参数资料
型号: MIC5209-3.3YS TR
厂商: Micrel Inc
文件页数: 10/13页
文件大小: 0K
描述: IC REG LDO 3.3V .5A SOT223
标准包装: 1
稳压器拓扑结构: 正,固定式
输出电压: 3.3V
输入电压: 最高 16V
电压 - 压降(标准): 0.35V @ 500mA
稳压器数量: 1
电流 - 输出: 500mA
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: TO-261-4,TO-261AA
供应商设备封装: SOT-223
包装: 标准包装
产品目录页面: 1097 (CN2011-ZH PDF)
其它名称: 576-1274-6
MIC5209
Micrel, Inc.
V IN
I N
OUT
EN
BYP
IN
OUT
EN
ADJ
FixedRegulatorCircuits
MIC5209-x.xBM
2 3
1 4
GND
5–8
V OUT
1μF
V IN
2
1
MIC5209BM
3
4
GND
5–8
470pF
R1
R2
V OUT
2.2μF
V IN
V OUT
I N
OUT
E N
BYP
470pF
V IN
V OUT
I N
OUT
R1
E N
ADJ
V IN
V OUT
I N
OUT
C IN
C OUT
0.1μF 22μF
R2
V OUT = 1.242V ? 1 +
? R2 ?
R1 ?
?
Figure1. Low-NoiseFixedVoltageRegulator
Figure 1 shows a basic MIC5209-x.xBM (SO-8) ? xed-voltage
regulator circuit. See Figure 5 for a similar con? guration us-
ing the more thermally-ef? cient MIC5209-x.xBS (SOT-223).
A 1μF minimum output capacitor is required for basic ? xed-
voltage applications.
MIC5209-x.xBM
2 3
1 4
GND 2.2μF
5–8
Figure 2. Ultra-Low-Noise Fixed Voltage Regulator
Figure 2 includes the optional 470pF noise bypass capacitor
between BYP and GND to reduce output noise. Note that the
minimum value of C OUT must be increased when the bypass
capacitor is used.
Adjustable Regulator Circuits
MIC5209BM
2 3
1 4
GND 1μF
5–8
Figure 3. Low-Noise Adjustable Voltage Regulator
The MIC5209BM/U can be adjusted to a speci? c output volt-
age by using two external resistors (Figure 3). The resistors
set the output voltage based on the equation:
?
This equation is correct due to the con? guration of the
bandgap reference. The bandgap voltage is relative to the
output, as seen in the block diagram. Traditional regula-
tors normally have the reference voltage relative to ground;
therefore, their equations are different from the equation for
the MIC5209BM/U.
Although ADJ is a high-impedance input, for best performance,
R2 should not exceed 470kΩ.
Figure 4. Ultra-Low-Noise Adjustable Application.
Figure 4 includes the optional 470pF bypass capacitor from
ADJ to GND to reduce output noise.
Slot-1 Power Supply
Intel’s Pentium II processors have a requirement for a 2.5V
±5% power supply for a clock synthesizer and its associated
loads. The current requirement for the 2.5V supply is depen-
dant upon the clock synthesizer used, the number of clock
outputs, and the type of level shifter (from core logic levels to
2.5V levels). Intel estimates a worst-case load of 320mA.
The MIC5209 was designed to provide the 2.5V power
requirement for Slot-1 applications. Its guaranteed perfor-
mance of 2.5V ±3% at 500mA allows adequate margin for
all systems, and its dropout voltage of 500mV means that it
operates from a worst-case 3.3V supply where the voltage
can be as low as 3.0V.
MIC5209-x.xBS
1 3
GND
2,TAB
Figure 5. Slot-1 Power Supply
A Slot-1 power supply (Figure 5) is easy to implement. Only
two capacitors are necessary, and their values are not criti-
cal. C IN bypasses the internal circuitry and should be at least
0.1μF. C OUT provides output ? ltering, improves transient
response, and compensates the internal regulator control
loop. Its value should be at least 22μF. C IN and C OUT may
be increased as much as desired.
Slot-1 Power Supply Power Dissipation
Powered from a 3.3V supply, the Slot-1 power supply of
Figure 5 has a nominal ef? ciency of 75%. At the maximum
anticipated Slot 1 load (320mA), the nominal power dissipa-
tion is only 256mW.
The SOT-223 package has suf? cient thermal characteristics
for wide design margins when mounted on a single layer
copper-clad printed circuit board. The power dissipation of
the MIC5209 is calculated using the voltage drop across the
device × output current plus supply voltage × ground current.
M9999-060906
10
June 2006
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