AD9954/PCBZ Analog Devices Inc, AD9954/PCBZ Datasheet - Page 20

• Manufacturer Part Number: AD9954/PCBZ
• Description: BOARD EVAL FOR 9954
• Manufacturer: Analog Devices Inc
• Series: AgileRF™r

Specifications of AD9954/PCBZ

• Main Purpose: Timing, Direct Digital Synthesis (DDS)
• Embedded: No
• Utilized Ic / Part: AD9954
• Primary Attributes: 14-Bit DAC, 32-Bit Tuning Word Width
• Secondary Attributes: 400MHz, Graphical User Interface
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD9954
The last method in which the sweep ramp rate timer can be
reset is changing from inactive linear sweep mode to active
linear sweep mode using the linear sweep enable bit (CFR1<21>).
For methods two and three, the ramp rate timer loads a value
determined by the state of PS0 (0 = FSRRW, 1 = RSRRW).
Power-Down Functions of the AD9954
The AD9954 supports an externally controlled (or hardware)
power-down feature as well as software-programmable power-
down bits capable of individually powering down specific unused
circuit blocks.
Table 9. Power-Down Control Functions
Control
PWRDWNCTL = 0, CFR1<3> don’t care
PWRDWNCTL = 1, CFR1<3> = 0
PWRDWNCTL = 1, CFR1<3> = 1
Mode Active
Software control
External control, fast recovery
power-down mode
External control, full power-down
mode
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Software-controlled power-down enables individual powering
down of the DAC, comparator, PLL, input clock circuitry, and
the digital logic (CFR1<7:4>). With the exception of CFR1<6>,
these bits are superseded when the externally controlled power-
down pin (PWRDWNCTL) is high. External power-down
control is supported on the AD9954 via the PWRDWNCTL
input pin. When the PWRDWNCTL input pin is high, the
AD9954 enters a power-down mode based on the CFR1<3> bit.
When the PWRDWNCTL input pin is low, it operates normally.
See CFR1<3> in Table 12 for details.
Table 9 details the logic level for each power-down bit that
drives out of the AD9954 core logic to the analog section and
the digital clock generation section of the chip for the external
power-down operation.
Description
Digital power-down = CFR1<7>
Comparator power-down = CFR1<6>
DAC power-down = CFR1<5>
Clock input power-down = CFR1<4>
Digital power-down = 1’b1
Comparator power-down = 1’b0 or CFR1<6>
DAC power-down = 1’b0
Clock input power-down = 1’b0
Digital power-down = 1’b1
Comparator power-down = 1’b1
DAC power-down = 1’b1
Clock input power-down = 1’b1