Rainbow-electronics MAX844 Bedienungsanleitung PDF herunterladen

_______________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

> 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 (V

CTRL

), the MAX843/MAX844 also achieve less

than 1mVp-p typical output ripple. Supply current is

750µA, and reduces to less than 1µA 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

____________________________Features

♦ Fixed -2V or Adjustable -0.5V to -9.4V Output

at 4mA (MAX840)

♦ 2.5V to 10V Input Voltage Range

♦ Operate with Small Capacitors (as low as 0.22µF)

♦ 1mVp-p Output Voltage Ripple

♦ Charge-Pump Switching Frequency:

100kHz in Normal Operation

20kHz in Shutdown Mode (MAX844)

♦ 1µA Max Logic-Level Shutdown Over Temp.

(MAX840/MAX843)

♦ Small 8-Pin SO Package

MAX840/MAX843/MAX844

Low-Noise, Regulated, -2V GaAsFET Bias

________________________________________________________________

Maxim Integrated Products

( ) ARE FOR MAX843/MAX844

GND

OUT

FB (CONT)

SHDN

NEGOUT

C1-

C1+

MAX840

MAX843

MAX844

TOP VIEW

__________________Pin Configuration

MAX840

OUT

SHDN



NEGOUT

C1-

C1+

GND

= 2.5V to 10.0V

(3 CELLS)

0.22µF

OUT

= -2.0V

of GaAsFET)

4.7µF

0.22µF

ON/OFF

__________Typical Operating Circuit

19-0388; Rev 1; 3/96

PART

MAX840C/D

MAX840ISA

MAX840ESA -40°C to +85°C

-25°C to +85°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

Dice*

8 SO

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

______________Ordering Information

* Dice are specified at T

= +25°C only.

MAX843C/D

0°C to +70°C Dice*

MAX843ISA -25°C to +85°C 8 SO

MAX843ESA -40°C to +85°C 8 SO

MAX844C/D

0°C to +70°C Dice*

MAX844ISA -25°C to +85°C 8 SO

MAX844ESA -40°C to +85°C 8 SO

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

1 2 3 4 5 6 7 8 9 10

MAX840/MAX843/MAX844 1

Inhaltsverzeichnis

Seite 1 - MAX840/MAX843/MAX844

_______________General DescriptionThe MAX840/MAX843/MAX844 low-noise, invertingcharge-pump power supplies are ideal for biasingGaAsFETs in cellular te

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MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias10 ______________________________________________________________________________________(

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MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias2 _______________________________________________________________________________________ABS

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MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias_______________________________________________________________________________________3-2.0

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MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias4 __________________________________________________________________________________________

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MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias_______________________________________________________________________________________5MAX8

Seite 7

MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias6 _______________________________________________________________________________________ST

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MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias_______________________________________________________________________________________ 7___

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MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias8 __________________________________________________________________________________________

Seite 10

MAX840/MAX843/MAX844Low-Noise, Regulated, -2V GaAsFET Bias_______________________________________________________________________________________ 9MAX

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Rainbow-electronics MAX844 Bedienungsanleitung

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