- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358818 > LM2574M-15 (NATIONAL SEMICONDUCTOR CORP) Precision Chopper-Stabilized Operational Amplifier 8-PDIP PDF資料下載
參數(shù)資料
| 型號： | LM2574M-15 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Precision Chopper-Stabilized Operational Amplifier 8-PDIP |
| 中文描述： | 1.8 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封裝： | SMT-14 |
| 文件頁數(shù)： | 11/24頁 |
| 文件大?。?/td> | 397K |
| 代理商： | LM2574M-15 |
LM2574
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 example is provided.
Procedure
Example
5. Output Capacitor Selection (Cout)
A.
Since the LM2574 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
100
μ
F and 470
μ
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 = 100
μ
F to 470
μ
F standard aluminium electrolytic.
B.
Capacitor voltage rating = 20 V.
Procedure (Adjustable Output Version: LM2574–ADJ)
Procedure
Example
Given Parameters:
Vout = Regulated Output Voltage
Vin(max) = Maximum DC Input Voltage
ILoad(max) = Maximum Load Current
Given Parameters:
Vout = 24 V
Vin(max) = 40 V
ILoad(max) = 0.4 A
1. Programming Output Voltage
To select the right programming resistor R1 and R2 value (see
Figure 2) use the following formula:
where Vref = 1.23 V
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
Vref1.0
R2
R1
R2
R1
1.0
1. Programming Output Voltage (selecting R1 and R2)
Select R1 and R2 :
Vout = 1.23
Select R1 = 1.0 k
R2 = 18.51 k
, choose a 18.7 k
metal film resistor.
1.0
R2
R1
R2
R1
Vout
Vref
1.0
1.0 k
10 V
1.23 V
1.0
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
“EXTERNAL COMPONENTS” section of this data sheet.
2. Input Capacitor Selection (Cin)
A 22
μ
F 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
LM2574 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 1.0 A current rating is adequate.
B.
Use a 50 V MBR150 Schottky diode or any suggested fast
recovery diodes in Table 1.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM2574M-5.0 | SIMPLE SWITCHER⑩ 0.5A Step-Down Voltage Regulator |
| LM2574N-3.3 | SIMPLE SWITCHER⑩ 0.5A Step-Down Voltage Regulator |
| LM2574N-15 | SIMPLE SWITCHER⑩ 0.5A Step-Down Voltage Regulator |
| LM2574N-12 | SIMPLE SWITCHER⑩ 0.5A Step-Down Voltage Regulator |
| LM2574M-12 | SIMPLE SWITCHER⑩ 0.5A Step-Down Voltage Regulator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2574M-15/NOPB | 功能描述:IC REG BUCK 15V 0.5A 14SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:SIMPLE SWITCHER® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3.3V 輸入電壓:4.5 V ~ 24 V PWM 型:- 頻率 - 開關(guān):- 電流 - 輸出:125mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-6 包裝:Digi-Reel® 供應(yīng)商設(shè)備封裝:SOT-6 其它名稱:MAX1836EUT33#TG16DKR |
| LM2574M-3.3 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| LM2574M-3.3/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 0.5A STEP-DOWN VLTG REG RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| LM2574M-3.3/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu |
| LM2574M-3.3LM2574M-5.0 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:SIMPLE SWITCHERT 0.5A Step-Down Voltage Regulator(639.73 k) |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。