MICRF610TR MICREL [Micrel Semiconductor], MICRF610TR Datasheet - Page 12

• Manufacturer Part Number: MICRF610TR
• Description: 868-870 MHz ISM Band Transceiver Module
• Manufacturer: MICREL [Micrel Semiconductor]

The typical start up time for the crystal oscillator (default
XCO_tune=13) is ~750us. If more capacitance is added
(higher XCO_tune value), then the start-up time will be
longer.
To save current in the crystal oscillator start-up period, the
XCO is turned on before any other circuit block. When the
XCO has settled, rest of the circuit will be turned on. No
programming should be made during this period.
The current consumption during the prestart period is
approximately 280µA.
VCO
The VCO has no external components. It has three bit to
set the bias current and two bit to set the VCO frequency.
These five bits are set by the RF frequency, as follows:
The bias bit will optimize the phase noise, and the
frequency bit will control a capacitor bank in the VCO. The
tuning range the RF frequency versus varactor voltage is
dependent on the VCO frequency setting, and can be
shown in Figure 6.
Micrel, Inc.
December 2005
0000011
A6..A0
RF freq.
868MHz
D7
‘1’
-15.0
-25.0
-35.0
-45.0
55.0
45.0
35.0
25.0
15.0
-5.0
5.0
VCO_IB2
D6
‘1’
0
0
4
D5
‘0’
Table 7. VCO Bit Setting
Figure 5. XCO Tuning
8
VCO_IB2 VCO_IB1 VCO_IB0 VCO_freq1 VCO_freq0
VCO_IB1
[XCO_tune value]
12
D4
1
16
20
VCO_IB0
D3
24
1
28
D2
VCO_freq1 VCO_freq0
32
0
D1
1
D0
12
Lock Detect
A lock detector can be enabled by setting LD_en = 1.
When pin LD is high, it indicates that the PLL is in lock.
When entering TX, the procedure is first to load the TX
word and then turn on the PA stage. During the PA ramp
up time, the LD signal may indicate out of lock. It is first
when the PA stage is fully on that the LD signal will
indicate in “Lock”. During transmission, the Lock Detect
signal will have transitions and the user should therefore,
ignore the Lock detect signal.
Modes of Operation
0000000
A6..A0
0000001
A6..A0
Mode1
1000
950
900
850
800
0
0
1
1
Figure 6. RF Frequency vs. Varactor Voltage
LNA_by
0
D7
‘1’
and VCO Frequency bit (V
D7
Mode0
0
1
0
1
D6
‘0’
0,5
PA2
D6
D5
‘0’
Varactor voltage (V)
Power down
Transmit
Standby
Receive
PA1
State
D5
D4
‘0’
Tuning range
1
PA0
RSSI_en
D4
D3
1,5
Comments
Keeps register configuration
Only crystal oscillator running
Full receive
Full transmit ex PA state
Sync_en
D3
LD_en
DD
D2
2
= 2.25V)
Mode1
D2
PF_FC1
M9999-120205
D1
2,5
MICRF610
Mode0
D1
PF_FC0
D0
D0
’1’
'10'
'11'