参数资料
| 型号： | SC2440TETRT |
| 厂商： | Semtech |
| 文件页数： | 12/26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
( V OUT + 0 . 45 )( V In ? V OUT ? 0 . 25 )
L =
( V IN + 0 . 2 )( 0 . 6 ) f
Power dissipated in the input capacitor is I RMS ( CIN ) ? ( ESR ) .
( at D =
I OUT 1
Equation (6) has a maximum value of ),
in size and DCR. Setting ? I L = 0 . 3 ( 2 ) = 0 . 6 A ,
V D = 0 . 45 V and V CESAT = 0 . 25 V in (3),
(4)
2
2 2
corresponding to the worst-case power dissipation
where L is in μ H and f is in MHz.
I 2OUT ? ESR
4
in C IN .
I OUT ( MAX ) = I LM ?
? I L ? I L
I OUT ( MAX ) = I LM ?
= I LM ?
= 0 . 85 ? I LM .
? V OUT = ? I L ? ? ESR +
?
8 fC OUT ? ?
?
Equation (3) shows that for a given V OUT , ? I L increases
as D decreases. If V IN varies over a wide range, then
choose L based on the nominal input voltage. Always
verify converter operation at the input voltage extremes.
The peak current limits of both SC2440 power transistors
are internally set at 2.6A. The peak current limits are
duty-cycle invariant and are guaranteed higher than 2A.
The maximum load current is therefore conservatively
= 2 A ? (5)
2 2
If ? I L = 0 . 3 ? I LM , then
? I L 0 . 3I LM
2 2
The saturation current of the inductor should be 20-30%
higher than the peak current limit (2A). Low-cost powder
iron cores are not suitable for high-frequency switching
power supplies due to their high core losses. Inductors
with ferrite cores should be used.
Input Capacitor
A buck converter draws pulse current with peak-to-peak
amplitude equal to its output current I OUT from its input
supply. An input capacitor placed between the supply
and the buck converter filters the AC current and keeps
the current drawn from the supply to a DC constant. The
input capacitance C IN should be high enough to filter the
pulse input current. Its equivalent series resistance (ESR)
should be low so that power dissipated in the capacitor
does not result in significant temperature rise and
degrade reliability. For a single channel buck converter,
the RMS ripple current in the input capacitor is
I RMS ( CIN ) = I OUT D ( 1 ? D ) . (6)
A dual-channel step-down converter with interleaved
switching reduces the RMS ripple current in the input
capacitor to a fraction of that of a single-phase buck
converter. If both power transistors in the SC2440 were
to switch on in phase, the current drawn by the SC2440
would consist of current pulses with amplitude equal to
the sum of the channel output currents. If each channel
were delivering I OUT and operating at 50% duty cycle, then
the input current would switch from zero to 2I OUT . The
RMS ripple current in the input capacitor would then be
I OUT . Power dissipated in C IN would be I 2OUT ? ESR , 4 times
that of a single-channel converter. The SC2440 produces
the highest RMS ripple current in C IN when only one
channel is running and delivering the maximum output
current ( ≈ 1 . 5 ? 2 A ). The input capacitor therefore should
have a RMS ripple current rating of at least 1A.
Multi-layer ceramic capacitors, which have very low ESR
(a few m ? ) and can easily handle high RMS ripple current,
are the ideal choice for input filtering. A single 4.7 μ F or
10 μ F X5R ceramic capacitor is adequate. For high voltage
applications, a small ceramic (1 μ F or 2.2 μ F) can be placed
in parallel with a low ESR electrolytic capacitor to satisfy
both the ESR and bulk capacitance requirements.
Output Capacitor
The output ripple voltage ? V OUT of a buck converter can
be expressed as
? 1 ?
(7)
where C OUT is the output capacitance.
Inductor ripple current ? I L increases as D decreases
(Equation (3)). The output ripple voltage is therefore the
highest when V IN is at its maximum. The first term in (7)
? 2005 Semtech Corp.
12
www.semtech.com
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相关代理商/技术参数 |
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|---|---|
| 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: |
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