參數資料
型號： EVAL-AD7877EB
廠商： Analog Devices, Inc.
英文描述： Touch Screen Controller
中文描述： 觸摸屏控制器
文件頁數： 19/44頁
文件大?。?/td> 1002K
代理商： EVAL-AD7877EB
AD7877
AUXILIARY INPUTS
The AD7877 has three auxiliary analog inputs, AUX1 to AUX3.
These channels have a full-scale input range from 0 V to V
REF
.
The ADC channel addresses for AUX1 to AUX3 are 0011b,
0100b, and 0101b, and the results are stored in Registers 10011b,
10100b, and 10101b. These pins can also be reconfigured as
general-purpose logic inputs/outputs, as described in the GPIO
Configuration section.
Rev. A | Page 19 of 44
LIMIT COMPARISON
The AUX1 measurement, the two battery measurements, and
the TEMP1 measurement can all be compared with high and
low limits, and an out-of-limit result made to generate an alarm
output at the ALERT pin. The limits are stored in registers with
addresses from 00100b to 01011b. After a measurement from
any one of the four channels is converted, it is compared with
the corresponding high and low limits. An out-of-limit result
sets one of the status bits in the alert status/enable register. For
details on these and other registers, see the Register Maps and
Detailed Register Descriptions sections. For details on writing
and reading data, see the Serial Interface section.
As mentioned previously, the temperature comparison is made
using the result of the TEMP1 measurement, which is the diode
forward voltage. Because the temperature coefficient of the
diode is known but the actual forward voltage can have a wide
tolerance, it is not possible to program the high and low limit
registers with predetermined values.
Instead, it is necessary to calibrate the temperature measure-
ment, calculate the TEMP1 readings at the high and low limit
temperatures, and then program those values into the limit
registers, as follows:
1.
Calculate
LSB per degree
=
2.1 mV/(
V
REF
/4096).
2.
Save the calibration reading
D
CAL
at calibration temperature
T
CAL
.
3.
Subtract
T
CAL
from limit temperatures
T
HIGH
and
T
LOW
to get
the difference in degrees between the limit temperatures
and the calibration temperature.
4.
Multiply this value by
LSB per degree
to get the value in
LSBs.
5.
Add these values to the digital value at the calibration
temperature to get the digital high and low limit values.
Example:
The internal 2.5 V reference is used.
1.
T
HIGH
= +65°C and
T
LOW
=
10°C.
2.
LSB per degree
=
2.1 × 10
3
/(2.5/4096) =
3.44.
3.
D
CAL
= 983 decimal at 25°C.
4.
D
HIGH
= (65
25) ×
3.44 + 983 = 845.
5.
D
LOW
= (
10
25) ×
3.44 + 983 = 1103.
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參數描述
EVAL-AD7877EBZ 功能描述:BOARD EVALUATION FOR AD7877 RoHS:是 類別:編程器，開發(fā)系統 >> 評估演示板和套件 系列:- 標準包裝:1 系列:- 主要目的:電信，線路接口單元（LIU） 嵌入式:- 已用 IC / 零件:IDT82V2081 主要屬性:T1/J1/E1 LIU 次要屬性:- 已供物品:板，電源，線纜，CD 其它名稱:82EBV2081
EVAL-AD7879-1EBZ 功能描述:BOARD EVALUATION FOR AD7879-1 RoHS:是 類別:編程器，開發(fā)系統 >> 評估演示板和套件 系列:- 標準包裝:1 系列:- 主要目的:電信，線路接口單元（LIU） 嵌入式:- 已用 IC / 零件:IDT82V2081 主要屬性:T1/J1/E1 LIU 次要屬性:- 已供物品:板，電源，線纜，CD 其它名稱:82EBV2081
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EVAL-AD7887CB4 制造商:AD 制造商全稱:Analog Devices 功能描述:2.7 V to 5.25 V, Micropower, 2-Channel, 125 kSPS, 12-Bit ADC in 8-Lead MSOP
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