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PDF MAX843 Data sheet ( Hoja de datos )
| Número de pieza | MAX843 | |
| Descripción | GaAsFET Bias | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-0388; Rev 1; 3/96
EVFAOLLULAOTWIOSNDKAITTAMSAHNEUEATL
Low-Noise, Regulated, -2V GaAsFET Bias
_______________General Description
The MAX840/MAX843/MAX844 low-noise, inverting
charge-pump power supplies are ideal for biasing
GaAsFETs in cellular telephone transmitter amplifiers.
They operate with inputs down to 2.5V.
The MAX840 offers both a -2V preset output and a -0.5V
to -9.4V adjustable output. The MAX843/MAX844 use
an external positive control voltage to set the negative
output voltage. Input voltage range for all the devices is
2.5V to 10V, and output current is 4mA with V IN > 2.7V.
These circuits can operate with small capacitors, as low
as 0.22µF.
An internal linear regulator reduces the MAX840’s out -
put voltage ripple to 1mVp-p. With a well-filtered control
voltage (VCTRL), the MAX843/MAX844 also achieve less
than 1mVp-p typical output ripple. Supply current is
750µA, and reduces to less than 1 µA in shutdown
(MAX840/MAX843). The MAX844’s unregulated output
is active in shutdown, with the charge pump switching at
20kHz. It provides a low-power LCD supply.
________________________Applications
Cellular Phones
GaAsFET Power Amplifier Modules
Personal Communicators, PDAs
Wireless Data Loggers
Continuously Adjustable GaAsFET Bias
LCD-Bias Contrast Control
Regulated Negative Power Supplies
__________Typical Operating Circuit
VIN = 2.5V to 10.0V
(3 CELLS)
0.22µF
0.22µF
IN
C1+
C1- MAX840 OUT
NEGOUT
0.22µF
VOUT = -2.0V
(VGG of GaAsFET)
4.7µF
ON/OFF
SHDN
GND
FB
____________________________Features
o Fixed -2V or Adjustable -0.5V to -9.4V Output
at 4mA (MAX840)
o 2.5V to 10V Input Voltage Range
o Operate with Small Capacitors (as low as 0.22µF)
o 1mVp-p Output Voltage Ripple
o Charge-Pump Switching Frequency:
100kHz in Normal Operation
20kHz in Shutdown Mode (MAX844)
o 1µA Max Logic-Level Shutdown Over Temp.
(MAX840/MAX843)
o Small 8-Pin SO Package
______________Ordering Information
PART
MAX840C/D
TEMP. RANGE
0°C to +70°C
MAX840ISA
MAX840ESA
MAX843C/D
MAX843ISA
MAX843ESA
MAX844C/D
MAX844ISA
MAX844ESA
-25°C to +85°C
-40°C to +85°C
0°C to +70°C
-25°C to +85°C
-40°C to +85°C
0°C to +70°C
-25°C to +85°C
-40°C to +85°C
* Dice are specified at TA = +25°C only.
PIN-PACKAGE
Dice*
8 SO
8 SO
Dice*
8 SO
8 SO
Dice*
8 SO
8 SO
__________________Pin Configuration
TOP VIEW
C1+ 1
C1- 2
NEGOUT 3
SHDN 4
MAX840
MAX843
MAX844
( ) ARE FOR MAX843/MAX844
SO
8 IN
7 GND
6 OUT
5 FB (CONT)
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
http://www.Datasheet4U.com/
1 page  
Low-Noise, Regulated, -2V GaAsFET Bias
____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 2a, VIN = 3.6V, TA = +25°C, unless otherwise noted.)
40
VIN = 3.6V,
30 IOUT = 4mA
MAX840 NOISE SPECTRUM
(C1 = C2 = C3 = 1µF, C4 = 10µF)
20
10
0
-10
0.1
50
VIN = 3.6V,
40 IOUT = 4mA
1 10 100
FREQUENCY (kHz)
MAX840 NOISE SPECTRUM
(C1 = C2 = C3 = 0.22µF, C4 = 4.7µF)
1000
30
20
10
0
0.1
40
VIN = 3.6V,
30 IOUT = 4mA
1 10 100
FREQUENCY (kHz)
MAX843/MAX844 NOISE SPECTRUM
(C1 = C2 = C3 = 1µF, C4 = 10µF)
1000
20
10
0
NOTE: dBµV = 20 LOG _V_O_U__T_
1µV
-10
0.1
1 10 100
FREQUENCY (kHz)
1000
_______________________________________________________________________________________ 5
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5 Page | ||
| Páginas | Total 10 Páginas | |
| PDF Descargar | [ Datasheet MAX843.PDF ] | |
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| Número de pieza | Descripción | Fabricantes |
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| MAX840ISA | Low-Noise / Regulated / -2V GaAsFET Bias | Maxim Integrated |
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