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PDF MAX1683EUK-T Data sheet ( Hoja de datos )
| Número de pieza | MAX1683EUK-T | |
| Descripción | Switched-Capacitor Voltage Doublers | |
| Fabricantes | Maxim Integrated | |
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19-1305; Rev 1; 8/98
Switched-Capacitor Voltage Doublers
General Description
The ultra-small MAX1682/MAX1683 monolithic, CMOS
charge-pump voltage doublers accept input voltages
ranging from +2.0V to +5.5V. Their high voltage-con-
version efficiency (over 98%) and low operating current
(110µA for MAX1682) make these devices ideal for
both battery-powered and board-level voltage-doubler
applications.
Oscillator control circuitry and four power MOSFET
switches are included on-chip. The MAX1682 operates
at 12kHz and the MAX1683 operates at 35kHz. A typi-
cal application includes generating a 6V supply to
power an LCD display in a hand-held PDA. Both parts
are available in a 5-pin SOT23 package and can deliver
30mA with a typical voltage drop of 600mV.
____________________________Features
o 5-Pin SOT23 Package
o +2.0V to +5.5V Input Voltage Range
o 98% Voltage-Conversion Efficiency
o 110µA Quiescent Current (MAX1682)
o Requires Only Two Capacitors
o Up to 45mA Output Current
________________________Applications
Small LCD Panels
Cell Phones
Handy-Terminals
PDAs
Typical Operating Circuit
Ordering Information
PART
TEMP.
RANGE
PIN-
SOT
PACKAGE TOP MARK
MAX1682C/D
0°C to +70°C
MAX1682EUK-T -40°C to +85°C
MAX1683C/D
0°C to +70°C
MAX1683EUK-T -40°C to +85°C
Dice*
5 SOT23-5
Dice*
5 SOT23-5
—
ACLL
—
ACCM
Note: These parts are available in tape-and-reel only. Minimum
order quantity is 2500 pieces.
*Dice are tested at TA = +25°C.
5
C1+
IN
4 VIN
INPUT
SUPPLY
VOLTAGE
C1
3
C1-
MAX1682
MAX1683
1
GND
OUT 2
OUTPUT
VOLTAGE
2 x VIN
C2
VOLTAGE DOUBLER
Pin Configuration
TOP VIEW
GND 1
5 C1+
MAX1682
OUT 2 MAX1683
C1- 3
4 IN
SOT23-5
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
1 page  
Switched-Capacitor Voltage Doublers
_____________________Pin Description
PIN NAME
FUNCTION
1 GND Ground
2
OUT
Doubled Output Voltage. Connect C2
between OUT and GND.
3
C1-
Negative Terminal of the Flying
Capacitor
4 IN Input Supply
5
C1+
Positive Terminal of the Flying
Capacitor
_______________Detailed Description
The MAX1682/MAX1683 capacitive charge pumps
double the voltage applied to their input. Figure 1
shows a simplified functional diagram of an ideal volt-
age doubler. During the first half-cycle, switches S1
and S2 close, and capacitor C1 charges to VIN. During
the second half cycle, S1 and S2 open, S3 and S4
close, and C1 is level shifted upward by VIN volts. This
connects C1 to the reservoir capacitor C2, allowing
energy to be delivered to the output as necessary. The
actual voltage is slightly lower than 2 x VIN, since
switches S1–S4 have resistance and the load drains
charge from C2.
Charge-Pump Output
The MAX1682/MAX1683 have a finite output resistance
of about 20Ω (Table 2). As the load current increases,
the devices’ output voltage (VOUT) droops. The droop
equals the current drawn from VOUT times the circuit’s
output impedance (RS), as follows:
VDROOP = IOUT x RS
VOUT = 2 x VIN - VDROOP
S1
VIN
S3
C1
S2 S4
VOUT
C2
VIN
Efficiency Considerations
The power efficiency of a switched-capacitor voltage
converter is affected by three factors: the internal losses
in the converter IC, the resistive losses of the capacitors,
and the conversion losses during charge transfer
between the capacitors. The total power loss is:
ΣPLOSS = PINTERNAL LOSSES
+ PPUMP CAPACITOR LOSSES
+ PCONVERSION 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:
PPUMP CAPACITOR LOSSES + PSWITCH LOSSES =
IOUT2 x ROUT
( )ROUT ≅
1
fOSC x
C1
+
2RSWITCHES
+
4ESRC1
+ ESRC2
where fOSC is the oscillator frequency. The first term is
the effective resistance from an ideal switched-
capacitor circuit (Figures 2a and 2b).
f
V+
VOUT
C2 RL
C1
Figure 2a. Switched-Capacitor Model
REQUIV
V+
REQUIV =
1
f × C1
C2
VOUT
RL
Figure 1. Simplified Functional Diagram of Ideal Voltage
Doubler
Figure 2b. Equivalent Circuit
_______________________________________________________________________________________ 5
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| PDF Descargar | [ Datasheet MAX1683EUK-T.PDF ] | |
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