參數(shù)資料
型號(hào)： L6566ATR
廠商： STMICROELECTRONICS
元件分類： 穩(wěn)壓器
英文描述： 0.8 A POWER FACTOR CONTROLLER WITH POST REGULATOR, 300 kHz SWITCHING FREQ-MAX, PDSO16
封裝： LEAD FREE, SOP-16
文件頁(yè)數(shù)： 20/51頁(yè)
文件大?。?/td> 646K
代理商： L6566ATR
L6566A
Application information
27/51
Figure 15.
Externally controlled burst-mode operation by driving pin COMP: timing
diagram
5.6
PWM comparator, PWM latch and voltage feedforward blocks
The PWM comparator senses the voltage across the current sense resistor Rs and, by
comparing it to the programming signal delivered by the feedforward block, determines the
exact time when the external MOSFET is to be switched off. Its output resets the PWM
latch, previously set by the oscillator or the ZCD triggering block, which will assert the gate
driver output low. The use of PWM latch avoids spurious switching of the MOSFET that
might result from the noise generated (“double-pulse suppression”).
Cycle-by-cycle current limitation is realized with a second comparator (OCP comparator)
that senses the voltage across the current sense resistor Rs as well and compares this
voltage to a reference value VCSX. Its output is or-ed with that of the PWM comparator (see
the circuit schematic in Figure 17 on page 29). In this way, if the programming signal
delivered by the feedforward block and sent to the PWM comparator exceeds VCSX, it will be
the OCP comparator to reset first the PWM latch instead of the PWM comparator. The value
of Vcsx, thereby, determines the overcurrent setpoint along with the sense resistor Rs.
The power that QR flyback converters with a fixed overcurrent setpoint (like fixed-frequency
systems) are able to deliver changes with the input voltage considerably. Obviously, this is
not a problem if the flyback converter runs off a fixed voltage bus generated by the PFC pre-
regulator; however, with a tracking boost PFC (a “boost follower” PFC), the regulated output
voltage at maximum mains voltage can be even twice the value at minimum mains voltage.
In this case the issue is still there, although not as big as without PFC and wide-range
mains. With a 1:2 voltage change, the maximum transferable power at maximum line can be
50 % higher than at minimum line, as shown by the upper curve in the diagram of Figure 16.
The L6566A has the line feedforward function available to solve this issue.
Vcc
(pin 5)
GD
(pin 4)
Vcc_OK
VccON
VccOFF
Vccrestart
Icharge
0.85 mA
Standby is commanded here
t
Vcc_PFC
(pin 6)
t
COMP
(pin 9)
t
Vout
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L6566B 功能描述:開(kāi)關(guān)變換器、穩(wěn)壓器與控制器 Multi Mode PWM Controller RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開(kāi)關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel
L6566B_08 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Multi-mode controller for SMPS
L6566BH 功能描述:電流型 PWM 控制器 Multimode Controller SMPS 800V <3mA RoHS:否 制造商:Texas Instruments 開(kāi)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
L6566BHTR 功能描述:電流型 PWM 控制器 MULTIMODE CONTROLLER SMPS 8V 3 mA RoHS:否 制造商:Texas Instruments 開(kāi)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
L6566BTR 功能描述:電流型 PWM 控制器 MultiMode Controller for SMPS RoHS:否 制造商:Texas Instruments 開(kāi)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
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