mc44871 Freescale Semiconductor, Inc, mc44871 Datasheet - Page 10

• Manufacturer Part Number: mc44871
• Description: Tuning Circuit With High Speed Tuning Supply
• Manufacturer: Freescale Semiconductor, Inc

DC–DC Converter Characteristics
voltage on the chip from V CC . Pin 2 only needs an external
capacitor (1.0 nF) instead of an external 30 V supply. The
charge pump switching frequency is taken from the oscillator.
shown in Figure 9.
10
The dc–to–dc converter block generates the 30 V supply
Typical charge pump output current capability at 25 C is
NOTES: 1. 330 pF minimum is required for stability.
Antenna
Filter
2.
Approximate values of the external components for generation of the tuning voltage are:
C1 = 1.0 nF
R1 = 750 k (560 k minimum)
C4 = 330 pF
C2 = 47 nF
C3 = 22 nF
R2 = 39 k
These component values depend on the application.
AGC
UHF
B. P. Filter
VHF
V TUN
B III
Charge Pump filter capacitor
Pull–up resistor
VTUN filter capacitor
Loop Filter
Loop Filter
Loop Filter
Oscillator
Mixer
Figure 8. Typical Tuner Application
(Note 1)
C4
F osc
IF
Gnd
1.0 nF
1.0 nF
MC44871
5.0 V
V CC
HF1
HF2
11
C1
3
4
5
2
CP
MC44871
R1
34
32
30
28
26
24
22
20
0
Figure 9. Typical Charge Pump Output Current
8
8
1
B0
20
C2
MOTOROLA ANALOG IC DEVICE DATA
7
B1
R2
C3
6
B2 B4
40
Program
Divider
16
Bus
Rec
CURRENT ( A)
9
V ref
External Switching
60
Phase
Comp
Ref Div
V CC = 4.5 V
Osc &
80
10
14
13
12
15
V CC = 5.0 V
Xtal
V CC = 5.5 V
100
ADC
SCL
SDA
ADD
C Xtal
3.2/4.0 MHz
120