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| 型号： | MIC261203YJL EV |
| 厂商： | Micrel Inc |
| 文件页数： | 17/31页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR MIC261203YJL |
| 标准包装： | 1 |
| 系列： | HyperLight Load®, SuperSwitcher IIG™ |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，隔离 |
| 输出电压： | 5V |
| 电流 - 输出： | 12A |
| 输入电压： | 5.5 ~ 28 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 600kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | MIC261203 |
| 其它名称： | 576-4014 |
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Micrel, Inc.
MIC261203
Current Limit
The MIC261203 uses the R DS(ON) of the internal low-side
power MOSFET to sense over-current conditions. This
method will avoid adding cost, board space and power
losses taken by a discrete current sense resistor. 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 MIC261203 converter, the
inductor current is sensed by monitoring the low-side
MOSFET in the OFF period. If the inductor current is
greater than 26A, then the MIC261203 turns off the high-
side MOSFET 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 load current-limit threshold has a fold
back characteristic related to the feedback voltage as
shown in Figure 5.
Figure 4. MIC261203 Control Loop Timing
(Discontinuous Mode)
During discontinuous mode, the zero crossing
comparator and the current limit comparator are turned
off. The bias current of most circuits are reduced. As a
result, the total power supply current during
discontinuous mode is only about 450 μ A, allowing the
MIC261203 to achieve high efficiency in light load
applications.
V DD Regulator
30
25
20
15
10
5
0
Current Limit Threshold
vs. Feedback Voltage
The MIC261203 provides a 5V regulated output for input
0.0
0.2
0.4
0.6
0.8
1.0
voltage V IN ranging from 5.5V to 28V. When V IN < 5.5V,
V DD should be tied to PVIN pins to bypass the internal
linear regulator.
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 MIC261203 implements an internal digital soft-start
by making the 0.8V reference voltage V REF ramp from 0
to 100% in about 5ms with 9.7mV steps. Therefore, the
output voltage is controlled to increase slowly by a stair-
case V FB ramp. Once the soft-start cycle ends, the
related circuitry is disabled to reduce current
consumption. V DD must be powered up at the same time
or after V IN to make the soft-start function correctly.
FEEDBACK VOLTAGE (V)
Figure 5. MIC261203 Current-Limit
Foldback Characteristic
Power Good (PG)
The Power Good (PG) pin is an open drain output which
indicates logic high when the output is nominally 92% of
its steady state voltage. A pull-up resistor of more than
10k ? should be connected from PG to VDD.
July 2011
17
M9999-071311-A
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC261203YJLTR | 制造商:Micrel 功能描述:DC DC Regulator 28V 12A 28Pin 5x6mm MLF |
| MIC261203YJL-TR | 功能描述:Buck Switching Regulator IC Positive Adjustable 0.8V 1 Output 12A 28-PowerVQFN Variant, 28-MLF? 制造商:microchip technology 系列:HyperLight Load?，SuperSwitcher IIG?? 包装:剪切带（CT） 零件状态:有效 功能:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:1 电压 - 输入（最小值）:4.5V 电压 - 输入（最大值）:28V 电压 - 输出（最小值/固定）:0.8V 电压 - 输出（最大值）:5.5V 电流 - 输出:12A 频率 - 开关:600kHz 同步整流器:是 工作温度:-40°C ~ 125°C （TJ） 安装类型:表面贴装 封装/外壳:28-PowerVQFN 变式，28-MLF? 供应商器件封装:28-MLF?（5x6） 标准包装:1 |
| MIC261203-ZAYJL TR | 制造商:Micrel Inc 功能描述:IC REG BUCK SYNC ADJ 12A 28MLF |
| MIC2619YD6 | 制造商:Micrel 功能描述:1.2MHz PWM Boost Converter with OVP |
| MIC2619YD6 TR | 功能描述:直流/直流开关转换器 1.2MHz PWM Boost Converter with OVP in Thin SOT-23 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 |
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