AD9717BCPZ Analog Devices Inc, AD9717BCPZ Datasheet - Page 46

• Manufacturer Part Number: AD9717BCPZ
• Description: IC DAC DUAL 14BIT LO PWR 40LFCSP
• Manufacturer: Analog Devices Inc
• Series: TxDAC®r

Specifications of AD9717BCPZ

• Data Interface: Serial
• Number Of Bits: 14
• Number Of Converters: 2
• Voltage Supply Source: Analog and Digital
• Power Dissipation (max): 86mW
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 40-LFCSP
• Resolution (bits): 14bit
• Sampling Rate: 125MSPS
• Input Channel Type: Parallel, Serial
• Supply Current: 11mA
• Digital Ic Case Style: CSP
• No. Of Pins: 40
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Settling Time: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

AD9714/AD9715/AD9716/AD9717
COARSE GAIN ADJUSTMENT
Option 1
A coarse full-scale output current adjustment can be achieved
using the lower six bits in Register 0x0D. This adds or subtracts
up to 20% from the band gap voltage on Pin 34 (REFIO), and
the voltage on the FSADJx resistors tracks this change. As a
result, the DAC full-scale current varies by the same amount.
A secondary effect to changing the REFIO voltage is that the
full-scale voltage in the AUXDAC also changes by the same
magnitude. The register uses twos complement format, in
which 011111 maximizes the voltage on the REFIO node
and 100000 minimizes the voltage.
Option 2
While using the internal FSADJx resistors, each main DAC can
achieve independently controlled coarse gain using the lower
six bits of Register 0x04 (IRSET[5:0]) and Register 0x07
(QRSET[5:0]). Unlike Coarse Gain Option 1, this impacts only
the main DAC full-scale output current. The register uses twos
complement format and allows the output current to be changed
in approximately 0.25 dB steps.
1.30
1.25
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
0
Figure 98. Typical V
8
10
V
OUT
Figure 99. Effect of xR
_
16
Q
OR V
20
OUT
24
xR
_
I
SET
30
CODE
REF
32
CODE
Voltage vs. Code
SET
40
40
Code
48
50
56
60
Rev. A | Page 46 of 80
Option 3
Even when the device is in pin mode, full-scale values can be
adjusted by sourcing or sinking current from the FSADJx pins.
Any noise injected here appears as amplitude modulation of the
output. Thus, a portion of the required series resistance (at least
20 kΩ) must be installed right at the pin. A range of ±10% is
quite practical using this method.
Option 4
As in Option 3, when the device is in pin mode, both full-scale
values can be adjusted by sourcing or sinking current from the
REFIO pin. Noise injected here appears as amplitude modulation
of the output; therefore, a portion of the required series resis-
tance (at least 10 kΩ) must be installed at the pin. A range of
±25% is quite practical when using this method.
Fine Gain
Each main DAC has independent fine gain control using the
lower six bits in Register 0x03 (I DAC gain) and Register 0x06
(Q DAC gain). Unlike Coarse Gain Option 1, this impacts only
the main DAC full-scale output current. These registers use straight
binary format. One application in which straight binary format
is critical is for side-band suppression while using a quadrature
modulator. This is described in more detail in the Applications
Information section.
2.22
2.20
2.18
2.16
2.14
2.12
2.10
0
Figure 100. Typical DAC Gain Characteristics
8
3.3V DAC1
3.3V DAC2
1.8V DAC1
1.8V DAC2
16
24
GAIN DAC CODE
32
40
48
56
64