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參數(shù)資料
| 型號(hào)： | MAX6979 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | AND-OR-invert Gates 14-CDIP -55 to 125 |
| 中文描述： | 16端口、5.5V恒流LED驅(qū)動(dòng)器，帶有LED故障檢測(cè)和看門狗 |
| 文件頁(yè)數(shù)： | 9/12頁(yè) |
| 文件大小： | 304K |
| 代理商： | MAX6979 |
Applications Information
Selecting External Component R
SET
to Set
LED Output Current
The MAX6971 uses an external resistor, R
SET
, to set the
LED current for outputs OUT0–OUT15. The minimum
allowed value of R
SET
is 327.3
, which sets the output
currents to 55mA. The maximum allowed value of R
SET
is 5k
. The reference value, 360
, sets the output cur-
rents to 50mA. To set a different output current, use the
formula:
R
SET
= 18,000 / I
OUT
where I
OUT
is the desired output current in mA.
Computing Power Dissipation
The upper limit for power dissipation (P
D
) for the
MAX6971 is determined by the following equation:
P
D
= (V+ x I+) + (V
OUT
x DUTY x I
OUT
x N)
where:
V+ = supply voltage
I+ = operating supply current when sinking I
OUT
LED
drive current into N outputs
DUTY = PWM duty cycle applied to
OE
N = number of MAX6971 outputs driving LEDs at the
same time (maximum is 16)
V
OUT
= MAX6971 port output voltage when driving load
LED(s)
I
OUT
= LED drive current programmed by R
SET
P
D
= power dissipation, in mW if currents are in mA
Dissipation example:
I
OUT
= 20mA, N = 16, DUTY = 1, V
OUT
= 2V, V+ =
5.25V
P
D
= (5.25V x 25mA) + (2V x 1 x 20mA x 16) = 0.77W
Thus, for a 24-pin TSSOP package (T
JA
= 1 / 0.0122 =
+82°C/W from the
Absolute Maximum Ratings
), the
maximum allowed ambient temperature T
A
is given by:
T
J(MAX)
= T
A
+ (P
D
x T
JA
) = +150°C =
T
A
+ (0.77 x 82°C/W)
so T
A
= +86°C.
Overtemperature Cutoff
The MAX6971 contains an internal temperature sensor
that turns off all outputs when the die temperature
exceeds approximately +165°C. The outputs are
enabled again when the die temperature drops below
approximately +140°C. Register contents are not
affected, so when a driver is overdissipating, the exter-
nal symptom is the load LEDs cycling between on and
off as the driver repeatedly overheats and cools, alter-
nately turning the LEDs off and then back on again.
Power-Supply Considerations
The MAX6971 operates with a chip supply V+, and one
or more LED supplies. Bypass each supply to GND
with a 0.1μF capacitor as close to the MAX6971 as pos-
sible. This is normally adequate for static LED driving.
For multiplex or PWM applications, it is necessary to
add an additional bulk electrolytic capacitor of 4.7μF or
more to each supply for every 4 to 16 MAX6971s. The
necessary capacitance depends on the LED load cur-
rent, PWM switching frequency, and serial-interface
speed. Inadequate V+ decoupling can cause timing
problems, and very noisy LED supplies can affect LED
current regulation.
Chip Information
PROCESS: BiCMOS
M
16-Port, 36V Constant-Current LED Driver
_______________________________________________________________________________________
9
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6979ANG | 功能描述:LED顯示驅(qū)動(dòng)器 RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)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 |
| MAX6979APG | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX6979AUG | 功能描述:LED顯示驅(qū)動(dòng)器 RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)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 |
| MAX6979AUG+ | 功能描述:LED照明驅(qū)動(dòng)器 16Port 5.5V Constant Current LED Driver RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
| MAX6979AUG+T | 功能描述:LED照明驅(qū)動(dòng)器 16Port 5.5V Constant Current LED Driver RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
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