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参数资料
| 型号： | TSC2003I |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | ADC |
| 英文描述： | 3-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, SERIAL ACCESS, PDSO16 |
| 封装： | PLASTIC, TSSOP-16 |
| 文件页数： | 4/20页 |
| 文件大小： | 309K |
| 代理商： | TSC2003I |
TSC2003
12
SBAS162A
www.ti.com
The absolute value of this diode voltage can vary a few
millivolts; the Temperature Coefficient (TC) of this voltage is
very consistent at –2.1mV/
°C. During the final test of the end
product, the diode voltage would be stored at a known room
temperature, in memory, for calibration purposes by the user.
The result is an equivalent temperature measurement resolu-
tion of 0.3
°C/LSB.
Differential reference mode always uses the supply voltage,
through the drivers, as the reference voltage for the A/D
converter. VREF cannot be used as the reference voltage in
differential mode.
It is possible to use a high-precision reference on VREF in
single-ended reference mode for measurements which do
not need to be ratiometric (i.e.: battery voltage, temperature
measurement, etc.). In some cases, it could be possible to
power the converter directly from a precision reference.
Most references can provide enough power for the TSC2003,
but they might not be able to supply enough current for the
external load, such as a resistive touch screen.
TOUCH SCREEN SETTLING
In some applications, external capacitors may be required
across the touch screen for filtering noise picked up by the
touch screen, i.e.: noise generated by the LCD panel or
backlight circuitry. These capacitors will provide a low-pass
filter to reduce the noise, but they will also cause a settling
time requirement when the panel is touched. The settling
time will typically show up as a gain error. The problem is
that the input and/or reference has not settled to its final
steady-state value prior to the A/D converter sampling the
input(s), and providing the digital output. Additionally, the
reference voltage may still be changing during the measure-
ment cycle.
To resolve these settling time problems, the TSC2003 can be
commanded to turn on the drivers only without performing
a conversion (see Table I). Time can then be allowed before
the command is issued to perform a conversion. Generally,
the time it takes to communicate the conversion command
over the I2C bus is adequate for the touch screen to settle.
TEMPERATURE MEASUREMENT
In some applications, such as battery recharging, a measure-
ment of ambient temperature is required. The temperature
measurement technique used in the TSC2003 relies on the
characteristics of a semiconductor junction operating at a
fixed current level to provide a measurement of the tempera-
ture of the TSC2003 chip. The forward diode voltage (VBE)
has a well-defined characteristic versus temperature. The
temperature can be predicted in applications by knowing the
25
°C value of the V
BE voltage and then monitoring the delta
of that voltage as the temperature changes. The TSC2003
offers two modes of temperature measurement.
The first mode requires calibrations at a known temperature,
but only requires a single reading to predict the ambient
temperature. A diode is used during this measurement cycle.
The voltage across the diode is connected through the MUX
for digitizing the diode forward bias voltage by the A/D
converter with an address of C3 = 0, C2 = 0, C1 = 0, and
C0 = 0 (see Table I and Figure 6 for details). This voltage is
typically 600mV at +25
°C, with a 20A current through it.
A/D
Converter
MUX
X+
Temperature Select
TEMP0
TEMP1
FIGURE 6. Functional Block Diagram of Temperature
Measurement Mode.
The second mode does not require a test temperature calibra-
tion, but uses a two-measurement method to eliminate the
need for absolute temperature calibration and for achieving
2
°C/LSB accuracy. This mode requires a second conversion
with an address of C3 = 0, C2 = 1, C1 = 0, and C0 = 0, with
an 91 times larger current. The voltage difference between the
first and second conversion using 91 times the bias current
will be represented by kT/q 1n (N), where N is the current
ratio = 91, k = Boltzmann's constant (1.38054 10–23 elec-
trons volts/degrees Kelvin), q = the electron charge (1.602189
10–19 C), and T = the temperature in degrees Kelvin. This
mode can provide improved absolute temperature measure-
ment over the first mode, but at the cost of less resolution
(1.6
°C/LSB). The equation to solve for °K is:
°
K=
q
k 1n(N)
V
(1)
where:
V
V(I ) – V(I ) (in mV)
K
2.573 V K/mV
C
2.573
V(mV) – 273 K
91
1
=
∴=
=
oo
NOTE: The bias current for each diode temperature mea-
surement is only turned ON during the acquisition mode,
and, therefore, does not add any noticeable increase in
power, especially if the temperature measurement only oc-
curs occasionally.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TSC2003IPW | 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 |
| TSC2003IPWG4 | 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 |
| TSC2003IPWR | 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 |
| TSC2003IPWR | 制造商:Texas Instruments 功能描述:Controller IC |
| TSC2003IPWRG4 | 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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