TDA6650TT Datasheet, PDF (12/55 Pages) NXP Semiconductors – 5 V mixer/oscillator and low noise PLL synthesizer for hybrid terrestrial tuner (digital and analog)

Philips Semiconductors
5 V mixer/oscillator and low noise PLL synthesizer
for hybrid terrestrial tuner (digital and analog)
Product specification
TDA6650TT;
TDA6651TT
8.1.4 AGC DETECTOR SETTING
The AGC take-over point can be selected out of 6 levels according to Table 8.
Table 8 AGC programming
AL2
AL1
AL0
TYPICAL TAKE-OVER POINT LEVEL
0
0
0
124 dBµV (p-p)
0
0
1
121 dBµV (p-p)
0
1
0
118 dBµV (p-p)
0
1
1
115 dBµV (p-p)
1
0
0
112 dBµV (p-p)
1
0
1
109 dBµV (p-p)
1
1
0
I_AGC = 0; note 1
1
1
1
V_AGC = 3.5 V; note 2
Notes
1. The AGC current sources are disabled. The AGC output goes into a high-impedance state and an external AGC
source can be connected in parallel and will not be influenced.
2. The AGC detector is disabled and I_AGC = 9 µA.
8.1.5 CHARGE PUMP CURRENT SETTING
The charge pump current can be chosen from 8 values depending on the value of bits CP2, CP1 and CP0 bits; see
Table 9. The programming of the CP bits are not taken into account when ALBC mode is in use.
Table 9 Charge pump current
CP2
CP1
CP0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
CHARGE PUMP CURRENT
NUMBER
1
2
3
4
5
6
7
8
TYPICAL CURRENT
(ABSOLUTE VALUE IN µA)
38
54
83
122
163
254
400
580
8.1.6 AUTOMATIC LOOP BANDWIDTH CONTROL (ALBC)
In a PLL controlled VCO in which the PLL reduces phase
noise close to the carrier, there is an optimum loop
bandwidth corresponding to the minimum integrated
phase jitter. This loop bandwidth depends on different
parameters like the VCO slope, the loop filter components,
the dividing ratio and the gain of the phase detector and
charge pump.
In order to reach the best phase noise performance it is
necessary, especially in a wide band system like a digital
tuner, to set the charge pump current to different values
depending on the band and frequency used. This is to
cope with the variations of the different parameters that set
the bandwidth. The selection can be done in the
application and requires for each frequency to program not
only the divider ratios, but also the band and the best
charge pump current.
The TDA6650TT; TDA6651TT includes the ALBC feature
that automatically sets the band and the charge pump
current, provided the IC is used in the DVB-T standard
2004 Mar 22
12