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| 型号： | LM2594PADJG |
| 厂商： | ON Semiconductor |
| 文件页数： | 8/25页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 0.5A 8DIP |
| 标准包装： | 50 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.23 V ~ 37 V |
| 输入电压： | 4.5 V ~ 40 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 150kHz |
| 电流 - 输出： | 500mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 通孔 |
| 封装/外壳： | 8-DIP（0.300"，7.62mm） |
| 包装： | 管件 |
| 供应商设备封装： | 8-PDIP |
LM2594
PCB LAYOUT GUIDELINES
As in any switching regulator, the layout of the printed
circuit board is very important. Rapidly switching currents
associated with wiring inductance, stray capacitance and
parasitic inductance of the printed circuit board traces can
generate voltage transients which can generate
electromagnetic interferences (EMI) and affect the desired
operation. As indicated in the Figure 16, to minimize
inductance and ground loops, the length of the leads
indicated by heavy lines should be kept as short as possible.
For best results, single ? point grounding (as indicated) or
On the other hand, the PCB area connected to the Pin 2
(emitter of the internal switch) of the LM2594 should be
kept to a minimum in order to minimize coupling to sensitive
circuitry.
Another sensitive part of the circuit is the feedback. It is
important to keep the sensitive feedback wiring short. To
assure this, physically locate the programming resistors near
to the regulator, when using the adjustable version of the
LM2594 regulator.
ground plane construction should be used.
DESIGN PROCEDURE
I L(on) +
d + on , where T is the period of switching.
d + out
Buck Converter Basics
The LM2594 is a “Buck” or Step ? Down Converter which
is the most elementary forward ? mode converter. Its basic
schematic can be seen in Figure 17.
The operation of this regulator topology has two distinct
time periods. The first one occurs when the series switch is
on, the input voltage is connected to the input of the inductor.
The output of the inductor is the output voltage, and the
rectifier (or catch diode) is reverse biased. During this
period, since there is a constant voltage source connected
across the inductor, the inductor current begins to linearly
ramp upwards, as described by the following equation:
V IN * V OUT t on
L
During this “on” period, energy is stored within the core
material in the form of magnetic flux. If the inductor is
properly designed, there is sufficient energy stored to carry
the requirements of the load during the “off” period.
This period ends when the power switch is once again
turned on. Regulation of the converter is accomplished by
varying the duty cycle of the power switch. It is possible to
describe the duty cycle as follows:
t
T
For the buck converter with ideal components, the duty
cycle can also be described as:
V
V in
Figure 18 shows the buck converter, idealized waveforms
of the catch diode voltage and the inductor current.
V on(SW)
Power
Switch
L
Power
Switch
Off
Power
Switch
On
Power
Switch
Off
Power
Switch
On
V D (FWD)
V in
D
C out
R Load
Time
Figure 17. Basic Buck Converter
The next period is the “off” period of the power switch.
When the power switch turns off, the voltage across the
inductor reverses its polarity and is clamped at one diode
voltage drop below ground by the catch diode. The current
now flows through the catch diode thus maintaining the load
current loop. This removes the stored energy from the
inductor. The inductor current during this time is:
I pk
I Load (AV)
I min
Power Power
Diode Switch Diode Switch
Time
Figure 18. Buck Converter Idealized Waveforms
I L(off) +
V OUT * V D t off
L
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| LM2595ADPBCKGEVB | 功能描述:电源管理IC开发工具 LM2595ADJ D2PAK BUCK DB RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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| LM2595DSADJR4G | 功能描述:直流/直流开关调节器 1A BUCK SW REG 150KHZ RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| LM2595S12 | 制造商:Texas Instruments 功能描述:SWITCHING REG, 1A 12V, SMD, 2595 制造商:Texas Instruments 功能描述:SWITCHING REG, 1A 12V, SMD, 2595; Primary Input Voltage:24V; No. of Outputs:1; Output Voltage:12V; Output Current:1A; Voltage Regulator Case Style:TO-263; No. of Pins:5; Operating Temperature Min:-25C; Operating Temperature ;RoHS Compliant: Yes |
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