- 您现在的位置：买卖IC网 > PDF目录1832 > LTC3811EUHF#TRPBF (Linear Technology)IC REG CTRLR BUCK PWM CM 38-QFN PDF资料下载
参数资料
| 型号： | LTC3811EUHF#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 24/48页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 38-QFN |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 850kHz |
| 占空比： | 90% |
| 电源电压： | 4.5 V ~ 30 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 ~ 85°C |
| 封装/外壳： | 38-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页当前第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页第37页第38页第39页第40页第41页第42页第43页第44页第45页第46页第47页第48页
LTC3811
APPLICATIONS INFORMATION
V OUT ? V OUT ?
ForCCMoperation,theinductorvaluecanbechosenusing
the following equation:
L = ? 1 – ?
? ?
f ? Δ I L ? V IN(MAX) ?
Choosing a larger value of Δ I L allows the use of a lower
value inductor, but results in higher output voltage ripple
and greater core losses. A reasonable starting point for
setting the ripple current is 40% to 50% of the maximum
output current, or:
Δ I L = 0.4 ? I OUT(MAX)
The inductor saturation current rating needs to be higher
than the peak inductor current during an overload condi-
tion. If I OUT(MAX) is the maximum rated load current, then
the maximum overload current, I MAX , would normally
be chosen to be some factor (e.g., 30%) greater than
I OUT(MAX) :
I MAX = 1.3 ? I OUT(MAX)
Ferrite designs have very low core loss and are preferred
at high switching frequencies, so design goals can con-
centrate on copper loss and preventing saturation. Ferrite
core materials exhibit “hard” saturation, meaning that
the inductance collapses abruptly when the peak current
capability is exceeded. This results in an abrupt increase
in inductor ripple current and output voltage ripple. Do
not allow the core to saturate!
Programming the Maximum Sense Voltage Using the
RNG Pin
The RNG pin can be used in two different ways in order to
program the maximum peak current sense voltage. The
easiest way to program the peak sense voltage is to tie
the RNG pin to either ground or INTV CC . Connecting the
RNG pin to ground results in a 24mV peak sense voltage
and connecting it to INTV CC programs in a 50mV peak
sense voltage. Alternately, an external resistor divider
from INTV CC to ground can be used to set the RNG pin
between 0.6V and 2V, resulting in a nominal peak sense
I L(PK) = I MAX +
1
2
? Δ I L
voltage range of 24mV to 85mV. Figure 10 illustrates the
transfer function from the RNG pin to the peak sense
voltage, which closely follows the following equation for
For a 40% ripple application, the minimum saturation
current rating of the inductor would therefore be:
I L(PK) = 1.5 ? I O(MAX)
In other words, for an application with 40% inductor ripple
current and a maximum output current 30% greater than
the full load current, the inductor’s saturation current rat-
ing needs to be at least 1.5 times the maximum output
current.
Inductor Core Selection
Once the value of L is known, the type of inductor must be
selected. High ef?ciency converters generally cannot afford
the core losses found in low cost powdered iron cores,
forcing the use of more expensive ferrite or molypermalloy
0.6V < V RNG < 2V:
V SENSE(MAX) = 0.0436 ? V RNG – 0.0022
In general, the accuracy of the SENSE pin threshold will
scale with the peak sense voltage de?ned by the RNG
90
80
70
60
50
40
30
20
10
cores. Actual core loss is independent of core size for a ?xed
0
0.5
0.7
0.9
1.1 1.3
1.5
1.7
1.9
inductor value, but is very dependent on the inductance
selected. As inductance increases, core losses go down.
Unfortunately, increased inductance requires more turns
of wire and therefore copper losses will increase.
V RNG VOLTAGE (V)
3811 G30
Figure 10. Maximum Current Sense Threshold
vs RNG Pin Voltage
3811f
24
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3812EFE-5#PBF | IC REG CTRLR BUCK PWM CM 16TSSOP |
| LTC3813EG#PBF | IC REG CTRLR BST PWM CM 28-SSOP |
| LTC3814EFE-5#PBF | IC REG CTRLR BST PWM CM 16-TSSOP |
| LTC3816IFE#TRPBF | IC CONTROLLER S-PHASE 38TSSOP |
| LTC3819EG#TRPBF | IC CNTRLR STEP DOWN 36-SSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3812EFE5#PBF | 制造商:Linear Technology 功能描述: |
| LTC3812EFE-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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 |
| LTC3812EFE-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
| LTC3812IFE-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
| LTC3812IFE-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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。