AD AD1865N-J

a
Complete Dual 18-Bit
16 ⴛ FS Audio DAC
AD1865*
FUNCTIONAL BLOCK DIAGRAM
(DIP Package)
FEATURES
Dual Serial Input, Voltage Output DACs
No External Components Required
110 dB SNR
0.003% THD+N
Operates at 16 ⴛ Oversampling per Channel
ⴞ5 Volt Operation
Cophased Outputs
116 dB Channel Separation
Pin Compatible with AD1864
DIP or SOIC Packaging
APPLICATIONS
Multichannel Audio Applications
Compact Disc Players
Multivoice Keyboard Instruments
DAT Players and Recorders
Digital Mixing Consoles
Multimedia Workstations
–V S
1
TRIM
2
23 TRIM
REFERENCE
MSB
24 +V S
AD1865
REFERENCE
3
22
MSB
IOUT
IOUT
4
21
AGND
5
20
AGND
19
SJ
SJ
6
RF
7
18
RF
VOUT
8
17
VOUT
+VL
9
16
NC
DR
10
15
DL
LR
11
14
LL
13
DGND
CLK
18-BIT
LATCH
18-BIT
D/A
18-BIT
D/A
12
18-BIT
LATCH
NC = NO CONNECT
PRODUCT DESCRIPTION
The AD1865 is a complete, dual 18-bit DAC offering excellent
THD+N and SNR while requiring no external components. Two
complete signal channels are included. This results in cophased
voltage or current output signals and eliminates the need for
output demultiplexing circuitry. The monolithic AD1865 chip
includes CMOS logic elements, bipolar and MOS linear elements and laser-trimmed thin-film resistor elements, all fabricated on Analog Devices’ ABCMOS process.
The DACs on the AD1865 chip employ a partially segmented
architecture. The first four MSBs of each DAC are segmented
into 15 elements. The 14 LSBs are produced using standard R-2R
techniques. Segment and R-2R resistors are laser trimmed to provide extremely low total harmonic distortion. This architecture
minimizes errors at major code transitions resulting in low output glitch and eliminating the need for an external deglitcher.
When used in the current output mode, the AD1865 provides
two ± 1 mA output signals.
Each channel is equipped with a high performance output amplifier. These amplifiers achieve fast settling and high slew rate,
producing ± 3 V signals at load currents up to 8 mA. Each output amplifier is short-circuit protected and can withstand indefinite short circuits to ground.
The AD1865 was designed to balance two sets of opposing requirements, channel separation and DAC matching. High channel separation is the result of careful layout. At the same time,
both channels of the AD1865 have been designed to ensure
matched gain and linearity as well as tracking over time and
temperature. This assures optimum performance when used in
stereo and multi-DAC per channel applications.
A versatile digital interface allows the AD1865 to be directly
connected to standard digital filter chips. This interface employs
five signals: Data Left (DL), Data Right (DR), Latch Left (LL),
Latch Right (LR) and Clock (CLK). DL and DR are the serial
input pins for the left and right DAC input registers. Input data
bits are clocked into the input register on the rising edge of
CLK. A low-going latch edge updates the respective DAC output. For systems using only a single latch signal, LL and LR
may be connected together. For systems using only one DATA
signal, DR and DL may be connected together.
The AD1865 operates with ± 5 V power supplies. The digital
supply, VL, can be separated from the analog supplies, VS and
–VS, for reduced digital feedthrough. Separate analog and digital
ground pins are also provided. The AD1865 typically dissipates
only 225 mW, with a maximum power dissipation of 260 mW.
The AD1865 is packaged in both a 24-pin plastic DIP and a
28-pin SOIC package. Operation is guaranteed over the temperature range of –25°C to +70°C and over the voltage supply
range of ± 4.75 V to ± 5.25 V.
PRODUCT HIGHLIGHTS
REV. 0
11.
12.
13.
14.
15.
16.
17.
18.
19.
10.
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
*Protected by U.S. Patents Nos.: RE 30,586; 3,961,326; 4,141,004;
4,349,811; 4,855,618; 4,857,862.
The AD1865 is a complete dual 18-bit audio DAC.
110 dB signal-to-noise ratio for low noise operation.
THD+N is typically 0.003%.
Interchannel gain and midscale matching.
Output voltages and currents are cophased.
Low glitch for improved sound quality.
Both channels are 100% tested at 16 × FS.
Low Power—only 225 mW typ, 260 mW max.
Five-wire interface for individual DAC control.
24-pin DIP or 28-pin SOIC packages available.
= +25ⴗC, +V = +V = +5 V and –V = –5 V, F = 705.6 kHz, no MSB adjustment
AD1865–SPECIFICATIONS or(T deglitcher)
A
L
Parameter
S
S
Min
RESOLUTION
S
Typ
Max
18
DIGITAL INPUTS VIH
VIL
IIH, VIH = +VL
IIL, VIL = 0.4 V
Clock Input Frequency
2.0
Bits
+VL
0.8
1.0
–10
V
V
µA
µA
MHz
1.0
0.8
% of FSR
% of FSR
mV
mV
dB
13.5
ACCURACY
Gain Error
Interchannel Gain Matching
Midscale Error
Interchannel Midscale Matching
Gain Linearity (0 dB to –90 dB)
0.2
0.3
4
5
<2
DRIFT (0°C to +70°C)
Gain Drift
Midscale Drift
± 25
±4
TOTAL HARMONIC DISTORTION + NOISE*
0 dB, 990.5 Hz
AD1865N, R
AD1865N-J, R-J
20 dB, 990.5 Hz AD1865N, R
AD1865N-J, R-J
–60 dB, 990.5 Hz AD1865N, R
AD1865N-J, R-J
0.004
0.003
0.010
0.010
1.0
1.0
Unit
ppm of FSR/°C
ppm of FSR/°C
0.006
0.004
0.040
0.020
4.0
2.0
%
%
%
%
%
%
CHANNEL SEPARATION*
0 dB, 990.5 Hz
110
116
dB
SIGNAL-TO-NOISE RATIO* (20 Hz to 30 kHz)
107
110
dB
D-RANGE* (With A-Weight Filter)
–60 dB, 990.5 Hz AD1865N, R
AD1865N-J, R-J
88
94
100
100
dB
dB
ⴞ2.94
± 3.0
0.1
OUTPUT
Voltage Output Configuration
Output Range (± 1%)
Output Impedance
Load Current
Short Circuit Duration
Current Output Configuration
Bipolar Output Range (± 30%)
Output Impedance (± 30%)
±8
ⴞ3.06
V
Ω
mA
Indefinite to Common
±1
1.7
POWER SUPPLY
+VL and +VS
–VS
+I, +VL and +VS = +5 V
–I, –VS = –5 V
4.75
–5.25
POWER DISSIPATION, +VL = +VS = +5 V, –VS = –5 V
TEMPERATURE RANGE
Specification
Operation
Storage
0
–25
–60
WARMUP TIME
1
mA
kΩ
5.0
–5.0
22
–23
5.25
–4.75
26
–26
V
V
mA
mA
225
260
mW
+25
+70
+70
+100
°C
°C
°C
min
Specifications shown in boldface are tested on production units at final test without optional MSB adjustment.
*Tested in accordance with EIAJ Test Standard CP-307 with 18-bit data.
Specifications subject to change without notice.
–2–
REV. 0
AD1865
ABSOLUTE MAXIMUM RATINGS*
*Stresses greater than those listed under “Absolute Maximum Ratings” may cause
permanent damage to the device. This is a stress rating only and functional
operation of the device at these or any other conditions above those indicated in the
operational section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
VL to DGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to 6.0 V
VS to AGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to 6.0 V
–VS to AGND . . . . . . . . . . . . . . . . . . . . . . . . . . –6.0 V to 0 V
AGND to DGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 0.3 V
Digital Inputs to DGND . . . . . . . . . . . . . . . . . . . . . –0.3 to VL
Short Circuit Protection . . . . . . . . Indefinite Short to Ground
Soldering (10 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD1865 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
Model
Temperature
Range
THD+N @ FS
Package
Option*
AD1865N
AD1865N-J
AD1865R
AD1865R-J
–25°C to +70°C
–25°C to +70°C
–25°C to +70°C
–25°C to +70°C
0.006%
0.004%
0.006%
0.004%
N-24A
N-24A
R-28
R-28
RIGHT
CHANNEL
*N = Plastic DIP, R = Small Outline IC Package.
–V S
1
24 +VS
TRIM
2
23 TRIM
MSB
3
22
MSB
IOUT
4
21
IOUT
AGND
5
20
AGND
19
SJ
18
RF
6
SJ
TOP VIEW
DIP SOIC
14
15
16
17
18
19
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
–VS
TRIM
MSB
Negative Analog Supply
Right Channel Trim Network Connection
Right Channel Trim Potentiometer
Wiper Connection
Right Channel Output Current
26
IOUT
28
AGND Analog Common Pin
11
SJ
Right Channel Amplifier Summing Junction
Right Channel Feedback Resistor
12
RF
13
VOUT
Right Channel Output Voltage
Positive Digital Supply
14
+VL
15
DR
Right Channel Data Input Pin
16
LR
Right Channel Latch Pin
17
CLK
Clock Input Pin
18
DGND Digital Common Pin
19
LL
Left Channel Latch Pin
10
DL
Left Channel Data Input Pin
11, 16, 18 NC
No Internal Connection*
25, 27
Left Channel Output Voltage
12
VOUT
Left Channel Feedback Resistor
13
RF
14
SJ
Left Channel Amplifier Summing Junction
15
AGND Analog Common Pin
17
IOUT
Left Channel Output Current
19
MSB
Left Channel Trim Potentiometer
Wiper Connection
20
TRIM Left Channel Trim Network Connection
21
+VS
Positive Analog Supply
RF
7
VOUT
8
17
VOUT
+VL
9
16
NC
DR
10
15
DL
LR
11
14
LL
CLK
12
13
DGND
(Not to Scale)
NC = NO CONNECT
(28-Pin SOIC Package)
SJ
1
RF
2
27 NC
VOUT
3
26 IOUT
+VL
4
25
NC
5
24
MSB
DR
LR
6
CLK
7
DGND
8
LL
V
*Pin 16 has no internal connection; –V L from AD1864 DIP socket can be safely
applied.
REV. 0
LEFT
CHANNEL
AD1865
PIN DESIGNATIONS
22
23
24
ESD SENSITIVE DEVICE
PINOUT
(24-Pin DIP Package)
ORDERING GUIDE
11
12
13
WARNING!
28 AGND
AD1865
TOP VIEW
(Not to Scale)
21 +VS
9
20 TRIM
DL 10
19 MSB
NC 11
18
OUT
NC
17 IOUT
12
RF 13
16 NC
SJ 14
15 AGND
NC = NO CONNECT
–3–
23 TRIM
22 –VS
AD1865
TOTAL HARMONIC DISTORTION + NOISE
INTERCHANNEL MIDSCALE MATCHING
Total harmonic distortion plus noise (THD+N) is defined as
the ratio of the square root of the sum of the squares of the amplitudes of the harmonics and noise to the value of the fundamental input frequency. It is usually expressed in percent.
The midscale matching specification indicates how closely the
amplitudes of the output signals of the two channels match
when the twos complement input code representing half scale is
loaded into the input register of both channels. It is expressed in
mV and is measured with half-scale output signals.
THD+N is a measure of the magnitude and distribution of linearity error, differential linearity error, quantization error and
noise. The distribution of these errors may be different, depending on the amplitude of the output signal. Therefore, to be most
useful, THD+N should be specified for both large (0 dB) and
small (–20 dB, –60 dB) signal amplitudes. THD+N measurements for the AD1865 are made using the first 19 harmonics
and noise out to 30 kHz.
SIGNAL-TO-NOISE RATIO
The signal-to-noise ratio is defined as the ratio of the amplitude
of the output when a full-scale code is entered to the amplitude
of the output when a midscale code is entered. It is measured
using a standard A-Weight filter. SNR for the AD1865 is measured for noise components out to 30 kHz.
CHANNEL SEPARATION
Channel separation is defined as the ratio of the amplitude of a
full-scale signal appearing on one channel to the amplitude of
that same signal which couples onto the adjacent channel. It is
usually expressed in dB. For the AD1865 channel separation is
measured in accordance with EIAJ Standard CP-307, Section
5.5.
D-RANGE DISTORTION
D-Range distortion is equal to the value of the total harmonic
distortion + noise (THD+N) plus 60 dB when a signal level of
–60 dB below full scale is reproduced. D-Range is tested with a
1 kHz input sine wave. This is measured with a standard A-Weight
filter as specified by EIAJ Standard CP-307.
FUNCTIONAL DESCRIPTION
The AD1865 is a complete, monolithic, dual 18-bit audio DAC.
No external components are required for operation. As shown in
the block diagram, each chip contains two voltage references,
two output amplifiers, two 18-bit serial input registers and two
18-bit DACs.
The voltage reference section provides a reference voltage for
each DAC circuit. These voltages are produced by low-noise
bandgap circuits. Buffer amplifiers are also included. This combination of elements produces reference voltages that are unaffected by changes in temperature and age.
The output amplifiers use both MOS and bipolar devices and
incorporate an all NPN output stage. This design technique
produces higher slew rate and lower distortion than previous
techniques. Frequency response is also improved. When combined with the appropriate on-chip feedback resistor, the output
op amps convert the output current to output voltages.
The 18-bit D/A converters use a combination of segmented decoder and R-2R architecture to achieve consistent linearity and
differential linearity. The resistors which form the ladder structure are fabricated with silicon chromium thin film. Laser trimming of these resistors further reduces linearity errors resulting
in low output distortion.
The input registers are fabricated with CMOS logic gates.
These gates allow the achievement of fast switching speeds and
low power consumption, contributing to the low glitch and low
power dissipation of the AD1865.
GAIN ERROR
The gain error specification indicates how closely the output of
a given channel matches the ideal output for given input data. It
is expressed in % of FSR and is measured with a full-scale output signal.
–V S
1
TRIM
2
23 TRIM
REFERENCE
INTERCHANNEL GAIN MATCHING
The gain matching specification indicates how closely the amplitudes of the output signals match when producing identical input data. It is expressed in % of FSR (Full-Scale Range = 6 V
for the AD1865) and is measured with full-scale output signals.
MIDSCALE ERROR
Midscale error is the deviation of the actual analog output of a
given channel from the ideal output (0 V) when the twos
complement input code representing half scale is loaded into the
input register of the DAC. It is expressed in mV and is measured with half-scale output signals.
24 +V S
AD1865
REFERENCE
22
MSB
4
21
IOUT
5
20
AGND
MSB
3
IOUT
AGND
SJ
6
19
SJ
RF
7
18
RF
VOUT
8
17
VOUT
+VL
9
DR
10
LR
11
CLK
12
18-BIT
LATCH
18-BIT
D/A
18-BIT
D/A
18-BIT
LATCH
16
NC
15
DL
14
LL
13
DGND
NC = NO CONNECT
AD1865 Block Diagram (DIP Package)
–4–
REV. 0
Typical Performance Data–AD1865
100
CHANNEL SEPARATION – dB
120
0dB
THD+N – dB
90
80
110
100
90
80
70
0
4
4
0
16
12
8
12
8
16
FREQUENCY – kHz
FREQUENCY – kHz
Figure 1. THD+N (dB) vs. Frequency (kHz)
Figure 2. Channel Separation (dB) vs. Frequency (kHz)
10
THD+N – %
1
–60dB
.1
.01
–20dB
0dB
.001
–30 –20
–10
0
10
20
30
40
50
60
70
80
90
TEMPERATURE – °C
Figure 3. THD+N (%) vs. Temperature (°C)
10
100
8
90
6
4
THD+N – dB
THD+N – dB
80
70
60
2
0
–2
–4
–6
50
–8
40
–10
0
500
1000
1500
2000
2500
3000
–100 –90
LOAD RESISTANCE – Ω
–70
–60
–50
–40
–30
–20
–10
0
INPUT AMPLITUDE – dB
Figure 4. THD+N (dB) vs. Load Resistance (Ω)
REV. 0
–80
Figure 5. Gain Linearity (dB) vs. Input Amplitude (dB)
–5–
AD1865–Analog Circuit Consideration
GROUNDING RECOMMENDATIONS
The AD1865 has three ground pins, two labeled AGND and
one labeled DGND. AGND, the analog ground pins, are the
“high quality” ground references for the device. To minimize
distortion and reduce crosstalk between channels, the analog
ground pins should be connected together only at the analog
common point in the system. As shown in Figure 6, the AGND
pins should not be connected at the chip.
–ANALOG
SUPPLY
AD1865
1 –VS
+VS 24
2 TRIM
TRIM 23
3 MSB
MSB 22
4 IOUT
IOUT 21
ANALOG
SUPPLY
As with most linear circuits, changes in the power supplies will
affect the output of the DAC. Analog Devices recommends that
well regulated power supplies with less than 1% ripple be incorporated into the design of an audio system.
DISTORTION PERFORMANCE AND TESTING
The THD+N figure of an audio DAC represents the amount of
undesirable signal produced during reconstruction and playback
of an audio waveform. The THD+N specification, therefore,
provides a direct method to classify and choose an audio DAC
for a desired level of performance. Figure 1 illustrates the typical THD+N performance of the AD1865 versus frequency. A
load impedance of at least 1.5 kΩ is recommended for best
THD+N performance.
5 AGND AGND 20
VOUT
DIGITAL
SUPPLY
6 SJ
SJ 19
7 RF
RF 18
8 VOUT
VOUT 17
9 +VL
NC 16
10 DR
DL 15
11 LR
12 CLK
VOUT
LL 14
DGND 13
NC = NO CONNECT
DIGITAL
COMMON
Analog Devices tests and grades all AD1865s on the basis of
THD+N performance. During the distortion test, a high-speed
digital pattern generator transmits digital data to each channel
of the device under test. Eighteen-bit data is transmitted at
705.6 kHz (16 × FS). The test waveform is a 990.5 Hz sine wave
with 0 dB, –20 dB and –60 dB amplitudes. A 4096 point FFT
calculates total harmonic distortion + noise, signal-to-noise ratio,
D-Range and channel separation. No deglitchers or MSB trims
are used in the testing of the AD1865.
OPTIONAL MSB ADJUSTMENT
Figure 6. Recommended Circuit Schematic
The digital ground pin returns ground current from the digital
logic portions of the AD1865 circuitry. This pin should be connected to the digital common pin in the system. Other digital
logic chips should also be referred to that point. The analog and
digital grounds should be connected together at one point in the
system, preferably at the power supply.
Use of optional adjust circuitry allows residual distortion error
to be eliminated. This distortion is especially important when
low amplitude signals are being reproduced. The MSB adjust
circuitry is shown in Figure 7. The trim potentiometer should
be adjusted to produce the lowest distortion using an input signal with a –60 dB amplitude.
AD1865
POWER SUPPLIES AND DECOUPLING
200kΩ
The AD1865 has three power supply input pins. ± VS provides
the supply voltages which operate the analog portions of the
DAC including the voltage references, output amplifiers and
control amplifiers. The ± VS supplies are designed to operate
from ± 5 V supplies. Each supply should be decoupled to analog
common using a 0.1 µF capacitor in parallel with a 10 µF
capacitor. Good engineering practice suggests that the bypass
capacitors be placed as close as possible to the package pins.
This minimizes the parasitic inductive effects of printed circuit
board traces.
100kΩ
470kΩ
1 –VS
+VS 24
2 TRIM
TRIM 23
3 MSB
MSB 22
4 IOUT
IOUT 21
470kΩ
100kΩ
200kΩ
5 AGND AGND 20
6 SJ
7 RF
8 VOUT
RF 18
VOUT 17
9 +VL
NC 16
10 DR
DL 15
11 LR
12 CLK
The +VL supply operates the digital portions of the chip including the input shift registers and the input latching circuitry.
This supply should be bypassed to digital common using a
0.1 µF capacitor in parallel with a 10 µF capacitor. +VL operates with a +5 V supply. In order to assure proper operation of
the AD1865, –VS must be the most negative power supply voltage at all times.
SJ 19
LL 14
DGND 13
NC = NO CONNECT
Figure 7. Optional THD+N Adjust Circuitry
Though separate positive power supply pins are provided for
the analog and digital portions of the AD1865, it is also possible
to use the AD1865 in systems featuring a single +5 V power
supply. In this case, both the +VS and +VL input pins should be
connected to the single +5 V power supply. This feature allows
reduction of the cost and complexity of the system power
supply.
–6–
REV. 0
Digital Circuit Considerations–AD1865
CURRENT OUTPUT MODE
VOLTAGE OUTPUT MODES
One or both channels of the AD1865 can be operated in current
output mode. IOUT can be used to directly drive an external
current-to-voltage (I-V) converter. The internal feedback resistor, RF, can still be used in the feedback path of the external I-V
converter, thus assuring that RF tracks the DAC over time and
temperature.
As shown on the block diagram, each channel of the AD1865 is
complete with an I-V converter and a feedback resistor. These
can be connected externally to provide direct voltage output
from one or both AD1865 channels. Figure 6 shows these connections. IOUT is connected to the Summing Junction, SJ. VOUT
is connected to the feedback resistor, RF. This implementation
results in the lowest possible component count and achieves the
specifications shown on the Specifications page while operating
at 16 × FS.
Of course, the AD1865 can also be used in voltage output mode
in order to utilize the onboard I-V converter.
CLK
DL
M
S
B
L
S
B
DR
M
S
B
L
S
B
LL
LR
Figure 8. AD1865 Control Signals
INPUT DATA
TIMING
Data is transmitted to the AD1865 in a bit stream composed of
18-bit words with a serial, twos complement, MSB first format.
Data Left (DL) and Data Right (DR) are the serial inputs for
the left and right DACs, respectively. Similarly, Latch Left (LL)
and Latch Right (LR) update the left and right DACs. The falling edge of LL and LR cause the last 18 bits which were clocked
into the Serial Registers to be shifted into the DACs, thereby
updating the DAC outputs. Left and Right channels share the
Clock (CLK) signal. Data is clocked into the input registers on
the rising edge of CLK.
Figure 9 illustrates the specific timing requirements that must
be met in order for the data transfer to be accomplished properly. The input pins of the AD1865 are both TTL and 5 V
CMOS compatible.
The minimum clock rate of the AD1865 is at least 13.5 MHz.
This clock rate allows data transfer rates of 2×, 4×, 8× and
16 × FS (where FS equals 44.1 kHz).
Figure 8 illustrates the general signal requirements for data
transfer for the AD1865.
>74.1ns
>30ns
>30ns
CLK
>40ns
>40ns
>15ns
>40ns
LL/LR
>15ns
>15ns
DL/DR
>30ns
MSB
1st BIT
INTERNAL DAC INPUT REGISTER
UPDATED WITH 18 MOST RECENT BITS
2nd BIT
LSB
18th BIT
NEXT
WORD
BITS CLOCKED
TO SHIFT REGISTER
Figure 9. AD1865 Timing Diagram
REV. 0
–7–
AD1865
–5V ANALOG SUPPLY
SM5813AP/
APT
+5V ANALOG SUPPLY
AD1865
28
1
–VS
+VS 24
2
27
2
TRIM
TRIM 23
3
BCKO 26
3
MSB
MSB 22
4
WCKO 25
4
IOUT
IOUT 21
5
DOL 24
5
AGND
6
DOR
23
6
SJ
SJ 19
7
VDD
22
7
RF
VSS2
21
8
VOUT
1
8
9
VSS1
DG
10
11
12
OW18
13
OW20
14
C1
AGND 20
1
+VS 8
RF 18
2
7
VOUT 17
3
6
NC 16
4
20
9
19
10 DR
DL 15
18
11 LR
LL 14
17
12 CLK
+VL
LEFT
CHANNEL
OUTPUT
C2
RIGHT
CHANNEL
OUTPUT
5
–VS
NE5532
DGND 13
16
15
+5V DIGITAL
SUPPLY
Figure 10. Complete 8 × FS 18-Bit CD Player
18-BIT CD PLAYER DESIGN
Figure 10 illustrates an 18-bit CD player design incorporating
an AD1865 D/A converter, an NE5532 dual op amp and the
SM5813 digital filter chip manufactured by NPC. In this design, the SM5813 filter transmits left and right digital data to
both channels of the AD1865. The left and right latch signals,
LL and LR, are both provided by the word clock signal
(WCKO) of the digital filter. The digital filter supplies data at
an 8 × FS oversample rate to each channel.
The digital data is converted to analog output voltages by the
output amplifiers on the AD1865. Note that no external components are required by the AD1865. Also, no deglitching circuitry is required.
An NE5532 dual op amp is used to provide the output antialias
filters required for adequate image rejection. One 2-pole filter
section is provided for each channel. An additional pole is created from the combination of the internal feedback resistors
(RF) and the external capacitors C1 and C2. For example, the
nominal 3 kΩ RF with a 360 pF capacitor for C1 and C2 will
place a pole at approximately 147 kHz, effectively eliminating
all high frequency noise components.
Low distortion, superior channel separation, low power consumption and a low parts count are all realized by this simple
design.
–8–
REV. 0
AD1865
In this application, the advantages of choosing the AD1865 are
clear. Its flexible digital interface allows the clock and data to be
shared among all DACs. This reduces PC board area requirements and also simplifies the actual layout of the board. The low
power requirements of the AD1865 (approximately 225 mW) is
an advantage in a multiple DAC system where any power advantage is multiplied by the number of DACs used. The AD1865
requires no external components, simplifying the design, reducing the total number of components required and enhancing
reliability.
MULTICHANNEL DIGITAL KEYBOARD DESIGN
Figure 11 illustrates how to cascade AD1865’s to add multiple
voices to an electronic musical instrument. In this example, the
data and clock signals are shared between all six DACs. As the
data representing an output for a specific voice is loaded, the appropriate DAC is updated. For example, after the 18-bits representing the next output value for Voice 4 is clocked out on the
data line, then “Voice 4 Load” is pulled low. This produces a
new output for Voice 4. Furthermore, all voices can be returned
to the same output by pulling all six load signals low.
VOICE 2
OUTPUT
VOICE 1
OUTPUT
VOICE 3
OUTPUT
VOICE 4
OUTPUT
VOICE 5
OUTPUT
VOICE 6
OUTPUT
+5V ANALOG
SUPPLY
–5V ANALOG
SUPPLY
AD1865
AD1865
1 –V S
2
ANALOG
COMMON
TRIM
24
1
–V S
TRIM
23
2
TRIM
AD1865
+V S
24
1
–VS
TRIM
23
2
TRIM
3
MSB
MSB 22
21
4
IOUT
IOUT
AGND 20
5
AGND
SJ 19
6
SJ
RF
3 MSB
MSB
22
3
MSB
MSB 22
4
IOUT
IOUT
21
4
IOUT
IOUT
5
AGND
AGND
20
5
AGND
SJ
19
6
SJ
RF
RF
6 SJ
7
8
RF
VOUT
9 +VL
VOICE 1 LOAD
+VS
+V S
24
TRIM
23
21
AGND 20
SJ 19
RF 18
7
VOUT 17
8
VOUT
+VL
NC 16
9
+VL
NC 16
18
7
VOUT
17
8
VOUT
NC
16
9
RF
18
VOUT 17
10 DR
DL
15
10
DR
DL 15
10
DR
DL 15
11 LR
LL
14
11 LR
LL 14
11
LR
LL 14
DGND 13
12
CLK
12 CLK
DGND 13
12
CLK
DGND
VOICE 6 LOAD
13
VOICE 2 LOAD
VOICE 5 LOAD
VOICE 3 LOAD
VOICE 4 LOAD
DATA
CLOCK
DIGITAL COMMON
+5V DIGITAL SUPPLY
Figure 11. Cascaded AD1865s in a Multichannel Keyboard Instrument
REV. 0
–9–
AD1865
ADDITIONAL APPLICATIONS
–5V ANALOG
SUPPLY
Figures 12 through 14 show connection diagrams for the AD1865
and standard digital filter chips from Yamaha, NPC and Sony.
Each figure is an example of cophase operation operating at 8 ×
FS for each channel. The 2-pole Rauch low-pass filters shown in
Figure 10 can be used with all of the applications shown in this
data sheet.
+5V ANALOG
SUPPLY
AD1865
1
+VS 24
–V
S
2
TRIM
3 MSB
2
3
4
V
DD2
GND
TEST 40
2
TEST
TEST 39
3
TEST 38
4
TEST 37
5
36
1 –V
S
16.9344
MHz
CXD1244S
35
2
TRIM
TRIM 23
3
MSB
MSB 22
8
BCKO 33
4
IOUT
9
XIN
DATAL 32
10 V
DD
11 VDD
GND 31
6 SJ
SJ 19
GND 30
7 R
RF 18
DATAR 29
12
13
28
9
+VL
14
LE/WS 27
10 DR
15
OUT 16/18 26
11 LR
16
25
17 LFS
12 CLK
NC 16
DL 15
OUT
L
6
WCO 11
11 LR
7
DRO 10
12 CLK
DLO
LL 14
DGND 13
9
LPF
RIGHT
CHANNEL
OUTPUT
LPF
LEFT
CHANNEL
OUTPUT
IOUT 21
AGND 20
F
8 V
OUT
+V
24
34
5 AGND
V
9
Figure 12. AD1865 with Yamaha YM3434 Digital Filter
S
7
6
8
13
SS
LEFT
CHANNEL
OUTPUT
VOUT 17
ST 14
V
LPF
+5V DIGITAL SUPPLY
AD1865
+V
RF 18
10 DR
+5V ANALOG
SUPPLY
–5V ANALOG
SUPPLY
SJ 19
BCO 12
DD1
1
SJ
5
8 V
OUT
AGND 20
7 R
F
6
SHR 16
16/18 15
21
I
5 AGND
YM3434
SHL
RIGHT
CHANNEL
OUTPUT
MSB 22
4 IOUT
1
LPF
23
TRIM
V
OUT
17
NC 16
DL 15
LL 14
DGND 13
DPOL 24
18 SONY/12S
23
19
TEST 22
20 TEST
TEST 21
–5V ANALOG
SUPPLY
+5V ANALOG
SUPPLY
AD1865
1 –V S
+5V DIGITAL SUPPLY
2 TRIM
Figure 13. AD1865 with Sony CXD1244s Digital Filter
3 MSB
SM5818
4
IOUT
5
AGND
1
VDD 16
6 SJ
2
BCKO 15
7
RF
8
VOUT
+VS 24
TRIM
23
RIGHT
CHANNEL
OUTPUT
LPF
LEFT
CHANNEL
OUTPUT
MSB 22
IOUT 21
AGND 20
SJ 19
RF
18
VOUT
17
3
WDCO 14
4
OMOD2 13
9 +VL
NC 16
5
DOR 12
10 DR
DL 15
6
DOL 11
11 LR
7
10
12 CLK
LPF
LL 14
DGND 13
8 VSS OMOD1 9
+5V DIGITAL SUPPLY
Figure 14. AD1865 with NPC SM5818AP Digital Filter
–10–
REV. 0
AD1865
OTHER DIGITAL AUDIO COMPONENTS AVAILABLE
FROM ANALOG DEVICES
–VS
1
DGND
2
+VL
3
NC
4
CLK
5
LE
6
DATA
7
–VL
8
16-BIT
LATCH
16-BIT
DAC
AD1856 16-BIT AUDIO DAC
16 +VS
15 TRIM
SERIAL
INPUT
REGISTER
14 MSB ADJ
IOUT
REF
CONTROL
LOGIC
13 IOUT
Complete, No External Components Required
0.0025% THD
Low Cost
16-Pin DIP or SOIC Package
Standard Pinout
12 AGND
11 SJ
10 RF
AD1856
9
VOUT
NC = NO CONNECT
–VS
1
DGND
2
+VL
3
NC
4
CLK
5
LE
6
DATA
7
–VL
8
18-BIT
LATCH
18-BIT
DAC
AD1860 18-BIT AUDIO DAC
16 +VS
15 TRIM
SERIAL
INPUT
REGISTER
14 MSB ADJ
IOUT
REF
CONTROL
LOGIC
13 IOUT
Complete, No External Components Required
0.0025% THD+N
108 dB Signal-to-Noise Ratio
16-Pin DIP or SOIC Package
Standard Pinout
12 AGND
11 SJ
10 RF
AD1860
9
VOUT
NC = NO CONNECT
AD1862 20-BIT AUDIO DAC
REV. 0
–VS
1
–VS
2
15 NR2
TRIM
3
14 ADJ
+VL
4
13 NR1
CLK
5
LE
6
DATA
7
–VL
8
VL
1
LL
2
DL
3
CLK
4
DR
5
LR
6
DGND
7
VBIAS R
8
VOLTAGE
REFERENCE
16 +VS
119 dB Signal-to-Noise Ratio
0.0016% THD+N
102 dB D-Range Performance
± 1 dB Gain Linearity
16-Pin DIP Package
12 AGND
INPUT
&
DIGITAL
OFFSET
20-BIT
DAC
11 IOUT
10 RF
AD1862
18-BIT
DAC
9
AD1868
18-BIT
SERIAL
REGISTER
VREF
18-BIT
SERIAL
REGISTER
18-BIT
DAC
DGND
VREF
16
VBIAS L
15
VS
14
VOUT L
13
NRL
12
AGND
11
NRR
10
VOUT R
9
AD1868 +5 V SINGLE SUPPLY DUAL 18-BIT
AUDIO DAC
No External Components Required
0.004% THD+N
92 dB D-Range Performance
± 3 dB Gain Linearity
16-Pin DIP or SOIC Package
VS
–11–
AD1865
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
24
C1468–8–8/91
24-Pin Plastic DIP
(N-24A) Package
13
0.580 (14.73)
0.485 (12.32)
PIN 1
1
12
1.290 (32.70)
1.150 (29.30)
0.250 (6.35)
SEATING
PLANE
0.200 (5.05)
0.125 (3.18)
0.022 (0.558)
0.014 (0.356)
0.625 (15.87)
0.600 (15.24)
0.060 (1.52)
0.015 (0.38)
0.195 (4.95)
0.125 (3.18)
0.015 (0.381)
0.008 (0.204)
0.150
(3.81)
0.070 (1.77)
0.030 (0.77)
0.100 (2.54)
BSC
28-Pin SOIC
(R-28) Package
0.708 (18.02)
0.696 (17.67)
15
28
0.299 (7.6)
0.291 (7.39)
0.414 (10.52)
0.398 (10.10)
14
1
0.003 (0.76)
0.02 (0.51)
0.096 (2.44)
0.089 (2.26)
0.019 (0.49)
0.014 (0.35)
0.01 (0.254)
0.006 (0.15)
0.013 (0.32)
0.009 (0.23)
0.042 (0.32)
0.009 (0.23)
6°
0°
PRINTED IN U.S.A.
0.050 (1.27) BSC
–12–
REV. 0