參數(shù)資料
型號(hào)： L6918AD
廠商： STMICROELECTRONICS
元件分類(lèi)： 穩(wěn)壓器
英文描述： SWITCHING CONTROLLER, 1200 kHz SWITCHING FREQ-MAX, PDSO28
封裝： SO-28
文件頁(yè)數(shù)： 16/35頁(yè)
文件大?。?/td> 431K
代理商： L6918AD
23/35
L6918 L6918A
AVERAGE CURRENT MODE (ACM) CONTROL LOOP
The average current mode control loop is reported in figure 15. The current information IFB sourced by the FB
pin flows into RFB implementing the dependence of the output voltage from the read current.
The ACM control loop gain results (obtained opening the loop after the COMP pin):
where:
–
is the equivalent output resistance determined by the droop function;
–ZP(s) is the impedance resulting by the parallel of the output capacitor (and its ESR) and the applied
load Ro;
–ZF(s) is the compensation network impedance;
–ZL(s) is the parallel of the two inductor impedance;
– A(s) is the error amplifier gain;
–
is the ACM PWM transfer function where
Vosc is the oscillator ramp amplitude
and has a typical value of 2V
Removing the dependence from the Error Amplifier gain, so assuming this gain high enough, the control loop
gain results:
With further simplifications, it results:
Considering now that in the application of interest it can be assumed that Ro>>RL; ESR<<Ro and
RDROOP<<Ro, it results:
The ACM control loop gain is designed to obtain a high DC gain to minimize static error and cross the 0dB axes
with a constant -20dB/dec slope with the desired crossover frequency
ωT. Neglecting the effect of ZF(s), the
transfer function has one zero and two poles. Both the poles are fixed once the output filter is designed and the
zero is fixed by ESR and the Droop resistance.
To obtain the desired shape an RF-CF series network is considered for the ZF(s) implementation.
A zero at
ωf=1/RFCF is then introduced together with an integrator. This integrator minimizes the static error
G
LOOP s
()
PW M Z
F s
() R
DROOP
Z
P s
()
+
()
Z
P s
() Z
L s
()
+
()
Z
F s
()
As
()
---------------
1
As
()
------------
+
R
FB
+
--------------------------------------------------------------------------------------------------------------------
–
=
R
DROOP
Rsense
Rg
---------------------- R
FB
=
PW M
4
5
---
V
IN
V
OS C
-------------------
=
G
LOOP s
()
4
5
---
V
IN
V
OS C
-------------------
Z
F s
()
Z
P s
() Z
L s
()
+
------------------------------------
Rs
Rg
--------
Z
P s
()
R
FB
---------------
+
–
=
G
LOOP s
()
4
5
---
V
IN
V
OSC
-------------------
Z
F s
()
R
FB
---------------
Ro
R
DROOP
+
Ro
R
L
2
-------
+
-------------------------------------
1s C o
R
DROOP //Ro
E SR
+
()
+
s
2
Co
L
2
---
s
L
2Ro
---------------
Co ESR
Co
R
L
2
-------
+
+
1
+
+
----------------------------------------------------------------------------------------------------------------------------------
–
=
G
LOOP s
()
4
5
---
V
IN
V
OSC
-------------------
Z
F s
()
R
FB
---------------
1s Co
R
DROOP
ESR
+
()
+
s
2
Co
L
2
---
s
L
2Ro
---------------
C o ESR
Co
R
L
2
-------
+
+
1
+
+
----------------------------------------------------------------------------------------------------------------------------------
–
=
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L6918ADTR 功能描述:DC/DC 開(kāi)關(guān)控制器 Prog Multi-Phase Cnt RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
L6918D 功能描述:DC/DC 開(kāi)關(guān)控制器 Prog Multi-Phase Cnt RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
L6918DTR 功能描述:DC/DC 開(kāi)關(guān)控制器 Prog Multi-Phase Cnt RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK
L6919 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:5 BIT PROGRAMMABLE DUAL-PHASE CONTROLLER WITH DYNAMIC VID MANAGEMENT
L6919C 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:5 BIT PROGRAMMABLE DUAL-PHASE CONTROLLER WITH DYNAMIC VID MANAGEMENT
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