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參數(shù)資料
| 型號： | MIC38300HYHL |
| 廠商： | MICREL INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3A SuperLNR⑩ Low Noise High Efficiency Regulator |
| 中文描述： | 5 A SWITCHING REGULATOR, QCC28 |
| 封裝： | 4 X 6 MM, 0.90 MM HEIGHT, LEAD FREE, MLF-28 |
| 文件頁數(shù)： | 7/10頁 |
| 文件大?。?/td> | 555K |
| 代理商： | MIC38300HYHL |
Micrel, Inc.
MIC38300
Application Information
July 2007
7
M9999-070607
(408) 944-0800
Enable Input
The MIC38300 features a TTL/CMOS compatible
positive logic enable input for on/off control of the device.
High enables the regulator while low disables the
regulator. In shutdown the regulator consumes very little
current (only a few microamperes of leakage). For
simple applications the enable (EN) can be connected to
V
IN
(IN).
Input Capacitor
VIN provides power to the MOSFETs for the switch
mode regulator section, along with the current limiting
sensing. Due to the high switching speeds, a 10μF
capacitor is recommended close to VIN and the power
ground (PGND) pin for bypassing.
Analog V
IN
(AVIN) provides power to the analog supply
circuitry. AVIN and VIN must be tied together. Careful
layout should be considered to ensure high frequency
switching noise caused by VIN is reduced before
reaching AVIN. A 1μF capacitor as close to AVIN as
possible is recommended.
Output Capacitor
The MIC38300 requires an output capacitor for stable
operation. As a μCap LDO, the MIC38300 can operate
with ceramic output capacitors of 10μF or greater.
Values of greater than 10μF improve transient response
and noise reduction at high frequency. X7R/X5R
dielectric-type ceramic capacitors are recommended
because of their superior temperature performance.
X7R-type capacitors change capacitance by 15% over
their operating temperature range and are the most
stable type of ceramic capacitors. Larger output
capacitances can be achieved by placing tantalum or
aluminum electrolytics in parallel with the ceramic
capacitor. For example, a 100μF electrolytic in parallel
with a 10μF ceramic can provide the transient and high
frequency noise performance of a 100μF ceramic at a
significantly lower cost. Specific undershoot/overshoot
performance will depend on both the values and
ESR/ESL of the capacitors.
For less than 5mV noise performance at higher current
loads, 20μF capacitors are recommended at LDOIN and
LDOOUT.
Low Pass Filter Pin
The MIC38300 features a Low Pass Filter (LPF) pin for
adjusting the switcher frequency. By tuning the
frequency, the user can further improve output ripple
without losing efficiency.
Adjustable Regulator Design
OUT
*C
0.1μF
R1
R2
ADJ
1.0V
*Required only for large
values of R1 and R2
Adjustable Regulator with Resistors
The adjustable MIC38300 output voltage can be
programmed from 1V to 5.0V using a resistor divider
from output to the SNS pin. Resistors can be quite large,
up to 100k
because of the very high input impedance
and low bias current of the sense amplifier. For large
value resistors (>50K
) R1 should be bypassed by a
small capacitor (C
FF
= 0.1μF bypass capacitor) to avoid
instability due to phase lag at the ADJ/SNS input.
The output resistor divider values are calculated by:
+
=
1
2
1
1
R
R
V
V
OUT
Efficiency Considerations
Efficiency is defined as the amount of useful output
power, divided by the amount of power supplied.
=
V
100
%
_
×
×
×
IN
IN
OUT
OUT
V
I
I
Efficiency
Maintaining high efficiency serves two purposes. It
reduces power dissipation in the power supply, reducing
the need for heat sinks and thermal design
considerations and it reduces consumption of current for
battery powered applications. Reduced current draw
from a battery increases the devices operating time and
is critical in hand held devices.
There are two types of losses in switching converters;
DC losses and switching losses. DC losses are simply
the power dissipation of I
2
R. Power is dissipated in the
high side switch during the on cycle. Power loss is equal
to the high side MOSFET R
DSON
multiplied by the Switch
Current
2
. During the off cycle, the low side N-channel
MOSFET conducts, also dissipating power. Device
operating current also reduces efficiency. The product of
the quiescent (operating) current and the supply voltage
is another DC loss.
Over 100mA, efficiency loss is dominated by MOSFET
R
DSON
and inductor losses. Higher input supply voltages
will increase the Gate to Source threshold on the internal
MOSFETs, reducing the internal RD
DSON
. This improves
efficiency by reducing DC losses in the device. All but
the inductor losses are inherent to the device. In which
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| MIC38300HYHL TR | 功能描述:低壓差穩(wěn)壓器 - LDO 3A HELDO -High Efficiency Low Dropout Regulator (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 |
| MIC38300HYHL-EV | 功能描述:MIC38300 HELDO? Series 1 - Single Channels per IC Positive Adjustable Linear Voltage Regulator Evaluation Board 制造商:microchip technology 系列:HELDO?? 零件狀態(tài):有效 每 IC 通道數(shù):1 - 單 電壓 - 輸出:1.8V 電流 - 輸出:3A 電壓 - 輸入:3 ~ 5.5 V 穩(wěn)壓器類型:正，可調(diào)式 工作溫度:-40°C ~ 125°C 板類型:完全填充 所含物品:板 使用的 IC/零件:MIC38300 標(biāo)準(zhǔn)包裝:1 |
| MIC38300HYHL-EV-PB | 制造商:Micrel Inc 功能描述: |
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