CS51411, CS51412, CS51413, CS51414
physically large, and not used in applications where the size,
and especially height is the major concern.
Ceramic capacitors are now available in values over 10 m F.
Since the ceramic capacitor has low ESR and ESL, a single
ceramic capacitor can be adequate for both low frequency
and high frequency noises. The disadvantage of ceramic
capacitors are their high cost. Solid tantalum capacitors can
have low ESR and small size. However, the reliability of the
tantalum capacitor is always a concern in the application
where the capacitor may experience surge current.
Output Capacitor
In a buck converter, the requirements on the output
capacitor are not as critical as those on the input capacitor.
The current to the output capacitor comes from the inductor
IP * P + O
VRIPPLE(ESL) + ESL( IN ) ) ESL( IN
) + ESL( IN )
and thus is triangular. In most applications, this makes the
RMS ripple current not an issue in selecting output
capacitors.
The output ripple voltage is the sum of a triangular wave
caused by ripple current flowing through ESR, and a square
wave due to ESL. Capacitive reactance is assumed to be
small compared to ESR and ESL. The peak ? to ? peak ripple
current of the inductor is:
V (VIN * VO)
(VIN)(L)(fS)
V RIPPLE(ESR) , the output ripple due to the ESR, is equal
to the product of I P ? P and ESR. The voltage developed
across the ESL is proportional to the di/dt of the output
capacitor. It is realized that the di/dt of the output capacitor
is the same as the di/dt of the inductor current. Therefore,
when the switch turns on, the di/dt is equal to (V IN ? V O )/L,
and it becomes V O /L when the switch turns off. The total
ripple voltage induced by ESL can then be derived from
V V * VO V
L L L
Figure 22. The Output Voltage Ripple Using One 100 m F
POSCAP Capacitor
Figure 23. The Output Voltage Ripple Using
One 100 m F OS ? CON
The total output ripple is the sum of the V RIPPLE(ESR) and
V RIPPLE(ESR) .
Figure 24. The Output Voltage Ripple Using
Figure 21. The Output Voltage Ripple Using Two 10 m F
Ceramic Capacitors in Parallel
http://onsemi.com
14
One 100 m F Tantalum Capacitor
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相关代理商/技术参数
CS51411GD8 功能描述:直流/直流开关调节器 1.5A Low Voltage RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
CS51411GD8G 功能描述:直流/直流开关调节器 1.5A Low Voltage Buck RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
CS51411GDR8 功能描述:直流/直流开关调节器 1.5A Low Voltage RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
CS51411GDR8G 功能描述:直流/直流开关调节器 1.5A Low Voltage Buck RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
CS51411GMNR2G 功能描述:直流/直流开关调节器 BUCK REGULATOR RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
CS51412ED8 功能描述:直流/直流开关调节器 1.5A Low Voltage RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
CS51412ED8G 功能描述:直流/直流开关调节器 1.5A Low Voltage Buck RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5
CS51412EDR8 功能描述:直流/直流开关调节器 1.5A Low Voltage RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5