Low-Noise, Regulated, -2V GaAsFET Bias
______________________________________________________________Pin Description
PIN
MAX840
1
2
3
4
5
MAX843
MAX844
1
2
3
4
—
NAME
FUNCTION
MAX840/MAX843/MAX844
C1+
C1-
NEGOUT
SHDN
FB
Positive Terminal for C1
Negative Terminal for C1
Negative Output Voltage (unregulated)
Active-Low, TTL Logic-Level Shutdown Input
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).
Control Voltage Input. To set V
OUT
, connect a resistor divider between OUT and a
positive control voltage between 0V and 10V (Figure 2c).
Regulated Negative Output Voltage
Ground
Positive Power-Supply Input
—
6
7
8
5
6
7
8
CONT
OUT
GND
IN
Dual Mode is a trademark of Maxim Integrated Products.
C1+
C1-
CHARGE
PUMP
IN
C1+
IN
CHARGE
PUMP
MAX840
C1-
N
OUT
NEGOUT
NEGOUT
N
MAX843
MAX844
OUT
SHDN
FB
CONNECT TO
GND TO SET
V
OUT
= -2V
-0.5V
REF
SHDN
R2
CONT
R1
GND
GND
CONTROL
VOLTAGE
Figure 1a. MAX840 Block Diagram
Figure 1b. MAX843/MAX844 Block Diagram
_______________________________________________________________________________________
7
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
