cx25870 Conexant Systems, Inc., cx25870 Datasheet - Page 18

• Manufacturer Part Number: cx25870
• Description: Video Encoder With Adaptive Flicker Filtering And Hdtv Output
• Manufacturer: Conexant Systems, Inc.

1.0 Functional Description
1.1 Pin Descriptions
Table 1-1. Pin Assignments (1 of 3)
1-2
VAA_VREF
AGND
FSADJUST
VBIAS
VREF
COMP
VAA_DACC
DACC
VAA_DACB
DACB
VAA_DACA
DACA
VAA_DACD
DACD
AGND_DAC
VSS_X
XTALIN
XTALOUT
VDD_X
VAA_PLL
AGND_PLL
Pin Name
I
O
O
O
O
O
O
O
I
O
I/O
—
—
—
—
—
—
—
—
—
—
—
Bt868/869, the CX25870/871 is completely pin-to-pin compatible with
Conexant’s first generation VGA encoder.
80
79
78
77
76
75
73
72
71
70
69
68
67
66
65, 74
64
63
62
61
59
58
Pin #
Aside from pins 2, 3, 65, 66, and 67, which are no connects within the
Analog power. All VAA and VDD pins must be connected together on the same
PCB plane to prevent latchup.
Analog ground. All AGND and VSS pins must be connected together on the
same PCB plane to prevent latchup.
Full-scale adjust control pin. A resistor (RSET) connected between this pin and
GND controls the full-scale output current on the analog outputs.
DAC bias voltage. A 0.1 !F ceramic capacitor must be used to bypass this pin to
GND. The capacitor must be as close to the device as possible to keep lead
lengths to an absolute minimum.
Voltage reference pin. A 1.0 !F ceramic capacitor must be used to decouple this
pin to GND. The decoupling capacitor must be as close to the device as possible
to keep lead lengths to an absolute minimum.
Compensation pin. A 0.1 !F ceramic capacitor must be used to bypass this pin
to VAA. The capacitor must be as close to the device as possible to keep lead
lengths to an absolute minimum.
DACC Analog power. All VAA and VDD pins must be connected together on the
same PCB plane to prevent latchup.
DACC Analog output.
DACB Analog power. All VAA and VDD pins must be connected together on the
same PCB plane to prevent latchup.
DACB Analog output.
DACA Analog power. All VAA and VDD pins must be connected together on the
same PCB plane to prevent latchup.
DACA Analog output.
DACD analog power. All VAA and VDD pins must be connected together on the
same PCB plane to prevent latchup.
DACD analog output. If unused, DACD should be left as a no connect.
Common DAC Analog ground return. All AGND and VSS pins must be
connected together on the same PCB plane to prevent latchup.
Crystal oscillator ground pin. This pin should be tied to the ground plane.
A crystal can be connected to these pins. The pixel clock output (CLKO) is
derived from these pins with a PLL. XTALIN can be driven as a CMOS input pin.
Internally, this is a CMOS inverter tying XTALOUT to XTALIN. If XTALOUT is
unused, it should be left as a no connect.
Crystal oscillator supply pin. This pin should be tied to the power supply.
Analog power for PLL. All VAA and VDD pins must be connected together on the
same PCB plane to prevent latchup.
Analog ground for PLL. All AGND and VSS pins must be connected together on
the same PCB plane to prevent latchup.
Conexant
Flicker-Free Video Encoder with Ultrascale Technology
Description
CX25870/871
100381B