參數(shù)資料
型號(hào)： IRU3137
廠商： International Rectifier
英文描述： 8-PIN SYNCHRONOUS PWM CONTROLLER
中文描述： 8引腳同步PWM控制器
文件頁(yè)數(shù)： 9/19頁(yè)
文件大?。?/td> 169K
代理商： IRU3137
IRU3137
9
Rev. 1.0
06/22/04
www.irf.com
Choose IRF7832 for both control MOSFET and synchro-
nous MOSFET. This device provides low on-resistance
in a compact SOIC 8-Pin package.
The MOSFET has the following data:
IRF7832
V
DSS
= 30V
I
D
= 20A @ 25 C
R
DS(ON)
= 4m
@ V
GS
=10V
The total conduction losses will be:
P
CON(TOTAL)
= P
CON(UPPER)
+ P
CON(LOWER)
P
CON(TOTAL)
= 1.166W
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 / turnoff delays and rise and fall times. The
control MOSFET contributes to the majority of the switch-
ing losses in synchronous Buck converter. The synchro-
nous 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:
V
2
T
The switching time waveform is shown in Figure 7.
Figure 7 - Switching time waveforms.
From IRF7832 data sheet we obtain:
These values are taken under a certain condition test.
For more details please refer to the IRF7466 and IRF7458
data sheets.
By using equation (12), we can calculate the total switch-
ing losses.
P
SW(TOTAL)
= 250mW
Feedback Compensation
The IRU3137 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 compensa-
tion 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 ).
The output LC filter introduces a double pole, –40dB/
decade gain slope above its corner resonant frequency,
and a total phase lag of 180 (see Figure 8). The Reso-
nant frequency of the LC filter is expressed as follows:
1
2
π×
L
O
×
C
O
Figure 9 shows gain and phase of the LC filter. Since we
already have 180 phase shift just from the output filter,
the system risks being unstable.
Figure 8 - Gain and phase of LC filter.
Where:
V
DS(OFF)
= Drain to Source Voltage at off time
t
r
= Rise Time
t
f
= Fall Time
T = Switching Period
I
LOAD
= Load Current
P
SW
=
I
LOAD
---(12)
×
t
r
+
t
f
×
IRF7832
t
r
= 12.3ns
t
f
= 21ns
F
LC
= ---(13)
V
DS
90%
V
GS
10%
t
d
(ON)
t
d
(OFF)
t
r
t
f
Gain
F
LC
0dB
Phase
0
F
LC
-180
Frequency
Frequency
-40dB/decade
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參數(shù)描述
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IRU3137CSTRPBF 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)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(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤(pán) 包裝:帶卷 (TR)
IRU3138 制造商:IRF 制造商全稱(chēng):International Rectifier 功能描述:SYNCHRONOUS PWM CONTROLLER FOR TERMINATION POWER SUPPLY APPLICATIONS
IRU3138CS 制造商:IRF 制造商全稱(chēng):International Rectifier 功能描述:SYNCHRONOUS PWM CONTROLLER FOR TERMINATION POWER SUPPLY APPLICATIONS
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