- 您现在的位置：买卖IC网 > PDF目录1833 > LTC3872ETS8#TRMPBF (Linear Technology)IC REG CTRLR BST PWM CM TSOT23-8 PDF资料下载
参数资料
| 型号： | LTC3872ETS8#TRMPBF |
| 厂商： | Linear Technology |
| 文件页数： | 14/22页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM TSOT23-8 |
| 标准包装： | 1 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 650kHz |
| 电源电压： | 2.75 V ~ 9.8 V |
| 降压： | 无 |
| 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： | SOT-23-8 薄型，TSOT-23-8 |
| 包装： | 标准包装 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
| 其它名称： | LTC3872ETS8#TRMPBFDKR |
LTC3872
APPLICATIONS INFORMATION
? I O(MAX) ? 2
? 1 – D MAX ?
20μs/DIV
? V O + V D – V IN ? 5 + 0.4 – 3.3
?
?
V O + V D
I IN(PEAK) = 1+ ? ?
? χ I O(MAX) 2
?
2 ? 1 – D MAX
?I L = χ ?
I O(MAX) 2
output current. Assuming an efficiency of 90%, this
sense resistor power dissipation represents 1.3% of the
overall input power. In other words, for this application,
the use of V DS sensing would increase the efficiency by
approximately 1.3%.
For more details regarding the various terms in these
equations, please refer to the section Boost Converter:
Power MOSFET Selection.
3. The losses in the inductor are simply the DC input cur-
rent squared times the winding resistance. Expressing this
loss as a function of the output current yields:
P R(WINDING) = ? R W
4. Losses in the boost diode. The power dissipation in the
boost diode is:
P DIODE = I O(MAX) ? V D
The boost diode can be a major source of power loss in
a boost converter. For the 3.3V input, 5V output at 7A ex-
ample given above, a Schottky diode with a 0.4V forward
voltage would dissipate 2.8W, which represents 7% of the
input power. Diode losses can become significant at low
output voltages where the forward voltage is a significant
percentage of the output voltage.
5. Other losses, including C IN and C O ESR dissipation and
inductor core losses, generally account for less than 2%
of the total additional loss.
Checking Transient Response
The regulator loop response can be verified by looking at
the load transient response. Switching regulators generally
take several cycles to respond to an instantaneous step
in resistive load current. When the load step occurs, V O
immediately shifts by an amount equal to ( D I LOAD )(ESR),
and then C O begins to charge or discharge (depending on
the direction of the load step) as shown in Figure 7. The
regulator feedback loop acts on the resulting error amp
output signal to return V O to its steady-state value. During
this recovery time, V O can be monitored for overshoot or
ringing that would indicate a stability problem.
V OUT
200mV/DIV
AC-COUPLED
I L
500mA/DIV
3872 F07
Figure 7. Load Transient Response for a 3.3V Input,
5V Output Boost Converter Application, 0.1A to 1A Step
A second, more severe transient can occur when con-
necting loads with large (>1μF) supply bypass capacitors.
The discharged bypass capacitors are effectively put in
parallel with C O , causing a nearly instantaneous drop in
V O . No regulator can deliver enough current to prevent
this problem if the load switch resistance is low and it is
driven quickly. The only solution is to limit the rise time
of the switch drive in order to limit the inrush current
di/dt to the load.
Boost Converter Design Example
The design example given here will be for the circuit shown
on the front page. The input voltage is 3.3V, and the output
is 5V at a maximum load current of 2A.
1. The duty cycle is:
D= = = 38.9%
5 + 0.4
2. An inductor ripple current of 40% of the maximum load
current is chosen, so the peak input current (which is also
the minimum saturation current) is:
= 1.2 ? = 3.9A
1 – 0. 39
The inductor ripple current is:
= 0.4 ? = 1.3A
1–D MAX 1– 0.39
3872fc
14
For more information www.linear.com/LTC3872
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3873EDDB#TRMPBF | IC REG CTRLR BST FLYBK PWM 8-DFN |
| LTC3873ITS8-5#TRPBF | IC REG CTRLR BST FLYBK TSOT23-8 |
| LTC3876EFE#PBF | IC CTLR DC/DC DDR DUAL 38-TSSOP |
| LTC3878EGN#PBF | IC REG CTRLR BUCK PWM CM 16-SSOP |
| LTC3879EUD#PBF | IC REG CTRLR BUCK PWM CM 16-QFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3872HDDB#TRMPBF | 功能描述:IC REG CTRLR BST PWM CM 8-DFN 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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 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-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3872HDDB#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 8-DFN 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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 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-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3872HTS8#PBF | 制造商:Linear Technology 功能描述:DP-SWREG/Controller, CUT TAPE No Rsense, Current Mode Boost DC/DC Controller |
| LTC3872HTS8#TRMPBF | 功能描述:IC REG CTRLR BST PWM CM TSOT23-8 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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 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-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3872HTS8#TRPBF | 功能描述:IC REG CTRLR BST PWM CM TSOT23-8 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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 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-WQFN 裸露焊盘 包装:带卷 (TR) |
发布紧急采购，3分钟左右您将得到回复。