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参数资料
| 型号： | LT3571IUD#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.57 A SWITCHING REGULATOR, 2300 kHz SWITCHING FREQ-MAX, PQCC16 |
| 封装： | 3 X 3 MM, 0.50 MM PITCH, LEAD FREE, PLASTIC, MO-220WEED-2, QFN-16 |
| 文件页数： | 16/16页 |
| 文件大小： | 215K |
| 代理商： | LT3571IUD#TRPBF |
LT3571
9
3571fa
Switching Frequency
There are two methods to set the switching frequency of the
LT3571. Both methods require a resistor connected at the
RT pin. Do not leave the RT pin open. Also, do not load this
pin with a capacitor. A resistor must always be connected
for proper operation. One way to set the frequency is simply
connecting an external resistor between the RT pin and
GND. See Table 1 or the Oscillator Frequency vs RT graph
in the Typical Performance Characteristics for resistor
values and corresponding switching frequencies. The other
way is to make the LT3571 synchronize with an external
clock via the SYNC pin. For proper operation, a resistor
should be connected at the RT pin and able to generate
a switching frequency 20% lower than the external clock
when the external clock is absent.
Table 1. Switching Frequency vs RT
Switching Frequency (kHz)
RT (k)
250
56.2
500
26.1
1000
12.1
1500
6.81
2000
4.22
2500
2.67
Inrush Current
The LT3571 has a built-in Schottky diode for the boost
converter. When supply voltage is applied to the VINpin,the
voltage difference between VIN and VOUT generates inrush
current owing from input through the inductor and the
Schottky diode (D1 in the Block Diagram), to charge the
output capacitor. The selection of inductor and capacitor
value should ensure the peak of the inrush current to below
1A. In addition, the LT3571 turn-on should be delayed until
the inrush current is less than the maximum current limit.
The peak inrush current can be estimated as follows:
IP =
VIN – 0.9
L
C
–1
exp –
π
2 L
C
–1
where L is the inductance, and C is the output capacitance.
Table 2 gives inrush peak currents for some component
selections.
Table 2. Inrush Peak Current
VIN (V)
L (μH)
C (μF)
IP (A)
5
10
1
0.81
5
22
1
0.63
Setting Output Voltage
The LT3571 is equipped with both an internal 1V reference
and an auxiliary reference input (the CTRL pin). This
feature allows users to select between using the built-in
reference and supplying an external reference voltage.
The voltage at the CTRL pin can be adjusted while the
chip is operating, to alter the output voltage of LT3571
for purposes such as APD’s bias voltage adjustment. To
use the internal 1V reference, the CTRL pin should be held
higher than 1.2V, which can be done by tying it to VREF.
When the CTRL pin is between 0V and 1V, the LT3571 will
regulate the output such that the FB pin voltage is equal
to the CTRL pin voltage. To set the output voltage, select
the values of R1 and R2 (see Figure 2) according to the
following equation:
R1 = R2
VMONIN
V1
–1
where V1 = 1V if the internal reference is used, or V1 =
CTRL if CTRL is between 0V and 1V. R2 can be selected to
load the output to maintain a constant switching frequency
when the APD load is very low. Preventing entry into
pulse-skipping mode is an important consideration for
post ltering the regulator output.
Figure 2. Output Voltage Feedback Connection
APPLICATIONS INFORMATION
MONIN
CTRL
R1
3
15
14
3571 F02
FB
LT3571
R2
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|---|---|
| LT3572 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Full-Bridge Piezo Driver with 900mA Boost Converter |
| LT3572EUF#PBF | 功能描述:IC DRIVER PIEZO DUAL 20-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电机和风扇控制器，驱动器 系列:- 标准包装:1 系列:- 应用:步进电机驱动器，1-2 相，2 相 评估套件:- 输出数:1 电流 - 输出:800mA 电压 - 负载:10 V ~ 28 V 电源电压:4.75 V ~ 5.25 V 工作温度:-20°C ~ 90°C 安装类型:表面贴装 封装/外壳:28-SOP + 2 翼片裸露焊盘 供应商设备封装:28-HSOPHC（15.2x7.9） 包装:剪切带 (CT) 其它名称:869-1268-1 |
| LT3572EUF#TRPBF | 功能描述:IC DRIVER PIEZO DL 20-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电机和风扇控制器，驱动器 系列:- 产品变化通告:ATA683(3,4)PLQW Obsolescence 09/Aug/2012 标准包装:1 系列:- 应用:DC 电机控制器，无刷（BLDC），3 相 评估套件:可供 输出数:1 电流 - 输出:100mA 电压 - 负载:5.25 V ~ 20 V 电源电压:5.25 V ~ 20 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-VQFN（7x7） 包装:剪切带 (CT) 其它名称:ATA6833-PLQWCT |
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| LT3572EUF-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Full-Bridge Piezo Driver with 900mA Boost Converter |
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