ADF7011BRU Analog Devices Inc, ADF7011BRU Datasheet - Page 16

• Manufacturer Part Number: ADF7011BRU
• Description: IC TX ASK/FSK/GFSK HP 24-TSSOP
• Manufacturer: Analog Devices Inc

Specifications of ADF7011BRU

• Rohs Status: RoHS non-compliant
• Frequency: 433 ~ 435MHz; 866 ~ 870MHz
• Applications: Data Transfer, RKE, Remote Control/Security Systems
• Modulation Or Protocol: ASK, FSK, GFSK, OOK
• Data Rate - Maximum: 76.8 kbps
• Power - Output: -16dBm ~ 12dBm
• Current - Transmitting: 34mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 2.3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 24-TSSOP
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 4.4mm
• Operating Supply Voltage (min): 2.3V
• Operating Supply Voltage (typ): 2.5/3.3V
• Operating Supply Voltage (max): 3.6V
• Features: -
• Memory Size: -
• Lead Free Status / Rohs Status: Not Compliant

ADF7011
Digital Lock Detect
Digital lock detect is active high. The lock detect circuit is con-
tained at the PFD. When the phase error on five consecutive
cycles is less than 15 ns, lock detect is set high. Lock detect
remains high until 25 ns phase error is detected at the PFD.
Since no external components are needed for digital lock detect,
it is more widely used than analog lock detect.
Analog Lock Detect
This N-channel open-drain lock detect should be operated with
an external pull-up resistor of 10 kΩ nominal. When lock has been
detected, this output will be high with narrow low-going pulses.
Voltage Regulator
The ADF7011 requires a stable voltage source for the VCO and
modulation blocks. The on-board regulator provides 2.2 V
using a band gap reference. A 2.2 µF capacitor from C
ground is used to improve stability of the regulator over a sup-
ply ranging from 2.3 V to 3.6 V. The regulator consumes less
than 400 µA and can only be powered down using the chip
enable (CE) pin. Bringing CE low disables the regulator and
also erases all values held in the registers. The serial interface
operates off the regulator supply; therefore, to write to the part,
the user must have CE high. Regulator status can be monitored
using the Regulator Ready signal from MUXOUT.
Loop Filter
The loop filter integrates the current pulses from the charge
pump to form a voltage that tunes the output of the VCO to the
desired frequency. It also attenuates spurious levels generated
by the PLL. A typical loop filter design is shown in Figure 6.
ANALOG LOCK DETECT
DIGITAL LOCK DETECT
R COUNTER/2 OUTPUT
N COUNTER/2 OUTPUT
R COUNTER OUTPUT
N COUNTER OUTPUT
REGULATOR READY
Figure 5. MUXOUT Stage
MUX
REG
to
–16–
In FSK, the loop should be designed so that the loop bandwidth
(LBW) is approximately five times the data rate. Widening
the LBW excessively reduces the time spent jumping between
frequencies but may cause insufficient spurious attenuation.
For ASK systems, the wider the loop BW the better. The sud-
den large transition between two power levels will result in VCO
pulling and can cause a wider output spectrum than is desired.
By widening the loop BW to >10 times the data rate, the amount
of the VCO pulling is reduced since the loop will quickly settle
back to the correct frequency. The wider LBW may restrict the
output power and data rate of ASK based systems, compared
with FSK based systems.
Narrow-loop bandwidths may result in the loop taking long
periods of time to attain lock. Careful design of the loop filter is
critical in obtaining accurate FSK/GFSK modulation.
For GFSK, it is recommended that an LBW of 2.0 to 2.5 times
the data rate be used to ensure sufficient samples are taken of
the input data while filtering system noise.
CONTROL
Figure 6. Typical Loop Filter Configuration––Third
Order Integrator
PUMP OUT
CHARGE
DGND
DV
DD
MUXOUT
VCO
REV. 0