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參數(shù)資料
| 型號(hào)： | MIC5245-2.8BM5 |
| 廠商： | MICREL INC |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | 150mA レCap CMOS LDO Regulator Preliminary Information |
| 中文描述： | 2.8 V FIXED POSITIVE LDO REGULATOR, 0.25 V DROPOUT, PDSO5 |
| 封裝： | SOT-23, 5 PIN |
| 文件頁(yè)數(shù)： | 8/12頁(yè) |
| 文件大?。?/td> | 630K |
| 代理商： | MIC5245-2.8BM5 |
MIC5245
Applications Information
Enable/Shutdown
The MIC5245 comes with an active-high enable pin that
allows the regulator to be disabled. Forcing the enable pin low
disables the regulator and sends it into a
“
zero
”
off-mode-
current state. In this state, current consumed by the regulator
goes nearly to zero. Forcing the enable pin high enables the
output voltage. This part is CMOS and the enable pin cannot
be left floating; a floating enable pin may cause an indetermi-
nate state on the output.
Input Capacitor
An input capacitor is not required for stability. A 1
μ
F input
capacitor is recommended when the bulk ac supply capaci-
tance is more than 10 inches away from the device, or when
the supply is a battery.
Output Capacitor
The MIC5245 requires an output capacitor for stability. The
design requires 1
μ
F or greater on the output to maintain
stability. The capacitor can be a low-ESR ceramic chip
capacitor. The MIC5245 has been designed to work specifi-
cally with the low-cost, small chip capacitors. Tantalum
capacitors can also be used for improved capacitance over
temperature. The value of the capacitor can be increased
without bound.
X7R dielectric ceramic capacitors are recommended be-
cause of their temperature performance. X7R-type capaci-
tors change capacitance by 15% over their operating tem-
perature range and are the most stable type of ceramic
capacitors. Z5U and Y5V dielectric capacitors change value
by as much 50% and 60% respectively over their operating
temperature ranges. To use a ceramic chip capacitor with
Y5V dielectric, the value must be much higher than an X7R
ceramic or a tantalum capacitor to ensure the same minimum
capacitance value over the operating temperature range.
Tantalum capacitors have a very stable dielectric (10% over
their operating temperature range) and can also be used with
this device.
Bypass Capacitor
A capacitor can be placed from the noise bypass pin to
ground to reduce output voltage noise. The capacitor by-
passes the internal reference. A 0.01
μ
F capacitor is recom-
mended for applications that require low-noise outputs.
Transient Response
The MIC5245 implements a unique output stage to dramati-
cally improve transient response recovery time. The output is
a totem-pole configuration with a P-channel MOSFET pass
device and an N-channel MOSFET clamp. The N-channel
clamp is a significantly smaller device that prevents the
output voltage from overshooting when a heavy load is
removed. This feature helps to speed up the transient re-
sponse by significantly decreasing transient response recov-
ery time during the transition from heavy load (100mA) to light
load (100
μ
A).
Micrel
MIC5245
8
June 2000
Active Shutdown
The MIC5245 also features an active shutdown clamp, which
is an N-channel MOSFET that turns on when the device is
disabled. This allows the output capacitor and load to dis-
charge, de-energizing the load.
Thermal Considerations
The MIC5245 is designed to provide 150mA of continuous
current in a very small package. Maximum power dissipation
can be calculated based on the output current and the voltage
drop across the part. To determine the maximum power
dissipation of the package, use the junction-to-ambient ther-
mal resistance of the device and the following basic equation:
P
T
T
D(max)
J(max)
A
JA
=
θ
T
J(max)
is the maximum junction temperature of the die,
125
°
C, and T
A
is the ambient operating temperature.
θ
JA
is
layout dependent; Table 1 shows examples of junction-to-
ambient thermal resistance for the MIC5245.
Package
θ
JA
Recommended
Minimum Footprint
θ
JA
1" Square
Copper Clad
θ
JC
SOT-23-5 (M5)
235
°
C/W
185
°
C/W
145
°
C/W
Table 1. SOT-23-5 Thermal Resistance
The actual power dissipation of the regulator circuit can be
determined using the equation:
P
D
= (V
IN
–
V
OUT
) I
OUT
+ V
IN
I
GND
Substituting P
D(max)
for P
D
and solving for the operating
conditions that are critical to the application will give the
maximum operating conditions for the regulator circuit. For
example, when operating the MIC5245-3.3BM5 at 50
°
C with
a minimum footprint layout, the maximum input voltage for a
set output current can be determined as follows:
P
125 C
235 C/W
50 C
D(max)
=
P
D(max)
= 315mW
The junction-to-ambient thermal resistance for the minimum
footprint is 235
°
C/W, from Table 1. The maximum power
dissipation must not be exceeded for proper operation. Using
the output voltage of 3.3V and an output current of 150mA,
the maximum input voltage can be determined. Because this
device is CMOS and the ground current is typically 87
μ
A over
the load range, the power dissipation contributed by the
ground current is < 1% and can be ignored for this calculation.
315mW = (V
IN
–
3.3V) 150mA
315mW = V
IN
×
150mA
–
495mW
810mW = V
IN
×
150mA
V
IN(max)
= 5.4V
Therefore, a 3.3V application at 150mA of output current can
accept a maximum input voltage of 5.4V in a SOT-23-5
package. For a full discussion of heat sinking and thermal
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| MIC5245-3.1BM5 | RZ Series - Econoline Regulated DC-DC Converters; Input Voltage (Vdc): 24V; Output Voltage (Vdc): 15V; Power: 0.5W; 1kVDC Isolation; SMD Package Styles; Single Regulated Output(Internal Linear Regulator); UL94V-0 Package Material; Optional Continuous Short Circuit Protected; Fully Encapsulated; Efficiency to 62% |
| MIC5245-3.3BM5 | 150mA レCap CMOS LDO Regulator Preliminary Information |
| MIC5245-3.3BMM | 150mA レCap CMOS LDO Regulator Preliminary Information |
| MIC5245 | 150mA μCap CMOS LDO Regulator(輸出電流150mA μCap技術(shù)的CMOS低壓差穩(wěn)壓器) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC5245-3.0BM5 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| MIC5245-3.0BM5 TR | 功能描述:IC REG LDO 3V .15A SOT23-5 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 系列:- 標(biāo)準(zhǔn)包裝:500 系列:- 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):正，固定式 輸出電壓:12V 輸入電壓:14.5 V ~ 35 V 電壓 - 壓降（標(biāo)準(zhǔn)）:- 穩(wěn)壓器數(shù)量:1 電流 - 輸出:500mA 電流 - 限制（最?。?- 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:TO-205AD，TO-39-3 金屬罐 供應(yīng)商設(shè)備封裝:TO-39 包裝:散裝 其它名稱:*LM78M12CH*LM78M12CH/NOPBLM78M12CH |
| MIC5245-3.0BM5TR | 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel |
| MIC5245-3.0YM5 | 制造商:Rochester Electronics LLC 功能描述: 制造商:RF Micro Devices Inc 功能描述: |
| MIC5245-3.0YM5 TR | 功能描述:低壓差穩(wěn)壓器 - LDO Low Noise, IttyBitty CMOS LDO (Lead Free) RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動(dòng)電壓（最大值）:307 mV 輸出電流:1 A 負(fù)載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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