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參數(shù)資料
| 型號： | IRU3048 |
| 廠商： | International Rectifier |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | DUAL SYNCHRONOUS PWM CONTROLLER CIRCUITRY AND LDO CONTROLLER |
| 中文描述： | 雙同步PWM控制器電路和LDO控制器 |
| 文件頁數(shù)： | 8/18頁 |
| 文件大?。?/td> | 154K |
| 代理商： | IRU3048 |
8
Rev. 1.7
09/12/02
IRU3048
www.irf.com
Feedback Compensation
The IRU3048 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
8
).
The output LC filter introduces a double pole, –40dB/
decade gain slope above its corner resonant frequency,
and a total phase lag of 180
8
(see Figure 5). The Reso-
nant frequency of the LC filter is expressed as follows:
Figure 5 shows gain and phase of the LC filter. Since we
already have 180
8
phase shift just from the output filter,
the system risks being unstable.
Figure 5 - Gain and phase of LC filter.
The IRU3048's error amplifier is a differential-input
transconductance amplifier. The output is available for
DC gain control or AC phase compensation.
The E/A can be compensated with or without the use of
local feedback. When operated without local feedback
the transconductance properties of the E/A become evi-
dent and can be used to cancel one of the output filter
poles. This will be accomplished with a series RC circuit
from Comp1 pin to ground as shown in Figure 6.
The ESR zero of the LC filter expressed as follows:
Figure 6 - Compensation network without local
feedback and its asymptotic gain plot.
The transfer function (Ve / V
OUT
) is given by:
( )
The (s) indicates that the transfer function varies as a
function of frequency. This configuration introduces a gain
and zero, expressed by:
The gain is determined by the voltage divider and E/A's
transconductance gain.
First select the desired zero-crossover frequency (Fo):
Use the following equation to calculate R4:
F
O1
> F
ESR
and F
O1
≤
(1/5 ~ 1/10)
×
f
S
V
OUT
V
REF
R
8
R
6
R
9
C
18
Ve
E/A
F
Z
H(s) dB
Frequency
Gain(dB)
Fb
Comp
F
LC
= 1
2
π
Lo
×
Co
F
ESR
= 1
2
π
×
ESR
×
Co
H(s) = g
m
× ×
R
6
+ R
8
R
8
1 ---(9)
9
C
18
sC
18
|H(s)| =
g
m
× ×
R
9
---(10)
×
8
F
Z
= 1
2
π
×
R
9
×
C
18
R
9
=
---(12)
V
OSC
V
IN1
F
O1
×
F
ESR1
F
LC12
R
8
+ R
6
R
8
1
g
m
×
×
×
Where:
V
IN1
= Maximum Input Voltage
V
OSC
= Oscillator Ramp Voltage
F
O1
= Crossover Frequency for the master E/A
F
ESR1
= Zero Frequency of the Output Capacitor
F
LC1
= Resonant Frequency of Output Filter
g
m = Error Amplifier Transconductance
R
8
and R
6
= Resistor Dividers for Output Voltage
Programming
Gain
F
LC
0dB
Phase
0
8
F
LC
-180
8
Frequency
Frequency
-40dB/decade
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| IRU3048CF | 制造商:IRF 制造商全稱:International Rectifier 功能描述:DUAL SYNCHRONOUS PWM CONTROLLER CIRCUITRY AND LDO CONTROLLER |
| IRU3048CFTR | 功能描述:IC REG CTRLR BUCK PWM VM 16TSSOP RoHS:否 類別: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:75 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.3 V ~ 13.5 V 降壓:是 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:0°C ~ 70°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:管件 產(chǎn)品目錄頁面:1051 (CN2011-ZH PDF) 其它名稱:296-2543-5 |
| IRU3048CS | 制造商:IRF 制造商全稱:International Rectifier 功能描述:DUAL SYNCHRONOUS PWM CONTROLLER CIRCUITRY AND LDO CONTROLLER |
| IRU3048CSTR | 功能描述:IC REG CTRLR BUCK PWM VM 16-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(biāo)準(zhǔn)包裝:75 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.3 V ~ 13.5 V 降壓:是 升壓:是 回掃:是 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:0°C ~ 70°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:管件 產(chǎn)品目錄頁面:1051 (CN2011-ZH PDF) 其它名稱:296-2543-5 |
| IRU3048CSTRPBF | 制造商:International Rectifier 功能描述:Dual Synchronous PWM Controller Circuitry and LDO Controller 16-Pin SOIC N T/R |
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