- 您现在的位置：买卖IC网 > PDF目录15283 > LTC3838IFE#PBF (Linear Technology)IC REG CTRLR BUCK PWM CM 38TSSOP PDF资料下载
参数资料
| 型号： | LTC3838IFE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 38/54页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 38TSSOP |
| 标准包装： | 50 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 2MHz |
| 电源电压： | 4.5 V ~ 38 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： | 38-TFSOP （0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 管件 |
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页当前第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页第49页第50页第51页第52页第53页第54页
LTC3838
APPLICATIONS INFORMATION
V OUT = 0.6V ? ? 1 + FB2 ?
3. DRV CC current. This is the sum of the MOSFET driver
and INTV CC control currents. The MOSFET driver cur-
rents result from switching the gate capacitance of the
power MOSFETs. Each time a MOSFET gate is switched
from low to high to low again, a packet of charge dQ
moves from DRV CC to ground. The resulting dQ/dt is a
current out of DRV CC that is typically much larger than
the controller I Q current. In continuous mode,
I GATECHG = f ? (Qg (TOP) + Qg (BOT) ),
where Qg (TOP) and Qg (BOT) are the gate charges of the
top and bottom MOSFETs, respectively.
Supplying DRV CC power through EXTV CC could save
several percents of efficiency, especially for high V IN
applications. Connecting EXTV CC to an output-derived
source will scale the V IN current required for the driver
and controller circuits by a factor of (Duty Cycle)/(Ef-
ficiency). For example, in a 20V to 5V application, 10mA
of DRV CC current results in approximately 2.5mA of V IN
current. This reduces the mid-current loss from 10%
or more (if the driver was powered directly from V IN )
to only a few percent.
Power losses in the switching regulator will reflect as
a higher than ideal duty cycle, or a longer on-time for a
constant frequency. This efficiency accounted on-time
can be calculated as:
t ON ≈ t ON(IDEAL) /Efficiency
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.
Design Example
Consider a channel of step-down converter from V IN =
4.5V to 26V to V OUT = 1.2V, with I OUT(MAX) = 15A, and
f = 350kHz (see Figure 13, Channel 1.
The regulated output voltage is determined by:
? R ?
? R FB1 ?
Using a 10k resistor for R FB1 , R FB2 is also 10k.
The frequency is programmed by:
4. C IN loss. The input capacitor filters large square-wave
input current drawn by the regulator into an averaged
DC current from the supply. The capacitor itself has
R T [ k Ω ] =
41550
f [ kHz ]
– 2.2 =
41550
350
– 2.2 ≈ 116.5
a zero average DC current, but square-wave-like AC
current flows through it. Therefore the input capacitor
must have a very low ESR to minimize the RMS current
loss on ESR. It must also have sufficient capacitance
to filter out the AC component of the input current to
prevent additional RMS losses in upstream cabling,
fuses or batteries. The LTC3838 2-phase architecture
improves the ESR loss.
“Hidden” copper trace, fuse and battery resistance, even
at DC current, can cause a significant amount of efficiency
Use the nearest 1% resistor standard value of 115k.
The minimum on-time occurs for maximum V IN . Using the
t ON(MIN) curves in the Typical Performance Characteristics
as references, make sure that the t ON(MIN) at maximum V IN
is greater than that the LTC3838 can achieve, and allow
sufficient margin to account for the extension of effective
on-time at light load due to the dead times (t D(TG/BG) +
t D(TG/BG) in the Electrical Characteristics). The minimum
on-time for this application is:
degradation, so it is important to consider them during
the design phase. Other losses, which include the C OUT
ESR loss, bottom MOSFET ’s body diode reverse-recovery
t ON(MIN) =
V OUT
V IN(MAX) ? f
=
1.2V
24V ? 350kHz
= 143ns
loss, and inductor core loss generally account for less
than 2% additional loss.
3838fa
38
相关PDF资料 |
PDF描述 |
|---|---|
| VI-25L-EW-F1 | CONVERTER MOD DC/DC 28V 100W |
| LTC3855IFE#PBF | IC REG CTRLR BUCK PWM CM 38-SSOP |
| VI-25K-EY-B1 | CONVERTER MOD DC/DC 40V 50W |
| LT3724IFE#TRPBF | IC REG CTRLR BST INV PWM 16TSSOP |
| VI-25K-EW-F4 | CONVERTER MOD DC/DC 40V 100W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3838IUHF#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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) |
| LTC3838IUHF#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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) |
| LTC3838IUHF-1#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 38QFN 制造商:Linear Technology 功能描述:BUCK DUAL CNTRL 4.5-38V 2MHZ 38QFN 制造商:Linear Technology 功能描述:BUCK, DUAL, CNTRL, 4.5-38V, 2MHZ, 38QFN 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Dual, Fast, Accurate Step-Down Controller with Differential 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, DUAL, BUCK, ADJ, QFN-38, Primary Input Voltage:38V, No. of Outputs:2, Output Current:25A, No. of Pins:38, Operating Temperature Min:-40C, Operating Temperature Max:125C, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes |
| LTC3838IUHF-1#TRPBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 38QFN 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Dual, Fast, Accurate Step-Down Controller with Differential 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, DUAL, BUCK, ADJ, QFN-38, Primary Input Voltage:38V, No. of Outputs:2, Output Current:25A, No. of Pins:38, Operating Temperature Min:-40C, Operating Temperature Max:125C, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes |
| LTC3838IUHF-2#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 38-QFN 制造商:Linear Technology 功能描述:BUCK DUAL CNTRL 4.5-38V 2MHZ 38QFN 制造商:Linear Technology 功能描述:DC-DC CONTROLLER BUCK 2MHZ QFN-38 制造商:Linear Technology 功能描述:BUCK, DUAL, CNTRL, 4.5-38V, 2MHZ, 38QFN 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Dual, Fast, Accurate Step-Down Controller with Differential |
发布紧急采购，3分钟左右您将得到回复。