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参数资料
| 型号： | L6566A |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 稳压器 |
| 英文描述： | 0.8 A POWER FACTOR CONTROLLER WITH POST REGULATOR, 300 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | LEAD FREE, SOP-16 |
| 文件页数： | 20/51页 |
| 文件大小： | 646K |
| 代理商： | L6566A |
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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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相关代理商/技术参数 |
参数描述 |
|---|---|
| L6566A_08 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:Multi-mode controller for SMPS with PFC front-end |
| L6566ATR | 功能描述:开关变换器、稳压器与控制器 Multi Mode PWM Controller RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| L6566B | 功能描述:开关变换器、稳压器与控制器 Multi Mode PWM Controller RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| L6566B_08 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:Multi-mode controller for SMPS |
| L6566BH | 功能描述:电流型 PWM 控制器 Multimode Controller SMPS 800V <3mA RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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