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参数资料
| 型号： | LM2633MTDX/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, 275 kHz SWITCHING FREQ-MAX, PDSO48 |
| 封装： | TSSOP-48 |
| 文件页数： | 28/40页 |
| 文件大小： | 1350K |
| 代理商： | LM2633MTDX/NOPB |
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Control Loop Design (Continued)
(45)
(46)
Back to the previous example. Let B = K, f
z1 =fp,fp2 =fz,fz2
=f
n, then:
f
c_o = 5.1 x 310Hz = 1581Hz
The corresponding Bode plots of the compensation network
and the loop transfer function are shown in
Figure 12 and
Figure 13 respectively.
It can be seen from
Figure 13 that the crossover frequency is
20kHz, and the phase margin is about 84 degrees.
One thing that should be pointed out is this Bode plot is only
for the 0.4
load. That is, when load current is 4A. If load
current is lower than 4A, the portion of the gain plot from the
corresponding f
p to 310Hz will be 40dB/dec. If load current
is higher than 4A, then the portion of the gain plot from
310Hz to fp will be flat. However, this usually does not have
much effect on the cross-over frequency and phase margin
because it happens at low frequencies.
If a shorter recovery time is desired during a load transient,
f
z1 can be increased so that the gain of the loop transfer
function becomes higher. However, try not to let f
z1 be higher
than the desired cross-over frequency, otherwise phase mar-
gin can be too low.
Figure 14 shows a situation where f
z1 is
placed at a higher frequency than the f
p, which results in a
40 dB/dec section before the cross-over frequency. Notice
the phase margin is lower.
Sometimes the slow transient response is caused by the
current source and sink capability of the error amplifier.
Reducing the value of the compensation capacitor helps, but
make sure the small-signal loop is stable.
The power stage component selection can be significantly
different from the example values.
Figure 15 shows how the
two high frequency poles of a current-mode-control buck
regulator change with the Q value.
20000876
FIGURE 12. Example Compensation Transfer Function
20000877
FIGURE 13. Example Loop Transfer Function
200008D6
FIGURE 14. Higher Low Frequency Gain
LM2633
www.national.com
34
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相关代理商/技术参数 |
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|---|---|
| LM2635 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:5-Bit Programmable Synchronous Buck Regulator Controller |
| LM2635A WAF | 制造商:Texas Instruments 功能描述: |
| LM2635M | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LM2635M/NOPB | 功能描述:IC REG SYNCH BUCK 5-BIT 20-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 应用说明:Ultrasound Imaging Systems Application Note 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:37 系列:- 应用:医疗用超声波成像，声纳 电流 - 电源:- 电源电压:2.37 V ~ 6 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:56-WFQFN 裸露焊盘 供应商设备封装:56-TQFN-EP（8x8） 包装:管件 |
| LM2635MX | 功能描述:IC REG SYNCH BUCK 5-BIT 20-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 应用说明:Ultrasound Imaging Systems Application Note 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:37 系列:- 应用:医疗用超声波成像，声纳 电流 - 电源:- 电源电压:2.37 V ~ 6 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:56-WFQFN 裸露焊盘 供应商设备封装:56-TQFN-EP（8x8） 包装:管件 |
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