datasheetbank_Logo
Integrated circuits, Transistor, Semiconductors Search and Datasheet PDF Download Site

ADF4001BRU-REEL View Datasheet(PDF) - Analog Devices

Part Name
Description
View to exact match
ADF4001BRU-REEL
ADI
Analog Devices ADI
ADF4001BRU-REEL Datasheet PDF : 17 Pages
First Prev 11 12 13 14 15 16 17
ADF4001
FUNCTION LATCH
With C2, C1 set to 1, 0, the on-chip function latch will be pro-
grammed. Table V shows the input data format for programming
the function latch.
Counter Reset
DB2 (F1) is the counter reset bit. When this is 1, the R counter
and the A, B counters are reset. For normal operation, this bit
should be 0. Upon powering up, the F1 bit needs to be disabled,
and the N counter resumes counting in close alignment with the
R counter. (The maximum error is one prescaler cycle.)
Power-Down
DB3 (PD1) and DB21 (PD2) on the ADF4001 family provide
programmable power-down modes. They are enabled by the
CE pin.
When the CE pin is low, the device is immediately disabled
regardless of the states of PD2, PD1.
In the programmed asynchronous power-down, the device pow-
ers down immediately after latching a 1 into Bit PD1, with the
condition that PD2 has been loaded with a 0.
In the programmed synchronous power-down, the device power-
down is gated by the charge pump to prevent unwanted frequency
jumps. Once the power-down is enabled by writing a 1 into Bit
PD1 (on condition that a 1 has also been loaded to PD2), the
device will go into power-down on the occurrence of the next
charge pump event.
When a power-down is activated (either synchronous or asyn-
chronous mode, including CE pin activated power-down), the
following events occur:
All active dc current paths are removed.
The R, N, and timeout counters are forced to their load
state conditions.
The charge pump is forced into three-state mode.
The digital clock detect circuitry is reset.
The RFIN input is debiased.
The reference input buffer circuitry is disabled.
The input register remains active and capable of loading
and latching data.
MUXOUT Control
The on-chip multiplexer is controlled by M3, M2, M1 on the
ADF4001. Table V shows the truth table.
Fastlock Enable Bit
DB9 of the function latch is the fastlock enable bit. Only when
this is 1 is fastlock enabled.
Fastlock Mode Bit
DB10 of the function latch is the fastlock mode bit. When fastlock
is enabled, this bit determines which fastlock mode is used. If the
fastlock mode bit is 0, fastlock mode 1 is selected; if the fastlock
mode bit is 1, fastlock mode 2 is selected.
Fastlock Mode 1
The charge pump current is switched to the contents of Current
Setting 2.
The device enters fastlock by having a 1 written to the CP gain
bit in the N counter latch. The device exits fastlock by having a
0 written to the CP gain bit in the AB counter latch.
Fastlock Mode 2
The charge pump current is switched to the contents of Current
Setting 2.
The device enters fastlock by having a 1 written to the CP gain bit
in the N counter latch. The device exits fastlock under the
control of the timer counter. After the timeout period determined
by the value in TC4–TC1, the CP gain bit in the N counter latch
is automatically reset to 0 and the device reverts to normal mode
instead of fastlock. See Table V for the timeout periods.
Timer Counter Control
The user has the option of programming two charge pump
currents. The intent is that the Current Setting 1 is used when
the RF output is stable and the system is in a static state. Cur-
rent Setting 2 is meant to be used when the system is dynamic
and in a state of change (i.e., when a new output frequency is
programmed). The normal sequence of events is as follows.
The user initially decides what the preferred charge pump cur-
rents are going to be. For example, they may choose 2.5 mA as
Current Setting 1 and 5 mA as Current Setting 2.
At the same time, they must also decide how long they want the
secondary current to stay active before reverting to the primary
current. This is controlled by the Timer Counter Control Bits
DB14 to DB11 (TC4–TC1) in the function latch. The truth
table is given in Table V.
Now, when the user wishes to program a new output frequency,
they can simply program the N counter latch with new value for N.
At the same time, they can set the CP gain bit to a 1, which sets
the charge pump with the value in CPI6–CPI4 for a period of
time determined by TC4–TC1. When this time is up, the charge
pump current reverts to the value set by CPI3–CPI1. At the
same time, the CP gain bit in the N counter latch is reset to 0 and
is now ready for the next time that the user wishes to change the
frequency.
Note that there is an enable feature on the timer counter. It is
enabled when Fastlock Mode 2 is chosen by setting the fastlock
mode bit (DB10) in the function latch to 1.
Charge Pump Currents
CPI3, CPI2, CPI1 program Current Setting 1 for the charge
pump. CPI6, CPI5, CPI4 program Current Setting 2 for the
charge pump. The truth table is given in Table V.
PD Polarity
This bit sets the PD polarity bit (see Table V).
CP Three-State
This bit sets the CP output pin. With the bit set high, the CP
output is put into three-state. With the bit set low, the CP
output is enabled.
–12–
REV. B
 

Share Link: 

datasheetbank.com [ Privacy Policy ] [ Request Datasheet ] [ Contact Us ]