AD9951YSVZ Analog Devices Inc, AD9951YSVZ Datasheet - Page 19

• Manufacturer Part Number: AD9951YSVZ
• Description: IC DDS DAC 14BIT 1.8V 48-TQFP
• Manufacturer: Analog Devices Inc

Specifications of AD9951YSVZ

• Resolution (bits): 14 b
• Master Fclk: 400MHz
• Tuning Word Width (bits): 32 b
• Voltage - Supply: 1.71 V ~ 1.96 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFP Exposed Pad, 48-eTQFP, 48-HTQFP, 48-VQFP
• Data Rate: 25Mbps
• Rf Ic Case Style: TQFP
• No. Of Pins: 48
• Supply Voltage Range: 1.8V To 3.3V
• Operating Temperature Range: -40°C To +105°C
• Msl: MSL 3 - 168 Hours
• Ic Function: Direct Digital Synthesizer
• Digital Ic Case Style: TQFP
• Svhc: No SVHC (15-Dec-2010)
• Rohs Compliant: Yes
• Termination Type: SMD
• Ic Generic Number: 9951
• Base Number: 9951
• Filter Terminals: SMD
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AD9951/PCB - BOARD EVAL FOR AD9951
• Lead Free Status / Rohs Status: Compliant

External Shaped On-Off Keying Mode Operation
The external shaped on-off keying mode is enabled by writing
CFR1<25> to a Logic 1 and writing CFR1<24> to a Logic 0.
When configured for external shaped on-off keying, the
content of the ASFR becomes the scale factor for the data path.
The scale factors are synchronized to SYNC_CLK via the
I/O UPDATE functionality.
Synchronization; Register Updates (I/O UPDATE)
Functionality of the SYNC_CLK and I/O UPDATE
Data into the AD9951 is synchronous to the SYNC_CLK signal
(supplied externally to the user on the SYNC_CLK pin). The
I/O UPDATE pin is sampled on the rising edge of the
SYNC_CLK.
Internally, SYSCLK is fed to a divide-by-4 frequency divider to
produce the SYNC_CLK signal. The SYNC_CLK signal is
provided to the user on the SYNC_CLK pin. This enables
synchronization of external hardware with the device’s internal
clocks. This is accomplished by forcing any external hardware
to obtain its timing from SYNC_CLK. The I/O UPDATE signal
TO CORE LOGIC
SYSCLK
Figure 19. I/O Synchronization Block Diagram
Q
D
REGISTER
MEMORY
OSK
Rev. A | Page 19 of 28
DETECTION
SYNC_CLK
GATING
LOGIC
÷ 4
EDGE
Q
I/O BUFFER
D
LATCHES
coupled with SYNC_CLK is used to transfer internal buffer
contents into the control registers of the device. The combina-
tion of the SYNC_CLK and I/O UPDATE pins provides the
user with constant latency relative to SYSCLK, and also ensures
phase continuity of the analog output signal when a new tuning
word or phase offset value is asserted. Figure 19 demonstrates
an I/O UPDATE timing cycle and synchronization.
Notes to synchronization logic:
1.
2.
The I/O UPDATE signal is edge detected to generate a
single rising edge clock signal that drives the register bank
flops. The I/O UPDATE signal has no constraints on duty
cycle. The minimum low time on I/O UPDATE is one
SYNC_CLK clock cycle.
The I/O UPDATE pin is set up and held around the rising
edge of SYNC_CLK and has zero hold time and 4 ns setup
time.
Q
D
0
SYNC_CLK
I/O UPDATE
DISABLE
SCLK
SDI
CS
AD9951