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参数资料
| 型号： | LT3574EMS#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.1 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | LEAD FREE, PLASTIC, MSOP-16 |
| 文件页数： | 7/24页 |
| 文件大小： | 285K |
| 代理商： | LT3574EMS#TRPBF |
LT3574
3574f
applications inForMation
Overdriving the BIAS Pin with a Third Winding
The LT3574 provides excellent output voltage regulation
without the need for an opto-coupler, or third winding, but
for some applications with higher input voltages (>20V),
it may be desirable to add an additional winding (often
called a third winding) to improve the system efficiency.
For proper operation of the LT3574, if a winding is used as
a supply for the BIAS pin, ensure that the BIAS pin voltage
is at least 3.15V and always less than the input voltage.
For a typical 24VIN application, overdriving the BIAS pin
will improve the efficiency gain 4% to 5%.
Loop Compensation
The LT3574 is compensated using an external resistor-
capacitor network on the VC pin. Typical values are in the
range of RC = 50k and CC = 1nF (see the numerous sche-
maticsintheTypicalApplicationssectionforotherpossible
values). If too large of an RC value is used, the part will be
more susceptible to high frequency noise and jitter. If too
small of an RCvalueisused,thetransientperformancewill
suffer. The value choice for CC is somewhat the inverse
of the RC choice: if too small a CC value is used, the loop
may be unstable, and if too large a CC value is used, the
transient performance will also suffer. Transient response
plays an important role for any DC/DC converter.
Design Example
The following example illustrates the converter design
process using LT3574.
Given the input voltage of 20V to 28V, the required output
is 5V, 0.5A.
VIN(MIN) = 20V, VIN(MAX) = 28V, VOUT = 5V, VF = 0.5V
and IOUT = 0.5A
1. Select the transformer turns ratio to accommodate
the output.
The output voltage is reflected to the primary side by a
factor of turns ratio N. The switch voltage stress VSW is
expressed as:
N
V
N V
V
P
S
SW MAX
IN
OUT
F
=
+
<
(
)
(
) 50
or rearranged to:
N
V
IN MAX
OUT
F
<
+
50
(
)
(
)
Ontheotherhand,theprimary-sidecurrentismultipliedby
the same factor of N. The converter output capability is:
I
D
NI
D
N V
V
N
OUT MAX
PK
OUT
F
IN
(
)
. (
)
(
)
=
=
+
0 8 1
1
2
((
)
V
OUT
F
+
The transformer turns ratio is selected such that the con-
verter has adequate current capability and a switch stress
below 50V. Table 6 shows the switch voltage stress and
output current capability at different transformer turns
ratio.
Table 6. Switch Voltage Stress and Output Current Capability vs
Turns Ratio
N
VSW(MAX) AT VIN(MAX)
(V)
IOUT(MAX) AT VIN(MIN)
(A)
DUTY CYCLE
(%)
1:1
33.5
0.34
16~22
2:1
39
0.57
28~35
3:1
44.5
0.73
37~45
4:1
50
0.84
44~52
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3574IMS | 制造商:LINER 制造商全称:Linear Technology 功能描述:Isolated Flyback Converter Without an Opto-Coupler |
| LT3574IMS#PBF | 功能描述:IC REG FLYBK ISO ADJ .65A 16MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3574IMS#TRPBF | 功能描述:IC REG FLYBK ISO ADJ .65A 16MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3574IMSPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Isolated Flyback Converter Without an Opto-Coupler |
| LT3574IMSTRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Isolated Flyback Converter Without an Opto-Coupler |
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