参数资料
| 型号： | SC173MLTRT |
| 厂商： | Semtech |
| 文件页数： | 18/27页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 3A 10MLPD |
| 产品培训模块： | Power Supplies 101 |
| 标准包装： | 1 |
| 系列： | EcoSpeed® |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.75 V ~ 5.23 V |
| 输入电压： | 3 V ~ 5.5 V |
| 频率 - 开关： | 200kHz ~ 1MHz |
| 电流 - 输出： | 3A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-VFDFN 裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 10-MLPD（3x3） |
| 其它名称： | SC173MLDKR |
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SC173
Applications Information (continued)
and discharging during the switching cycle. For most ap-
plications, the total output ripple voltage is dominated
by the output capacitors, typically SP or POSCAP devices.
For stability the ESR zero of the output capacitor should
be lower than approximately one-third the switching fre-
quency. The formula for minimum ESR is shown by the
following equation.
Output Voltage Dropout
The output voltage adjustable range for continuous-
conduction operation is limited by the fixed 320ns (typi-
cal) minimum off-time. When working with low input
voltages, the duty-factor limit must be calculated using
worst-case values for on and off times. The duty-factor
limitation is shown by the next equation.
ESR MIN =
3
2 × π × C OUT × f SW
DUTY
T ON ( MIN )
T ON ( MIN ) T OFF ( MAX )
Using Ceramic Output Capacitors
When applications use ceramic output capacitors, the
ESR is normally too small to meet the previously stated
ESR criteria. In these applications it is necessary to add
a small signal injection network as shown in Figure 9. In
this network R L and C L filter the LX switching waveform to
generate an in-phase ripple voltage comparable to the
ripple seen on higher ESR capacitors. C C is a coupling ca-
pacitor used to AC couple the generated ripple onto the
FB pin. Capacitor C FF is required for min C OUT applications.
This capacitor introduces a lead/lag into the control with
the maximum phase placed at 1/2 f SW for added stability.
The inductor resistance and MOSFET on-state voltage
drops must be included when performing worst-case
dropout duty-factor calculations.
System DC Accuracy — V OUT Controller
Three factors affect V OUT accuracy: the trip point of the FB
error comparator, the ripple voltage variation with line
and load, and the external resistor tolerance. The error
comparator offset is trimmed so that under static condi-
tions it trips when the feedback pin is 750mV, + 1%.
The on-time pulse from the SC173 in the design example
Q1
V IN
V LX
L
is calculated to give a pseudo-fixed frequency of 800kHz.
Some frequency variation with line and load is expected.
This variation changes the output ripple voltage. Be-
cause adaptive on-time converters regulate to the valley
of the output ripple, ? of the output ripple appears as a
Q2
R L
C L
C C
C FF
R1
R2
C OUT
DC regulation error. For example, if the output ripple is
50mV with V IN = 5 volts, then the measured DC output
will be 25mV above the comparator trip point. If the rip-
ple increases to 30mV with V IN = 5.5V, then the measured
DC output will be 15mV above the comparator trip. The
best way to minimize this effect is to minimize the output
ripple.
Figure 9 — Signal Injection Circuit
The values of R L , C L , C C and C FF are dependent on the con-
ditions of the specific application such as V IN , V OUT , f SW and
I OUT . For switching frequencies ranging from 600kHz to
800kHz, calculations plus experimental test results show
that the following combination of R L =2.5k W , C L =10nF,
C C =68pF and C FF =39pF can be used for many output volt-
ages and loads.
? 2010 Semtech Corporation
To compensate for valley regulation, it may be desirable
to use passive droop. Take the feedback directly from the
output side of the inductor and place a small amount of
trace resistance between the inductor and output ca-
pacitor. This trace resistance should be optimized so that
at full load the output droops to near the lower regula-
tion limit. Passive droop minimizes the required output
capacitance because the voltage excursions due to load
steps are reduced as seen at the load.
18
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SC174 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:4A EcoSpeedTM Synchronous Step-Down Regulator with Optional Ultrasonic Power Save |
| SC1743 | 制造商:ROEBUCK 功能描述:HAND STRETCH FILM |
| SC174EVB | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:4A EcoSpeedTM Synchronous Step-Down Regulator with Optional Ultrasonic Power Save |
| SC174ML.TRT | 制造商:Semtech Corporation 功能描述: |
| SC174MLTRT | 功能描述:IC REG BUCK SYNC ADJ 4A 10MLPD RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:EcoSpeed® 标准包装:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
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