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參數(shù)資料
| 型號： | MM74C912 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | Simplified Multi-Digit LED Display Controller(多數(shù)字式LED顯示控制器) |
| 中文描述： | 簡化的多位LED顯示控制器（多數(shù)字式的LED顯示控制器） |
| 文件頁數(shù)： | 4/26頁 |
| 文件大?。?/td> | 639K |
| 代理商： | MM74C912 |
As an example, suppose the NSN781 (2-digit, 0.7" common
catholde LED display) has been selected. These displays re-
quire an average current of 8 mA per segment for good illu-
mination. The MM74C911 multiplexes four digits; thus, any
one digit is on
1
4
of the time. Each digit must have a peak
current four times its average current to achieve the same
brightness. The MM74C911 must supply about 32 mA per
segment, and the MM74C912/MM74C917 would have to
supply a current six times the average current or about 48
mA.
The maximum digit driver current is the maximum number of
“on” segments multiplied by the segment current. For the
MM74C911 design, the digit current is
z
260 mA, and is
z
380 mA for the MM74C912/MM74C917. Using this digit
current value, the digit driver can be selected. Figure 7
shows possible digit driver ICs, but discrete transistors or
Darlingtons may also be used, and may be desirable in
some higher current applications. It is also important to keep
in mind that the output voltage of the driver at the designed
current, as this voltage can affect the display controllers cur-
rent drive. For most designs, an output voltage of
<
2V is
reasonable.
Once the digit driver has been chosen and the output voltage
at the desired current is known, the segment resistor, R
SEG
can be calculated using:
where V
is the voltage across the LED, 1.8V; V
DO
is the
digit driver output voltage at the chosen current; I
SEG
is the
AN006030-5
(a)
AN006030-6
(b)
FIGURE 6. Typical LED Connections for (a) MM74C912/MM74C917 (b) MM74C911
www.fairchildsemi.com
4
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MM74C917 | Simplified Multi-Digit LED Display Controller(多數(shù)字式LED顯示控制器) |
| MM74C912N | 6-Digit BCD Display Controller/Driver |
| MM74C914 | Hex Schmitt Trigger with Extended Input Voltage |
| MM74C914M | Hex Schmitt Trigger with Extended Input Voltage |
| MM74C914N | Hex Schmitt Trigger with Extended Input Voltage |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MM74C912N | 功能描述:LED顯示驅(qū)動器 6-Dgt BCD Dis Con/Dr RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
| MM74C914 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Hex Schmitt Trigger with Extended Input Voltage |
| MM74C914J | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Hex Schmitt Trigger with Extended Input Voltage |
| MM74C914M | 功能描述:變換器 Hex Schmitt Trigger RoHS:否 制造商:NXP Semiconductors 電路數(shù)量:6 邏輯系列:74ABT 邏輯類型:BiCMOS 高電平輸出電流:- 15 mA 低電平輸出電流:20 mA 傳播延遲時間:2.2 ns 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 工作溫度范圍: 封裝 / 箱體:DIP-14 封裝:Tube |
| MM74C914M_Q | 功能描述:變換器 Hex Schmitt Trigger RoHS:否 制造商:NXP Semiconductors 電路數(shù)量:6 邏輯系列:74ABT 邏輯類型:BiCMOS 高電平輸出電流:- 15 mA 低電平輸出電流:20 mA 傳播延遲時間:2.2 ns 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 工作溫度范圍: 封裝 / 箱體:DIP-14 封裝:Tube |
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