參數(shù)資料
型號(hào): L5980TR
廠商: STMICROELECTRONICS
元件分類: 穩(wěn)壓器
英文描述: 1.6 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
封裝: 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, VFQFPN-8
文件頁(yè)數(shù): 8/42頁(yè)
文件大?。?/td> 1188K
代理商: L5980TR
Application information
L5980
16/42
Doc ID 13003 Rev 6
5.2
Inductor selection
The inductance value fixes the current ripple flowing through the output capacitor. So the
minimum inductance value in order to have the expected current ripple has to be selected.
The rule to fix the current ripple value is to have a ripple at 20%-40% of the output current.
The inductance value can be calculated by the following equation:
Equation 6
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 40% of the maximum output current, the
minimum inductance value can be calculated:
Equation 7
where FSW is the switching frequency, 1/(TON + TOFF).
For example for VOUT = 3.3 V, VIN = 12 V, IO = 0.7 A and FSW = 250 kHz the minimum
inductance value to have
ΔI
L = 30% of IO is about 45 μH.
The peak current through the inductor is given by:
Equation 8
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)
Wurth
PD3 L
33 to 68
1.35 to 1.8
Coilcraft
MSS1038
39 to 68
1.62 to 2.04
LPS6235
12 to 33
1.4 to 2.2
Coiltronics
DRQ73
10 to 22
1.67 to 2.47
LD2
27 to 47
1.64 to 2.1
SUMIDA
CDR6D28MN
10 to 22
1.65 to 2.5
CDRH105RNP
27 to 56
1.9 to 2.7
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
--------
+
=
相關(guān)PDF資料
PDF描述
L5983 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
L5983TR 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO8
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