参数资料
型号: LM2574N-3.3
厂商: ON Semiconductor
文件页数: 8/26页
文件大小: 0K
描述: IC REG BUCK 3.3V 0.5A 8DIP
产品变化通告: Product Discontinuation 27/Jun/2007
标准包装: 50
类型: 降压(降压)
输出类型: 固定
输出数: 1
输出电压: 3.3V
输入电压: 4.75 V ~ 40 V
PWM 型: 电压模式
频率 - 开关: 52kHz
电流 - 输出: 500mA
同步整流器:
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
其它名称: LM2574N-3.3OS
LM2574, NCV2574
Fixed Output Voltage Versions
Feedback
V in
1 (12)
LM2574
Fixed Output
(3)
(14)
1
Output
L1
330 m H
V out
7.0 ? 40 V
Unregulated
DC Input
C in
22 m F
4
Pwr 2
Gnd
(6)
Sig
Gnd
(4)
3
7
ON/OFF
(5)
D1
1N5819
C out
220 m F
Load
C in
C out
D1
L1
R1
R2
?
?
?
?
?
?
22 m F, 60 V, Aluminium Electrolytic
220 m F, 25 V, Aluminium Electrolytic
Schottky, 1N5819
330 m H, (For 5.0 V in , 3.3 V out , use 100 m H)
2.0 k, 0.1%
6.12 k, 0.1%
Adjustable Output Voltage Versions
Feedback
V in
1 (12)
LM2574
Adjustable
(3)
(14)
1
Output
L1
330 m H
V out
5.0 V
7.0 V ? 40 V
Unregulated
DC Input
C in
22 m F
4
Pwr 2
Gnd
(6)
Sig
Gnd
(4)
3
7
ON/OFF
(5)
D1
1N5819
C out
220 m F
R2
6.12 k
R1
2.0 k
Load
1.0 ) R2
V out + V
ref
R1
ref
R2 + R1
V out
V
– 1.0
Where V ref = 1.23 V, R1
between 1.0 k W and 5.0 k W
NOTE: Pin numbers in ( ) are for the SO?16W package.
Figure 16. Test Circuit and Layout Guidelines
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.
On the other hand, the PCB area connected to the Pin 7
(emitter of the internal switch) of the LM2574 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
LM2574 regulator.
For best results, single?point grounding (as indicated) or
ground plane construction should be used.
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