TDA6502 Datasheet, PDF (30/44 Pages) NXP Semiconductors – 5 V mixers/oscillators and synthesizers for cable TV and VCR 2-band tuners

Philips Semiconductors
5 V mixers/oscillators and synthesizers for
cable TV and VCR 2-band tuners
Preliminary specification
TDA6502; TDA6502A;
TDA6503; TDA6503A
Table 19 Transistors
COMPONENT
TR1
TR2
VALUE
BC847B
BC847B
13.3 Tuning amplifier
The tuning amplifier is capable of driving the varicap
voltage without an external transistor. The tuning voltage
output must be connected to an external load of 27 kΩ
which is connected to the tuning voltage supply rail.
The loop filter design depends on the oscillator
characteristics and the selected reference frequency.
13.4 Crystal oscillator
The crystal oscillator uses a 4 MHz crystal connected in
series with an 18 pF capacitor thereby operating in the
series resonance mode. Connecting the crystal to the
ground is preferred, but it can also be connected to the
supply voltage.
13.5 Examples of I²C-bus data format sequences for
TDA6502 and TDA6503
Tables 20 to 24 show the various write sequences where:
S = START bit
A = acknowledge bit
P = STOP bit.
Conditions:
f_xtal = 4 MHz
N = 1600
f_osc = 100 MHz
f_step = 62.5 kHz
Port register VHFL is ‘on’ to switch-on band VHF low
Port register FMST is ‘on’ to switch-on an FM sound trap
I_CP = 280 µA.
13.5.1 WRITE SEQUENCES TO REGISTER C2
Table 20 Complete sequence with first the divider bytes (first data bit = 0)
START
ADDRESS
BYTE
ACK
DIVIDER
BYTE 1
ACK
DIVIDER
BYTE 2
ACK
CONTROL
BYTE
ACK
S
C2
A
06
A
40
A
CE
A
BAND-
SWITCH
BYTE
09
ACK STOP
A
P
Table 21 Complete sequence with first the control and band-switch bytes (first data bit = 1)
START
S
ADDRESS
BYTE
C2
ACK
A
CONTROL
BYTE
CE
ACK
A
BAND-
SWITCH
BYTE
09
ACK
A
DIVIDER
BYTE 1
06
ACK
A
DIVIDER
BYTE 2
40
ACK STOP
A
P
Table 22 Sequence with divider bytes only (first data bit = 0)
START
S
ADDRESS BYTE
C2
ACK
A
DIVIDER BYTE 1
06
ACK
A
DIVIDER BYTE 2
40
ACK STOP
A
P
Table 23 Sequence with control and band-switch bytes only (first data bit = 1)
START
S
ADDRESS BYTE
C2
ACK
A
CONTROL BYTE
CE
ACK BAND-SWITCH BYTE ACK STOP
A
09
A
P
Table 24 Sequence with control byte only (first data bit = 1)
START
S
ADDRESS BYTE
C2
ACK
A
CONTROL BYTE
CE
ACK STOP
A
P
2000 Mar 16
30