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參數(shù)資料
| 型號： | AD5227 |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | 數(shù)字電位計 |
| 英文描述： | 64-Position Up/Down Control Digital Potentiometer |
| 中文描述： | 64工位上/下控制數(shù)字電位器 |
| 文件頁數(shù)： | 13/16頁 |
| 文件大小： | 331K |
| 代理商： | AD5227 |
AD5227
The U1 ADP3333ARM-1.5 is a 1.5 V LDO that is lifted above or
lowered below 0 V. When V
WB
of the AD5227 is at minimum,
there is no current through D1, so the GND pin of U1 would be
at –1.5 V if U3 were biased with the dual supplies. As a result,
some of the U2 low resistance steps have no effect on the output
until the U1 GND pin is lifted above 0 V. When V
WB
of the
AD5227 is at its maximum, V
OUT
becomes V
L
+ V
AB
, so the U1
supply voltage must be biased with adequate headroom.
Similarly, a PWM signal can be applied at the U1 shutdown pin
for power efficiency. This circuit works well for a single LED.
Rev. 0 | Page 13 of 16
ADJUSTABLE HIGH POWER LED DRIVER
Figure 35 shows a circuit that can drive three to four high power
LEDs. ADP1610 is an adjustable boost regulator that provides
the voltage headroom and current for the LEDs. The AD5227
and the op amp form an average gain of 12 feedback network
that servos the R
SET
voltage and ADP1610’s FB pin 1.2 V band
gap reference voltage. As the loop is set, the voltage across R
SET
is
regulated around 0.1 V and adjusted by the digital
potentiometer.
SET
R
LED
R
V
I
SET
=
(6)
R
SET
should be small enough to conserve power but large
enough to limit maximum LED current. R3 should also be used
in parallel with AD5227 to limit the LED current within an
achievable range. A wider current adjustment range is possible
by lowering the R2 to R1 ratio, as well as changing R3 accordingly.
0
SS
RT GND
IN
ADP1610
SD
SW
FB
COMP
PWM
1.2V
C
10nF
C
C
390pF
R
C
100k
L1
10
μ
F
D1
C3
10
μ
F
R4
13.5k
D2
D3
D4
V
OUT
C2
10
μ
F
5V
+
–
AD8541
U1
L1–SLF6025-100M1R0
D1–MBR0520LT1
U3
V+
V–
5V
C8
0.1
μ
F
U1
AD5227
B
A
10k
R3
200
W
R1
100
R2
1.1k
R
SET
0.25
Figure 35. Adjustable Current Source for LEDs in Series
AUTOMATIC LCD PANEL BACKLIGHT CONTROL
With the addition of a photocell sensor, an automatic brightness
control can be achieved. As shown in Figure 36, the resistance of
the photocell changes linearly but inversely with the light output.
The brighter the light output, the lower the photocell resistance
and vice versa. The AD5227 sets the voltage level that is gained
up by U2 to drive N1 to a desirable brightness. With the photocell
acting as the variable feedback resistor, the change in the light
output changes the R2 resistance, therefore causing U2 to drive
N1 accordingly to regulate the output. This simple low cost
implementation of the LED controller can compensate for the
temperature and aging effects typically found in high power
LEDs. Similarly, for power efficiency, a PWM signal can be
applied at the gate of N2 to switch the LED on and off without
any noticeable effect.
0
CS
CLK
U/D
A
W
B
GND
10k
V
DD
U1
AD5227
C1
1
μ
F
C2
0.1
μ
F
5V
U2
AD8591
+
–
V+
V–
5V
C3
0.1
μ
F
R1
1k
R2
5V
PWM
N1
2N7002
WHITE
LED
D1
5V
PHOTOCELL
SD
Figure 36. Automatic LCD Panel Backlight Control
6-BIT CONTROLLER
The AD5227 can form a simple 6-bit controller with a clock
generator, a comparator, and some output components. Figure 37
shows a generic 6-bit controller with a comparator that first
compares the sampling output with the reference level and
outputs either a high or low level to the AD5227 U/D pin. The
AD5227 then changes step at every clock cycle in the direction
indicated by the U/D state. Although this circuit is not as elegant
as the one shown in Figure 36, it is self-contained, very easy to
design, and can adapt to various applications.
0
CLK
U/D
B
GND
5V
V
DD
CS
AD5227
+
–
COMU2
SAMPLING_OUTPUT
REF
AD8531
+
–
OUTPUT
OP AMP
Figure 37. 6-Bit Controller
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| AD5227BUJZ10 | 制造商:Analog Devices 功能描述:DGTL POTENTIOMETER 64POS 10KOHM SGL 8PIN TSOT - Bulk 制造商:Analog Devices 功能描述:IC,Digital Pot,AD5227BUJZ10 |
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| AD5227BUJZ100-R2 | 功能描述:IC DGTL POT 100K UP/DN TSOT23-8 RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)字電位器 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:DPP 接片:32 電阻（歐姆）:10k 電路數(shù):1 溫度系數(shù):標(biāo)準(zhǔn)值 300 ppm/°C 存儲器類型:非易失 接口:3 線串行（芯片選擇，遞增，增/減） 電源電壓:2.5 V ~ 6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-WFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:8-TDFN（2x3） 包裝:帶卷 (TR) |
| AD5227BUJZ100-R22 | 制造商:AD 制造商全稱:Analog Devices 功能描述:64-Position Up/Down Control Digital Potentiometer |
| AD5227BUJZ100-RL7 | 功能描述:IC DGTL POT UP/DN 100K TSOT23-8 RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)字電位器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- 接片:256 電阻（歐姆）:100k 電路數(shù):1 溫度系數(shù):標(biāo)準(zhǔn)值 35 ppm/°C 存儲器類型:非易失 接口:3 線串口 電源電壓:2.7 V ~ 5.25 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-WDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:8-TDFN-EP（3x3） 包裝:剪切帶 (CT) 產(chǎn)品目錄頁面:1399 (CN2011-ZH PDF) 其它名稱:MAX5423ETA+TCT |
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