- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄385553 > MAX870EUK (MAXIM INTEGRATED PRODUCTS INC) Switched-Capacitor Voltage Inverters PDF資料下載
參數(shù)資料
| 型號： | MAX870EUK |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Switched-Capacitor Voltage Inverters |
| 中文描述： | SWITCHED CAPACITOR CONVERTER, 194 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封裝： | SOT-23, 5 PIN |
| 文件頁數(shù)： | 5/8頁 |
| 文件大小： | 97K |
| 代理商： | MAX870EUK |
_______________Detailed Desc ription
The MAX870/MAX871 capacitive charge pumps invert
the voltage applied to their input. For highest perfor-
mance, use low equivalent series resistance (ESR)
capacitors (e.g., ceramic).
During the first half-cycle, switches S2 and S4 open,
switches S1 and S3 close, and capacitor C1 charges to
the voltage at IN (Figure 2). During the second half-
cycle, S1 and S3 open, S2 and S4 close, and C1 is level
shifted downward by V
IN
volts. This connects C1 in par-
allel with the reservoir capacitor C2. If the voltage across
C2 is smaller than the voltage across C1, then charge
flows from C1 to C2 until the voltage across C2 reaches
-V
IN
. The actual voltage at the output is more positive
than -V
IN
, since switches S1–S4 have resistance and the
load drains charge from C2.
Charge-Pump Output
The MAX870/MAX871 are not voltage regulators: the
charge pump’s output source resistance is approxi-
mately 20
at room temperature (with V
IN
= +5V), and
V
OUT
approaches -5V when lightly loaded. V
OUT
will
droop toward GND as load current increases. The
droop of the negative supply (V
DROOP-
) equals the cur-
rent draw from OUT (I
OUT
) times the negative convert-
er’s source resistance (RS-):
V
DROOP-
= I
OUT
x RS-
The negative output voltage will be:
V
OUT
= -(V
IN
– V
DROOP-
)
Effic ienc y Considerations
The power efficiency of a switched-capacitor voltage
converter is affected by three factors: the internal loss-
es in the converter IC, the resistive losses of the pump
capacitors, and the conversion losses during charge
transfer between the capacitors. The total power loss is:
Σ
P
= P
LOSS
INTERNAL LOSSES
The internal losses are associated with the IC’s internal
functions, such as driving the switches, oscillator, etc.
These losses are affected by operating conditions such
as input voltage, temperature, and frequency.
The next two losses are associated with the voltage
converter circuit’s output resistance. Switch losses
occur because of the on-resistance of the MOSFET
switches in the IC. Charge-pump capacitor losses
occur because of their ESR. The relationship between
these losses and the output resistance is as follows:
where f
OSC
is the oscillator frequency. The first term is
the effective resistance from an ideal switched-
capacitor circuit. See Figures 3a and 3b.
+ P
+ P
+ P
SWITCH LOSSES
PUMP CAPACITOR LOSSES
CONVERSION LOSSES
M
S witc hed-Capac itor Voltage Inverters
_______________________________________________________________________________________
5
S1
IN
S2
S3
S4
C1
C2
V
OUT
= -(V
IN
)
Figure 2. Ideal Voltage Inverter
V+
C1
f
C2
R
L
V
OUT
Figure 3a. Switched-Capacitor Model
R
EQUIV
=
R
EQUIV
V
OUT
R
L
1
V+
f
×
C1
C2
Figure 3b. Equivalent Circuit
P
+P
= I
x R
1
PUMP CAPACITOR LOSSES
2
CONVERSION LOSSES
OUT
OUT
R
f
x C
R
ESR
4
ESR
OUT
OSC
SWITCHES
C
C
(
)
+
+
+
1
2
1
2
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX871EUK | Switched-Capacitor Voltage Inverters |
| MAX872 | 10μA, Low-Dropout, Precision Voltage References(10μA,低壓降,2.5V高精度基準(zhǔn)電壓) |
| MAX877 | Adjustable-Output, DC-DC Converters(3.3V/3V輸出,1.8V~6V輸入,步升/步降DC-DC變換器) |
| MAX878 | Adjustable-Output, DC-DC Converters(3.3V/3V輸出,1.8V~6V輸入,步升/步降DC-DC變換器) |
| MAX879 | Adjustable-Output, DC-DC Converters(3.3V/3V輸出,1.8V~6V輸入,步升/步降DC-DC變換器) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX870EUK+ | 制造商:Maxim Integrated Products 功能描述:CHG PUMP INV -5.5V TO -1.4V 25MA 5PIN SOT-23 - Bulk 制造商:Maxim Integrated Products 功能描述:Charge Pump INV -1.4V to -5.5V 25mA 5-Pin SOT-23 Bulk |
| MAX870EUK+T | 功能描述:電荷泵 Switched-Capacitor Voltage Inverter 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 |
| MAX870EUK-T | 功能描述:電荷泵 Switched-Capacitor Voltage Inverter 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 |
| MAX870EUK-TG069 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX8710ETG | 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。