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參數(shù)資料
| 型號： | MAX749 |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 通用總線功能 |
| 英文描述： | Synchronous 4-Bit Up/Down Binary Counters 16-CFP -55 to 125 |
| 中文描述： | 數(shù)字調(diào)節(jié)LCD偏置電源 |
| 文件頁數(shù)： | 7/12頁 |
| 文件大?。?/td> | 105K |
| 代理商： | MAX749 |
Figure 4. Count-Up Operation
Figure 5. Reset Sequence without Shutdown. The device is not
shut down during reset.
Figure 6. Reset Sequence with Shutdown
In Figure 3, the MAX749 is reset when it is taken out of
shutdown, which sets the output at mid-scale. Figure 4
shows how to increment the counter. Figure 5 illustrates
a reset without shutting the device down.
Figure 7 provides an example of a sequence of opera-
tions: Starting from shutdown, the device is turned on,
incremented, reset to mid-scale without being shut
down, incremented again, and finally shut down.
S hutdown Mode
When CTRL and ADJ are both low, the MAX749 is shut
down (Table 1): The internal reference and biasing cir-
cuitry turn off, the output voltage drops to zero, and the
supply current drops to 15μA. The MAX749 retains its
DAC setting, simplifying software control.
Reset Mode
If ADJ is high when CTRL is low, the DAC set point is
reset to mid-scale and the MAX749 is not shut down.
Mid-scale is 32 steps from the minimum, 31 steps from
the maximum.
Design Proc edure
_________and Component S elec tion
S etting the Output V oltage
The MAX749’s output voltage is set using an external
resistor and the internal current-output DAC. The full-
scale output voltage is set by selecting the feedback
resistor R
FB
according to the formula:
-V
OUT(MAX)
= R
FB
x 20μA (Figure 1).
The device is in regulation when V
FB
= 0V.
DAC Adjustment
On power-up or after a reset, the counter sets the DAC
output to mid-range, and -V
= R
x 13.33μA. Each
rising edge of ADJ increments the counter (and there-
fore the DAC output) in the direction of -V
OUT(MAX)
by
one count. When incremented beyond -V
OUT(MAX)
, the
M
Digitally Adjustable LCD Bias S upply
_______________________________________________________________________________________
7
Figure 3. Shutdown-Reset-On-Shutdown Sequence of Operation.
The device is not shut down during reset.
Figure 7. Control Sequence Example (see Output Voltage
Control section)
ADJ
CTRL
SHUTDOWN RESET
ON
SHUTDOWN
t
R
t
SD
ADJ
CTRL
HIGH
t
SH
t
SL
ADJ
CTRL
ON
RESET
ON
t
RS
t
RH
t
R
ADJ
CTRL
SHUTDOWN
RESET
ON
SHUTDOWN
INCREMENT
INCREMENT
ADJ
CTRL
SHUTDOWN
RESET
ON
t
RH
t
R
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX749CSA | 4-Bit D-type Registers with 3-State Outputs 16-CDIP -55 to 125 |
| MAX749EPA | 4-Bit D-type Registers with 3-State Outputs 20-LCCC -55 to 125 |
| MAX749ESA | Digitally Adjustable LCD Bias Supply |
| MAX7524 | Retriggerable Monostable Multivibrators 16-CFP -55 to 125 |
| MAX7624 | CMOS 8-Bit Buffered Multiplying DACs |
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| MAX7490CEE-T | 功能描述:有源濾波器 RoHS:否 制造商:Maxim Integrated 通道數(shù)量:1 截止頻率:150 KHz 電源電壓-最大:11 V 電源電壓-最小:4.74 V 最大工作溫度:+ 85 C 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP N 封裝:Tube |
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