AD780

REV. B

–9–

NEGATIVE (–2.5 V OR –3.0 V) REFERENCE

The AD780 can produce a negative output voltage in shunt

mode, simply by connecting the input and output to ground

connecting the AD780’s GND pin to a negative supply via a

bias resistor as shown in Figure 18.

NC

TEMP

TRIM

GND

O/P SELECT

2.5V – NC

3.0V – GND

NC

1 F

AD780

V–

NOTE:

NC = NO CONNECT

R =

Figure 18. Negative (–2.5 V) Shunt Mode Reference

A precise –2.5 V (or –3.0 V) reference capable of supplying up

to 100 mA to a load can be implemented with the AD780 in se-

ries mode using the bootstrap circuit following.

AD780

2N3906

+5V

+5V

OP07

CONNECT IF

–3V OUTPUT

DESIRED

–5V

100mA)

–5V

OUT

1k

1000pF

Figure 19. –2.5 V High Load Current Reference