参数资料
| 型号： | MIC2169BMM TR |
| 厂商： | Micrel Inc |
| 文件页数： | 11/15页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 10-MSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 550kHz |
| 占空比： | 92% |
| 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 ~ 85°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
| 其它名称： | MIC2169BMMTR MIC2169BMMTR-ND |
1 + R1 × S × C1
Error Amplifier(z) = g m × ?
? s × C1 + C2 1 + R1 × C1 × C2 × S ? ?
( ) ? ?
?
f LC =
f ZERO =
? s × ( C1 ) ( 1 + R1 × C2 × S ) ?
MIC2169
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 (0.025 Ω ) 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 com-
parison purposes, Figure 6 shows the same phase curve
with an ESR value of 0.002 Ω .
Figure 6. The Phase Curve with ESR = 0.002 Ω
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 MIC2169 voltage control loop by using high ESR
value output capacitors.
Micrel
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 desireable 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:
? ?
? ?
?
?
? ?
? C1 + C2 ? ?
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 Ω –1 . It can be seen that at 50kHz, the error
ampli ? er exhibits approximately 45° of phase margin.
Figure 7. Error Ampli ? er Gain Curve
March 2009
11
M9999-032409
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2169BYMM | 功能描述:DC/DC 开关控制器 500kHz PWM Synchronous Buck Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MIC2169BYMM TR | 功能描述:DC/DC 开关控制器 500kHz PWM Synchronous Buck Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MIC2169BYMME | 功能描述:直流/直流开关转换器 Synchronous Step Down Converter 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 |
| MIC2169BYMME TR | 功能描述:直流/直流开关转换器 Synchronous Step Down Converter 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 |
| MIC2169MM | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:500 KHZ PWM SYNCHRONOUS BUCK CONTROL IC |
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