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參數(shù)資料
| 型號(hào)： | SC1401 |
| 廠商： | Semtech Corporation |
| 英文描述： | High Performance Synchronous Buck Controller with LDO for Portable Power(用于便攜式電源帶低壓差輸出的高性能同步步降控制器（1.25-5.5V可調(diào)輸出）) |
| 中文描述： | 高性能同步降壓控制器用于便攜式電源穩(wěn)壓器（用于便攜式電源帶低壓差輸出的高性能同步步降控制器（1.25 - 5.5V的可調(diào)輸出）） |
| 文件頁數(shù)： | 16/17頁 |
| 文件大?。?/td> | 268K |
| 代理商： | SC1401 |
16
2001 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
Applications Information (Cont.)
SC1401
circuit condition. These are 30V, 9A FETs. Based on 85°C
ambient temperature, 150°C junction temperature and
thermal resistance, their power handling is calculated as
follows:
Power Limit for Upper & Lower FET:
T
J
= 150°C; T
A
= 85°C;
θ
JA
= 50°C/W
Each FET must not exceed 1.3W of power dissipation.
The conduction losses for the upper & lower FET can be
determined. For the calculations below, a nominal input
voltage of 12V, for V
= 2.0V, I
= 7A and f = 300kHz.
The R
value for the upper & lower FET is 11 milliohms.
We will calculate the conduction losses and switching
losses for each FET. From the calulations below we are
well within the 1.3 watt dissipation limit as calulated
above.
Conduction Losses Upper FET:
P
CU
= 0.090W
Conduction Losses Lower FET:
P
CL
= 0.225W
Switching Losses Upper FET:
Note: Switching losses exist on the upper FET only
because the clamp diode across the lower FET will turn
on prior to the lower FET turning on.
P
SU
= 0.065W
Crss is the reverse transfer capacitance of the FET; in
case it equals 215pF for the IRF7805.
Where I
is the gate driver current. This is equal to 2A for
the SC1401.
So the total FET losses equate to:
P
FETS
= 0.09 + 0.225 + 0.065 = 0.38W.
Note that as V
increases, the power dissipation from
switching losses will also increase. This is especially
important if the input to the supply is from an AC adapter.
Therefore, it is necessary to check the calulations with
your maximum input voltage specification. In addition,
the distribution of power in the upper and lower FET will
change as input voltage increases.
Other losses to consider are gate charge losses, inductor
switching and copper losses, and losses in the input and
output capacitors. All these items will decrease efficiency
and need to be carefully analyzed to obtain the highest
efficiency possible, especially if running off battery power.
1.3W
50
85
150
T
T
P
JA
A
J
T
=
=
=
θ
2
DS
CU
I
D
R
P
=
2
CU
7
12
2
0.011
P
=
2
DS
CL
I
D)
(1
R
P
=
2
CL
7
12
2
1
0.0055
P
=
7
1
300000
12
10
215
I
I
F
V
C
P
2
12
G
O
2
IN
RSS
SU
=
=
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SC1402 | Multi-Output, Low-Noise Power Supply Controller for Notebook Computers |
| SC1402ISS | Multi-Output, Low-Noise Power Supply Controller for Notebook Computers |
| SC1403ITSTRT | Mobile Multi-Output PWM Controller with Lossless Current Sense |
| SC1403 | Mobile Multi-Output PWM Controller with Virtual Current SenseTM |
| SC1403ITSTR | Mobile Multi-Output PWM Controller with Virtual Current SenseTM |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SC1401ISS | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:HIGH PERFORMANCE SYNCHRONOUS BUCK CONTROLLER WITH LDO FOR PORTABLE POWER |
| SC1402 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Multi-Output, Low-Noise Power Supply Controller for Notebook Computers |
| SC1402ISS | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Multi-Output, Low-Noise Power Supply Controller for Notebook Computers |
| SC1403 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Mobile Multi-Output PWM Controller with Virtual Current SenseTM |
| SC1403_04 | 制造商:SEMTECH 制造商全稱:Semtech Corporation 功能描述:Mobile Multi-Output PWM Controller with Lossless Current Sense |
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