TDA6502 Datasheet, PDF (3/44 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
1 FEATURES
• Single-chip 5 V mixer/oscillator and synthesizer for
cable TV and VCR tuners
• Pin-to-pin compatible with TDA6402, TDA6402A,
TDA6403 and TDA6403A
• Universal bus protocol (I²C-bus or 3-wire bus)
– Bus protocol for 18 or 19-bit transmission (3-wire
bus)
– Extra protocol for 27-bit transmission (test modes and
features for 3-wire bus)
– Address + 4 data bytes transmission (I²C-bus ‘write’
mode)
– Address + 1 status byte (I²C-bus ‘read’ mode)
– 4 independent I²C-bus addresses.
• 1 PMOS buffer for UHF band selection (25 mA)
• 3 PMOS buffers for general purpose, e.g. 2 VHF
sub-bands, FM sound trap (25 mA)
• 33 V tuning voltage output
• In-lock detector
• 5-step analog-to-digital converter (3 bits in I²C-bus
mode)
• 15-bit programmable divider
• Programmable reference divider ratio (64, 80 or 128)
• Programmable charge pump current (60 or 280 µA)
• Varicap drive disable
• Balanced mixer with a common emitter input for VHF
(single input)
• Balanced mixer with a common base input for UHF
(balanced input)
• 2-pin common emitter oscillator for VHF
• 4-pin common emitter oscillator for UHF
• IF preamplifier with asymmetrical 75 Ω output
impedance able to drive loads from 75 Ω upwards
• Low power
• Low radiation
• Small size
• The TDA6502A and TDA6503A differ from the TDA6502
and TDA6503 by the UHF port protocol in the I²C-bus
mode (see Tables 3 and 4).
2 APPLICATIONS
• Cable tuners for TV and VCR (switched concept for
VHF).
3 GENERAL DESCRIPTION
The TDA6502, TDA6502A, TDA6503 and TDA6503A are
programmable 2-band mixers/oscillators and synthesizers
intended for VHF/UHF TV and VCR tuners (see Fig.1).
Partitioning of the bands is the responsibility of the
customer providing VHF is below 500 MHz and UHF is
below 900 MHz.
The devices include two double balanced mixers and two
oscillators for the VHF and UHF band respectively, an
IF amplifier and a PLL synthesizer. The VHF band can be
split-up into two sub-bands using a proper oscillator
application and a switchable inductor.
Two pins are available between the mixer output and the
IF amplifier input to enable IF filtering for improved signal
handling.
The port register provides four PMOS ports. Band
selection is provided by port register UHF. When port
register UHF is ‘on’, the UHF mixer-oscillator is active and
the VHF band is switched off. When port register UHF is
‘off’, the VHF mixer-oscillator is active and the UHF band
is off. Port registers VHFL and VHFH are used to select
the VHF sub-bands. Port register FMST is a general
purpose port, that can be used to switch an FM sound trap.
When the ports are used, the sum of the drain currents has
to be limited to 30 mA.
The synthesizer consists of a 15-bit programmable divider,
a crystal oscillator and its programmable reference divider
and a phase comparator (phase/frequency detector)
combined with a charge pump which drives the tuning
amplifier, including the 33 V output at pin VT. Depending
on the reference divider ratio (64, 80 or 128), the phase
comparator operates at 62.5, 50 or 31.25 kHz with a
4 MHz crystal.
2000 Mar 16
3