AD1868N Analog Devices Inc, AD1868N Datasheet - Page 7

• Manufacturer Part Number: AD1868N
• Description: IC DAC AUDIO 18BIT DUAL 16-DIP
• Manufacturer: Analog Devices Inc

Specifications of AD1868N

• Rohs Status: RoHS non-compliant
• Number Of Bits: 18
• Data Interface: Serial
• Number Of Converters: 2
• Voltage Supply Source: Analog and Digital
• Power Dissipation (max): 70mW
• Operating Temperature: -35°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 16-DIP (0.300", 7.62mm)
• Settling Time: -

REV. A
TIMING
Figure 10 illustrates the specific timing requirements that must
be met in order for the data transfer to be accomplished prop-
erly. The input pins of the AD1868 are TTL and 5 V CMOS
compatible.
The maximum clock rate of the AD1868 is specified to be at
least 13.5 MHz. This clock rate allows data transfer rates of 2 ,
4 , 8 , and 16 F
tions section of this data sheet contains additional guidelines for
using the AD1868.
APPLICATIONS OF THE AD1868
The AD1868 is a high performance audio DAC specifically de-
signed for portable and automotive digital audio applications.
These market segments have technical requirements fundamen-
tally different than those found in the high-end or home-use
market segments. Portable equipment must rely on components
which require low amounts of power to offer reasonable playing
times. Also, battery voltages drop as the end of the discharge
cycle is approached. The AD1868’s ability to operate from a
single +5 V supply makes it a good choice for battery-operated
gear. As the battery voltage drops, the power dissipation of the
DATA
CLK
LATCH
ENABLE (LE)
>30ns
>10ns
> 74./ ns
1st BIT
>30ns
MSB
1
2
3
4
5
6
7
8
9
>10ns
>30ns
TEST
8Fs/4Fs
V
Figure 10. Input Signal Timing
INIT
DD
CXD2550P
S
(where F
UPDATED WITH 18 MOST RECENT BITS
DATAR
LRCK0
DATAL
2nd BIT
BCKO
SLOT
INTERNAL DAC INPUT REGISTER
V
SS
S
18
17
16
15
14
13
12
11
10
equals 44.1 kHz). The applica-
+5V POWER
SUPPLY
Figure 11. AD1868 with Sony CXD2550P Digital Filter
(18th BIT)
1
2
3
5
6
8
4
7
LSB
V
CK
DR
V
LL
DL
LR
DGND
L
B
R
>60ns
AD1868
>40ns
TO SHIFT REGISTER
BITS CLOCKED
>15ns
AGND
NRL
NRR
V
V
V
>40ns
WORD
O
NEXT
B
V
O
V
R
L
S
L
S
16
15
14
13
12
11
10
9
–7–
AD1868 drops. This extends the usable battery life. Finally, as
the battery supply voltage drops, the bias voltages and signal
swings also drop, preventing signal clipping and abrupt degra-
dation of distortion. Figure 3 illustrates that THD+N perfor-
mance of the AD1868 remains constant through a wide range
of supply voltages.
Automotive equipment rely on components which are able to
consistently perform in a wide range of temperatures. In addi-
tion, due to the limited space available in automotive applica-
tions, small size is essential. The AD1868 is able to satisfy both
of these requirements. The device has guaranteed specified per-
formance between 0 C and +70 C, and the 16-pin DIP or 16-
pin SOIC package is particularly attractive where overall size is
important.
Since the AD1868 provides dc bias voltages, the entire signal
chain can be dc-coupled. This eliminate ac-coupling capacitors
from the signal path, improving low frequency performance and
lowering system cost and size.
In summary, the AD1868 is an excellent choice for battery op-
erated portable or automotive digital audio systems. In the fol-
lowing sections, some examples of high performance audio
applications featuring the AD1868 are described.
AD1868 with Sony CXD2550P Digital Filter
Figure 11 illustrates an 18-bit CD player design incorporating
an AD1868 DAC, a Sony CXD2550P digital filter and 2-pole
antialias filters. This high performance, single supply design op-
erates at 8 F
plications. In this design, the CXD2550P filter transmits left
and right channel digital data to the AD1868. The left and
right latch signals, LL and LR, are both provided by the word
clock signal (LRCKO) of the digital filter. The digital data is
converted to low distortion output voltages by the output
amplifiers on the AD1868. Also, no deglitching circuitry or
external adjustments are required. Bypass capacitors, noise
reduction capacitors and the antialias filter details are omitted
for clarity.
1
4
2
3
AGND
S
and is suitable for portable and automotive ap-
V
S
8
6
7
5
AD1868
LEFT
CHANNEL
OUTPUT
RIGHT
CHANNEL
OUTPUT