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參數(shù)資料
| 型號： | LM2576D2T-12 |
| 廠商： | MOTOROLA INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | EASY SWITCHERE⑩ 3.0 A STEP-DOWN VOLTAGE REGULATOR |
| 中文描述： | 3 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSSO5 |
| 封裝： | PLASTIC, D2PAK-5 |
| 文件頁數(shù)： | 11/26頁 |
| 文件大?。?/td> | 278K |
| 代理商： | LM2576D2T-12 |
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LM2576
http://onsemi.com
11
Procedure Fixed Output Voltage Version) (continued)
In order to simplify the switching regulator design, a stepbystep
design procedure and some examples are provided.
Procedure
Example
5. Output Capacitor Selection (C
out
)
A.
Since the LM2576 is a forwardmode switching regulator
with voltage mode control, its open loop 2pole1zero
frequency characteristic has the dominant polepair
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 (C
out
)
A.
C
out
= 680 F to 2000 F standard aluminium electrolytic.
B.
Capacitor voltage rating = 20 V.
Procedure (Adjustable Output Version: LM2576ADJ)
Procedure
Example
Given Parameters:
V
out
= Regulated Output Voltage
V
in(max)
= Maximum DC Input Voltage
I
Load(max)
= Maximum Load Current
Given Parameters:
V
out
= 8.0 V
V
in(max)
= 25 V
I
Load(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
Vout
Vref
1.0
R2
R1
R2
R1
– 1.0
where V
ref
= 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
Vref
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 (C
in
)
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 +V
in
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 (C
in
)
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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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2576D2T-15 | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:EASY SWITCHERE⑩ 3.0 A STEP-DOWN VOLTAGE REGULATOR |
| LM2576D2T-15G | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 15V 3A Buck PWM RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| LM2576D2T-3.3 | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3.3V 3A Buck PWM RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| LM2576D2T-3.3G | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3.3V 3A Buck PWM RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| LM2576D2T-5 | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:Easy Switcher 3.0A Step-Down Voltage Regulator |
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