MICRF506BML Micrel Inc, MICRF506BML Datasheet - Page 17

• Manufacturer Part Number: MICRF506BML
• Manufacturer: Micrel Inc

Specifications of MICRF506BML

• Operating Frequency (max): 450000kHz
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Modulation Type: FSK
• Lead Free Status / Rohs Status: Not Compliant

If an external reference is used instead of a crystal,
the signal shall be applied to pin 24, XTALOUT. Due
to internal DC setting in the XCO, an AC coupling is
recommended to be used between the external
reference and the XTALOUT-pin.
July 2006
Table 7. Typical values with C
XCOtune
16
31
0
1
2
4
8
Start-up Time (µs)
1140
2050
590
590
700
700
810
EXT
= 1.5pF
17
0000011
A6..A0
RF freq.
410MHz
410-423MHz
423-436MHz
436-450MHz
VCO
The VCO has no external components. If has three
bit to set the bias current and two bit to set the VCO
frequency. These five bit 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 7.
When the tuning voltage is in the range from 0.9V to
1.4V, the VCO gain is at its maximum, approximately
32 to 35MHz/V. It is recommended that the varactor
voltage stays in this range.
The input capacitance at the varactor pin must be
taken into consideration when designing the PLL
loop filter. This is most critical when designing a loop
filter with high bandwidth, which gives relatively
small component values. The input capacitance is
approximately 6pF.
Figure 7. RF Frequency vs. Varactor Voltage
480
470
460
450
440
430
420
410
400
390
380
D7
‘1’
0
and VCO Frequency bit (V
VCO_IB2
D6
‘1’
1
1
1
0
0.4
D5
‘0’
Table 8. VCO Bit Setting
VCO frequency gain, Vdd=2.5V
VCO_IB2 VCO_IB1 VCO_IB0 VCO_freq1 VCO_freq0
VCO_IB1
0.8
D4
0
0
0
1
V_varactor [V]
1.2
D3
VCO_IB0
1
1
0
1
1.6
DD
D2
VCO_freq1 VCO_freq0
[phone]
= 2.25V)
2
M9999-092904
0
0
1
1
D1
2.4
11
10
01
00
1
1
0
1
D0