DAC8728_14 Datasheet, PDF (35/56 Pages) Texas Instruments – Octal, 16-Bit, Low-Power, High-Voltage Output, Parallel Input DIGITAL-TO-ANALOG CONVERTER

DAC8728
www.ti.com
SBAS466A – JUNE 2009 – REVISED NOVEMBER 2009
INPUT DATA FORMAT
The USB/BTC pin defines the input data format and the Offset DAC format. When this pin connects to DGND,
the Input DAC data and Offset DAC data are straight binary, as shown in Table 2 and Table 4. When this pin is
connected to IOV_DD, the Input DAC data and Offset DAC data are twos complement, as shown in Table 3 and
Table 5.
Table 2. Bipolar Output vs Straight Binary Code Using Dual Power Supplies with Gain = 6
USB CODE
FFFFh
••• •••
8001h
8000h
7FFFh
••• •••
0000h
NOMINAL OUTPUT
+3 × V_REF × (32767/32768)
••• •••
+3 × V_REF × (1/32768)
0
–3 × V_REF × (1/32768)
••• •••
–3 × V_REF × (32768/32768)
DESCRIPTION
+Full-Scale – 1 LSB
••• •••
+1 LSB
Zero
–1 LSB
••• •••
–Full-Scale
Table 3. Bipolar Output vs Twos Complement Code Using Dual Power Supplies with Gain = 6
BTC CODE
7FFFh
••• •••
0001h
0000h
FFFFh
••• •••
8000h
NOMINAL OUTPUT
+3 × V_REF × (32767/32768)
••• •••
+3 × V_REF × (1/32768)
0
–3 × V_REF × (1/32768)
••• •••
–3 × V_REF × (32768/32768)
DESCRIPTION
+Full-Scale – 1 LSB
••• •••
+1 LSB
Zero
–1 LSB
••• •••
–Full-Scale
Table 4. Unipolar Output vs Straight Binary Code Using Single Power Supply with Gain = 6
USB CODE
FFFFh
••• •••
8001h
8000h
7FFFh
••• •••
0000h
NOMINAL OUTPUT
+6 × V_REF × (65535/65536)
••• •••
+6 × V_REF × (32769/65536)
+6 × V_REF × (32768/65536)
+6 × V_REF × (32767/65536)
••• •••
0
DESCRIPTION
+Full-Scale – 1 LSB
••• •••
Midscale + 1 LSB
Midscale
Midscale – 1 LSB
••• •••
0
Table 5. Unipolar Output vs Twos Complement Code Using Single Power Supply with Gain = 6
BTC CODE
7FFFh
••• •••
0001h
0000h
FFFFh
••• •••
8000h
NOMINAL OUTPUT
+6 × V_REF × (65535/65536)
••• •••
+6 × V_REF × (32769/65536)
+6 × V_REF × (32768/65536)
+6 × V_REF × (32767/65536)
••• •••
0
DESCRIPTION
+Full-Scale – 1 LSB
••• •••
Midscale + 1 LSB
Midscale
Midscale – 1 LSB
••• •••
0
The data written to the Gain Register are always in straight binary, data to the Zero Register are in twos
complement, and data to all other control registers are as specified in the definitions, regardless of the USB/BTC
pin status.
In reading operation, the read-back data are in the same format as written.
Copyright © 2009, Texas Instruments Incorporated
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