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參數(shù)資料
| 型號： | IRU3138 |
| 廠商： | International Rectifier |
| 英文描述： | SYNCHRONOUS PWM CONTROLLER FOR TERMINATION POWER SUPPLY APPLICATIONS |
| 中文描述： | 同步PWM控制器終止電源應(yīng)用 |
| 文件頁數(shù)： | 8/18頁 |
| 文件大?。?/td> | 281K |
| 代理商： | IRU3138 |
8
Rev. 1.0
01/29/04
IRU3138
www.irf.com
For higher efficiency, a low ESR capacitor is recom-
mended. Choose three Poscap from Sanyo 6TPC150M
(6.3V, 150
μ
F, 40m
) with a maximum allowable ripple
current of 5.7A.
Inductor Selection
The inductor is selected based on operating frequency,
transient performance and allowable output voltage ripple.
Low inductor value results to faster response to step
load (high
i/
t) and smaller size but will cause larger
output ripple due to increase of inductor ripple current.
As a rule of thumb, select an inductor that produces a
ripple current of 10-40% of full load DC.
For the buck converter, the inductor value for desired
operating ripple current can be determined using the fol-
lowing relation:
i
V
V
IN
×
i
×
f
S
Where:
V
IN
= Maximum Input Voltage
V
OUT
= Output Voltage
i = Inductor Ripple Current
f
S
= Switching Frequency
t = Turn On Time
D = Duty Cycle
If
i = 25%(I
O
), then the output inductor will be:
The Panasonic PCCN6B series provides a range of in-
ductors in different values, low profile suitable for large
currents, 1.1
μ
H, 16A is a good choice for this applica-
tion. This will result to a ripple approximately 22% of
output current.
Output Capacitor Selection
The criteria to select the output capacitor is normally
based on the value of the Effective Series Resistance
(ESR). In general, the output capacitor must have low
enough ESR to meet output ripple and load transient
L = 0.91
μ
H
For V
IN
=5V, I
OUT
=12A and D=0.36, the I
RMS
=5.7A
I
RMS
= I
OUT
D
×
(1-D)
---(9)
Where:
D is the Duty Cycle, D=V
OUT
/V
IN.
I
RMS
is the RMS value of the input capacitor current.
I
OUT
is the output current for each channel.
V
IN
- V
OUT
= L
×
t
t = D
×
f
1
S
V
OUT
V
IN
L = (V
IN
- V
OUT
)
×
---(11)
Where:
V
O
= Output Voltage Ripple
i = Inductor Ripple Current
V
O
= 50mV and
I
22% of 12A = 2.64A
This results to: ESR=18.9m
ESR
≤
---(10)
I
O
V
O
requirements, yet have high enough ESR to satisfy sta-
bility requirements. The ESR of the output capacitor is
calculated by the following relationship:
The Sanyo TPC series, Poscap capacitor is a good choice.
The 6TPC330M, 330
μ
F, 6.3V has an ESR 40m
. Se-
lecting three of these capacitors in parallel, results to an
ESR of
13.3m
which achieves our low ESR goal.
The capacitor value must be high enough to absorb the
inductor's ripple current. The larger the value of capaci-
tor, the lower will be the output ripple voltage.
Power MOSFET Selection
The IRU3138 uses two N-Channel MOSFETs. The se-
lections criteria to meet power transfer requirements is
based on maximum drain-source voltage (V
DSS
), gate-
source drive voltage (V
GS
), maximum output current, On-
resistance R
DS(ON)
and thermal management.
The MOSFET must have a maximum operating voltage
(V
DSS
) exceeding the maximum input voltage (V
IN
).
The gate drive requirement is almost the same for both
MOSFETs. Logic-level transistor can be used and cau-
tion should be taken with devices at very low V
GS
to pre-
vent undesired turn-on of the complementary MOSFET,
which results a shoot-through current.
The total power dissipation for MOSFETs includes con-
duction and switching losses. For the Buck converter,
the average inductor current is equal to the DC load cur-
rent. The conduction loss is defined as:
The R
DS(ON)
temperature dependency should be consid-
ered for the worst case operation. This is typically given
in the MOSFET data sheet. Ensure that the conduction
losses and switching losses do not exceed the package
ratings or violate the overall thermal budget.
P
COND
(Upper Switch) = I
LOAD2
×
R
DS(ON)
×
D
×
P
COND
(Lower Switch) = I
LOAD2
×
R
DS(ON)
×
(1 - D)
×
= R
DS(ON)
Temperature Dependency
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| IRU3138CS | 制造商:IRF 制造商全稱:International Rectifier 功能描述:SYNCHRONOUS PWM CONTROLLER FOR TERMINATION POWER SUPPLY APPLICATIONS |
| IRU3138CSTR | 功能描述:IC REG CTRLR BUCK PWM VM 14-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| IRU3138CSTRPBF | 功能描述:電壓模式 PWM 控制器 SYNC PWM CTRLLER 1A .8V 200 to 400kHz RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| IRU3146 | 制造商:IRF 制造商全稱:International Rectifier 功能描述:DUAL SYNCHRONOUS PWM CONTROLLER WITH CURRENT SHARING CIRCUITRY AND AUTO-RESTART |
| IRU3146CF | 制造商:International Rectifier 功能描述:DC DC CNTRLR DUAL-OUT SYNC BUCK/W/PWM 4.5V TO 16V 28TSSOP - Bulk |
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