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参数资料
| 型号： | LT3800EFE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR INV PWM CM 16-TSSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 220kHz |
| 占空比： | 95% |
| 电源电压： | 4 V ~ 60 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 是 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 带卷 (TR) |
LT3800
APPLICATIONS INFORMATION
Some magnetics vendors specify a volt-second product
in their data sheet. If they do not, consult the vendor to
make sure the speci?cation is not being exceeded by your
design. The required volt-second product is calculated as
follows:
duty cycle, to generate an equivalent slope of at least
1E 5 ? I LIMIT A/sec, where I LIMIT is the programmed con-
verter current limit. Current limit is programmed by using
a sense resistor (R S ) such that I LIMIT = 150mV/R S , so the
equation for the minimum inductance to meet the current
? 1– OUT
Volt-Second
V OUT
f O
V
V IN
mode instability criterion can be reduced to:
L MIN = (5E –5 )(V OUT )(R S )
Magnetics vendors specify either the saturation current, the
RMS current, or both. When selecting an inductor based
on inductor saturation current, the peak current through
the inductor, I OUT(MAX) + ( ? I/2), is used. When selecting
an inductor based on RMS current the maximum load
current, I OUT(MAX) , is used.
The requirement for avoiding current mode instability is
keeping the rising slope of sensed inductor ripple current
(S1) greater than the falling slope (S2). During continuous-
current switcher operation, the rising slope of the current
waveform in the switched inductor is less than the falling
slope when operating at duty cycles (DC) greater than 50%.
To avoid the instability condition during this operation, a
false signal is added to the sensed current, increasing the
perceived rising slope. To prevent current mode instability,
the slope of this false signal (Sx) must be suf?cient such
For example, with V OUT = 5V and R S = 20mΩ:
L MIN = (5E –5 )(5)(0.02) = 5μH
After calculating the minimum inductance value, the volt-
second product, the saturation current and the RMS current
for your design, an off the shelf inductor can be selected
from a magnetics vendor. A list of magnetics vendors
can be found at http://www.linear.com/ezone/vlinks or by
contacting the Linear Technology Applications department.
Output Voltage Programming
Output voltage is programmed through a resistor feedback
network to V FB (Pin 6) on the LT3800. This pin is the inverting
input of the error ampli?er, which is internally referenced
to 1.231V. The divider is ratioed to provide 1.231V at the
V FB pin when the output is at its desired value. The output
voltage is thus set following the relation:
that the sensed rising slope exceeds the falling slope, or
S1 + Sx ≥ S2. This leads to the following relations:
Sx ≥ S2 (2DC – 1)/DC
R2 = R1?
V OUT
1.231
–1
where:
S2 ~ V OUT /L
Solving for L yields a relation for the minimum inductance
that will satisfy slope compensation requirements:
when an external resistor divider is connected to the
output as shown.
Programming LT3800 Output Voltage
V OUT
L MIN = V OUT ?
2DC – 1
DC ? Sx
LT3800
V FB
6
R2
The LT3800 maximizes available dynamic range using a
slope compensation generator that continuously increases
SGND
R1
the additional signal slope as duty cycle increases. The
slope compensation waveform is calibrated at an 80%
17
3800 AI03
3800fc
15
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相关代理商/技术参数 |
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| LT3800IFE | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 4V to 60V 16-Pin TSSOP EP |
| LT3800IFE#PBF | 功能描述:IC REG CTRLR INV PWM CM 16-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LT3800IFE#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN REGULATOR CTRL 16-TSSO |
| LT3800IFE#TR | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 4V to 60V 16-Pin TSSOP EP T/R |
| LT3800IFE#TRPBF | 功能描述:IC REG CTRLR INV PWM CM 16-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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