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參數(shù)資料
| 型號： | IR3638SPBF |
| 廠商： | International Rectifier |
| 英文描述： | HIGH FREQUENCY SYNCHRONOUS PWM BUCK CONTROLLER FOR TRACKING APPLIACTIONS |
| 中文描述： | 高頻同步PWM降壓控制器進行跟蹤APPLIACTIONS |
| 文件頁數(shù)： | 11/15頁 |
| 文件大?。?/td> | 300K |
| 代理商： | IR3638SPBF |
IR3638SP
b
F
3/19/07
Power MOSFET Selection (Cont..)
The IRF8910 has the following data:
The conduction losses will be:
P
con
=0.724W
The switching loss is more difficult to calculate,
even though the switching transition is well
understood. The reason is the effect of the
parasitic components and switching times during
the switching procedures such as turn-on / turn-
off delays and rise and fall times. The control
MOSFET contributes to the majority of the
switching losses in synchronous Buck converter.
The synchronous MOSFET turns on under zero
voltage conditions, therefore, the turn on losses
for synchronous MOSFET can be neglected.
With a linear approximation, the total switching
loss can be expressed as:
Where:
V ds(off) = Drain to source voltage at the off time
t
r
= Rise time
t
f
= Fall time
T = Switching period
Iload = Load current
The switching time waveforms is shown in
figure9.
V
DS
90%
V
10
V
m
4
.
13
R
A
@
10
Ω
I
,
V
20
=
)
V
gs
on
ds
d
ds
=
=
=
(
(7)
-
I
T
t
t
2
V
P
load
f
r
off
ds
sw
*
*
)
(
+
=
V
GS
10%
t
d
(ON)
t
d
(OFF)
t
r
t
f
Fig. 9: switching time waveforms
11
From IRF8910 data sheet:
t
r
= 10ns, t
f
= 4.1ns
These values are taken under a certain condition
test. For more details please refer to the IRF8910
data sheet.
By using equation (7), we can calculate the
switching losses.
P
sw
=0.37W
Feedback Compensation
The IR3638 is a voltage mode controller; the
control loop is a single voltage feedback path
including error amplifier and error comparator. To
achieve fast transient response and accurate
output regulation, a compensation circuit is
necessary. The goal of the compensation
network is to provide a closed loop transfer
function with the highest 0dB crossing frequency
and adequate phase margin (greater than 45
o
).
The output LC filter introduces a double pole, –
40dB/decade gain slope above its corner
resonant frequency, and a total phase lag of 180
o
(see figure 10). The resonant frequency of the LC
filter expressed as follows:
Figure 10 shows gain and phase of the LC filter.
Since we already have 180
o
phase shift just from
the output filter, the system risks being unstable.
The IR3638’s error amplifier is a differential-input
transconductance amplifier. The output is
available for DC gain control and AC phase
compensation.
The error amplifier can be compensated either in
type II or typeIII compensation. When it is used in
typeII
compensation
properties of the error amplifier become evident
and can be used to cancel one of the output filter
poles. This will be accomplished with a series RC
circuit from Comp pin to ground as shown in
figure 11.
This method requires that the output capacitor
should have enough ESR to satisfy stability
requirements. In general the output capacitor’s
ESR generates a zero typically at 5kHz to 50kHz
which is essential for an acceptable phase
margin.
the
transconductance
(8)
-
C
L
2
1
F
o
o
LC
=
π
Gain
F
LC
0dB
Phase
0
F
LC
-180
Frequency
Frequency
-40dB/decade
Fig. 10: Gain and Phase of LC filter
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| IR3638STRPBF | 功能描述:電壓模式 PWM 控制器 HI FREQ SYNC PWM 400kHz 0.6V Track 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 |
| IR3640MPBF | 功能描述:IC REG CTRLR BUCK PWM VM 20-MLPQ RoHS:是 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) |
| IR3640MTRPBF | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 HI FREQ SYNC PWM 4.5 to 5.5V 1.5MHz RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| IR3651 | 制造商:IRF 制造商全稱:International Rectifier 功能描述: |
| IR3651SPBF | 功能描述:IC REG CTRLR BUCK PWM VM 14-SOIC RoHS:是 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) |
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