3.0 PC Board Considerations
CX25870/871
3.6 Applications Information
Flicker-Free Video Encoder with Ultrascale Technology
Table 3-3. Hardware Modifications to Bt868/869-based PCB Required to Accommodate the CX25870/871 (3 of 3)
75
COMP
COMP
A 0-10 ohm resistor between COMP and 0.1 µF capacitor (which is connected to VAA)
was originally recommended for Bt868/9-designs.
The 0-10 ohm resistor placed between the 0.1 µF cap and the COMP pin was
recommended to better tune the COMP circuit to prevent an internal op-amp from
oscillating. Based on the Bt868/9's DAC performance over time and the CX25870/1's
continued usage of these same DACs, this resistor was deemed to not be necessary
and should be removed for all CX25870/1 designs.
76
78
VREF
VREF
Capacitor from VREF to GND must be 1.0 µF for the CX25870/1. Capacitor from VREF
to GND must be 0.1 µF for the Bt868/9.
FSADJUST
FSADJUST
RSET, the resistor from FSADJUST pin to GND, must be 75 Ω, +/- 1% for all
CX25870/1-based designs.
RSET must be 100 ohm, +/- 1% for all Bt868/9-based designs.
NOTE(S):
N/C = No connect
To ensure proper operation of the CX25870/871, the designer must adhere to
each recommendation contained in Table 3-3.
3-14
Conexant
100381B
CONEXANT [ CONEXANT SYSTEMS, INC ]
