參數(shù)資料
型號(hào): L6728AHTR
廠商: STMICROELECTRONICS
元件分類: 穩(wěn)壓器
英文描述: SWITCHING CONTROLLER, PDSO10
封裝: 3 X 3 MM, ROHS COMPLIANT, VFDFPN-10
文件頁數(shù): 6/33頁
文件大小: 1033K
代理商: L6728AHTR
Application details
L6728AH
14/33
Doc ID 15726 Rev 1
9
Application details
9.1
Compensation network
The control loop showed in Figure 5 is a voltage mode control loop. The output voltage is
regulated to the internal reference (when present, offset resistor between FB node and GND
can be neglected in control loop calculation).
Error amplifier output is compared to oscillator saw-tooth waveform to provide PWM signal
to the driver section. PWM signal is then transferred to the switching node with VIN
amplitude. This waveform is filtered by the output filter.
The converter transfer function is the small signal transfer function between the output of the
EA and VOUT. This function has a double pole at frequency FLC depending on the L-C output
filter and a zero at FESR depending on the output capacitor ESR. The DC gain of the
modulator is simply the input voltage VIN divided by the peak-to-peak oscillator voltage
ΔV
OSC.
Figure 5.
PWM control loop
The compensation network closes the loop joining VOUT and EA output with transfer
function ideally equal to -ZF/ZFB.
Compensation goal is to close the control loop assuring high DC regulation accuracy, good
dynamic performances and stability. To achieve this, the overall loop needs high DC gain,
high bandwidth and good phase margin.
High DC gain is achieved giving an integrator shape to compensation network transfer
function. Loop bandwidth (F0dB) can be fixed choosing the right RF/RFB ratio, however, for
stability, it should not exceed FSW/2π. To achieve a good phase margin, the control loop gain
has to cross 0 dB axis with -20 dB/decade slope.
As an example, Figure 6 shows an asymptotic bode plot of a type III compensation.
L
R
C
OUT
ESR
R
F
C
F
C
P
R
FB
C
S
OSC
V
IN
ΔV
OSC
+
_
V
OUT
V
REF
ZF
Z
FB
PWM
COMPARATOR
ERROR
AMPLIFIER
R
S
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L6728ATR 功能描述:電壓模式 PWM 控制器 HIGH FREQ SINGLE PHASE PWM CNTRL RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(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
L6728D 功能描述:電流型 PWM 控制器 SNGL PHASE PWM CONTROLLER RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
L6728DTR 功能描述:電流型 PWM 控制器 Single-Phase PWM 5V to 12V Controller RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
L6728H 功能描述:電壓模式 PWM 控制器 Sgl Output 300 KHz DFN-10 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(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
L6728HTR 功能描述:電流型 PWM 控制器 SINGLE PHASE PWM CNTRL PWR GOOD RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14