adv7342 Analog Devices, Inc., adv7342 Datasheet - Page 65

• Manufacturer Part Number: adv7342
• Description: Multiformat Video Encoder Six, 11-bit, 297 Mhz Dacs
• Manufacturer: Analog Devices, Inc.

PRINTED CIRCUIT BOARD LAYOUT AND DESIGN
DAC CONFIGURATIONS
The ADV7342/ADV7343 contain six DACs. All six DACs can
be configured to operate in low drive mode. Low drive mode is
defined as 4.33 mA full-scale current into a 300 Ω load, R
DAC 1, DAC 2, and DAC 3 can also be configured to operate in
full-drive mode. Full-drive mode is defined as 34.7 mA full-
scale current into a 37.5 Ω load, R
mode of operation for DAC 1, DAC 2, and DAC 3.
The ADV7342/ADV7343 contain two R
connected between the R
the full-scale output current and, therefore, the DAC output
voltage levels of DAC 1, DAC 2, and DAC 3. For low drive
operation, R
value of 300 Ω. For full-drive operation, R
of 510 Ω, and R
A resistor connected between the R
to control the full-scale output current and, therefore, the DAC
output voltage levels of DAC 4, DAC 5, and DAC 6. R
have a value of 4.12 kΩ, and R
is, low drive operation only).
The resistors connected to the R
1% tolerance.
The ADV7342/ADV7343 contain two compensation pins,
COMP1 and COMP2. A 2.2 nF compensation capacitor should
be connected from each of these pins to V
VOLTAGE REFERENCE
The ADV7342/ADV7343 contain an on-chip voltage reference
that can be used as a board-level voltage reference via the V
pin. Alternatively, the ADV7342/ADV7343 can be used with an
external voltage reference by connecting the reference source to
the V
reference such as the AD1580 should be used with the ADV7342/
ADV7343. If an external voltage reference is not used, a 0.1 μF
capacitor should be connected from the V
VIDEO OUTPUT BUFFER AND OPTIONAL
OUTPUT FILTER
An output buffer is necessary on any DAC that operates in low
drive mode (R
produces a range of op amps suitable for this application, for
example, the AD8061. For more information about line driver
buffering circuits, see the relevant op amp data sheet.
An optional reconstruction (anti-imaging) low-pass filter (LPF)
may be required on the ADV7342/ADV7343 DAC outputs if
the ADV7342/ADV7343 are connected to a device that requires
this filtering.
The filter specifications vary with the application. The use of
16× (SD), 8× (ED), or 4× (HD) oversampling can remove the
requirement for a reconstruction filter altogether.
REF
pin. For optimal performance, an external voltage
SET1
SET
L
must have a value of 4.12 kΩ, and R
must have a value of 37.5 Ω.
= 4.12 kΩ, R
SET1
pin and AGND is used to control
L
L
must have a value of 300 Ω (that
= 300 Ω). Analog Devices, Inc.
L
SET1
. Full-drive is the recommended
SET2
and R
pin and AGND is used
SET
SET2
SET1
AA
REF
pins. A resistor
.
pin to V
must have a value
pins should have a
L
must have a
SET2
AA
.
must
L
.
REF
Rev. 0 | Page 65 of 88
For applications requiring an output buffer and reconstruction
filter, the ADA4430-1, ADA4411-3, and
video filter buffers should be considered.
Table 53. ADV7342/ADV7343 Output Rates
Input Mode
(0x01, Bits[6:4])
SD Only
ED Only
HD Only
Table 54. Output Filter Requirements
Application
SD
SD
ED
ED
HD
HD
OUTPUT
OUTPUT
OUTPUT
DAC
DAC
DAC
300Ω
Figure 84. Example of Output Filter for SD, 16× Oversampling
Figure 86. Example of Output Filter for HD, 4× Oversampling
Figure 85. Example of Output Filter for ED, 8× Oversampling
600Ω
3
4
600Ω
10µH
22pF
Oversampling
2×
16×
1×
8×
1×
4×
6.8pF
4.7µH
6.8pF
1
PLL Control
(0x00, Bit 1)
Off
On
Off
On
Off
On
75Ω
600Ω
390nH
33pF
600Ω
560Ω
560Ω
3
4
3
4
33pF
Cutoff
Frequency
(MHz)
>6.5
>6.5
>12.5
>12.5
>30
>30
ADV7342/ADV7343
560Ω
560Ω
75Ω
ADA4410-6
1
1
500Ω
3
4
75Ω
75Ω
Output Rate (MHz)
27
216
27
216
74.25
297
500Ω
Attenuation
–50 dB @
(MHz)
20.5
209.5
14.5
203.5
44.25
267
1
integrated
OUTPUT
BNC
OUTPUT
BNC
OUTPUT
(2x)
(16x)
(1x)
(8x)
(1x)
(4x)
BNC