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參數(shù)資料
| 型號： | AD7877 |
| 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(shù)： | 27/44頁 |
| 文件大小： | 1002K |
| 代理商： | AD7877 |
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AD7877
V
OUT
falls. If the DAC output exceeds V
REF
, it starts to source
current, and V
OUT
has to further decrease to compensate. When
the DAC output is at full scale, V
OUT
is at its minimum.
Rev. A | Page 27 of 44
Note that the effect of the DAC on V
OUT
is opposite in voltage
mode to that in current mode. In current mode, increasing DAC
code increases the sink current, so V
OUT
increases with
increasing DAC code. In voltage mode, increasing DAC code
increases the DAC output voltage, reducing the sink current.
Calculate the resistor values as follows:
1.
Decide on the feedback current as before.
2.
Calculate the parallel combination of R1 and R3 when the
DAC output is zero:
R
P
=
REF
/
I
FB
3.
Calculate R2 as before, but use R
P
and V
OUTMAX
:
R2
=
R
P
(
V
OUT(MAX)
V
REF
)/
V
REF
4.
Calculate the change in feedback current between
minimum and maximum output voltages as before using
I
=
V
R2(MAX)
/
R2
V
R2(MIN)
/
R2
This is equal to the change in current through R1 between
zero output and full scale, which is also given by
I
=
current at zero
current at full scale
=
V
/
R1
(
V
REF
V
)/
R1
=
V
/
R1
5.
R1
=
V
FS
/
.
6.
Calculate R3 from R1 and R using
R3
= (
R1
×
R
P
)/(
R1
R
P
)
Example:
1.
V
CC
= 5 V and
V
FS
=
V
CC
.
V
OUT(MIN)
is 20 V and
V
OUT(MAX)
is
25 V.
V
REF
is 1.25 V. Allow 100 μA around the feedback
loop.
2.
R
P
= 1.25 V/100 μA = 12.5 k.
3.
R2
= 12.5 k × (25 1.25 )/1.25 = 237 k.
Use nearest preferred value of 240 k.
4.
I
= 25 V/240 k 20 V/240 k = 21 μA.
5.
R1
= 5 V/21 μA = 238 k.
Use nearest preferred value of 250 k.
6.
R3
= (180 k × 12.5 k)/(180 k 12.5 k) =13.4 k.
Use nearest preferred value of 13 k.
The actual adjustment range using these values is 21 V to 26 V.
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|---|---|
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| AD7877ACP-REEL7 | Touch Screen Controller |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD7877AACPZ-500RL7 | 制造商:Analog Devices 功能描述: |
| AD7877AACPZ-REEL7 | 制造商:Analog Devices 功能描述: |
| AD7877ACBZ-REEL | 功能描述:IC CTRLR TOUCH SCREEN 25-WLCSP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 觸摸屏控制器 系列:- 標準包裝:96 系列:- 類型:- 觸摸面板接口:- 輸入數(shù)/鍵:- 分辨率（位）:- 評估套件:* 數(shù)據(jù)接口:- 數(shù)據(jù)速率/采樣率 (SPS，BPS):- 電壓基準:- 電源電壓:- 電流 - 電源:- 工作溫度:- 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:帶卷 (TR) |
| AD7877ACBZ-REEL7 | 功能描述:IC CTRLR TOUCH SCREEN 25-WLCSP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 觸摸屏控制器 系列:- 標準包裝:96 系列:- 類型:- 觸摸面板接口:- 輸入數(shù)/鍵:- 分辨率（位）:- 評估套件:* 數(shù)據(jù)接口:- 數(shù)據(jù)速率/采樣率 (SPS，BPS):- 電壓基準:- 電源電壓:- 電流 - 電源:- 工作溫度:- 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:帶卷 (TR) |
| AD7877ACP | 制造商:Analog Devices 功能描述:TOUCH SCREEN CNTRLR 32LFCSP - Bulk |
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