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| 型号： | LT3581EMSE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 22/36页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG ADJ 16MSOP |
| 标准包装： | 37 |
| 类型： | 升压（升压），反相，回扫，Sepic |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.22 V ~ 42 V |
| 输入电压： | 2.5 V ~ 22 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz ~ 2.5MHz |
| 电流 - 输出： | 3.3A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TFSOP（0.118"，3.00mm 宽）裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 16-MSOP，裸露焊盘 |
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LT3581
APPENDIX
R FB =
( ) ? 100%
DC MIN =
DC SEPIC _&_ INVERT ?
DC SI _ INVERT =
SETTING THE OUTPUT VOLTAGE
The output voltage is set by connecting a resistor (R FB )
from V OUT to the FB pin. R FB is determined by using the
following equation:
| V OUT – V FB |
83 . 3 μA
where V FB is 1.215V (typical) for non-inverting topologies
(i.e. boost and SEPIC regulators) and 5mV (typical) for
inverting topologies.
POWER SWITCH DUTY CYCLE
In order to maintain loop stability and deliver adequate
current to the load, the power NPNs (Q1 and Q2 in the
Block Diagram) cannot remain “on” for 100% of each clock
cycle. The maximum allowable duty cycle is given by:
DC MAX = ( T P – MinOffTime ) ? 100 %
T P
where T P is the clock period and MinOffTime (found in the
Electrical Characteristics) is typically 60ns.
Conversely, the power NPNs (Q1 and Q2 in the Block Dia-
gram) cannot remain “off” for 100% of each clock cycle,
and will turn on for a minimum on time (MinOnTime) when
in regulation. This MinOnTime governs the minimum al-
lowable duty cycle given by:
MinOnTime
T P
Where T P is the clock period and MinOnTime (found in
the Electrical Characteristics) is typically 100ns.
For the SEPIC or Dual Inductor Inverting topology (see
Figures 6 and 7):
V D + | V OUT |
V IN + | V OUT | + V D ? V CE S AT
For the Single Inductor Inverting topology (see Figure 13):
| V OUT | ? V IN + V CESAT + 3 ? V D
| V OUT | + 3 ? V D
The LT3581 can be used in configurations where the duty
cycle is higher than DC MAX , but it must be operated in
the discontinuous conduction mode so that the effective
duty cycle is reduced.
INDUCTOR SELECTION
General Guidelines: The high frequency operation of the
LT3581 allows for the use of small surface mount inductors.
For high efficiency, choose inductors with high frequency
core material, such as ferrite, to reduce core losses. Also
to improve efficiency, choose inductors with more volume
for a given inductance. The inductor should have low
DCR (copper-wire resistance) to reduce I 2 R losses, and
must be able to handle the peak inductor current without
saturating. Note that in some applications, the current
handling requirements of the inductor can be lower, such
as in the SEPIC topology where each inductor only carries
one half of the total switch current. Molded chokes or chip
inductors usually do not have enough core area to support
peak inductor currents in the 2A to 6A range. To minimize
radiated noise, use a toroidal or shielded inductor. See
Table 5 for a list of inductor manufacturers.
The application should be designed such that the operating
duty cycle is between DC MIN and DC MAX .
Duty cycle equations for several common topologies are given
below where V D is the diode forward voltage drop and V CESAT
is the collector to emitter saturation voltage of the switch.
V CESAT , with SW1 and SW2 tied together, is typically 250mV
when the combined switch current (I SW1 + I SW2 ) is 2.75A.
Table 5. Inductor Manufacturers
Sumida CDR6D28MN and CDR7D28MN
Series
Coilcraft MSD7342 Series
Vishay IHLP-1616BZ-01, IHLP-2020BZ-01
and IHLP-2525CZ-01 Series
Taiyo Yuden NR Series
Wurth WE-PD Series
www.sumida.com
www.coilcraft.com
www.vishay.com
www.t-yuden.com
www.we-online.com
For the boost topology (see Figure 5):
V OUT – V IN + V D
DC BOOST ?
V OUT + V D – V CESAT
TDK
VLF, SLF and RLF Series
www.tdk.com
3581fa
22
For more information www.linear.com/LT3581
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相关代理商/技术参数 |
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|---|---|
| LT3581EMSE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:3.3A Boost/Inverting DC/DC Converter with Fault Protection |
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| LT3581HDE#TRPBF | 制造商:Linear Technology 功能描述:IC REG MULTI CONFIG ADJ 14DFN |
| LT3581IDE#PBF | 功能描述:IC REG MULTI CONFIG ADJ 14DFN 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:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 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:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3581IDE#TRPBF | 功能描述:IC REG MULTI CONFIG ADJ 14DFN 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:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 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:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
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