参数资料
| 型号： | SC2440TETRT |
| 厂商： | Semtech |
| 文件页数： | 9/26页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 2A DL 16TSSOP |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出数： | 2 |
| 输入电压： | 2.8 V ~ 20 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 1.4MHz |
| 电流 - 输出： | 2A |
| 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： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 16-TSSOP |
| 产品目录页面： | 1358 (CN2011-ZH PDF) |
| 其它名称： | SC2440TEDKR |
SC2440
POWER MANAGEMENT
Applications Information
Setting the Output Voltage
The regulator output voltage is set with an external
resistive divider (Figure 4) with its center tap tied to the
FB pin.
VOUT
Choosing the Operating Frequency
The free-running frequency of the master oscillator is
set with an external resistor from the ROSC pin to ground.
Channel frequency is one-half of that of the master
oscillator. A graph of channel frequency against R OSC is
shown in the “Typical Performance Characteristics ”.
R1
15nA
R2
FB
SC2440
Before choosing the operating frequency, tradeoffs
among efficiency, operating duty cycle, component size
and EMI interferences must be considered. High
frequency operation reduces the size of passive
components but switching losses are higher. Lowering
the switching frequency improves efficiency. However the
required inductor and capacitor are larger. Channel
Figure 4. V OUT is set with a Resistive Divider
frequencies between 1 and 2MHz are good compromises.
R 1 = R 2 ( V OUT ? 1 )
(1)
In order to quantify the tradeoff between switching
frequency and efficiency, the 12V to 5V DC-DC converter
? V OUT ? 15 nA ? 100 ? ( R 1 ?? R 2 )
The percentage error due the input bias current of the
error amplifier is
= .
V OUT 1 V
Example: Determine the output voltage error of a
V OUT = 5 V converter with R 2 = 51 . 1 K ? .
From (1),
R 1 = 51 . 1 K ? ? ( 5 ? 1 ) = 205 K ?
in Figure 1 is modified to run at 500KHz and 2.5MHz
while keeping the inductor ripple current constant. The
modified component values are tabulated in Table 1 and
efficiencies at these frequencies are shown in Figure 5.
The efficiency of the 1.3MHz 5V regulator in Figure 1 is
also plotted for the ease of comparison. The efficiency
at 500KHz is only marginally higher than that at 1.3MHz.
The peak efficiency at 2.5MHz is only 2% lower compared
to those at lower frequencies.
? V OUT
V OUT
=
? 15 nA ? 100 ? ( 51 . 1 K ?? 205 K )
1 V
= ? 0 . 061 % .
90
Efficiency vs Load Current
500KHz
This error is at least an order of magnitude lower than
the ratio tolerance resulting from the use of 1% resistors
in the divider string.
85
80
1.3MHz
2.5MHz
f ( M H z )
R 9 ( K ? )
L 2 ( μ H )
R 7 ( K ? )
C 8 ( p F )
C 9 ( p F )
0 . 5
5 3 . 6
1 0 ( C o i l t r o n i c s D R 7 3 - 1 0 0 )
1 2 . 4
4 7 0
2 2
V IN =12V
1 . 3
1 5 . 0
4 . 4 4 ( F a l c o D 0 4 0 1 2 )
2 4 . 3
2 2 0
1 0
75
V OUT =5V
2 . 5
4 . 0 2
2 . 7 ( S u m i d a C R 4 3 - 2 R 7 )
3 2 . 4
2 2 0
1 0
0.0
0.5
1.0
1.5
2.0
Load Current (A)
Table 1. The 12V to 5V Converter in Figure 1 is modified
to run at Different Frequencies.
Figure 5. Efficiencies of 500KHz, 1.3MHz and 2.5MHz
12V to 5V Step-down Converters.
? 2005 Semtech Corp.
9
www.semtech.com
相关PDF资料 |
PDF描述 |
|---|---|
| SC2443MLTRT | IC DUAL SYNC STP-DN CTRLR 24MLPQ |
| SC2446ITETRT | IC SYNC STEP DOWN CTRLR 28-TSSOP |
| SC2544TSTRT | IC REG CTRLR BUCK PWM VM 24TSSOP |
| SC2595MLTRT | IC DDR TERMINATION REG 16-MLPQ |
| SC2596STRT | IC INTEGRTD DDRII TERM REG 8SOIC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| SC2441 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441A | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441A_09 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441AEVB | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter |
| SC2441ATETRT | 制造商:Semtech Corporation 功能描述: |
发布紧急采购，3分钟左右您将得到回复。