參數(shù)資料
型號(hào): L7981TR
廠商: STMICROELECTRONICS
元件分類: 穩(wěn)壓器
英文描述: SWITCHING REGULATOR, DSO8
封裝: 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, VFQFP-8
文件頁數(shù): 9/44頁
文件大?。?/td> 1315K
代理商: L7981TR
L7981
Application informations
Doc ID 15182 Rev 3
17/44
Equation 9
Where TON is the conduction time of the internal high side switch and TOFF is the conduction
time of the external diode (in CCM, FSW=1/(TON + TOFF)). The maximum current ripple, at
fixed Vout, is obtained at maximum TOFF that is at minimum duty cycle (see previous section
to calculate minimum duty). So fixing
ΔI
L=20% to 30% of the maximum output current, the
minimum inductance value can be calculated:
Equation 10
where FSW is the switching frequency, 1/(TON + TOFF).
For example for VOUT=5 V, VIN=24 V, IO=3 A and FSW=250 kHz the minimum inductance
value to have
ΔI
L = 30% of IO is about 18 μH.
The peak current through the inductor is given by:
Equation 11
So if the inductor value decreases, the peak current (that has to be lower than the current
limit of the device) increases. The higher is the inductor value, the higher is the average
output current that can be delivered, without reaching the current limit.
In the table below some inductor part numbers are listed.
Table 7.
Inductors
Manufacturer
Series
Inductor value (
μH)
Saturation current (A)
Coilcraft
MSS1038
3.8 to 10
3.9 to 6.5
MSS1048
12 to 22
3.84 to 5.34
Wurth
PD Type L
8.2 to 15
3.75 to 6.25
PD Type M
2.2 to 4.7
4 to 6
SUMIDA
CDRH6D226/HP
1.5 to 3.3
3.6 to 5.2
CDR10D48MN
6.6 to 12
4.1 to 5.7
ΔI
L
V
IN
V
OUT
L
------------------------------ T
ON
V
OUT
V
F
+
L
---------------------------- T
OFF
==
L
MIN
V
OUT
V
F
+
ΔI
MAX
----------------------------
1D
MIN
F
SW
-----------------------
=
I
LPK
,
I
O
ΔI
L
2
--------
+
=
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L7983 制造商:Leviton Manufacturing Co 功能描述:
L7985 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) 2A Step Down REG 4.5V to 38V 250 KHz RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L
L7985A 功能描述:直流/直流開關(guān)調(diào)節(jié)器 2A DC 4.5V to 38V 250 KHz Step-Down RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)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(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
L7985ATR 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) 2A Step-Down REG 2A DC 4.5 to 38V RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L
L7985TR 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) 2A Step-Down Reg 4.5V to 38V 250 KHz RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L