Datasheet

AD8290
Rev. B | Page 15 of 20
CURRENT SOURCE
The AD8290 generates an excitation current that is
programmable with an external resistor, R
SET
, as shown in
Figure 44. A1 and M1 are configured to produce 0.9 V across
R
SET
, which is based on an internal 0.9 V reference and creates a
current equal to 0.9 V/R
SET
internal to the AD8290. This current
is passed to a precision current mirror and a replica of the current
is sourced from the IOUT pin. This current can be used for the
excitation of a sensor bridge. C
BRIDGE
is used to filter noise from
the current excitation circuit.
06745-024
M1
IOUT
V
REF
= 0.9V
PRECISION CURRENT
MIRROR
C
BRIDGE
SENSOR
BRIDGE
R
SET
RSETGND
A1
Figure 44. Current Excitation