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参数资料
| 型号： | LM2575-12IKTGR |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | 3.2 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSSO5 |
| 封装： | POWER FLEX, PLASTIC, 5 PIN |
| 文件页数： | 13/13页 |
| 文件大小： | 188K |
| 代理商： | LM2575-12IKTGR |
LM2575
1A SIMPLE STEPDOWN SWITCHING VOLTAGE REGULATOR
SLVS569A JANUARY 2005 REVISED FEBRUARY 2005
9
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
APPLICATION INFORMATION
layout guidelines (see Figure 2)
With any switching regulator, circuit layout plays an important role in circuit performance. Wiring and parasitic
inductances, as well as stray capacitances, are subjected to rapidly switching currents, which can result in
unwanted voltage transients. To minimize inductance and ground loops, the length of the leads indicated by
heavy lines should be minimized. Optimal results can be achieved by single-point grounding (as illustrated) or
by ground-plane construction. For the same reasons, the two programming resistors used in the adjustable
version should be located as close as possible to the regulator to keep the sensitive feedback wiring short.
input capacitor (CIN)
For stability concerns, an input bypass capacitor (electrolytic, CIN ≥ 47 mF) needs to be located as close as
possible to the regulator. For operating temperatures below 25
°C, CIN may need to be larger in value. In
addition, since most electrolytic capacitors have decreasing capacitances and increasing ESR as temperature
drops, adding a ceramic or solid tantalum capacitor in parallel will increase the stability in cold temperatures.
To extend the capacitor operating lifetime, the capacitor’s RMS ripple current rating should be:
I
C,RMS u 1.2
ton
T
I
LOAD, where :
ton
T
+
V
OUT
V
IN
{buck regulator}, and
ton
T
+
|V
OUT|
(|V
OUT| ) VIN)
{buck
* boost regulator}
output capacitor (COUT)
For both loop stability and filtering of ripple voltage, an output capacitor also is required, again in close proximity
to the regulator. For best performance, low-ESR aluminum electrolytics are recommended, although standard
aluminum electrolytics may be adequate for some applications. Based on the equation below:
Output Ripple Voltage = (ESR of COUT) × (inductor ripple current)
50 mV to 150 mV of output ripple typically can be achieved with capacitor values of 220
mF to 680 mF. Larger
COUT can reduce the ripple 20 mV 50 mV peak-to-peak. To improve further on output ripple, paralleling of
standard electrolytic capacitors may be used. Alternatively, higher grade capacitors such as “high frequency”,
“low inductance”, or “low ESR” can be used.
The following should be taken into account when selecting COUT:
1.
At cold temperatures, the ESR of the electrolytic capacitors can rise dramatically (typically 3x nominal value
at 25
°C). Because solid tantalum capacitors have significantly better ESR specifications at cold
temperatures, they should be used at operating temperature
< 25°C. As an alternative, tantalums also can
be paralleled to aluminum electrolytics and should contribute 10% 20% to the total capacitance.
2.
Low ESR for COUT is desirable for low output ripple. However, the ESR should be >0.05 W to avoid the
possibility of regulator instability. Hence, a sole tantalum capacitor used for COUT is most susceptible to this
occurrence.
3.
The capacitor’s ripple current rating of 52 kHz should be at least 50% higher than the peak-to-peak inductor
ripple current.
PRODUCT
PREVIEW
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2575-12IKTT | 制造商:TI 制造商全称:Texas Instruments 功能描述:1-A SIMPLE STEP DOWN SWITCHING VOLTAGE REGULATOR |
| LM2575-12IKTTR | 制造商:TI 制造商全称:Texas Instruments 功能描述:1-A SIMPLE STEP DOWN SWITCHING VOLTAGE REGULATOR |
| LM2575-12IN | 制造商:TI 制造商全称:Texas Instruments 功能描述:1-A SIMPLE STEP DOWN SWITCHING VOLTAGE REGULATOR |
| LM2575-12T | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Easy Switcher 1.0 A Step-Down Voltage Regulator(389.50 k) |
| LM2575-12TA5R | 制造商:FCI 制造商全称:First Components International 功能描述:1.0A Step - Down Voltage Switching Regulators 1A output current |
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