- 您現(xiàn)在的位置：買(mǎi)賣(mài)IC網(wǎng) > PDF目錄376803 > DM9374 (Fairchild Semiconductor Corporation) 7-Segment Decoder/Driver/Latch with Constant Current Sink Outputs(恒流耗散輸出的7段顯示譯碼器/驅(qū)動(dòng)器/鎖存器) PDF資料下載
參數(shù)資料
| 型號(hào)： | DM9374 |
| 廠(chǎng)商： | Fairchild Semiconductor Corporation |
| 英文描述： | 7-Segment Decoder/Driver/Latch with Constant Current Sink Outputs(恒流耗散輸出的7段顯示譯碼器/驅(qū)動(dòng)器/鎖存器) |
| 中文描述： | 7段解碼器/驅(qū)動(dòng)器/接收器輸出恒定電流（恒流耗散輸出的7段顯示譯碼器/驅(qū)動(dòng)器/鎖存器鎖存） |
| 文件頁(yè)數(shù)： | 4/8頁(yè) |
| 文件大?。?/td> | 91K |
| 代理商： | DM9374 |
www.fairchildsemi.com
4
D
Applications
It is possible with common anode 7-segment LED displays
and constant current sink decoder drivers to save substan-
tial amounts of power by carefully choosing operating
points on display supply voltage. First, examine the power
used in the normal display driving method where the dis-
play and decoder driver are both operated from a
+
5.0V
regulated supply (V
CC
=
V
S
).
The power dissipated by the LED and the driver outputs is
(V
CC
x I
seg
x n Segments). The total power dissipated with
a 15 mA LED displaying an eight (8) would be:
P
TOT
=
5.0V x 15 mA x 7
=
525 mW
Of this 525 mW, the power actually required to drive the
LED is dependent on the V
F
drop of each segment. Most
GaAsP LEDs exhibit either a 1.7V or a 3.4V forward volt-
age drop. Therefore, the required total power for seven
segments would be:
P
(1.7)
=
1.7V x 15 mA x 7
=
178.5 mW
P
(3.4)
=
3.4V x 15 mA x 7
=
357 mW
The remaining power is dissipated by the driver outputs
which are maintaining the 15 mA constant current required
by the LEDs. Most of this power is wasted, since the driver
can maintain approximately 15 mA with as little as 0.5V
across the output device. By using a separate power
source (V
S
, Figure 1) for the LEDs, which is set to the LED
V
F
plus the offset voltage of the driver, as much as 280 mW
can be saved per digit. i.e.,
V
S
=
V
F
(Max)
+
V
offset
=
2.0V
+
0.5V
=
2.5V
P
T
=
2.5V x 14 mA (from Figure 6) x 7
=
245 mW
These figures show that using a separate supply to drive
the LEDs can offer significant display power savings. In
battery powered equipment, two rechargeable nickel-cad-
mium cells in series would be sufficient to drive the display,
while four such cells would be needed to operate the logic
units.
Another method to save power is to apply intensity modula-
tion to the displays (Figure 2). It is well known that LED dis-
plays are more efficient when operated in pulse mode.
There are two reasons: one, the quantum efficiency of the
LED material is better; secondly the eye tends to peak
detect. Typically a 20% off duty cycle to displays (GaAsP)
will produce the same brightness as operating under dc
conditions.
FIGURE 1. Separate Supply for LED Displays
All Inverters are DTL 9936 or Open Collector TTL 7405
FIGURE 2. Intensity Control by RBO Pulse Duty Cycle
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DM9374N | 7-Segment Decoder/Driver/Latch with Constant Current Sink Outputs |
| DM93L14 | Quad Latch(四鎖存器) |
| DM93L14N | Quad Latch |
| DM93L28 | Dual 8-Bit Shift Register(雙8位移位寄存器) |
| DM93L28N | Dual 8-Bit Shift Register |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DM9374N | 功能描述:編碼器、解碼器、復(fù)用器和解復(fù)用器 7-Seg Dec/Drv/Latch RoHS:否 制造商:Micrel 產(chǎn)品:Multiplexers 邏輯系列:CMOS 位數(shù): 線(xiàn)路數(shù)量（輸入/輸出）:2 / 12 傳播延遲時(shí)間:350 ps, 400 ps 電源電壓-最大:2.625 V, 3.6 V 電源電壓-最小:2.375 V, 3 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Tray |
| DM9386 | 制造商:NSC 制造商全稱(chēng):National Semiconductor 功能描述:4-Bit Quad Exclusive-NOR with Open-Collector Outputs |
| DM93L00 | 制造商:未知廠(chǎng)家 制造商全稱(chēng):未知廠(chǎng)家 功能描述: |
| DM93L01 | 制造商:未知廠(chǎng)家 制造商全稱(chēng):未知廠(chǎng)家 功能描述: |
| DM93L08 | 制造商:未知廠(chǎng)家 制造商全稱(chēng):未知廠(chǎng)家 功能描述: |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。