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| 型号： | CS5171BSTGEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 12/21页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR CS5171BST |
| 设计资源： | CS5171BSTGEVB Gerber Files |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步升 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 5V |
| 电流 - 输出： | 400mA |
| 输入电压： | 3.3V |
| 稳压器拓扑结构： | 升压 |
| 频率 - 开关： | 260kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | CS5171 |
| 其它名称： | CS5171BSTEVBOS CS5171BSTEVBOS-ND CS5171BSTGEVBOS |
CS5171, CS5172, CS5173, CS5174
fZ1 +
The first zero generated by C1 and R1 is:
1
2 p C1R1
The phase lead provided by this zero ensures that the loop
? V OUT
R1
2V
R P
200 k W
fP +
has at least a 45 ° phase margin at the crossover frequency.
Therefore, this zero should be placed close to the pole
generated in the power stage which can be identified at
frequency:
1
2 p CORLOAD
R2
NFB
R IN
250 k W
+
?
Negative Error ? Amp
fP2 +
* (15 m A
R1) v VOFFSET
* (5 m A
0.0.5 (R1 ) R2)
R2
where:
C O = equivalent output capacitance of the error amplifier
≈ 120pF;
R LOAD = load resistance.
The high frequency pole, f P2 , can be placed at the output
filter ’s ESR zero or at half the switching frequency. Placing
the pole at this frequency will cut down on switching noise.
The frequency of this pole is determined by the value of C2
and R1:
1
2 p C2R1
One simple method to ensure adequate phase margin is to
design the frequency response with a ? 20 dB per decade
slope, until unity ? gain crossover. The crossover frequency
should be selected at the midpoint between f Z1 and f P2 where
the phase margin is maximized.
f P1
Figure 33. Negative Error Amplifier and NFB Pin
It is shown that if R1 is less than 10 k, the deviation from
the design target will be less than 0.1 V. If the tolerances of
the negative voltage reference and NFB pin input current are
considered, the possible offset of the output V OFFSET varies
in the range of:
* 0.0.5 (R1 ) R2)
R2
v R1)
V SW Voltage Limit
In the boost topology, V SW pin maximum voltage is set by
the maximum output voltage plus the output diode forward
voltage. The diode forward voltage is typically 0.5 V for
Schottky diodes and 0.8 V for ultrafast recovery diodes
VSW(MAX) + VOUT(MAX) ) VF
f Z1
f P2
where:
V F = output diode forward voltage.
In the flyback topology, peak V SW voltage is governed by:
VSW(MAX) + VCC(MAX) ) (VOUT ) VF)
N
where:
N = transformer turns ratio, primary over secondary.
Frequency (LOG)
Figure 32. Bode Plot of the Compensation Network
Shown in Figure 31
Negative Voltage Feedback
Since the negative error amplifier has finite input
impedance as shown in Figure 33, its induced error has to be
considered. If a voltage divider is used to scale down the
negative output voltage for the NFB pin, the equation for
calculating output voltage is:
When the power switch turns off, there exists a voltage
spike superimposed on top of the steady ? state voltage.
Usually this voltage spike is caused by transformer leakage
inductance charging stray capacitance between the V SW and
PGND pins. To prevent the voltage at the V SW pin from
exceeding the maximum rating, a transient voltage
suppressor in series with a diode is paralleled with the
primary windings. Another method of clamping switch
voltage is to connect a transient voltage suppressor between
the V SW pin and ground.
* VOUT +
* 2.5 (R1 ) R2)
R2
* 10 m A
R1
http://onsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| CS5171ED8 | 功能描述:直流/直流开关调节器 1.5A High Efficiency 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 |
| CS5171ED8G | 功能描述:直流/直流开关调节器 1.5A High Efficiency Boost 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 |
| CS5171EDR8 | 功能描述:直流/直流开关调节器 1.5A High Efficiency 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 |
| CS5171EDR8G | 功能描述:直流/直流开关调节器 1.5A High Efficiency Boost 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 |
| CS5171GD8 | 功能描述:直流/直流开关调节器 1.5A High Efficiency 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 |
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