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参数资料
| 型号： | LTC3780IG#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 23/30页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 24-SSOP |
| 标准包装： | 1,800 |
| 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 ~ 125°C |
| 封装/外壳： | 24-SSOP（0.209"，5.30mm 宽） |
| 包装： | 带卷 (TR) |
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LTC3780
APPLICATIONS INFORMATION
V IN ? V IN ?
? I L , BOOST = ? ? 1 – ?
I RIPPLE,BOOST =
? I L,BOOST ? 100
R SENSE =
V OUT ? R1
? ? 1 – OUT ?
? I L , BUCK =
I RIPPLE,BUCK =
? I L,BUCK ? 100
? 12
?
P A , BOOST = ? ? 5 ? ? 1 . 5 ? 0 . 009 = 1 . 94 W
3. INTV CC current. This is the sum of the MOSFET driver
and control currents. This loss can be reduced by sup-
plying INTV CC current through the EXTV CC pin from a
high efficiency source, such as an output derived boost
network or alternate supply if available.
4. C IN and C OUT loss. The input capacitor has the difficult
job of filtering the large RMS input current to the regula-
tor in buck mode. The output capacitor has the more
difficult job of filtering the large RMS output current in
boost mode. Both C IN and C OUT are required to have
low ESR to minimize the AC I 2 R loss and sufficient
capacitance to prevent the RMS current from causing
additional upstream losses in fuses or batteries.
5. Other losses. Schottky diode D1 and D2 are respon-
sible for conduction losses during dead time and light
load conduction periods. Inductor core loss occurs
predominately at light loads. Switch C causes reverse
recovery current loss in boost mode.
When making adjustments to improve efficiency, the input
current is the best indicator of changes in efficiency. If you
make a change and the input current decreases, then the
efficiency has increased. If there is no change in input
current, then there is no change in efficiency.
Design Example
As a design example, assume V IN = 5V to 18V (12V nomi-
nal), V OUT = 12V (5%), I OUT(MAX) = 5A and f = 400kHz.
Set the PLLFLTR pin at 2.4V for 400kHz operation. The
inductance value is chosen first based on a 30% ripple
current assumption. In buck mode, the ripple current is:
V OUT ? V ?
f ? L ? V IN ?
%
I OUT
The highest value of ripple current occurs at the maximum
input voltage. In boost mode, the ripple current is:
f ? L ? V OUT ?
%
I IN
The highest value of ripple current occurs at V IN = V OUT /2.
A 6.8μH inductor will produce 11% ripple in boost mode
(V IN = 6V) and 29% ripple in buck mode (V IN = 18V).
The R SENSE resistor value can be calculated by using the
maximum current sense voltage specification with some
accommodation for tolerances.
2 ? 160mV ? V IN(MIN)
2 ? I OUT(MAX,BOOST) ? V OUT + ? I L,BOOST ? V IN(MIN)
Select an R SENSE of 10mΩ.
Output voltage is 12V. Select R1 as 20k. R2 is:
R2 = – R1
0.8
Select R2 as 280k. Both R1 and R2 should have a toler-
ance of no more than 1%.
Next, choose the MOSFET switches. A suitable choice is
the Siliconix Si4840 (R DS(ON) = 0.009Ω (at V GS = 6V),
C RSS = 150pF, θ JA = 40°C/W).
The maximum power dissipation of switch A occurs in
boost mode when switch A stays on all the time. Assum-
ing a junction temperature of T J = 150°C with ρ 150°C =
1.5, the power dissipation at V IN = 5V is:
2
? 5 ?
3780ff
For more information www.linear.com/LTC3780
23
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相关代理商/技术参数 |
参数描述 |
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| LTC3780IUH | 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 |
| LTC3780IUH#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 |
| LTC3780IUH#PBF | 制造商:Linear Technology 功能描述:DC/DC Controller IC |
| LTC3780IUH#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 |
| LTC3780IUH#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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