参数资料
| 型号： | SC4620MLTRT |
| 厂商： | Semtech |
| 文件页数： | 13/19页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 2.5A 20MLPQ |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.5 V ~ 5.5 V |
| 输入电压： | 2.3 V ~ 5.5 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 200kHz ~ 2MHz |
| 电流 - 输出： | 2.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-MLPQ |
| 包装： | 标准包装 |
| 供应商设备封装： | 20-MLPQ（4x4） |
| 其它名称： | SC4620MLDKR |
SC4620
POWER MANAGEMENT
Application information (Cont.)
550kHz, the hiccup period is around 238ms. (refer to
Figure 7).
A poor layout will make OCP trip point shift and is not
easily to calculate by R ISET . This is because it is affected
by ground bounce, spiker voltage between Vin pin and PH
pin, and internal parameter tolerance. Users can refer to
Figure 14, it shows how to set maximum output current
by R ISET .
After the required inductor value is selected, the proper
selection of the core material is based on the peak
inductor current and efficiency requirements. The core
must be able to handle the peak inductor current I PEAK
without saturation and produce low core loss during the
high frequency operation and is given as follows:
Vout
A
B
The power loss for the inductor includes its core loss and
copper loss. If possible, the winding resistance should be
minimized to reduce any copper loss of the inductor, (the
core loss can be found in the manufacturer’s datasheet).
0
0 . 6 * Vout
C
The inductor’s copper loss can be estimated as follows:
Vo
D
Iout
0
Imax
where
I LRMS is the RMS current in the inductor.
Figure 16. Over Current Protection Characteristic
Inductor Selection
For a typical SC4620 application, the inductor selection
is mainly based on its value, saturation current and DC
resistance. The inductor should be able to handle the
peak current without saturating and its copper resistance
in the winding should be as low as possible to minimize its
resistive power loss.
The inductor value can be determined according to its
operating point and the switching frequency as follows:
where
fs = switching frequency.
D I = ratio of the peak to peak inductor current to the
maximum output load current.
The peak to peak inductor current is:
This current can be calculated as follows:
Output Capacitor Selection
Basically there are two major factors to consider in select-
ing the type and quantity of the output capacitors. The
first one is the required ESR (Equivalent Series Resis -
tance) which should be low enough to reduce the voltage
deviation from its nominal one during its load changes.
The second one is the required capacitance, which should
be high enough to hold up the output voltage. Before the
SC4620 regulates the inductor current to a new value
during a load transient, the output capacitor delivers all
the additional current needed by the load.
The ESR and ESL of the output capacitor, the loop para-
sitic inductance between the output capacitor and the
load combined with inductor ripple current are all major
contributors to the output voltage ripple.
Input Capacitor Selection
The input capacitor selection is based on its ripple cur-
rent level, required capacitance and voltage rating. This
capacitor must be able to provide the ripple current by the
? 2008 Semtech Corp.
13
www.semtech.com
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| SC4624AMLTRT | 功能描述:IC REG BUCK ADJ 4A 20MLPQ RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:50 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:5 V ~ 25 V 输入电压:2.3 V ~ 5.5 V PWM 型:电流模式 频率 - 开关:600kHz，1.2MHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 包装:管件 供应商设备封装:8-MSOP |
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