Low-Noise, Regulated, -2V GaAsFET Bias

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7

______________________________________________________________Pin Description

Dual Mode is a trademark of Maxim Integrated Products.

MAX843

MAX844

1

2

3

—

4

8

7

6

5

MAX840

NAME

FUNCTION

1

C1+

Positive Terminal for C1

PIN

2

C1-

Negative Terminal for C1

3

NEGOUT

Negative Output Voltage (unregulated)

5

FB

Dual Mode™ Feedback Input. When FB is grounded, the output is preset to -2V. To

select other output voltages, connect FB to an external resistor divider (Figure 2b).

4

SHDN

Active-Low, TTL Logic-Level Shutdown Input

8

IN

Positive Power-Supply Input

7

GND

Ground

6

OUT

Regulated Negative Output Voltage

—

CONT

positive control voltage between 0V and 10V (Figure 2c).

MAX840

-0.5V

REF

CHARGE

PUMP

IN

N

C1+

C1-

NEGOUT

SHDN

OUT

CONNECT TO

GND TO SET

FB

GND

MAX843

MAX844

CHARGE

PUMP

IN

N

C1+

C1-

NEGOUT

SHDN

OUT

CONTROL

VOLTAGE

CONT

GND

R2

R1

Figure 1a. MAX840 Block Diagram

Figure 1b. MAX843/MAX844 Block Diagram