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參數(shù)資料
| 型號： | MIC2295BD5 |
| 廠商： | MICREL INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | High Power Density 1.2A Boost Regulator |
| 中文描述： | 2.5 A SWITCHING REGULATOR, 1350 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封裝： | TSOT-23, 5 PIN |
| 文件頁數(shù)： | 9/13頁 |
| 文件大?。?/td> | 1267K |
| 代理商： | MIC2295BD5 |
Micrel
MIC2295
July 2004
M9999-052402
(408) 955-1690
9
Application Information
DC to DC PWM Boost Conversion
The MIC2295 is a constant frequency boost
converter. It operates by taking a DC input voltage
and regulating a higher DC output voltage. Figure 2
shows a typical circuit.
L1
10uH
1D1
Schottky
C2
10uF
Vin
Gnd
Vout
MIC2288BML
R1
R2
Gnd
VIN
SW
FB
GND
EN
Figure 2. Typical Application
OVP
Boost regulation is achieved by turning on an
internal switch, which draws current through the
inductor (L1). When the switch turns off, the
inductor’s magnetic field collapses, causing the
current to be discharged into the output capacitor
through an external Schottkey diode (D1). Voltage
regulation is achieved my modulating the pulse
width or pulse width modulation (PWM).
Duty Cycle Considerations
Duty cycle refers to the switch on-to-off time ratio
and can be calculated as follows for a boost
regulator;
D
=
1
V
IN
V
OUT
The duty cycle required for voltage conversion
should be less than the maximum duty cycle of 85%.
Also, in light load conditions where the input voltage
is close to the output voltage, the minimum duty
cycle can cause pulse skipping. This is due to the
energy stored in the inductor causing the output to
overshoot slightly over the regulated output voltage.
During the next cycle, the error amplifier detects the
output as being high and skips the following pulse.
This effect can be reduced by increasing the
minimum load or by increasing the inductor value.
Increasing the inductor value reduces peak current,
which in turn reduces energy transfer in each cycle.
Over Voltage Protection
For MLF package of MIC2295, there is an over
voltage protection function. If the feedback resistors
are disconnected from the circuit or the feedback pin
is shorted to ground, the feedback pin will fall to
ground potential. This will cause the MIC2295 to
switch at full duty-cycle in an attempt to maintain the
feedback voltage. As a result the output voltage will
climb out of control. This may cause the switch
node voltage to exceed its maximum voltage rating,
possibly damaging the IC and the external
components. To ensure the highest level of
protection, the MIC2295 OVP pin will shut the switch
off when an over-voltage condition is detected
saving itself and other sensitive circuitry
downstream.
Component Selection
Inductor
Inductor selection is a balance between efficiency,
stability, cost, size and rated current. For most
applications a 10uH is the recommended inductor
value. It is usually a good balance between these
considerations. Efficiency is affected by inductance
value in that larger inductance values reduce the
peak to peak ripple current. This has an effect of
reducing both the DC losses and the transition
losses.
There is also a secondary effect of an inductors DC
resistance (DCR). The DCR of an inductor will be
higher for more inductance in the same package
size. This is due to the longer windings required for
an increase in inductance. Since the majority of
input current (minus the MIC2295 operating current)
is passed through the inductor, higher DCR
inductors will reduce efficiency.
Also, to maintain stability, increasing inductor size
will have to be met with an increase in output
capacitance. This is due to the unavoidable “right
half plane zero” effect for the continuous current
boost converter topology. The frequency at which
the right half plane zero occurs can be calculated as
follows;
Frhpz
=
V
IN
L I
OUT
2
V
OUT
2
The right half plane zero has the undesirable effect
of increasing gain, while decreasing phase. This
requires that the loop gain is rolled off before this
has significant effect on the total loop response. This
can be accomplished by either reducing inductance
(increasing RHPZ frequency) or increasing the
output capacitor value (decreasing loop gain).
Output Capacitor
Output capacitor selection is also a trade-off
between performance, size and cost. Increasing
output capacitance will lead to an improved transient
response, but also an increase in size and cost. X5R
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| MIC2295BML | High Power Density 1.2A Boost Regulator |
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| MIC2505-1BM | Single 2A / Dual 1A / High-Side Switches |
| MIC2505-1BN | Single 2A / Dual 1A / High-Side Switches |
| MIC2505 | Single 2A / Dual 1A / High-Side Switches |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC2295BD5 TR | 功能描述:IC REG BOOST ADJ 1.2A TSOT23-5 RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關(guān):52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應(yīng)商設(shè)備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12 |
| MIC2295BML | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:High Power Density 1.2A Boost Regulator |
| MIC2295BML TR | 功能描述:IC REG BOOST ADJ 1.2A 8MLF RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關(guān):52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應(yīng)商設(shè)備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12 |
| MIC2295YD5 | 制造商:Rochester Electronics LLC 功能描述: 制造商:RF Micro Devices Inc 功能描述: |
| MIC2295YD5 TR | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 1.2MHz 1.2A PWM Boost Converter (Lead Free) 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 |
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