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| 型号： | LM2588S-ADJ/NOPB |
| 厂商： | National Semiconductor |
| 文件页数： | 28/38页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG ADJ TO263-7 |
| 产品培训模块： | SIMPLE SWITCHER® Regulators |
| 标准包装： | 45 |
| 系列： | SIMPLE SWITCHER® |
| 类型： | 升压（升压），回扫，正向转换器 |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 可调 |
| 输入电压： | 4 V ~ 40 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz ~ 200kHz |
| 电流 - 输出： | 5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | TO-263-8，D²Pak（7 引线+接片），TO-263CA |
| 包装： | 管件 |
| 供应商设备封装： | TO-263-7 |
| 产品目录页面： | 1304 (CN2011-ZH PDF) |
| 配用： | 551011367-051-ND - BOARD WEBENCH BUILD IT LM2586/88 |
| 其它名称： | *LM2588S-ADJ LM2588S-ADJ |
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SNVS117D – APRIL 1998 – REVISED APRIL 2013
where V F is the forward biased voltage of the output diode, and is typically 0.5V for Schottky diodes and 0.8V for
ultra-fast recovery diodes. In certain circuits, there exists a voltage spike, V LL , superimposed on top of the
steady-state voltage (see Figure 21 , waveform A). Usually, this voltage spike is caused by the transformer
leakage inductance and/or the output rectifier recovery time. To “clamp” the voltage at the switch from exceeding
its maximum value, a transient suppressor in series with a diode is inserted across the transformer primary (as
shown in the circuit in Figure 20 and other flyback regulator circuits throughout the datasheet). The schematic in
Figure 58 shows another method of clamping the switch voltage. A single voltage transient suppressor (the
SA51A) is inserted at the switch pin. This method clamps the total voltage across the switch, not just the voltage
across the primary.
If poor circuit layout techniques are used (see the CIRCUIT LAYOUT GUIDELINES section), negative voltage
transients may appear on the Switch pin (pin 5). Applying a negative voltage (with respect to the IC's ground) to
any monolithic IC pin causes erratic and unpredictable operation of that IC. This holds true for the LM2588 IC as
well. When used in a flyback regulator, the voltage at the Switch pin (pin 5) can go negative when the switch
turns on. The “ringing” voltage at the switch pin is caused by the output diode capacitance and the transformer
leakage inductance forming a resonant circuit at the secondary(ies). The resonant circuit generates the “ringing”
voltage, which gets reflected back through the transformer to the switch pin. There are two common methods to
avoid this problem. One is to add an RC snubber around the output rectifier(s), as in Figure 58 . The values of the
resistor and the capacitor must be chosen so that the voltage at the Switch pin does not drop below ? 0.4V. The
resistor may range in value between 10 Ω and 1 k Ω , and the capacitor will vary from 0.001 μ F to 0.1 μ F. Adding a
snubber will (slightly) reduce the efficiency of the overall circuit.
The other method to reduce or eliminate the “ringing” is to insert a Schottky diode clamp between pins 5 and 4
(ground), also shown in Figure 58 . This prevents the voltage at pin 5 from dropping below ? 0.4V. The reverse
voltage rating of the diode must be greater than the switch off voltage.
Figure 59. Input Line Filter
OUTPUT VOLTAGE LIMITATIONS
The maximum output voltage of a boost regulator is the maximum switch voltage minus a diode drop. In a
flyback regulator, the maximum output voltage is determined by the turns ratio, N, and the duty cycle, D, by the
equation:
V OUT ≈ N × V IN × D/(1 ? D)
(4)
The duty cycle of a flyback regulator is determined by the following equation:
(5)
Theoretically, the maximum output voltage can be as large as desired—just keep increasing the turns ratio of the
transformer. However, there exists some physical limitations that prevent the turns ratio, and thus the output
voltage, from increasing to infinity. The physical limitations are capacitances and inductances in the LM2588
switch, the output diode(s), and the transformer—such as reverse recovery time of the output diode (mentioned
above).
28
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2588SX-12 | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM2588SX-12/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM2588SX-3.3 | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM2588SX-3.3/NOPB | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| LM2588SX-5.0 | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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