Rainbow Electronics MAX844 - Manual (Page 7)

MAX840/MAX843/MAX844
Low-Noise, Regulated, -2V GaAsFET Bias
_______________________________________________________________________________________ 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
Control Voltage Input. To set V OUT , connect a resistor divider between OUT and a
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
V
OUT = -2V
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