AD9511/PCB Analog Devices Inc, AD9511/PCB Datasheet - Page 54

• Manufacturer Part Number: AD9511/PCB
• Description: BOARD EVAL CLOCK DISTR 48LFCSP
• Manufacturer: Analog Devices Inc
• Type: Clock Distributionr

Specifications of AD9511/PCB

• Contents: Evaluation Board
• For Use With/related Products: AD9511
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD9511
POWER SUPPLY
The AD9511 requires a 3.3 V ± 5% power supply for V
The tables in the Specifications section give the performance
expected from the AD9511 with the power supply voltage
within this range. The absolute maximum range of −0.3 V to
+3.6 V, with respect to GND, must never be exceeded on
the VS pin.
Good engineering practice should be followed in the layout of
power supply traces and ground plane of the PCB. The power
supply should be bypassed on the PCB with adequate
capacitance (>10 μF). The AD9511 should be bypassed with
adequate capacitors (0.1 μF) at all power pins, as close as
possible to the part. The layout of the AD9511 evaluation board
(AD9511/PCB or AD9511-VCO/PCB) is a good example.
The AD9511 is a complex part that is programmed for its
desired operating configuration by on-chip registers. These
registers are not maintained over a shutdown of external power.
This means that the registers can lose their programmed values
if V
Careful bypassing should protect the part from memory loss
under normal conditions. Nonetheless, it is important that the
V
losing its programming.
The internal bias currents of the AD9511 are set by the R
CPR
the values given as conditions in the Specifications section
(R
1% resistor values and should be readily obtainable. The bias
currents set by these resistors determine the logic levels and
operating conditions of the internal blocks of the AD9511. The
performance figures given in the Specifications section assume
that these resistor values are used.
The VCP pin is the supply pin for the charge pump (CP). The
voltage at this pin (V
to match the tuning voltage range of a specific VCO/VCXO.
This voltage must never exceed the absolute maximum of 6 V.
V
V
The exposed metal paddle on the AD9511 package is an
electrical connection, as well as a thermal enhancement. For
the device to function properly, the paddle must be properly
attached to ground (GND). The PCB acts as a heat sink for the
AD9511; therefore, this GND connection should provide a
good thermal path to a larger dissipation area, such as a ground
plane on the PCB. See the layout of the AD9511 evaluation
board (AD9511/PCB or AD9511-VCO/PCB) for a good
example.
S
CP
S
SET
power supply not become intermittent, or the AD9511 risks
or GND, whichever is lower.
S
should also never be allowed to be less than −0.3 V below
SET
is lost long enough for the internal voltages to collapse.
= 4.12 kΩ and CPR
resistors. These resistors should be as close as possible to
CP
) may be from V
SET
= 5.1 kΩ). These values are standard
S
up to 5.5 V, as required
S
.
SET
and
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POWER MANAGEMENT
The power usage of the AD9511 can be managed to use only the
power required for the functions that are being used. Unused
features and circuitry can be powered down to save power. The
following circuit blocks can be powered down, or are powered
down when not selected (see the Register Map and Description
section):
•
•
•
•
•
Powering down a functional block does not cause the
programming information for that block (in the registers) to be
lost. This means that blocks can be powered on and off without
otherwise having to reprogram the AD9511. However,
synchronization is lost. A SYNC must be issued to
resynchronize (see the Single-Chip Synchronization section).
The PLL section can be powered down if not needed.
Any of the dividers are powered down when bypassed—
equivalent to divide-by-one.
The adjustable delay block on OUT4 is powered down
when not selected.
Any output may be powered down. However, LVPECL
outputs have both a safe and an off condition. When the
LVPECL output is terminated, only the safe shutdown
should be used to protect the LVPECL output devices. This
still consumes some power.
The entire distribution section can be powered down when
not needed.