PRODUCT SPECIFICATION
TMC3033
Applications Discussion
Figure 4 illustrates a typical TMC3033 interface circuit.
In this example, an optional 1.2 Volt bandgap reference is
connected to the V
REF
output, overriding the internal volt-
age reference source.
the power supply for the TMC3033 is the same as that of
the system's digital circuitry, power to the TMC3033
should be decoupled with 0.1µF and 0.01µF capacitors
and isolated with a ferrite bead.
3.
The ground plane should be solid, not cross-hatched.
Connections to the ground plane should have very short
leads.
If the digital power supply has a dedicated power plane
layer, it should not be placed under the TMC3033, the
voltage reference, or the analog outputs. Capacitive cou-
pling of digital power supply noise from this layer to the
TMC3033 and its related analog circuitry can have an
adverse effect on performance.
CLK should be handled carefully. Jitter and noise on
this clock will degrade performance. Terminate the
clock line carefully to eliminate overshoot and ringing.
Grounding
It is important that the TMC3033 power supply is well-
regulated and free of high-frequency noise. Careful power
supply decoupling will ensure the highest quality video sig-
nals at the output of the circuit. The TMC3033 has separate
analog and digital circuits. To keep digital system noise from
the D/A converter, it is recommended that power
supply voltages (V
DD
) come from the system analog power
source and all ground connections (GND) be made to the
analog ground plane. Power supply pins should be individu-
ally decoupled at the pin.
4.
5.
Printed Circuit Board Layout
Designing with high-performance mixed-signal circuits
demands printed circuits with ground planes. Overall
system performance is strongly influenced by the board lay-
out. Capacitive coupling from digital to analog circuits may
result in poor D/A conversion. Consider the following
suggestions when doing the layout:
1.
Keep the critical analog traces (V
REF
, I
REF
, COMP,
IO
R
, IO
G
, IO
B
) as short as possible and as far as possi-
ble from all digital signals. The TMC3033 should be
located near the board edge, close to the analog output
connectors.
The power plane for the TMC3033 should be separate
from that which supplies the digital circuitry. A single
power plane should be used for all of the V
DD
pins. If
Related Products
•
•
•
•
•
•
•
•
•
•
•
TMC3503 Triple 8-bit 80 Msps D/A Converters
TMC1175A 40 Msps CMOS 8-bit A/D Converter
TMC1275 40 Msps CMOS 8-bit A/D Converter
TMC22091, TMC22191 Digital Video Encoders
TMC2242C/TMC2243/TMC2246A Video Filters
TMC2249A Digital Mixer
TMC2250A Matrix Multiplier
TMC2272A Colorspace Converter
TMC2302 Image Manipulation Sequencer
TMC2340A Digital Synthesizer
TMC2081 Digital Video Mixer
2.
+3.3V
10µF
0.1µF
VDD
RED PIXEL
INPUT
GREEN PIXEL
INPUT
BLUE PIXEL
INPUT
R9-0
G9-0
B9-0
GND
Red
IO R
IO G
75Ω
75Ω
75Ω
COMP
0.1µF
+3.3V
3.3kΩ
ZO=75Ω
75Ω
75Ω
75Ω
Green
ZO=75Ω
Blue
ZO=75Ω
TMC3033
Triple 10-bit
D/A Converter
IO B
CLOCK
SYNC
BLANK
CLK
SYNC
BLANK
VREF
RREF
LM185-1.2
(Optional)
0.1µF
572Ω
65-3033-04
Figure 4. Typical Interface Circuit
9
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
