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参数资料
| 型号： | LT3480EDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/24页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 2A 10DFN |
| 标准包装： | 121 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.79 V ~ 20 V |
| 输入电压： | 3.6 V ~ 36 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 200kHz ~ 2.4MHz |
| 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： | 10-WFDFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 10-DFN（3x3） |
| 产品目录页面： | 1331 (CN2011-ZH PDF) |
LT3480
OPERATION
R1 = R2 ? OUT ? 1 ?
V D + V OUT
t ON(MIN) ( V D + V IN – V SW )
TheLT3480containsapowergoodcomparatorwhichtrips
when the FB pin is at 86% of its regulated value. The PG
output is an open-collector transistor that is off when the
output is in regulation, allowing an external resistor to pull
the PG pin high. Power good is valid when the LT3480 is
enabled and V IN is above 3.6V.
APPLICATIONS INFORMATION
FB Resistor Network
The output voltage is programmed with a resistor divider
between the output and the FB pin. Choose the 1% resis-
tors according to:
? V ?
? 0.79V ?
Reference designators refer to the Block Diagram.
Setting the Switching Frequency
The LT3480 uses a constant frequency PWM architecture
that can be programmed to switch from 200kHz to 2.4MHz
by using a resistor tied from the RT pin to ground. A table
showing the necessary R T value for a desired switching
frequency is in Figure 1.
SWITCHING FREQUENCY (MHz) R T VALUE (k ? )
0.2 187
0.3 121
0.4 88.7
0.5 68.1
0.6 56.2
0.7 46.4
0.8 40.2
0.9 34
1.0 29.4
1.2 23.7
1.4 19.1
1.6 16.2
1.8 13.3
2.0 11.5
2.2 9.76
2.4 8.66
Figure 1. Switching Frequency vs. R T Value
The LT3480 has an overvoltage protection feature which
disables switching action when the V IN goes above 38V
typical (36V minimum). When switching is disabled, the
LT3480 can safely sustain input voltages up to 60V.
Operating Frequency Tradeoffs
Selection of the operating frequency is a tradeoff between
efficiency, component size, minimum dropout voltage, and
maximum input voltage. The advantage of high frequency
operation is that smaller inductor and capacitor values may
be used. The disadvantages are lower efficiency, lower
maximum input voltage, and higher dropout voltage. The
highest acceptable switching frequency (f SW(MAX) ) for a
given application can be calculated as follows:
f SW(MAX) =
where V IN is the typical input voltage, V OUT is the output
voltage, V D is the catch diode drop (~0.5V) and V SW is the
internal switch drop (~0.5V at max load). This equation
shows that slower switching frequency is necessary to
safely accommodate high V IN /V OUT ratio. Also, as shown
in the next section, lower frequency allows a lower dropout
voltage. The reason input voltage range depends on the
switching frequency is because the LT3480 switch has finite
minimum on and off times. The switch can turn on for a
minimum of ~150ns and turn off for a minimum of ~150ns.
Typical minimum on time at 25°C is 80ns. This means that
the minimum and maximum duty cycles are:
DC MIN = f SW t ON(MIN)
DC MAX = 1– f SW t OFF(MIN)
where f SW is the switching frequency, the t ON(MIN) is the
minimum switch on time (~150ns), and the t OFF(MIN) is
the minimum switch off time (~150ns). These equations
show that duty cycle range increases when switching
frequency is decreased.
3480fe
For more information www.linear.com/LT3480
9
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相关代理商/技术参数 |
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| LT3480EDD-TR | 制造商:LINER 制造商全称:Linear Technology 功能描述:36V, 2A, 2.4MHz Step-Down Switching Regulator with 70μA Quiescent Current |
| LT3480EDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:36V, 2A, 2.4MHz Step-Down Switching Regulator with 70μA Quiescent Current |
| LT3480EMSE | 制造商:LINER 制造商全称:Linear Technology 功能描述:36V, 2A, 2.4MHz Step-Down Switching Regulator with 70μA Quiescent Current |
| LT3480EMSE#PBF | 功能描述:IC REG BUCK ADJ 2A 10MSOP 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 |
| LT3480EMSE#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC 制造商:Linear Technology 功能描述:IC, BUCK REGULATOR, MSOP-10 |
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