TDA9899_3 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 03 — 15 January 2008 14 of 103
NXP Semiconductors
TDA9899
Multistandard hybrid IF processing including car mobile
8.3.4 Tuner AGC
Independent integral tuner gain control loop (not nested with VIF AGC). Integral
characteristic provides high control accuracy.
Accurate setting of tuner control onset (TOP) for integral tuner gain control loop via
I
2
C-bus.
For L standard, TAGC remains VIF AGC nested, as from field experience in the past this
narrow-band TAGC gives best performance.
Thus two switchable TAGC systems for negative/DIF and positive modulation
implemented.
L standard TAGC output changed from current output to voltage output, as it is not
necessary to adapt for other than 5 V tuner.
L standard tuner time constant switching integrated (= speed up function in the event of
step into high input levels), to minimize external application.
For high TOP accuracy at L standard, additional adjustment via optional potentiometer or
I
2
C-bus is provided.
Tuner AGC status bit provided. This function enables TOP alignment without need for
TAGC voltage measurement (e.g. for TOP alignment in a complete set, where access to
internal signals is not possible).
8.4 DIF/SIF FM and AM sound AGC
External AGC control input for DIF. DIF includes 1st IF, zero IF and low IF.
Integrated gain control loop for SIF.
Bandwidth of AGC control for FM SIF related to used SAW bandwidth.
Peak AGC control in the event of FM SIF.
Ultra fast SIF AGC time constant for mobile mode.
Slow average AGC control in the event of AM sound.
AM sound AGC related to AM sound carrier level.
Fast AM sound AGC in the event of fast VIF AGC (speed up).
SIF AGC DC voltage monitor output with expanded internal characteristic.
8.5 Frequency phase-locked loop for VIF
Basic function as previous TDA9887 design.
PLL gating mode for positive and negative modulation, optional.
PLL optimized for either overmodulation or strong multipath (car mobile).
