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| 型号： | LT3579EFE-1#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PDSO20 |
| 封装： | 4.40 MM, LEAD FREE, PLASTIC, TSSOP-20 |
| 文件页数： | 17/40页 |
| 文件大小： | 503K |
| 代理商： | LT3579EFE-1#PBF |
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LT3579/LT3579-1
24
35791f
appenDix
SETTING THE OUTPUT VOLTAGE
The output voltage is set by connecting a resistor (RFB)
from VOUT to the FB pin. RFB is determined from the
following equation:
RFB =
| VOUT – VFB |
83.3A
where VFB is 1.215V (typical) for non-inverting topologies
(i.e. boost and SEPIC regulators) and 9mV (typical) for
inverting topologies (see Electrical Characteristics).
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
BlockDiagram)cannotremain“on”for100%ofeachclock
cycle. The maximum allowable duty cycle is given by:
DCMAX =
TP –MinOffTime
(
)
TP
100%
where TP is the clock period and MinOffTime (found in the
Electrical Characteristics) is typically 45nS.
Conversely, the power NPNs (Q1 and Q2 in the Block
Diagram) cannot remain “off” for 100% of each clock
cycle, and will turn on for a minimum time (MinOnTime)
wheninregulation.ThisMinOnTimegovernstheminimum
allowable duty cycle given by:
DCMIN =
MinOnTime
(
)
TP
100%
where TP is the clock period and MinOnTime (found in the
Electrical Characteristics) is typically 55nS.
Theapplicationshouldbedesignedsuchthattheoperating
duty cycle is between DCMIN and DCMAX.
Duty cycle equations for several common topologies are
given below where VD is the diode forward voltage drop
and VCESAT is typically 250mV at 5.5A for a combined
SW1 and SW2 current.
For the boost topology (see Figure 6):
DCBOOST
VOUT – VIN + VD
VOUT + VD – VCESAT
For the SEPIC or Dual Inductor Inverting topology (see
Figures 7 and 8):
DCSEPIC_&_INVERT
VD +|VOUT |
VIN +|VD | + VOUT VCESAT
For the Single Inductor Inverting topology (see Figure 14):
DCSI_INVERT
| VOUT |VIN + VCESAT + 3 VD
| VOUT | + 3 VD
The LT3579 can be used in configurations where the duty
cycle is higher than DCMAX, but it must be operated in
the discontinuous conduction mode so that the effective
duty cycle is reduced.
INDUCTOR SELECTION
The high frequency operation of the LT3579 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 I2R 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. Multilayer chokes or
chip inductors usually do not have enough core volume to
support peak inductor currents in the 4A to 7A range. To
minimizeradiatednoise,useatoroidalorshieldedinductor.
See Table 5 for a list of inductor manufacturers.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3579EFE-1-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection |
| LT3579EFE-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection |
| LT3579EFE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection |
| LT3579EUFD#PBF | 功能描述:IC REG MULTI CONFIG SYNC 20QFN 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 |
| LT3579EUFD#TRPBF | 功能描述:IC REG MULTI CONFIG SYNC 20QFN 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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