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參數(shù)資料
| 型號(hào)： | MAX684EUA |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Dual D-type Positive-Edge-Triggered Flip-Flops With Preset And Clear 14-CDIP -55 to 125 |
| 中文描述： | 0.05 A SWITCHED CAPACITOR REGULATOR, 1300 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | UMAX-8 |
| 文件頁(yè)數(shù)： | 6/12頁(yè) |
| 文件大?。?/td> | 154K |
| 代理商： | MAX684EUA |
M
3.3V-Input to Regulated 5V-Output
Charge Pumps
6
_______________________________________________________________________________________
Detailed Desc ription
The MAX682/MAX683/MAX684 charge pumps provide
a regulated 5V output from a 2.7V to 5.5V input. They
deliver a maximum of 250mA, 100mA, or 50mA load
current, respectively. Designed specifically for com-
pact applications, a complete regulator circuit requires
only three small external capacitors and one resistor.
An externally adjustable switching frequency and inno-
vative control scheme allow the circuit to be optimized
for efficiency, size, or output noise. The devices also
contain a shutdown feature.
The MAX682/MAX683/MAX684 consist of an error
amplifier, a 1.23V bandgap reference, an internal resis-
tive feedback network, an oscillator, high-current MOS-
FET switches, and shutdown and control logic (Figure
1). Figure 2 shows an idealized unregulated charge-
pump voltage doubler. The oscillator runs at a 50%
duty cycle. During one half of the period, the transfer
capacitor (C
X
) charges to the input voltage. During the
other half, the doubler stacks the voltage across C
X
and the input voltage, and transfers the sum of the two
voltages to the output filter capacitor (C
OUT
). Rather
than simply doubling the input voltage, the
MAX682/MAX683/MAX684 provide a regulated fixed
output voltage (5V) using either skip mode or constant-
frequency mode. Skip mode and constant-frequency
mode are externally selected via the
SKIP
input pin.
S kip Mode
In skip mode (
SKIP
= low), the error amplifier disables
switching when it detects an output higher than 5V. The
device then skips switching cycles until the output volt-
age drops. Then the error amplifier reactivates the
oscillator. Figure 3 illustrates the regulation scheme.
This regulation method minimizes operating current
because the device does not switch continuously.
SKIP
is a logic input and should not remain floating.
Constant-Frequenc y Mode
When
SKIP
is high, the charge pump runs continuously
at the selected frequency. Figure 4 shows a block dia-
gram of the device in constant-frequency mode. The
error amplifier controls the charge on C
X
by driving the
gate of the N-channel FET. When the output voltage
falls, the gate drive increases, resulting in a larger volt-
age across C
X
. This regulation scheme minimizes out-
put ripple. Since the device switches continuously, the
CXP
OUT
1.23V
EN
SHDN
PGND
SWITCHES
CONTROL
LOGIC
CXN
SHDN
SKIP
IN
OSC
IN
S1
S2
C
IN
C
OUT
OUT
C
X
OSC
Figure 2. Unregulated Voltage Doubler
IN
S1
S2
C
IN
C
X
OUT
OSCILLATOR
EN
Figure 3. Skip-Mode Regulation
Figure 1. Functional Block Diagram
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX684EUA+ | 功能描述:電荷泵 3.3Vin to Reg 5Vout Charge Pump 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 |
| MAX684EUA+T | 功能描述:電荷泵 3.3Vin to Reg 5Vout Charge Pump 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 |
| MAX684EUA-T | 功能描述:電荷泵 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 |
| MAX6850AEE | 功能描述:VFD驅(qū)動(dòng)器 RoHS:否 制造商:Maxim Integrated 工作電源電壓:8 V to 76 V, 3 V to 5.5 V 電源電流:0.9 mA, 700 uA 最大工作溫度:+ 125 C 封裝 / 箱體:SOIC-20 封裝:Tube |
| MAX6850AEE+T | 功能描述:VFD驅(qū)動(dòng)器 RoHS:否 制造商:Maxim Integrated 工作電源電壓:8 V to 76 V, 3 V to 5.5 V 電源電流:0.9 mA, 700 uA 最大工作溫度:+ 125 C 封裝 / 箱體:SOIC-20 封裝:Tube |
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