参数资料
| 型号： | MIC2166YMME TR |
| 厂商： | Micrel Inc |
| 文件页数： | 12/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM HYBRID 10TSOP |
| 标准包装： | 2,500 |
| 系列： | Hyper Speed Control™ |
| PWM 型： | 混合物 |
| 输出数： | 1 |
| 频率 - 最大： | 750kHz |
| 占空比： | 82% |
| 电源电压： | 4.5 V ~ 28 V |
| 降压： | 无 |
| 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）裸露焊盘 |
| 包装： | 带卷 (TR) |
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Micrel, Inc.
Figure 3 shows the load transient operation of the
MIC2166 converter. The output voltage drops due to the
sudden load increase, which causes V FB to be less than
V REF . This will cause the error comparator to trigger an
ON-time period. At the end of the ON-time period, a
minimum OFF-time T OFF(min) is generated to charge C BST
since V FB is still below V REF . Then, the next ON-time
period is triggered due to the low V FB . Therefore, the
switching frequency changes during the load transient.
With the varying duty-cycle and switching frequency, the
output recovery time is fast and the output voltage
deviation is small in MIC2166 converter.
Figure 3. MIC2166 Load-Transient Response
Unlike in current-mode control, the MIC2166 uses the
output voltage ripple, which is proportional to the
inductor current ripple if the ESR of the output capacitor
is large enough, to trigger an ON-time period. The
predetermined ON-time makes MIC2166 control loop
have the advantage of constant ON-time mode control
and eliminates the need for slope compensation.
MIC2166
Soft-Start
Soft-start reduces the power supply input surge current
at startup by controlling the output voltage rise time. The
input surge appears while the output capacitor is
charged up. A slower output rise time will draw a lower
input surge current.
The MIC2166 implements an internal digital soft-start by
making the 0.8V reference voltage V REF ramp from 0 to
100% in about 5ms. Therefore, the output voltage is
controlled to increase slowly by a stair-case V REF ramp.
Once the soft-start cycle ends, the related circuitry is
disabled to reduce current consumption.
Current Limit
The MIC2166 uses the R DS(ON) of the low-side power
MOSFET to sense over-current conditions. This method
will avoid adding cost, board space and power losses
taken by discrete current sense resistors. The low-side
MOSFET is used because it displays much lower
parasitic oscillations during switching than the high-side
MOSFET.
In each switching cycle of the MIC2166 converter, the
inductor current is sensed by monitoring the low-side
MOSFET in the OFF period. The sensed voltage is
compared with a current-limit threshold voltage V CL after
a blanking time of 150ns. If the sensed voltage is over
V CL , which is 133mV typical at 0.8V V FB , then the
MIC2166 turns off the high-side and low-side MOSFETs
and a soft-start sequence is triggered. This mode of
operation is called “hiccup mode” and its purpose is to
protect the downstream load in case of a hard short. The
current limit threshold V CL has a back fold characteristic
related to the FB voltage. Please refer to the “Typical
Characteristics” for the curve of current limit threshold vs.
FB voltage percentage. The circuit in Figure 4 illustrates
the MIC2166 current limiting circuit.
The MIC2166 has its own stability concern: V FB ripple
should be in phase with the inductor current ripple and
large enough to be sensed by the g m amplifier and the
error comparator. The recommended V FB ripple is
20mV~100mV. If a low ESR output capacitor is selected,
the V FB ripple may be too small to be sensed by the g m
amplifier and the error comparator. Also, the V OUT ripple
and the V FB ripple are not in phase with the inductor
current ripple if the ESR of the output capacitor is very
low. Therefore, ripple injection is required for a low ESR
output capacitor. Please refer to “Ripple Injection”
subsection in “Application Information” for more details.
Figure 4. MIC2166 Current Limiting Circuit
September 2010
12
M9999-092410-C
相关PDF资料 |
PDF描述 |
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| MIC2168AYMM | IC REG CTRLR BUCK PWM VM 10-MSOP |
| MIC2168BMM TR | IC REG CTRLR BUCK PWM VM 10-MSOP |
| MIC2169AYMM | IC REG CTRLR DIVIDER PWM 10-MSOP |
| MIC2169BMM TR | IC REG CTRLR BUCK PWM VM 10-MSOP |
| MIC2169BYMME | IC REG CTRLR BUCK PWM VM 10-MSOP |
相关代理商/技术参数 |
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| MIC2168 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:1MHz PWM Synchronous Buck Control IC |
| MIC2168_05 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:1MHz PWM Synchronous Buck Control IC |
| MIC2168A | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:1MHz PWM Synchronous Buck Control IC |
| MIC2168ABMM | 功能描述:IC REG CTRLR BUCK PWM VM 10-MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| MIC2168ABMM TR | 功能描述:IC REG CTRLR BUCK PWM VM 10-MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
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