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參數(shù)資料
| 型號(hào)： | MIC2204BML |
| 廠商： | MICREL INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | High-Efficiency 2MHz Synchronous Buck Converter |
| 中文描述： | 2 A SWITCHING REGULATOR, 2200 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | 3 X 3 MM, MLF-10 |
| 文件頁(yè)數(shù)： | 9/11頁(yè) |
| 文件大?。?/td> | 112K |
| 代理商： | MIC2204BML |
January 2004
9
M0214-012904
MIC2204
Micrel
Figure 2 shows an efficiency curve. On the non-shaded
portion, from 0 to 200mA, efficiency losses are dominated by
quiescent current losses, gate drive and transition losses. In
this case, lower supply voltages yield greater efficiency in that
they require less current to drive the MOSFETs and have
reduced input power consumption.
50
55
60
65
70
75
80
85
90
95
100
0
100
OUTPUT CURRENT (A)
Figure 2.
200
300
400
500
E
3.3V
OUT
4.2V
IN
3.6V
IN
Efficiency
vs. Output Current
5V
IN
On the shaded region, 200mA to 500mA, efficiency loss is
dominated by MOSFET R
DSON
and inductor losses. Higher
input supply voltages will increase the Gate-to-Source thresh-
old on the internal MOSFETs, reducing the internal R
DSON
.
This improves efficiency by reducing DC losses in the device.
All but the inductor losses are inherent to the device, making
inductor selection even more critical in efficiency calcula-
tions. As the inductors are reduced in size, the DC resistance
(DCR) can become quite significant. The DCR losses can be
calculated as follows:
L
PD
=I
OUT2
x DCR
From that, the loss in efficiency due to inductor resistance can
be calculated as follows:
Efficiency Loss
1
–
V
I
V
I
L
100
OUT
×
OUT
+
OUT
OUT
PD
=
×
×
Efficiency loss due to DCR is minimal at light loads and gains
significance as the load is increased. Inductor selection
becomes a trade-off between efficiency and size in this case.
Compensation
The MIC2204 is an internally compensated, voltage-mode
buck regulator. Voltage mode is achieved by creating an
internal 2MHz ramp signal and using the output of the error
amplifier to pulsewidth modulate the switch node, maintain-
ing output voltage regulation. With a typical gain bandwidth of
200kHz, the MIC2204 is capable of extremely fast transient
responses.
The MIC2204 is designed to be stable with a 4.7
μ
H inductor
and a 4.7
μ
F ceramic (X5R) output capacitor for output
voltages greater than 1.6V. For output voltages less than
1.6V, a 10
μ
F capacitor is required. Also, when a feed forward
capacitor is used, the gain bandwidth is increased to unity
gain. This will also require increasing the output capacitor to
10
μ
F.
Feedback
The MIC2204 provides a feedback pin to adjust the output
voltage to the desired level. This pin connects internally to an
error amplifier. The error amplifier then compares the voltage
at the feedback to the internal 1V reference voltage and
adjusts the output voltage to maintain regulation. To calculate
the resistor divider network for the desired output is as
follows:
R2
R1
V
V
–
1
OUT
REF
=
Where V
REF
is 1.0V and V
OUT
is the desired output voltage.
A 10k
or lower resistor value from the output to the feedback
is recommended. Larger resistor values require an additional
capacitor (feed-forward) from the output to the feedback. The
large high-side resistor value and the parasitic capacitance
on the feedback pin (~10pF) can cause an additional pole in
the loop. The additional pole can create a phase loss at
high-frequency. This phase loss degrades transient response
by reducing phase margin. Adding feed-forward capacitance
negates the parasitic capacitive effects of the feedback pin.
A minimum 1000pF capacitor is recommended for feed-
forward capacitance.
Also, large feedback resistor values increase the impedance,
making the feedback node more susceptible to noise pick-up.
A feed-forward capacitor would also reduce noise pick-up by
providing a low impedance path to the output.
When using a feed-forward capacitor, the gain bandwidth of
the device reaches unity gain at high-frequency. Therefore,
output capacitance will need to be increased to a minimum
10
μ
F. For more information on output capacitor selection for
stability, see the
“
Compensation
”
section.
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| MIC2204BML TR | 功能描述:IC REG BUCK SYNC ADJ 0.6A 10MLF RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)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(kāi)關(guān):52kHz 電流 - 輸出:1A 同步整流器:無(wú) 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 |
| MIC2204BMM | 功能描述:IC REG BUCK SYNC ADJ 0.6A 10MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)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(kāi)關(guān):52kHz 電流 - 輸出:1A 同步整流器:無(wú) 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 |
| MIC2204BMM TR | 功能描述:IC REG BUCK SYNC ADJ 0.6A 10MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)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(kāi)關(guān):52kHz 電流 - 輸出:1A 同步整流器:無(wú) 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 |
| MIC2204YML | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 2MHz Synchronous Buck Regulator - Pb Free Finish RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)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(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MIC2204YML TR | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 2MHz Synchronous Buck Regulator (Lead Free) RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)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(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
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