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參數資料
| 型號： | MAX828 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Parallel-Load 8-Bit Shift Registers 16-CDIP -55 to 125 |
| 中文描述： | 開關電容電壓反相器 |
| 文件頁數： | 6/18頁 |
| 文件大小： | 158K |
| 代理商： | MAX828 |
MAX828, MAX829
http://onsemi.com
6
MAX828: C
1
= C
2
= C
3
= 10
F
MAX829: C
1
= C
2
= C
3
= 3.3 F
6
4
2
3
1
OSC
V
out
C
1
C
2
+
R
L
+
+C
3
V
in
Figure 20. Test Setup/Voltage Inverter
DETAILED OPERATING DESCRIPTION
The MAX828/829 charge pump converters inverts the
voltage applied to the V
in
pin. Conversion consists of a
twophase operation (Figure 21). During the first phase,
switches S
2
and S
4
are open and S
1
and S
3
are closed. During
this time, C
1
charges to the voltage on V
in
and load current
is supplied from C
2
. During the second phase, S
2
and S
4
are
closed, and S
1
and S
3
are open. This action connects C
1
across C
2
, restoring charge to C
2
.
Figure 21. Ideal Switched Capacitor Charge Pump
S3
S4
C
2
C
1
S1
S2
V
in
V
out
From Osc
APPLICATIONS INFORMATION
Output Voltage Considerations
The MAX828/829 performs voltage conversion but does
not provide regulation. The output voltage will drop in a
linear manner with respect to load current. The value of this
equivalent output resistance is approximately 26 nominal
at 25
°
C and V
in
= 5.0 V. V
out
is approximately 5.0 V at light
loads, and drops according to the equation below:
VDROP
Iout
Rout
Vout
(Vin
VDROP)
Charge Pump Efficiency
The overall power efficiency of the charge pump is
affected by four factors:
1. Losses from power consumed by the internal
oscillator, switch drive, etc. (which vary with input
voltage, temperature and oscillator frequency).
2. I
2
R losses due to the onresistance of the MOSFET
switches onboard the charge pump.
3. Charge pump capacitor losses due to Equivalent
Series Resistance (ESR).
4. Losses that occur during charge transfer from the
commutation capacitor to the output capacitor when
a voltage difference between the two capacitors
exists.
Most of the conversion losses are due to factors 2, 3 and 4.
These losses are given by Equation 1.
PLOSS(2,3,4)
Iout
2
Rout
Iout
2
1
(fOSC)C1
8RSWITCH
4ESRC1
ESRC2
(eq. 1)
The 1/(f
OSC
)(C
1
) term in Equation 1 is the effective output
resistance of an ideal switched capacitor circuit (Figures 22
and 23).
The losses due to charge transfer above are also shown in
Equation 2. The output voltage ripple is given by Equation 3.
0.5C2(VRIPPLE
2
2VoutVRIPPLE)]
fOSC
PLOSS
[ 0.5C1(Vin
2
Vout
2
)
(eq. 2)
VRIPPLE
Iout
(fOSC)(C2)
2(Iout)(ESRC2)
(eq. 3)
R
L
C
2
C
1
V
in
V
out
f
Figure 22. Ideal Switched Capacitor Model
R
L
C
2
V
in
V
out
R
EQUIV
REQUIV
1
f
C1
Figure 23. Equivalent Output Resistance
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PDF描述 |
|---|---|
| MAX829 | Switched Capacitor Voltage Converter |
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| MAX828EUKG | Switched Capacitor Voltage Converter |
| MAX829EUKG | Switched Capacitor Voltage Converter |
| MAX828SNTR | Switched Capacitor Voltage Converters |
相關代理商/技術參數 |
參數描述 |
|---|---|
| MAX828/D | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Switched Capacitor Voltage Converters |
| MAX828_05 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:Switched Capacitor Voltage Converter |
| MAX828C/D | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Switched-Capacitor Voltage Inverters |
| MAX828C/D DIE | 制造商:Maxim Integrated Products 功能描述: |
| MAX828EPA | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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