Datasheet

4
dc846af
DEMO MANUAL DC846A
HARDWARE SET-UP
JUMPERS
JP1, JP2 : Select the positive and negative supply voltages
for the onboard amplifier. Supplies can be GND and V
CC
or supplied externally to the AMP V
+
and AMP V
–
turrets.
JP3, JP5: Select the source for REF
+
and REF
–
, respec-
tively. REF
+
can be 5V from the onboard LT1236 refer-
ence (default) or supplied externally. REF
–
can be ground
(0V, default) or supplied externally.
JP4: Select source for analog COM input, either tied to
ground or supplied externally to the COM turret post.
JP6: Trigger mode, either normal (default) or externally
triggered.
JP7: Trigger input signal. Pin 1 is a 5V logic signal, pin 2 is
ground. When triggered mode is selected on JP3, a rising
edge starts a new conversion. Note that since a conversion
cannot be terminated once started, this signal can only be
used to slow down the conversion rate.
CONNECTION TO DC590 SERIAL CONTROLLER
J2 is the power and digital interface connector. Connect
to DC590 serial controller with supplied 14 conductor
ribbon cable.
ANALOG CONNECTIONS
Analog signal connections are made via the row of turret
posts along the edge of the board. Also, if you are connect-
ing the board to an existing circuit, the exposed ground
planes along the edges of the board may be used to form
a solid connection between grounds.
GND: Ground turrets are connected directly to the internal
analog ground plane.
PWR GND: Power ground, connected to the power return
trace.
V
CC
: This is the supply for the ADC. Do not draw any
power from this point. External power may be applied to
this point after disabling the switching supply on DC590.
If the DC590 serial controller is being used, the voltage
must be regulated 5V only, as the isolation circuitry will
also be powered from this supply. See the DC590 quick
start guide for details.
REF
+
, REF
–
: These turrets are connected to the LTC2447
global reference pins (REF
+
and REF
–
). If the onboard
reference is being used, the reference voltage may be
monitored from this point. An external reference may be
connected to these terminals if JP3 and JP5 are configured
for external reference.
REF01
+
, REF01
–
, REF23
+
, REF23
–
, etc.: dedicated
reference inputs for each input channel.
Note: The REF
+
,REF
–
, REF01
+
, REF01
–
, REF23
+
, REF23
–
,
etc. terminals are decoupled to ground with 0.1F and 10F
capacitors. Thus any source connected to these terminals
must be able to drive a capacitive load and have very low
impedance at DC. Examples are series references that
require an output capacitor and C-load stable op amps
such as the LT1219 and LT1368.
CH0 – CH7: These are the differential inputs to the LTC2447.
They may be configured either as single-ended inputs with
respect to the COM pin, or adjacent pairs may be config-
ured as differential inputs (CH0 to CH1, CH2 to CH3, etc.)