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参数资料
| 型号： | L6668 |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 稳压器 |
| 英文描述： | 0.8 A SWITCHING CONTROLLER, 105 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | LEAD FREE, SOP-16 |
| 文件页数： | 11/23页 |
| 文件大小： | 720K |
| 代理商： | L6668 |
19/23
L6668
4.7 Disable function
Latched OTP or OVP functions can be easily realized with the L6668: the IC is equipped with a compara-
tor whose non-inverting input is externally available on pin #7 (DIS), and whose inverting input is inter-
nally referenced to 2.2V.
As the voltage on the pin exceeds the threshold the IC is immediately shut down and its consumption re-
duced at a low value. The information is latched and it is necessary to let the voltage on the Vcc pin go
below the UVLO threshold to reset the latch and restart the IC.
To keep the latch supplied as long as the converter is connected to the input source, the HV generator is
activated periodically so that Vcc oscillates between the start-up threshold VccON and VccON - 0.5V. It is
then necessary to disconnect the converter from the input source to restart the IC. This operation is shown
in the timing diagram of figure 44. Activating the HV generator in this way cuts its power dissipation ap-
proximately by three and keeps peak silicon temperature close to the average value.
4.8 Slope compensation
A pin of the device (#15, S-COMP) provides a voltage ramp during MOSFET's ON-time which is a repeti-
tion of the oscillator sawtooth, buffered (0.8 mA min. capability) and level shifted down by one Vbe.
This ramp is intended for implementing additive slope compensation on current sense. This is needed to
avoid the sub-harmonic oscillation that arises in all peak-current-mode-controlled converters working in
continuous conduction mode with a duty cycle close to or exceeding 50%.
Figure 45. Slope compensation waveforms
The compensation will be realized by connecting a programming resistor between this pin and the current
sense input (pin 12, ISEN). The pin has to be connected to the sense resistor with another resistor to make
a summing node on the pin.
Since no ramp is delivered during MOSFET OFF-time (see figure 45), no external component other than
the programming resistor is needed to ensure a clean operation at light loads. If slope compensation is
not required the pin shall be left floating.
RCT
OUT
S-COMP
t
RCT
OUT
S-COMP
t
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相关代理商/技术参数 |
参数描述 |
|---|---|
| L6668_06 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:SMART PRIMARY CONTROLLER |
| L6668B2 | 功能描述:电流型 PWM 控制器 POWER SUPPLY 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 |
| L6668TR | 功能描述:电流型 PWM 控制器 SMART CONTROLLER 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 |
| L667 | 制造商:BURNDY 功能描述:L-DIE |
| L-667 | 制造商:RHOMBUS-IND 制造商全称:Rhombus Industries Inc. 功能描述:Common Mode Inductor For DC/DC Power supply |
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