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參數(shù)資料
| 型號： | L5981TR |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 3 X 3 MM, 1.08 MM HEIGHT, LEAD FREE, VFQFPN-8 |
| 文件頁數(shù)： | 6/37頁 |
| 文件大?。?/td> | 714K |
| 代理商： | L5981TR |
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Application information
L5981
14/37
Doc ID 13004 Rev 6
5
Application information
5.1
Input capacitor selection
The capacitor connected to the input has to be capable to support the maximum input
operating voltage and the maximum RMS input current required by the device. The input
capacitor is subject to a pulsed current, the RMS value of which is dissipated over its ESR,
affecting the overall system efficiency.
So the input capacitor must have a RMS current rating higher than the maximum RMS input
current and an ESR value compliant with the expected efficiency.
The maximum RMS input current flowing through the capacitor can be calculated as:
Equation 3
Where Io is the maximum DC output current, D is the duty cycle,
η is the efficiency.
Considering η = 1, This function has a maximum at D = 0.5 and it is equal to Io/2.
In a specific application the range of possible duty cycles has to be considered in order to
find out the maximum RMS input current. The maximum and minimum duty cycles can be
calculated as:
Equation 4
and
Equation 5
Where VF is the forward voltage on the freewheeling diode and VSW is voltage drop across
the internal PDMOS. In Table 6 some multi layer ceramic capacitors suitable for this device
are reported
Table 6.
Input MLCC capacitors
Manufacturer
Series
Cap value (
μF)
Rated voltage (V)
MURATA
GRM31
10
25
GRM55
10
25
TDK
C3225
10
25
I
RMS
I
O
D
2D
2
η
---------------
–
D
2
η2
-------
+
=
D
MAX
V
OUT
V
F
+
V
INMIN
V
SW
–
-------------------------------------
=
D
MIN
V
OUT
V
F
+
V
INMAX
V
SW
–
--------------------------------------
=
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| L5983 | 功能描述:直流/直流開關調節(jié)器 1.5A STEP-DOWN SWITCHING REGULATOR RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| L5983_08 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:1.5 A step-down switching regulator |
| L5983TR | 功能描述:直流/直流開關調節(jié)器 1.5a Step-Down Switching Reg RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| L5985 | 功能描述:直流/直流開關調節(jié)器 2A STEP-DOWN SWITCH REGULATOR RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| L5985_08 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:2 A step-down switching regulator |
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