参数资料
| 型号： | SC4620MLTRT |
| 厂商： | Semtech |
| 文件页数： | 14/19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
Operation
Application Information (Cont.)
switching actions. For the continuous conduction mode,
the RMS value of the input capacitor can be calculated
from:
5
4
3
2
1
C1
SC4620
IN
This current gives the capacitor’s power loss as follows:
D
Vout
C8
R1
L1
C2
COMP
FB
PH
C
R
C4
R8
R7
This capacitor’s RMS loss can be a significant part of the
total loss in the converter and reduces the overall convert-
er efficiency. The input ripple voltage mainly depends on
the input capacitor’s ESR and its capacitance for a given
load, input voltage and output voltage. Assuming that the
input current of the converter is constant, the required
input capacitance for a given voltage ripple can be calcu-
lated by:
B
A
5
R9
Figure 17. Compensation Network
4 3
Provides 3 Poles and 2 Zeros
2
1
?
where
D = V O /V I , duty ratio.
D V I = the given input voltage ripple.
Loop Compensation Design
For a DC/DC converter, it is usually required that the con-
verter has a loop gain of a high cross-over frequency for
fast load response, high DC and low frequency gain for low
steady state error, and enough phase margin for its oper-
ating stability. Often one can not have all these properties
at the same time. The purpose of the loop compensation
is to arrange the poles and zeros of the compensation
network to meet the requirements for a specific applica -
tion.
For voltage mode step down applications as shown in Fig-
ure 17, the power stage transfer function is:
where
R = load resistance
R C = C4’s ESR.
The compensation network will have these characteris-
tics:
G COMP ( s ) = I ?
The SC4620 has an internal error amplifier and requires
the compensation network to connect among the COMP
pin and FB pin, GND, and the output as shown in Figure
17. The compensation network includes C1, C2, R1, R7,
R8 and C8. R9 is used to program the output voltage ac -
cording to:
w
s
1 +
1 +
s
w Z 1
s
w P 1
?
1 +
? 1 +
s
w Z 2
s
w P 2
? 2008 Semtech Corp.
14
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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