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2
Analog Interface
2.1
EVM Output Voltage
Analog Interface
For maximum flexibility, the DAC8803/14 EVM is designed for easy interfacing to multiple analog sources.
Samtec part numbers SSW-110-22-F-D-VS-K and TSM-110-01-T-DV-P provide a convenient ten pin dual
row header/socket combination at J1. This header/socket provides access to the analog output pins of the
DAC through the on-board buffer amplifiers. Consult Samtec at
or call 1-800-SAMTEC-9
for a variety of mating connector options.
Pin Number
Signal
Description
J1.2
Vout DACd
Controlled by W2; DACd output – range depends on the position of SW4 and W8
J1.4
Vout DACd
J1.6
Vout DACa
Controlled by W4; DACa output – range depends on the position of SW3 and W7
J1.8
Vout DACa
J1.10
Vout DACb
Controlled by W1; DACb output – range depends on the position of SW2 and W6
J1.12
Vout DACb
J1.14
Vout DACc
Controlled by W3; DACc output – range depends on the position of SW1 and W5
J1.16
Vout DACc
J1.18
REF(–)
Unused
J1.20
Ext. Ref.
External reference voltage input; selected with shunt on W10, pins 2-3
J1.15
Unused
J1.1–J1.19 (odd)
AGND
Analog ground connections (except J1.15)
Switches SW1 through SW4 provide a means to allow unipolar or bipolar output operation of the
DAC8803/14 EVM. When the slide switch is to the right, the output voltage on J1.x is
±
VREF. With the
10-V on-board reference, this means the output voltage is –10 VDC to +10 VDC. When the switch is to
the left, the output from the buffer is 0 V to +10 VDC or 0 V to –10 VDC depending on the position of the
associated reference jumper. In the factory default condition, a –10-V reference, derived from the
combination of U1 and U5, is applied to all four DACs via jumpers W5 through W8 and the output voltage
is 0 V to –10 V. A +10-V reference voltage, derived through U1 and U6 (W5 through W8 with shunt to the
left) produces a negative output voltage.
For a wider dynamic output range, the EVM can be configured to use an external reference in one of two
ways. The user can remove the shunts at W5 through W8 and apply a reference source to the center pin
associated with a specific DAC reference input. In this case, an external reference of up to
±
10 V may be
applied to the associated jumper.
An alternate method is to apply an external reference to J1 pin 20. This allows the on-board buffer (U6) to
drive all four DAC reference inputs simultaneously when the shunt on W10 covers pins 2-3. J1 pin 20 can
accept bipolar inputs. Keep in mind that the external reference must be supplied by a clean source for
best performance.
DAC8803/14 EVM
2
SLAU184 – May 2006
