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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： | 6/24页 |
| 文件大小： | 285K |
| 代理商： | LT3574EMS#TRPBF |
LT3574
3574f
applications inForMation
Setting the Current Limit Resistor
The maximum current limit can be set by placing a resistor
between the RILIM pin and ground. This provides some
flexibilityinpickingstandardoff-the-shelftransformersthat
may be rated for less current than the LT3574’s internal
power switch current limit. If the maximum current limit
is needed, use a 10k resistor. For lower current limits, the
following equation sets the approximate current limit:
R
A I
k
ILIM
LIM
=
+
65 10 0 9
10
3
( .
)
The Switch Current Limit vs RILIM plot in the Typical Per-
formance Characteristics section depicts a more accurate
current limit.
Undervoltage Lockout (UVLO)
The SHDN/UVLO pin is connected to a resistive voltage
divider connected to VIN as shown in Figure 8. The voltage
threshold on the SHDN/UVLO pin for VIN rising is 1.22V.
To introduce hysteresis, the LT3574 draws 2.5A from the
SHDN/UVLOpinwhenthepinisbelow1.22V.Thehysteresis
is therefore user-adjustable and depends on the value of
R1. The UVLO threshold for VIN rising is:
V
V R R
R
A R
IN UVLO RISING
(
,
)
.
(
)
.
=
+
1 22
1
2
2 5
1
The UVLO threshold for VIN falling is:
V
V R R
R
IN UVLO FALLING
(
,
)
.
(
)
=
+
1 22
1
2
To implement external run/stop control, connect a small
NMOS to the UVLO pin, as shown in Figure 8. Turning the
NMOS on grounds the UVLO pin and prevents the LT3574
from operating, and the part will draw less than a 1A of
quiescent current.
Minimum Load Requirement
The LT3574 obtains output voltage information through
thetransformerwhilethesecondarywindingisconducting
current. During this time, the output voltage (multiplied
times the turns ratio) is presented to the primary side of
the transformer. The LT3574 uses this reflected signal to
regulate the output voltage. This means that the LT3574
must turn on every so often to sample the output voltage,
which delivers a small amount of energy to the output.
This sampling places a minimum load requirement on the
output of 1% to 2% of the maximum load.
BIAS Pin Considerations
For applications with an input voltage less than 15V, the
BIAS pin is typically connected directly to the VIN pin. For
input voltages greater than 15V, it is preferred to leave the
BIAS pin separate from the VIN pin. In this condition, the
BIAS pin is regulated with an internal LDO to a voltage of
3V.BykeepingtheBIASpinseparatefromtheinputvoltage
at high input voltages, the physical size of the capacitors
can be minimized (the BIAS pin can then use a 6.3V or
10V rated capacitor).
Figure 8. Undervoltage Lockout (UVLO)
LT3574
SHDN/UVLO
GND
R2
R1
VIN
3574 F08
RUN/STOP
CONTROL
(OPTIONAL)
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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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