- 您现在的位置：买卖IC网 > PDF目录20516 > 750108 (Wurth Electronics Inc)BOARD EVAL FOR LT3748 PDF资料下载
参数资料
| 型号： | 750108 |
| 厂商： | Wurth Electronics Inc |
| 文件页数： | 12/30页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR LT3748 |
| 设计资源： | LT3748 Design Schematic/Tips |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，隔离 |
| 功率 - 输出： | 30W |
| 输出电压： | 12V |
| 电流 - 输出： | 2.5A |
| 输入电压： | 22 ~ 75 V |
| 稳压器拓扑结构： | 回扫 |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | LT3748 |
| 相关产品： | LT3748HMS#TRPBF-ND - IC REG CTRLR FLYBK ISO CM 16MSOP LT3748HMS#PBF-ND - IC REG CTRLR FLYBK ISO CM 16MSOP LT3748IMS#TRPBF-ND - IC REG CTRLR FLYBK ISO CM 16MSOP LT3748IMS#PBF-ND - IC REG CTRLR FLYBK ISO CM 16MSOP LT3748EMS#TRPBF-ND - IC REG CTRLR FLYBK ISO CM 16MSOP LT3748EMS#PBF-ND - IC REG CTRLR FLYBK ISO CM 16MSOP |
| 其它名称： | 732-3308 |
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页当前第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
LT3748
APPLICATIONS INFORMATION
The current limitation on output power delivery is gen-
erally constrained by transformer saturation current in
higher power applications, although the MOSFET switch
and output diode will need to be rated for the desired
currents, as well. Increasing the peak current on the pri-
mary side of the flyback by reducing the R SENSE resistor
is the primary way to increase output power, and power
delivered increases fairly linearly with current limit as
shown in Figure 2, until parasitic losses begin to dominate.
However, once the saturation current of the transformer
is exceeded the energy coupling between the primary and
the secondary will be reduced and incremental power will
not be delivered to the output. In addition, the primary
inductance will drop, the SENSE pin overcurrent threshold
may trip due to a corresponding rapid rise in current, and
the transformer will have to absorb the energy that is not
transferred through the saturated core, leading to heating.
Some manufacturers may not specify the rated saturation
current but it is a necessary specification when trying to
minimize transformer size and maximize output power
and efficiency. Also necessary for proper design is data
on saturation current over temperature—the saturation
of typical power ferrites may reduce by over 20% from
25°C to 100°C.
The thermal limitation in flyback applications for lower
output voltages will be dominated by losses in the output
diode, with resistive and leakage losses in the transformer
50
I LIM = 3A
40
I LIM = 2A
30
increasing as a percentage basis of loss as the output
voltage is increased. As power levels increase the output
diode and transformer may exceed their rated temperature
specifications. Minimizing RMS output diode current,
selecting a diode with minimal forward drop at expected
currents and minimizing parasitic resistances and leakage
inductance in the transformer will keep those components
below their maximum temperatures while maximizing
efficiency. The following section discussing transformer
selection will further help focus on how to minimize losses
in the output diode.
While quiescent current in the LT3748 itself is low (ap-
proximately 300μA from V IN and 1mA from INTV CC ), the
current required to drive the external MOSFET (f SW ? Q G ), if
drawn from V IN through the LT3748 INTV CC LDO, dissipates
(V IN – INTV CC ) ? f SW ? Q G . If that power is high enough to
cause significant heating of the LT3748 the current may
need to be drawn from a third winding. Doing so will push
all thermal limitations outside of the LT3748.
Selecting a Transformer
Transformer specification and design is perhaps the most
critical part of successfully applying the LT3748. In addition
to the usual list of caveats dealing with high frequency
isolated power supply transformer design, the following
information should be carefully considered.
First and most importantly, since the voltage on the sec-
ondary side of the transformer is inferred by the voltage
sampled on the primary, the transformer turns ratio must
be tightly controlled to ensure a consistent output volt-
age. A tolerance of ±5% in turns ratio from transformer to
transformer could result in a variation of more than ±5% in
output regulation. Fortunately, most magnetic component
20
10
I LIM = 1A
manufacturers are capable of guaranteeing a turns ratio
tolerance of 1% or better.
Linear Technology has worked with several leading mag-
0
0
20
40 60
INPUT VOLTAGE (V)
80
100
netic component manufacturers to produce predesigned
flyback transformers for use with the LT3748. Table 1
3748 F02
shows the details of several of these transformers.
Figure 2. Maximum Output Power at 12V OUT
with 150V V DS(MAX) and I LIM = 1A, 2A, 3A
3748fa
12
相关PDF资料 |
PDF描述 |
|---|---|
| BAS40-06LT1 | DIODE SCHOTTKY 40V CA SOT23 |
| 396-062-526-802 | CARD EDGE 62POS DL .125X.250 BLK |
| 396-062-526-204 | CARD EDGE 62POS DL .125X.250 BLK |
| 396-062-526-202 | CARD EDGE 62POS DL .125X.250 BLK |
| 396-062-526-201 | CARD EDGE 62POS DL .125X.250 BLK |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 750109 | 制造商:Pilz International 功能描述:CONTACT MODULE 3NO/1NC 24V 制造商:PILZ 功能描述:CONTACT MODULE, 3NO/1NC, 24V, 30OHM 制造商:PILZ 功能描述:CONTACT MODULE, 3NO/1NC, 24V, 30OHM; Coil Voltage VDC Nom:24V; Contact Current Max:6A; Contact Voltage AC Nom:240V; Contact Voltage DC Max:24V; Coil Resistance:30ohm; Contact Configuration:3PST-NO, SPST-NC; Average Power ;RoHS Compliant: Yes |
| 750-109 | 功能描述:安装硬件 CIRC-O-GIDE .75in Nylon Black 94V-0 RoHS:否 制造商:Harwin 类型:SMT Cable Clip 材料:Phosphor Bronze 安装孔大小: 长度:5 mm 外径: 内径: 厚度: 电镀:Tin 螺纹大小: |
| 75010BK002 | 制造商:Alpha Wire Company 功能描述:Cat5e cable 2 pair solid 105deg 152m |
| 75010-BK002 | 制造商:Alpha Wire 功能描述: |
| 75-010BP | 制造商:RAYHOME 功能描述:ST/STEEL SHIM 0.10X75X75 |
发布紧急采购，3分钟左右您将得到回复。