参数资料
| 型号： | SC2446ITETRT |
| 厂商： | Semtech |
| 文件页数： | 19/38页 |
| 文件大小： | 0K |
| 描述： | IC SYNC STEP DOWN CTRLR 28-TSSOP |
| 标准包装： | 1 |
| 应用： | 控制器，DDR |
| 输入电压： | 4.7 V ~ 16 V |
| 输出数： | 2 |
| 输出电压： | 可调至 0.5V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SOIC（0.173"，4.40mm 宽）裸露焊盘 |
| 供应商设备封装： | 28-TSSOP 裸露焊盘 |
| 包装： | 标准包装 |
| 产品目录页面： | 1358 (CN2011-ZH PDF) |
| 其它名称： | SC2446ITEDKR |
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SC2446
POWER MANAGEMENT
Application Information (Cont.)
1) lossless current sensing,
2) higher signal-to-noise ratio, and
3) preventing thermal run-away.
Vin
Rds1
The basic arrangement of the Combi-sense is shown in
Figure 14.
Cin
PN
iL(t)
L
Rs
RL
Cs
Where, R L is the equivalent series resistance of the output
inductor. The added R s and C s form a RC branch for
inductor current sensing. This branch is driven from a
VPN
vC(t)
Cout
Rload
Vo
small totem pole driver (Q3 and Q4) integrated within
SC2446. The base driving signals Vbe3 and Vbe4
Vin
Q1
Vgs1
Figure 15 a). Equivalent sub-circuit.
C in
PN
i L (t )
L
Rs
RL
Cs
Vo
Vin
Vgs2
Q2
v C (t )
C ou t
R l o ad
C
i n
PN
iL(t)
L
Rs
RL
Cs
Vbe 3
Q3
Rds2
VP N
C ou t
Rload
Vo
Vbe 4
VP N
Q4
vC (t)
Figure 14. The basic structure of Combi-Sense.
are designed to follow the gate drive signals Vgs1 and
Vgs2, respectively, with minimal delay drive. Ideally, the
leading and falling edges of the Virtual Phase Node (VPN)
follow that of the Phase Node (PN) when Q1~Q4 switch
accordingly.
Specifically, when Q1/Q3 are ON and Q2/Q4 are OFF,
the equivalent circuit of Figure 14 reduces to Figure 15
a). Where, Rds1 is the on-resistance of the top MOSFET.
The two branches, consisting of {(Rds1+RL), L} and {R s ,
C S }, are in parallel. The DC voltage drop (Rds1+RL)I o
equals V Cs . In this way, the output current is sensed from
V Cs when (Rds1+RL) is known.
When Q1/Q3 are OFF and Q2/Q4 are ON, the equivalent
circuit of Figure 14 becomes the sub-circuit as shown in
Figure 15 b). Where, Rds2 is the channel resistance of
the bottom MOSFET. In this case, the branch {R s ,C s } is in
parallel with {(Rds2+RL), L} and V Cs =(Rds2+RL)I o . In
average,
Figure 15 b). Equivalent sub-circuit.
V Cs =[D(Rds1+RL)+(1-D)(Rds2+RL)]I o ,
or equivalently
V Cs =[D Rds1+(1-D)Rds2+RL]I o =R eq I o .
It is noted that the DC value of V Cs is independent of the
value of L, R s and C s . This means that, if only the average
load current information is needed (such as in average
current mode control), this current sensing method is
effective without time constant matching requirement.
In the current mode control as implemented in SC2446,
the voltage ripple on C s is critical for PWM operation. In
fact, the AC voltage ripple peak-to-peak value of V Cs
(denoted as ? V Cs ) directly effects the signal-to-noise ratio
of the PWM operation. In general, smaller ? V Cs leads to
lower signal-to-noise ratio and more noise sensitive
operation. Larger ? V Cs leads to more circuit (power stage)
? 2004 Semtech Corp.
19
www.semtech.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SC2446ITSTRT | 制造商:Semtech Corporation 功能描述:Controller IC 制造商:Semtech Corporation 功能描述:SC Series 4.7 to 16 V 1 MHz Dual-Phase Synchronous Step-Down Controller TSSOP-28 |
| SC2447 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Dual-Phase, Single or Dual Output Synchronous Step-Down Controller |
| SC24-470-R | 功能描述:INDUCTOR SHIELD 47UH 150MA SMD RoHS:是 类别:电感器，线圈，扼流圈 >> 固定式 系列:SC24 标准包装:500 系列:1331 电感:1.2µH 电流:247mA 电流 - 饱和:247mA 电流 - 温升:- 类型:铁芯体 容差:±10% 屏蔽:屏蔽 DC 电阻(DCR):最大 730 毫欧 Q因子@频率:40 @ 7.9MHz 频率 - 自谐振:130MHz 材料 - 芯体:铁 封装/外壳:0.312" L x 0.115" W x 0.135" H（7.94mm x 2.92mm x 3.43mm） 安装类型:表面贴装 包装:带卷 (TR) 工作温度:-55°C ~ 105°C 频率 - 测试:7.9MHz |
| SC24-471-R | 功能描述:INDUCTOR SHIELD 470UH 50MA SMD RoHS:是 类别:电感器，线圈，扼流圈 >> 固定式 系列:SC24 标准包装:500 系列:1331 电感:1.2µH 电流:247mA 电流 - 饱和:247mA 电流 - 温升:- 类型:铁芯体 容差:±10% 屏蔽:屏蔽 DC 电阻(DCR):最大 730 毫欧 Q因子@频率:40 @ 7.9MHz 频率 - 自谐振:130MHz 材料 - 芯体:铁 封装/外壳:0.312" L x 0.115" W x 0.135" H（7.94mm x 2.92mm x 3.43mm） 安装类型:表面贴装 包装:带卷 (TR) 工作温度:-55°C ~ 105°C 频率 - 测试:7.9MHz |
| SC2447EVB | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Dual-Phase, Single or Dual Output Synchronous Step-Down Controller |
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