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| 型号： | LM2576TV-ADJ |
| 厂商： | MOTOROLA INC |
| 元件分类： | 稳压器 |
| 英文描述： | 3 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSFM5 |
| 封装： | TO-220, 5 PIN |
| 文件页数： | 3/28页 |
| 文件大小： | 415K |
| 代理商： | LM2576TV-ADJ |
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LM2576
11
MOTOROLA ANALOG IC DEVICE DATA
Procedure (Fixed Output Voltage Version) (continued)In order to simplify the switching regulator design, a step–by–step
design procedure and some examples are provided.
Procedure
Example
5. Output Capacitor Selection (Cout)
A. Since the LM2576 is a forward–mode switching regulator
with voltage mode control, its open loop 2–pole–1–zero
frequency characteristic has the dominant pole–pair
determined by the output capacitor and inductor values. For
stable operation and an acceptable ripple voltage,
(approximately 1% of the output voltage) a value between
680
F and 2000 F is recommended.
B. Due to the fact that the higher voltage electrolytic capacitors
generally have lower ESR (Equivalent Series Resistance)
numbers, the output capacitor’s voltage rating should be at
least 1.5 times greater than the output voltage. For a 5.0 V
regulator, a rating at least 8.0 V is appropriate, and a 10 V or
16 V rating is recommended.
5. Output Capacitor Selection (Cout)
A. Cout = 680 F to 2000 F standard aluminium electrolytic.
B. Capacitor voltage rating = 20 V.
Procedure (Adjustable Output Version: LM2576–ADJ)
Procedure
Example
Given Parameters:
Vout = Regulated Output Voltage
Vin(max) = Maximum DC Input Voltage
ILoad(max) = Maximum Load Current
Given Parameters:
Vout = 8.0 V
Vin(max) = 25 V
ILoad(max) = 2.5 A
1. Programming Output Voltage
To select the right programming resistor R1 and R2 value (see
Figure 2) use the following formula:
Resistor R1 can be between 1.0 k and 5.0 k
. (For best
temperature coefficient and stability with time, use 1% metal
film resistors).
Vout + Vref 1.0 )
R2
R1
R2
+ R1
Vout
V
ref
–1.0
where Vref = 1.23 V
1. Programming Output Voltage (selecting R1 and R2)
Select R1 and R2:
R2 = 9.91 k
, choose a 9.88 k metal film resistor.
R2
+ R1
Vout
V
ref
* 1.0 + 1.8 k
8.0 V
1.23 V
* 1.0
Vout + 1.23 1.0 )
R2
R1
Select R1 = 1.8 k
2. Input Capacitor Selection (Cin)
To prevent large voltage transients from appearing at the input
and for stable operation of the converter, an aluminium or
tantalum electrolytic bypass capacitor is needed between the
input pin +Vin and ground pin Gnd This capacitor should be
located close to the IC using short leads. This capacitor should
have a low ESR (Equivalent Series Resistance) value.
For additional information see input capacitor section in the
“Application Hints” section of this data sheet.
2. Input Capacitor Selection (Cin)
A 100
F, 150 V aluminium electrolytic capacitor located near
the input and ground pin provides sufficient bypassing.
3. Catch Diode Selection (D1)
A. Since the diode maximum peak current exceeds the
regulator maximum load current the catch diode current
rating must be at least 1.2 times greater than the maximum
load current. For a robust design, the diode should have a
current rating equal to the maximum current limit of the
LM2576 to be able to withstand a continuous output short.
B. The reverse voltage rating of the diode should be at least
1.25 times the maximum input voltage.
3. Catch Diode Selection (D1)
A. For this example, a 3.0 A current rating is adequate.
B. Use a 30 V 1N5821 Schottky diode or any
suggested fast recovery diode in the Table 1.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2576TV-ADJG | 功能描述:直流/直流开关调节器 3A 1.23-37V ADJ Buck PWM 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 |
| LM2576TV-AJD | 制造商:MOTOROLA 制造商全称:Motorola, Inc 功能描述:EASY SWITCHERE⑩ 3.0 A STEP-DOWN VOLTAGE REGULATOR |
| LM2576WT | 功能描述:直流/直流开关调节器 3A Step-Down SMPS Regulator (ROHS Compliant) 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 |
| LM2576WT L3 | 制造商:Micrel Inc 功能描述:Micrel LM2576WT L3 DC to DC Conversion |
| LM2576WU | 功能描述:直流/直流开关调节器 3A Step-Down SMPS Regulator (ROHS Compliant) 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 |
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