AD1868R Analog Devices Inc, AD1868R Datasheet - Page 4

• Manufacturer Part Number: AD1868R
• Description: IC DAC AUDIO 18BIT DUAL 16-SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD1868R

• 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: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Settling Time: -

AD1868
DEFINITION OF SPECIFICATIONS
Total Harmonic Distortion + Noise
Total harmonic distortion plus noise (THD+N) is defined as
the ratio of the square root of the sum of the squares of the am-
plitudes of the harmonics and noise to the amplitude of the fun-
damental input frequency. It is usually expressed in percent (%)
or decibels (dB).
D-Range Distortion
D-range distortion is the ratio of the amplitude of the signal at
an amplitude of –60 dB to the amplitude of the distortion plus
noise. In this case, an A-weight filter is used. The value speci-
fied for D-range performance is the ratio measured plus 60 dB.
Signal-to-Noise Ratio
The signal-to-noise ratio is defined as the ratio of the amplitude
of the output when a full-scale output is present to the ampli-
tude of the output with no signal present. It is expressed in
decibels (dB) and measured using an A-weight filter.
Gain Linearity
Gain linearity is a measure of the deviation of the actual output
amplitude from the ideal output amplitude. It is determined by
measuring the amplitude of the output signal as the amplitude
of that output signal is digitally reduced to a lower level. A per-
fect D/A converter exhibits no difference between the ideal and
actual amplitudes. Gain linearity is expressed in decibels (dB).
Midscale Error
Midscale error is the difference between the analog output and
the bias when the twos complement input code representing
midscale is loaded in the input register. Midscale error is ex-
pressed in mV.
Model
AD1868N
AD1868R
AD1868N-J
AD1868R-J
*N = Plastic DIP; R = SOIC.
DGND
V
DL
CK
DR
LR
B
LL
V
R
L
PIN CONFIGURATION
1
2
3
4
5
6
7
8
THD + N
@ F
ORDERING GUIDE
0.008%
0.008%
0.006%
0.006%
S
(Not To Scale)
AD1868
TOP VIEW
SNR
95 dB
95 dB
95 dB
95 dB
16
15
14
13
12
11
10
9
V
V
V
AGND
NRR
V
NRL
V
B
O
S
O
S
L
L
R
Package
Option*
N-16
R-16
N-16
R-16
–4–
11
12
13
14
15
16
17
18
19
10
11
12
13
14
15
16
FUNCTIONAL DESCRIPTION
The AD1868 is a complete, voltage output dual 18-bit digital
audio DAC which operates with a single +5 volt supply. As
shown in the block diagram, each channel contains a voltage
reference, an 18-bit DAC, an output amplifier, an 18-bit input
latch, and an 18-bit serial-to-parallel input register.
The voltage reference section provides a reference voltage and a
false ground voltage for each channel. The low noise bandgap
circuits produce reference voltages that are unaffected by
changes in temperature, time, and power supply.
The output amplifier uses both MOS and bipolar devices and
incorporates an NPN class-A output stage. It is designed to pro-
duce high slew rate, low noise, low distortion, and optimal fre-
quency response.
Each 18-bit DAC uses a combination of segmented decoder
and R-2R architecture to achieve good integral and differential
linearity. The resistors which form the ladder structure are fab-
ricated with silicon-chromium thin film. Laser trimming of
these resistors further reduces linearity error, resulting in low
output distortion.
The input registers are fabricated with CMOS logic gates.
These gates allow fast switching speeds and low power con-
sumption, contributing to the fast digital timing, low glitch, and
low power dissipation of the AD1868.
V
LL
DL
CK
DR
LR
DGND
V
V
V
NRR
AGND
NRL
V
V
V
L
B
S
O
O
S
B
R
L
R
L
PIN DESIGNATIONS
Digital Supply (+5 Volts)
Left Channel Latch Enable
Left Channel Data Input
Clock Input
Right Channel Data Input
Right Channel Latch Enable
Digital Common
Right Channel Bias
Analog Supply (+5 Volts)
Right Channel Output
Right Channel Noise Reduction
Analog Common
Left Channel Noise Reduction
Left Channel Output
Analog Supply (+5 Volts)
Left Channel Bias
REV. A