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參數(shù)資料
| 型號： | MIC4685BR |
| 廠商： | MICREL INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3A SPAK SuperSwitcher⑩ Buck Regulator |
| 中文描述： | SWITCHING REGULATOR, 225 kHz SWITCHING FREQ-MAX, PSSO7 |
| 封裝： | SPAK-7 |
| 文件頁數(shù)： | 9/15頁 |
| 文件大?。?/td> | 154K |
| 代理商： | MIC4685BR |
MIC4685
Block Diagrams
Micrel
September 2002
9
MIC4685
SW
FB
R1
R2
C
OUT
V
IN
IN
V
OUT
MIC4685
Internal
Regulator
Bootstrap
Charger
Enable
200kHz
Oscillator
Thermal
Shutdown
Reset
Current
Limit
Com-
parator
Error
Amp
Driver
1.235V
Bandgap
Reference
V
V
R1
R2
1
R1 R2
=
V
V
1
V
1.235V
OUT
REF
OUT
REF
REF
=
+
=
FIgure 1. Adjustable Regulator
Functional Description
The MIC4685 is a variable duty cycle switch-mode regulator
with an internal power switch. Refer to the above block
diagram.
Supply Voltage
The MIC4685 operates from a +4V to +30V (34V transient)
unregulated input. Highest efficiency operation is from a
supply voltage around +12V. See the efficiency curves in the
Typical Characteristicssection on page 5.
Enable/Shutdown
The enable (EN) input is TTL compatible. Tie the input high
if unused. A logic-high enables the regulator. A logic-low
shuts down the internal regulator which reduces the current
to typically 150
μ
A when V
EN
= 0V.
Feedback
An external resistive voltage divider is required from the
output voltage to ground, center tapped to the
FB
pin. See
Table 1 and Table 2 for recommended resistor values.
Duty Cycle Control
A fixed-gain error amplifier compares the feedback signal
with a 1.235V bandgap voltage reference. The resulting error
amplifier output voltage is compared to a 200kHz sawtooth
waveform to produce a voltage controlled variable duty cycle
output.
A higher feedback voltage increases the error amplifier
output voltage. A higher error amplifier voltage (comparator
inverting input) causes the comparator to detect only the
peaks of the sawtooth, reducing the duty cycle of the com-
parator output. A lower feedback voltage increases the duty
cycle. The MIC4685 uses a voltage-mode control architec-
ture.
Output Switching
When the internal switch is ON, an increasing current flows
from the supply V
IN,
through external storage inductor L1, to
output capacitor C
OUT
and the load. Energy is stored in the
inductor as the current increases with time.
When the internal switch is turned OFF, the collapse of the
magnetic field in L1 forces current to flow through fast
recovery diode D1, charging C
OUT
.
Output Capacitor
External output capacitor C
OUT
provides stabilization and
reduces ripple.
Return Paths
During the ON portion of the cycle, the output capacitor and
load currents return to the supply ground. During the OFF
portion of the cycle, current is being supplied to the output
capacitor and load by storage inductor L1, which means that
D1 is part of the high-current return path.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC4685BR TR | 功能描述:IC REG BUCK ADJ 3A SPAK-7 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:SuperSwitcher™ 標準包裝: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 |
| MIC4685BRTR | 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel |
| MIC4685WR | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3A Buck Regulator in SPAK-7 (ROHS Compliant) RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MIC4685WR TR | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3A Buck Regulator in SPAK-7 (ROHS Compliant) RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MIC4685WREV | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:3A SPAK SuperSwitcher Buck Regulator |
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