Datasheet
Data Sheet ADV7390/ADV7391/ADV7392/ADV7393
Rev. J | Page 69 of 107
PRINTED CIRCUIT BOARD LAYOUT AND DESIGN
UNUSED PINS
If the
HSYNC
and
VSYNC
pins are not used, they should be tied
to V
DD_IO
through a pull-up resistor (10 kΩ or 4.7 kΩ). Any
other unused digital inputs should be tied to ground. Unused
digital output pins should be left floating. DAC outputs can
either be left floating or connected to GND. Disabling these
outputs is recommended.
DAC CONFIGURATIONS
The ADV7390/ADV7391/ADV7392/ADV7393 contain three
DACs. All three DACs can 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
L
. Full drive is the recommended
mode of operation for the DACs.
Alternatively, all three 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
L
.
The ADV7390/ADV7391/ADV7392/ADV7393 contain an R
SET
pin. A resistor connected between the R
SET
pin and AGND is
used to control the full-scale output current and, therefore, the
output voltage levels of DAC 1, DAC 2, and DAC 3. For full-
drive operation, R
SET
must have a value of 510 Ω and RL must
have a value of 37.5 Ω. For low drive operation, R
SET
must have a
value of 4.12 kΩ, and R
L
must have a value of 300 Ω. The resistor
connected to the R
SET
pin should have a 1% tolerance.
The ADV7390/ADV7391/ADV7392/ADV7393 contain a
compensation pin, COMP. A 2.2 nF compensation capacitor
should be connected from the COMP pin to V
AA
.
VIDEO OUTPUT BUFFER AND OPTIONAL
OUTPUT FILTER
An output buffer is necessary on any DAC that operates in low-
drive mode (R
SET
= 4.12 kΩ, R
L
= 300 Ω). Analog Devices
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 ADV7390/ADV7391/ADV7392/ADV7393
DAC outputs. 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.
For applications requiring an output buffer and reconstruction
filter, the ADA4430-1 and ADA4411-3 integrated video filter
buffers should be considered.
Table 57. ADV7390/ADV7391/ADV7392/ADV7393 Output
Rates
Input Mode
(Subaddress 0x01,
Bits[6:4]) Oversampling Output Rate (MHz)
SD Off 27 (2×)
On 108 (8×)
On 216 (16×)
ED Off 27 (1×)
On 108 (4×)
On 216 (8×)
HD Off 74.25 (1×)
On 148.5 (2×)
On
297
(4×)
Table 58. Output Filter Requirements
Application Oversampling
Cutoff
Frequency
(MHz)
Attenuation
–50 dB
at
(MHz)
SD 2× > 6.5 20.5
8×
> 6.5
101.5
16× > 6.5 209.5
ED 1× > 12.5 14.5
4× > 12.5 95.5
8× > 12.5 203.5
HD 1× > 30 44.25
2×
> 30
118.5
4× > 30 267
560Ω
600Ω22pF600Ω
DAC
OUTPUT
75Ω
BNC
OUTPUT
10µH
560Ω
3
4
1
06234-086
Figure 87. Example of Output Filter for SD, 16× Oversampling
560Ω
6.8pF
600Ω
6.8pF
600Ω
DAC
OUTPUT
75Ω
BNC
OUTPUT
4.7µH
560Ω
3
4
1
06234-087
Figure 88. Example of Output Filter for ED, 8× Oversampling
DAC
OUTPUT
390nH
33pF 33pF
75Ω
500
Ω
300Ω
75Ω
BNC
OUTPUT
500Ω
3
4
1
3
4
1
06234-088
Figure 89. Example of Output Filter for HD, 4× Oversampling
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