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參數(shù)資料
| 型號(hào)： | MCP1252 |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | Low Noise, Positive-Regulated Charge Pump |
| 中文描述： | 低噪聲，正調(diào)節(jié)電荷泵 |
| 文件頁數(shù)： | 11/18頁 |
| 文件大?。?/td> | 440K |
| 代理商： | MCP1252 |
2002 Microchip Technology Inc.
DS21752A-page 11
MCP1252/3
5.1
Capacitor Selection
The style and value of capacitors used with the
MCP1252 and MCP1253 family of devices determine
several important parameters such as output voltage
ripple and charge pump strength. To minimize noise
and ripple, it is recommended that low ESR (0.1
)
capacitors be used for both C
IN
and C
OUT
. These
capacitors should be either ceramic or tantalum and
should be 10 μF or higher. Aluminum capacitors are not
recommended because of their high ESR.
If the source impedance to V
IN
is very low, up to several
megahertz, C
IN
may not be required. Alternatively, a
somewhat smaller value of C
IN
may be substituted for
the recommended 10 μF, but will not be as effective in
preventing ripple on the V
IN
pin.
The value of C
OUT
controls the amount of output volt-
age ripple present on V
OUT
. Increasing the size of
C
OUT
will reduce output ripple at the expense of a
slower turn-on time from shutdown and a higher in-rush
current.
The flying capacitor (C
FLY
) controls the strength of the
charge pump. In order to achieve the maximum rated
output current (120 mA), it is necessary to have at least
1 μF of capacitance for the flying capacitor. A smaller
flying capacitor delivers less charge per clock cycle to
the output capacitor, resulting in lower output ripple.
The output ripple is reduced at the expense of maxi-
mum output current and efficiency.
5.2
Output Voltage Setting
The MCP1252-33X50 and MCP1253-33X50 feedback
controllers select between an internally-set, regulated
output voltage (3.3V or 5.0V). Connect SELECT to
GND for a regulated 5.0V output and connect SELECT
to V
IN
for a regulated 3.3V output.
The MCP1252-ADJ and MCP1253-ADJ utilize an
external resistor divider that allows the output voltage
to be adjusted between 1.5V and 5.5V. For an adjust-
able output, connect a resistor between V
OUT
and FB
(R
1
) and another resistor between FB and GND (R
2
). In
the following equation, choose R
2
to be less than or
equal to 30 k
and calculate R
1
from the following
formula:
EQUATION
and
EQUATION
Note that the tolerance of the external resistors will
have an effect on the accuracy of the output voltage.
For optimum results, it is recommended that the
external resistors have a tolerance no larger than 1%.
5.3
Recommended Layout
The MCP1252 and MCP1253 family of devices transfer
charge at high switching frequencies, producing fast,
high peak, transient currents. As a result, any stray
inductance in the component layout will produce
unwanted noise in the system. Proper board layout
techniques are required to ensure optimum perfor-
mance. Figure 5-3 depicts the recommended board
layout. The input capacitor connected between V
IN
and
GND, and the output capacitor connected between
V
OUT
and GND, are 10 μF ceramic, X7R dielectric, in
1206 packages. The flying capacitor connected
between C+ and C- is a 1 μF ceramic, X7R dielectric in
a 0805 package. The layout is scaled 3:1.
FIGURE 5-3:
Circuit Board Layout.
Recommended Printed
R1
R2
VOUTVFB
(
)
1
–
[
]
=
VOUT
VFB1
R1R2
+
)
=
where:
V
OUT
is the desired output voltage from 1.5V to 5.5V
V
FB
is the internal regulation voltage, nominally 1.21V
PGOOD
V
OUT
GND
V
IN
C+
C-
SHDN
SELECT
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MCP1252_13 | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:Low Noise, Positive-Regulated Charge Pump |
| MCP1252-33X50I/MS | 功能描述:電荷泵 120mA Regulated RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| MCP1252-33X50I/MS | 制造商:Microchip Technology Inc 功能描述:DC/DC Charge Pump Converter (DC-DC) IC |
| MCP1252-ADJI/MS | 功能描述:電荷泵 120mA Regulated Adj RoHS:否 制造商:Maxim Integrated 功能:Inverting, Step Up 輸出電壓:- 1.5 V to - 5.5 V, 3 V to 11 V 輸出電流:100 mA 電源電流:1 mA 最大工作溫度:+ 70 C 封裝 / 箱體:SOIC-8 Narrow 封裝:Tube |
| MCP1252DM-BKLT | 功能描述:電源管理IC開發(fā)工具 MCP1252 Charge Pump Backlight Demo Brd RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
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