参数资料
| 型号： | LTC3780EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/30页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 24-SSOP |
| 标准包装： | 59 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 99% |
| 电源电压： | 4 V ~ 36 V |
| 降压： | 是 |
| 升压： | 是 |
| 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 ~ 85°C |
| 封装/外壳： | 24-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
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LTC3780
APPLICATIONS INFORMATION
V IN ( MIN ) 2 ? ( V OUT – V IN ( MIN ) ) ? 100
? ? I OUT ( M AX ) ? % Ripple ? V OUT 2
V OUT ? ( V IN ( MAX ) – V O U T ) ? 100
? ? I OUT ( MAX ) ? % Ripple ? V IN ( MAX )
I OUT ( MAX , BOOST ) = ?
? 160 mV ? I L ? V IN ( M IN )
2 ? ?
Figure 11 is a basic LTC3780 application circuit. External
component selection is driven by the load requirement,
and begins with the selection of R SENSE and the inductor
value. Next, the power MOSFETs are selected. Finally, C IN
and C OUT are selected. This circuit can be configured for
operation up to an input voltage of 36V.
Selection of Operation Frequency
The LTC3780 uses a constant frequency architecture and
has an internal voltage controlled oscillator. The switching
frequency is determined by the internal oscillator capacitor.
This internal capacitor is charged by a fixed current plus
an additional current that is proportional to the voltage
applied to the PLLFLTR pin. The frequency of this oscillator
can be varied over a 2-to-1 range. The PLLFLTR pin can
be grounded to lower the frequency to 200kHz or tied to
2.4V to yield approximately 400kHz. When PLLIN is left
open, the PLLFLTR pin goes low, forcing the oscillator to
minimum frequency.
A graph for the voltage applied to the PLLFLTR pin vs
frequency is given in Figure 7. As the operating frequency
is increased the gate charge losses will be higher, reducing
efficiency. The maximum switching frequency is approxi-
mately 400kHz.
450
400
350
300
250
200
150
100
50
0
0 0.5 1 1.5 2 2.5
PLLFLTR PIN VOLTAGE (V)
3780 F07
Figure 7. Frequency vs PLLFLTR Pin Voltage
Inductor Selection
The operating frequency and inductor selection are inter-
related in that higher operating frequencies allow the use of
smaller inductor and capacitor values. The inductor value
has a direct effect on ripple current. The inductor current
ripple ? I L is typically set to 20% to 40% of the maximum
inductor current at boost mode V IN(MIN) . For a given ripple
the inductance terms in continuous mode are as follows:
L BOOST > H ,
L BUCK > H
where:
f is operating frequency, Hz
% Ripple is allowable inductor current ripple, %
V IN(MIN) is minimum input voltage, V
V IN(MAX) is maximum input voltage, V
V OUT is output voltage, V
I OUT(MAX) is maximum output load current
For high efficiency, choose an inductor with low core
loss, such as ferrite and molypermalloy (from Magnetics,
Inc.). Also, the inductor should have low DC resistance to
reduce the I 2 R losses, and must be able to handle the peak
inductor current without saturation. To minimize radiated
noise, use a toroid, pot core or shielded bobbin inductor.
R SENSE Selection and Maximum Output Current
R SENSE is chosen based on the required output current.
The current comparator threshold sets the peak of the
inductor current in boost mode and the maximum inductor
valley current in buck mode. In boost mode, the maximum
average load current at V IN(MIN) is:
– ?
? R SENSE V OUT
3780ff
For more information www.linear.com/LTC3780
17
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| LTC3780EUH | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 32-Pin QFN EP |
| LTC3780EUH#PBF | 功能描述:IC REG CTRLR BST PWM CM 32-QFN 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 |
| LTC3780EUH#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC |
| LTC3780EUH#TR | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 32-Pin QFN EP T/R |
| LTC3780EUH#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 32-QFN 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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