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参数资料
| 型号： | MIC2168YMM |
| 厂商： | Micrel Inc |
| 文件页数： | 11/14页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 10-MSOP |
| 标准包装： | 100 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1.1MHz |
| 占空比： | 90% |
| 电源电压： | 3 V ~ 14.5 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1092 (CN2011-ZH PDF) |
| 其它名称： | 576-1708-5 MIC2168YMM-ND |
MIC2168
Micrel, Inc.
30
30
0
0
7.5
15
50
100
37.5
150
1.10
1 .10
1 .10
1 .10
1.10
1 .10
1 .10
1 .10
60 60
100
100
3
f
4
5
6
1000000
180
100
100
3
f
4
5
6
1000000
0
1.10
1 .10
1 .10
1 .10
100
F C =
F ZERO =
ERROR AMPLIFIER (Z) - G M ×
C1 × C2 × S ?
C1 + C2 ? ?
S × (C1 + C2) ? 1 + R1 ×
? S × (C1)(1+ R1 × C2 × S) ?
Figure4. TheGainCurveforG(s)
0
50
100
150
180
3 4 5 6
100 f 1000000
Figure 5. Phase Curve for G(s)
It can be seen from the transfer function G(s) and the gain
curve that the output inductor and capacitor create a two pole
system with a break frequency at:
1
2 × π √ L × C OUT
Therefore, f LC = 3.6kHz
By looking at the phase curve, it can be seen that the output
capacitor ESR (0.050 ? ) cancels one of the two poles (LC OUT )
system by introducing a zero at:
1
2 × π × ESR × C OUT
Therefore, F ZERO = 6.36kHz.
From the point of view of compensating the voltage loop, it is
recommended to use higher ESR output capacitors since they
provide a 90° phase gain in the power path. For comparison
purposes, Figure 6, shows the same phase curve with an
ESR value of 0.002 ? .
Figure 6. The Phase Curve with ESR = 0.002 ?
It can be seen from Figure 5 that at 50kHz, the phase is
approximately –90° versus Figure 6 where the number is
–150°. This means that the transconductance error ampli-
?er has to provide a phase boost of about 45° to achieve a
closed loop phase margin of 45° at a crossover frequency
of 50kHz for Figure 4, versus 105° for Figure 6. The simple
RC and C2 compensation scheme allows a maximum error
ampli?er phase boost of about 90°. Therefore, it is easier to
stabilize the MIC2168 voltage control loop by using high ESR
value output capacitors.
g m Error Ampli?er
It is undesirable to have high error ampli?er gain at high
frequencies because high frequency noise spikes would be
picked up and transmitted at large amplitude to the output,
thus, gain should be permitted to fall off at high frequencies.
At low frequency, it is desired to have high open-loop gain to
attenuate the power line ripple. Thus, the error ampli?er gain
should be allowed to increase rapidly at low frequencies.
The transfer function with R1, C1, and C2 for the internal
g m error ampli?er can be approximated by the following
equation:
1+ R1 × S × C1
?
?
The above equation can be simplified by assuming
C2<<C1,
? 1+ R1 × S × C1 ?
ERROR AMPLIFIER (Z) - G M ×
? ?
From the above transfer function, one can see that R1 and
C1 introduce a zero and R1 and C2 a pole at the following
frequencies:
Fzero= 1 / 2 π × R1 × C1
Fpole = 1 / 2 π × C2 × R1
Fpole@origin = 1 / 2 π × C1
Figures 7 and 8 show the gain and phase curves for the above
transfer function with R1 = 9.3k, C1 = 1000pF, C2 = 100pF,
and g m = .005 ? –1 . It can be seen that at 50kHz, the error
ampli?er exhibits approximately 45° of phase margin.
April 2005
11
M9999-040805
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相关代理商/技术参数 |
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| MIC2168YMM TR | 功能描述:直流/直流开关调节器 Replaced by MIC2168AYMM TR (Lead Free) 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 |
| MIC2169 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:500kHz PWM Synchronous Buck Control IC |
| MIC2169_09 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:500kHz PWM Synchronous Buck Control IC |
| MIC2169A | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:500kHz PWM Synchronous Buck Control IC |
| MIC2169A_09 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:500kHz PWM Synchronous Buck Control IC |
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