mc13109 Freescale Semiconductor, Inc, mc13109 Datasheet - Page 23

• Manufacturer Part Number: mc13109
• Description: Universal Cordless Telephone Subsystem
• Manufacturer: Freescale Semiconductor, Inc

Auxiliary Register
Selection latch and a 4–bit Test Mode latch. Operation of
these latch bits are explained in Figures 28, 29 and 30.
First Local Oscillator Capacitor Selection for 25
Channel U.S. Operation
minimum and maximum channel frequencies in the proposed
25 Channel U.S. standard. The sensitivity of the 1st LO is not
large enough to accommodate this large frequency variation.
Fixed capacitors can be connected across the 1st LO tank
circuit to change the 1st LO sensitivity. Internal switches and
capacitors are provided to enable microprocessor control
over internal fixed capacitor values. Figure 29 shows the
MOTOROLA ANALOG IC DEVICE DATA
MSB
1st LO
The auxiliary register contains a 3–bit 1st LO Capacitor
There is a very large frequency difference between the
Cap.
Bit 2
0
0
0
0
0
1
Figure 28. Auxiliary Register Latch Bits
4–Bit Test Mode
1st LO
Cap.
Bit 1
0
0
0
1
1
0
1st LO
Bit 0
Cap
0
0
1
0
1
0
LSB
MSB
1st LO
Select
Cap.
Figure 30. 1st LO Capacitor Select for U.S. 25 Channels
0
0
1
2
3
4
3–Bit 1st LO Capacitor
Selection
Channels
16 – 25
7 – 15
Base
1 – 6
U.S.
–
–
–
MC13109
LSB
Channels
Handset
16 – 25
7 – 15
1 – 6
U.S.
–
–
–
schematic of the 1st LO tank circuit. Figure 30 shows the
latch control bit values.
(C O = 8.9 pF at 25 C, V cap control voltage = 1.2 V, F req =
36 MHz). Customer is suggested to use a negative
temperature coefficient capacitor in 1st LO tank circuit when
the whole operating temperature range of –40 to +85 C is
considered.
The internal varactor temperature coefficient is 1800 ppm/ C
1st LO
(Excluding
Cap. Value
Varactor)
Internal
0.92 pF
0.92 pF
2.61 pF
1.82 pF
8.69 pF
7.19 pF
Internal Capacitor
Figure 29. 1st LO Schematic
0.5 to 2.2 V
Value over
10 – 6.4 pF
10 – 6.4 pF
10 – 6.4 pF
10 – 6.4 pF
10 – 6.4 pF
10 – 6.4 pF
Varactor
Range
Varactor
Varactor
Capacitor
External
Value
27 pF
33 pF
27 pF
27 pF
33 pF
33 pF
V cap Ctrl
LO 1 In
LO 1 Out
40
41
42
C ext
External
Inductor
0.47 H
0.47 H
0.47 H
0.47 H
0.47 H
0.47 H
Value
L ext
23