参数资料
| 型号： | LTC3780EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/30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
where ? I L is peak-to-peak inductor ripple current. In buck
mode, the maximum average load current is:
to handle the maximum RMS current. For buck operation,
the input RMS current is given by:
I OUT(MAX,BUCK) =
130mV
R SENSE
+
? I L
2
I RMS ≈ I OUT(MAX) ?
V OUT
V IN
?
V IN
V OUT
–1
R SENSE(MAX) =
( ) V
I OUT(MAX) ? V OUT – V IN(MIN)
( ) V
I OUT(MAX) ? V IN(MAX) – V OUT
Figure 8 shows how the load current (I MAXLOAD ? R SENSE )
varies with input and output voltage
The maximum current sensing R SENSE value for the boost
mode is:
R SENSE(MAX) =
2 ? 160mV ? V IN(MIN)
2 ? I OUT(MAX,BOOST) ? V OUT + ? I L,BOOST ? V IN(MIN)
The maximum current sensing R SENSE value for the buck
mode is:
2 ? 130mV
2 ? I OUT(MAX,BUCK) – ? I L,BUCK
The final R SENSE value should be lower than the calculated
R SENSE(MAX) in both the boost and buck modes. A 20% to
30% margin is usually recommended.
C IN and C OUT Selection
In boost mode, input current is continuous. In buck mode,
input current is discontinuous. In buck mode, the selection
of input capacitor C IN is driven by the need to filter the
input square wave current. Use a low ESR capacitor sized
160
This formula has a maximum at V IN = 2V OUT , where
I RMS = I OUT(MAX) /2. This simple worst-case condition
is commonly used for design because even significant
deviations do not offer much relief. Note that ripple cur-
rent ratings from capacitor manufacturers are often based
on only 2000 hours of life which makes it advisable to
derate the capacitor.
In boost mode, the discontinuous current shifts from the
input to the output, so C OUT must be capable of reducing
the output voltage ripple. The effects of ESR (equivalent
series resistance) and the bulk capacitance must be
considered when choosing the right capacitor for a given
output ripple voltage. The steady ripple due to charging
and discharging the bulk capacitance is given by:
Ripple (Boost,Cap) =
C OUT ? V OUT ? f
Ripple (Buck,Cap) =
C OUT ? V IN(MAX) ? f
where C OUT is the output filter capacitor.
The steady ripple due to the voltage drop across the ESR
is given by:
150
140
130
120
110
100
0.1
1
V IN /V OUT (V)
10
3780 F08
? V BOOST,ESR = I L(MAX,BOOST) ? ESR
? V BUCK,ESR = I L(MAX,BUCK) ? ESR
Multiple capacitors placed in parallel may be needed to
meet the ESR and RMS current handling requirements.
Dry tantalum, special polymer, aluminum electrolytic and
ceramic capacitors are all available in surface mount
packages. Ceramic capacitors have excellent low ESR
characteristics but can have a high voltage coefficient.
Capacitors are now available with low ESR and high ripple
current ratings, such as OS-CON and POSCAP.
Figure 8. Load Current vs V IN /V OUT
3780ff
18
For more information www.linear.com/LTC3780
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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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