 16-Clocks per conversion. Operation of 15-Clocks The fastest operation (15-clocks per conversion) of SS7646 is shown on Figure 4. This operation will not work with the serial interface of most microcontrollers and digital signal processors, as they are not capable of providing 15 clocks cycles per serial transfer. MODE1 MODE0 Resolution ADC Reference 0 1 12bits V REF 0 0 12bits VDD 1 1 8bits V REF 1 0 8bits V DD Table IV. Resolution and Reference Configuration * When measuring Y(001), X(101), Z1(011) and Z2(100) positions, otherwise Invalid configuration PD1 PD0 /PENIRQ DESCRIPTION 0 0 Enable The reference is switching OFF and the ADC will power down between conversions. Y- switch is on while in power-down. 0 1 Enable The reference is switching OFF and the ADC is ON permanently. No power down between conversions. 1 0 Enable The reference is ON and the ADC will power down between conversions. 1 1 Disable The reference and the ADC are ON. No power down between conversions, the ADC always power up. The pen interrupt functionality will be disabled. Table V. Power-Down and Pen Interrupt Selection
Figure 5. Diagram of Input Channel and Reference Input SS7646. The control bits are set via the DIN pin. with PD1=”0” is required before /CS goes HIGH.
voltage V BE has a well-defined characteristic vs. Differential Conversion Mode. predicted accuracy of ± 3°C. resolution is redu ced to approximately 1.5 °C/LSB.
6 Channel
Figure 8. Block Diagram of Temperature Figure 9. Block Diagram of Battery
Information furnished by Silicon Standard Corporation is believed to be accurate and reliable. However, Silicon Standard Corporation makes no guarantee or warranty, express or implied, as to the reliability, accuracy, timeliness or completeness of such information and assumes no responsibility for its use, or for infringement of any patent or other intellectual property rights of third parties that may result from its use. Silicon Standard reserves the right to make changes as it deems necessary to any products described herein for any reason, including without limitation enhancement in reliability, functionality or design. No license is granted, whether expressly or by implication, in relation to the use of any products described herein or to the use of any information provided herein, under any patent or other intellectual property rights of Silicon Standard Corporation or any third parties. www.SiliconStandard.com 5 of 5 SS7646 8/21/2004 Rev.2.01
PACKAGE INFORMATION
DIMENSIONS (MM) DIMENSIONS (MIL) SYMBOLS A b C D E H e 0.6358 BSC 25 BSC L h θθθθ° 916 E H b L θ Detail F h x 45° See Detail F C D Seating Plane A1 A2 A T(4X) e 1.75 0.25 1.50 0.30 0.25 5.00 4.00 6.80 1.27 0.50 1.60 0.254 0.203 3.90 6.00 0.635 0.42 4.90 0.15 1.35 0.10 0.20 0.18 4.80 3.80 5.80 0.40 0.25 189 150 228 193 154 236 197 157 244