AD9856/PCB Analog Devices Inc, AD9856/PCB Datasheet - Page 14

• Manufacturer Part Number: AD9856/PCB
• Description: BOARD EVAL FOR AD9856
• Manufacturer: Analog Devices Inc
• Type: DDS Modulatorsr

Specifications of AD9856/PCB

• Rohs Status: RoHS non-compliant
• For Use With/related Products: AD9856
• Lead Free Status / RoHS Status: Not Compliant

AD9856
REGISTER BIT DEFINITIONS
Control Bits—Register Address 00h and 01h
SDO Active—Register Address 00h, Bit 7. Active high indicates
serial port uses dedicated in/out lines. Default low configures
serial port as single-line I/O.
LSB First—Register Address 00h, Bit 6. Active high indicates
serial port access is LSB-to-MSB format. Default low indicates
MSB-to-LSB format.
REFCLK Multiplier—Register Address 00h, Bits 5, 4, 3, 2, 1
form the reference clock multiplier. Valid entries range from
4–20 (decimal). Straight binary to decimal conversion is
implemented. For example, to multiply the reference clock by
19 decimal, Program Register Address 00h, Bits 5–1, as 13h.
Default value is 0A (hex).
Reserved Bit—Register Address 00h, Bit 0. This bit is reserved.
Always set this bit to Logic 1 when writing to this register.
CIC Gain—Register Address 01h, Bit 7. The CIC GAIN bit
multiplies the CIC filter output by 2. See the Cascaded
Integrator Comb (CIC) Filter section for more details. Default
value is 0 (inactive).
Continuous Mode—Register Address 01h, Bit 6 is the
continuous mode configuration bit. Active high configures the
AD9856 to accept continuous-mode timing on the TxENABLE
input. A low configures the device for burst-mode timing.
Default value is 0 (burst mode).
Full Sleep Mode—Register Address 01h, Bit 5. Active high
full sleep mode bit. When activated, the AD9856 enters a full
shutdown mode, consuming less than 2 mA after completing
a shutdown sequence. Default value is 0 (awake).
Single-Tone Mode—Register Address 01h, Bit 4. Active high
configures the AD9856 for single-tone applications. The
AD9856 supplies a single-frequency output as determined by
the frequency tuning word (FTW) selected by the active profile.
In this mode, the 12 input data pins are ignored but should be
tied high or low. Default value is 0 (inactive).
Bypass Inverse Sinc Filter—Register Address 01h, Bit 3.
Active high configures the AD9856 to bypass the SIN(x)/x
compensation filter. Default value is 0 (inverse SINC filter
enabled).
Bypass REFCLK Multiplier—Register Address 01h, Bit 2.
Active high configures the AD9856 to bypass the REFCLK
multiplier function. When active, effectively causes the
REFCLK multiplier factor to be 1. Default value is 1 (REFCLK
multiplier bypassed).
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Input Format Select—Register Address 01h, Bits 1 and 0, form
the input format mode bits.
Default value is 10b (12-bit mode).
Profile 1 Registers—Active when PROFILE Inputs are 00b
Frequency Tuning Word (FTW)—The frequency tuning word
for Profile 1 is formed via a concatenation of register addresses
05h, 04h, 03h, and 02h. Bit 7 of Register Address 05h is the
most significant bit of the Profile 1 frequency tuning word. Bit 0
of Register Address 02h is the least significant bit of the Profile
1 frequency tuning word. The output frequency equation is
given as: f
Interpolation Rate—Register Address 06h, Bit 7 through Bit 2
form the Profile 1 CIC filter interpolation rate value. Allowed
values range from 2 to 63 (decimal).
Spectral Inversion—Register Address 06h, Bit 1. Active
high, Profile 1 spectral inversion bit. When active, inverted
modulation is performed [I Cos(ωt) + Q × Sin( t)]. The
Default is inactive, Logic 0, noninverted modulation
[I × Cos(ωt) − Q × Sin(ωt)].
Bypass Half-Band Filter 3—Register Address 06h, Bit 0.
Active high, causes the AD9856 to bypass the third half-band
filter stage that precedes the CIC interpolation filter. Bypassing
the third half-band filter negates the 2× upsample inherent with
this filter and reduces the overall interpolation rate of the half-
band filter chain from 8× to 4×. Default value is 0 (Half-Band 3
enabled).
AD8320/AD8321 Gain Control—Register Address 07h, Bit 7
through Bit 0 form the Profile 1 AD8320/AD8321 gain bits.
The AD9856 dedicates three output pins, which directly
interface to the AD8320/AD8321 cable driver amp. This
allows direct control of the cable driver via the AD9856. See
the Error! Reference source not found. section for more
details. Bit 7 is the MSB, Bit 0 is the LSB. Default value is 00h.
Profile 2 Registers—
Profile 2 register functionality is identical to Profile 1, with the
exception of the register addresses.
Profile 3 Registers—Active when PROFILE Inputs are 10b
Profile 3 register functionality is identical to Profile 1, with the
exception of the register addresses.
Profile 4 Registers—
Profile 4 register functionality is identical to Profile 1, with the
exception of the register addresses.
10b = 12-bit mode
01b = 6-bit mode
00b = 3-bit mode
OUT
= (FTW SYSCLK)/2
Active when PROFILE Inputs are 01b
Active when PROFILE Inputs are 11b
32
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