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参数资料
| 型号： | LTC3417AIFE-1#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 12/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ DL 20TSSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 输出电压： | 0.8 V ~ 5 V |
| 输入电压： | 2.25 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 1.5MHz，600kHz ~ 4MHz |
| 电流 - 输出： | 1A，1.5A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-TSSOP（0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 20-TSSOP-EP |
LTC3417A-1
APPLICATIONS INFORMATION
V OUT1 0.8V 1 +
Inmostcases,0.1μFto1μFofceramiccapacitorsshould
also be placed close to the LTC3417A-1 in parallel with
the main capacitors for high frequency decoupling.
Ceramic Input and Output Capacitors
Higher value, lower cost ceramic capacitors are now
becoming available in smaller case sizes. Because the
LTC3417 control loop does not depend on the output
capacitor’s ESR for stable operation, ceramic capacitors
can be used freely to achieve very low output ripple and
small circuit size. When choosing the input and output
ceramic capacitors, choose the X5R or X7R dielectric
formulations. These dielectrics have the best temperature
and voltage characteristics of all the ceramics for a given
value and size.
More capacitance may be required depending on the duty
cycle and load step requirements.
In most applications, the input capacitor is merely required
to supply high frequency bypassing, since the impedance
to the supply is very low. A 10μF ceramic capacitor is
usually enough for these conditions.
Setting the Output Voltage
The LTC3417A-1 develops a 0.8V reference voltage between
the feedback pins, V FB1 and V FB2 , and the signal ground
as shown in Figure 4. The output voltages are set by two
resistive dividers according to the following formulas:
R1
R2
Great care must be taken when using only ceramic input
and output capacitors. When a ceramic capacitor is used
at the input and the power is being supplied through long
V OUT2 0.8V 1 +
R3
R4
C OUT ≈ 2.5
wires,suchasfromawalladapter,aloadstepattheoutput
can induce ringing at the V IN pin. At best, this ringing can
couple to the output and be mistaken as loop instability.
At worst, the ringing at the input can be large enough to
damage the part.
Since the ESR of a ceramic capacitor is so low, the input
and output capacitor must ful?ll a charge storage re-
quirement. During a load step, the output capacitor must
instantaneously supply the current to support the load
until the feedback loop raises the switch current enough
to support the load. The time required for the feedback
loop to respond is dependent on the compensation com-
ponents and the output capacitor size. Typically, 3 to 4
cycles are required to respond to a load step, but only in
the ?rst cycle does the output drop linearly. The output
droop, V DROOP , is usually about 2 to 3 times the linear
droop of the ?rst cycle. Thus, a good place to start is with
the output capacitor size of approximately:
Δ I OUT
f O ? V DROOP
Keeping the current small (<5μA) in these resistors
maximizes ef?ciency, but making the current too small
may allow stray capacitance to cause noise problems and
reduce the phase margin of the error amp loop.
To improve the frequency response, a feed-forward ca-
pacitor, C F , may also be used. Great care should be taken
to route the V FB node away from noise sources, such as
the inductor or the SW line.
Power-On Reset
The POR pin is an open-drain output which pulls low when
either regulator is out of regulation. When both output
voltages are above –6% of regulation, a timer is started
which allows the POR output to go high after 212,992
clock cycles (when FREQ is tied to V IN ) or 294,912 clock
cycles (when FREQ is tied to ground through an external
resistor). This results in a delay of approximately 150ms
when the oscillator is set to 2MHz. When either channel
is shut down, the POR output re?ects the condition of the
running regulator.
3417a1fa
12
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相关代理商/技术参数 |
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|---|---|
| LTC3417AIFE-2#PBF | 功能描述:IC REG BUCK SYNC ADJ DL 20TSSOP 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: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 |
| LTC3417AIFE-2#TRPBF | 功能描述:IC REG BUCK SYNC ADJ DL 20TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LTC3417AIFE-2-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous 1.5A/1A 4MHz Step-Down DC/DC Regulator |
| LTC3417AIFE-2-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Synchronous 1.5A/1A 4MHz Step-Down DC/DC Regulator |
| LTC3417AIFEPBF | 制造商:Linear Technology 功能描述:Conv DC-DC Dual Step-Down 5.5V TSSOP20EP |
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