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参数资料
型号： TSC2046EIPWG4
厂商： TEXAS INSTRUMENTS INC
元件分类： 消费家电
英文描述： SPECIALTY CONSUMER CIRCUIT, PDSO16
封装： GREEN, PLASTIC, TSSOP-16
文件页数： 13/33页
文件大小： 774K
代理商： TSC2046EIPWG4
TSC2046
SBAS265G OCTOBER 2002 REVISED JANUARY 2008
www.ti.com
20
LAYOUT
The following layout suggestions provide the most
optimum performance from the TSC2046. Many portable
applications, however, have conflicting requirements
concerning power, cost, size, and weight. In general, most
portable devices have fairly clean power and grounds
because most of the internal components are very low
power. This situation means less bypassing for the
converter power and less concern regarding grounding.
Still,
each
situation
is
unique
and
the
following
suggestions should be reviewed carefully.
For optimum performance, care should be taken with the
physical layout of the TSC2046 circuitry. The basic SAR
architecture is sensitive to glitches or sudden changes on
the power supply, reference, ground connections, and
digital inputs that occur just prior to latching the output of
the analog comparator. Therefore, during any single
conversion for an n-bit SAR converter, there are n
‘windows’ in which large external transient voltages can
easily affect the conversion result. Such glitches can
originate from switching power supplies, nearby digital
logic, and high-power devices. The degree of error in the
digital output depends on the reference voltage, layout,
and the exact timing of the external event. The error can
change if the external event changes in time with respect
to the DCLK input.
With this in mind, power to the TSC2046 should be clean
and well bypassed. A 0.1
F ceramic bypass capacitor
should be placed as close to the device as possible. A 1
F
to 10
F capacitor may also be needed if the impedance of
the connection between +VCC or IOVDD and the power
supplies is high. Low-leakage capacitors should be used
to minimize power dissipation through the bypass
capacitors when the TSC2046 is in power-down mode.
A bypass capacitor is generally not needed on the VREF
pin because the internal reference is buffered by an
internal op amp. If an external reference voltage originates
from an op amp, make sure that it can drive any bypass
capacitor that is used without oscillation.
The TSC2046 architecture offers no inherent rejection of
noise or voltage variation in regards to using an external
reference input. This is of particular concern when the
reference input is tied to the power supply. Any noise and
ripple from the supply appears directly in the digital results.
Whereas high-frequency noise can be filtered out, voltage
variation due to line frequency (50Hz or 60Hz) can be
difficult to remove.
The GND pin must be connected to a clean ground point.
In many cases, this is the analog ground. Avoid
connections which are too near the grounding point of a
microcontroller or digital signal processor. If needed, run
a ground trace directly from the converter to the
power-supply entry or battery connection point. The ideal
layout includes an analog ground plane dedicated to the
converter and associated analog circuitry.
In the specific case of use with a resistive touch screen,
care should be taken with the connection between the
converter and the touch screen. Although resistive touch
screens have fairly low resistance, the interconnection
should be as short and robust as possible. Longer
connections are a source of error, much like the
on-resistance of the internal switches. Likewise, loose
connections can be a source of error when the contact
resistance changes with flexing or vibrations.
As indicated previously, noise can be a major source of
error in touch screen applications (e.g., applications that
require a backlit LCD panel). This EMI noise can be
coupled through the LCD panel to the touch screen and
cause flickering of the converted data. Several things can
be done to reduce this error, such as using a touch screen
with a bottom-side metal layer connected to ground to
shunt the majority of noise to ground. Additionally, filtering
capacitors from Y+, Y–, X+, and X pins to ground can also
help.
Caution
should
be
observed
under
these
circumstances for settling time of the touch screen,
especially operating in the single-ended mode and at high
data rates.
相关PDF资料
PDF描述
TSC2046IGQCR SPECIALTY CONSUMER CIRCUIT, PBGA48
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TSC2046IRGVT SPECIALTY CONSUMER CIRCUIT, PQCC16
相关代理商/技术参数
参数描述
TSC2046EIPWR 功能描述:触摸屏转换器和控制器 4-Wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20
TSC2046EIPWRG4 功能描述:触摸屏转换器和控制器 4-Wire w/ Low Voltage Digital I/O RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20
TSC2046EIRGVR 功能描述:触摸屏转换器和控制器 4-Wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20
TSC2046EIRGVRG4 功能描述:触摸屏转换器和控制器 4-Wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20
TSC2046EIRGVT 功能描述:触摸屏转换器和控制器 4-Wire Touch Screen Controller RoHS:否 制造商:Microchip Technology 类型:Resistive Touch Controllers 输入类型:3 Key 数据速率:140 SPS 分辨率:10 bit 接口类型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 电源电压:2.5 V to 5.25 V 电源电流:17 mA 工作温度:- 40 C to + 85 C 封装 / 箱体:SSOP-20
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