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參數(shù)資料
| 型號(hào)： | RT8805C |
| 廠商： | Richtek Technology Corporation |
| 英文描述： | Two Phase General Purpose PWM Controller |
| 中文描述： | 兩相通用PWM控制器 |
| 文件頁數(shù)： | 13/18頁 |
| 文件大?。?/td> | 391K |
| 代理商： | RT8805C |
RT8805C
Preliminary
13
DS8805C-03 August 2007
www.richtek.com
Figure 8. Type 2 Bode Plot
10 100 1k 10k 100k 1M
Frequency (Hz)
-40
0
40
80
-60
80
40
0
20
60
-20
-40
-60
Loop Gain
Compensation
Gain
Modulator
Gain
G
There is another type of compensation called Type 3
compensation that adds a pole-zero pair to the Type 2
network. It's used to compensate output capacitor whose
ESR value is much lower (pure MLCC or OSCON
Capacitors).
As shown in Figure 9, to insert a network between V
OUT
and FB in the original Type 2 compensation network can
result in Type 3 compensation. Figure 10 shows the
difference of their AC response. Type 3 compensation has
an additional pole-zero pair that causes a gain boost at
the flat gain region. But the gain boosted is limited by the
ratio (R1+R4)/R4; if R3 << R4.
+
-
GM
V
COMP
C2
R2
C1
R4
V
OUT
R1
R3
C3
FB
Figure 9. Additional Network of Type 3 Compensation
(Add between V
OUT
and FB)
Figure 10. AC Response Curves of Type 2 and 3
Type 3 will induce additional one pole and one zero.
Zeros :
π
2
=
×
Z2
1
F
(R1 R3) C3
P3
F
1
2
R3
C3
π
=
×
×
Poles :
which is in the origin.
We recommend F
Z1
placed in 0.5 x F
P(LC)
; F
Z2
placed in
F
P(LC)
; F
P3
placed in F
ESR
and F
P2
placed in 0.5 x F
SW
.
Figure 11 shows Type 3 Bode Plot.
Figure 11. Type 3 Bode Plot
Protection
OCP
The RT8805C uses
“
Cycle by Cycle
”
current comparison.
The over current level is set by IMAX pin. When OC
function occurs and SS > 3.7V, a constant current of 10
μ
A
starts to discharge the capacitor connected to SS pin
right away. When OC occurs, UGATE and LGATE will be
off.
Loop Gain
-80
-60
-40
-20
0
20
40
60
2
3
4
5
6
7
Log Frequency
d
Compensation Gain
Gain
Modulator Gain
Pole
F
P2
F
Z2
Add Type 3 compensation
Original Type 2 compensation
F
P3
F
Z1
F
P1
F
P2
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相關(guān)代理商/技術(shù)參數(shù) |
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| RT8805CGQV | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Two Phase General Purpose PWM Controller |
| RT8805CGQVA | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Two Phase General Purpose PWM Controller |
| RT8805CPQV | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Two Phase General Purpose PWM Controller |
| RT8805CPQVA | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Two Phase General Purpose PWM Controller |
| RT8805GQV | 功能描述:IC REG CTRLR BUCK PWM VM 16-VQFN RoHS:是 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:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 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 ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
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