Analog Devices AD1895 b Datasheet

192 kHz Stereo Asynchronous

a

FEATURES
Automatically Senses Sample Frequencies
No Programming Required
Attenuates Sample Clock Jitter

3.3 V to 5 V Input and 3.3 V Core Supply Voltages
Accepts 16-/18-/20-/24-Bit Data
Up to 192 kHz Sample Rate
Input/Output Sample Ratios from 7.75:1 to 1:8
Bypass Mode
Multiple AD1895 TDM Daisy-Chain Mode
128 dB Signal-to-Noise and Dynamic Range

(A-Weighted, 20 Hz to 20 kHz BW)
Up to –122 dB THD + N
Linear Phase FIR Filter
Hardware Controllable Soft Mute
Supports 256 ⴛ f

Clock
Flexible 3-Wire Serial Data Port with Left-Justified,

2

S, Right-Justified (16-, 18-, 20-, 24-Bit), and TDM

I

Serial Port Modes
Master/Slave Input and Output Modes
28-Lead SSOP Plastic Package

APPLICATIONS
Home Theater Systems, Automotive Audio Systems,

DVD, DVD-R, CD-R, Set-Top Boxes, Digital Audio

Effects Processors

PRODUCT OVERVIEW

The AD1895 is a 24-bit, high performance, single-chip, second
generation asynchronous sample rate converter. Based upon
Analog Devices’ experience with its first asynchronous sample
rate converter, the AD1890, the AD1895 offers improved perfor­mance and additional features. This improved performance
includes a THD + N range of –115 dB to –122 dB depending
on sample rate and input frequency, 128 dB (A-Weighted)
dynamic range, 192 kHz sampling frequencies for both input and
output sample rates, improved jitter rejection, and 1:8 upsampling
and 7.75:1 downsampling ratios. Additional features include
more serial formats, a bypass mode, and better interfacing to
digital signal processors.

The AD1895 has a 3-wire interface for the serial input and
output ports that supports left-justified, I
(16-, 18-, 20-, 24-bit) modes. Additionally, the serial output
port supports TDM Mode for daisy-chaining multiple AD1895s to

, 512 ⴛ fS, or 768 ⴛ fS Master Mode

S

2

S, and right-justified

Sample Rate Converter

AD1895

FUNCTIONAL BLOCK DIAGRAM

VDD_CORE

VDD_IO

RESET

FS

OUT

FS

FIR

FILTER

ROM

IN

AD1895

SERIAL

OUTPUT

, 512 × fS, and

S

(continued on page 15)

MUTE_IN

SDATA_I

SCLK_I

LRCLK_I

SMODE_IN_0
SMODE_IN_1
SMODE_IN_2

BYPASS

MUTE_OUT

MCLK_IN

MCLK_OUT

SERIAL

INPUT

CLOCK DIVIDER

MMODE_0

FIFO

DIGITAL

PLL

MMODE_2

MMODE_1

a digital signal processor. The serial output data is dithered down
to 20, 18, or 16 bits when 20-, 18-, or 16-bit output data is
selected. The AD1895 sample rate converts the data from the
serial input port to the sample rate of the serial output port. The
sample rate at the serial input port can be asynchronous with
respect to the output sample rate of the output serial port. The
master clock to the AD1895, MCLK, can be asynchronous to
both the serial input and output ports.

MCLK can either be generated off-chip or on-chip by the AD1895
master clock oscillator. Since MCLK can be asynchronous to the
input or output serial ports, a crystal can be used to generate
MCLK internally to reduce noise and EMI emissions on the
board. When MCLK is synchronous to either the output or input
serial port, the AD1895 can be configured in a master mode where
MCLK is divided down and used to generate the left/right
and bit clocks for the serial port that is synchronous to MCLK.
The AD1895 supports master modes of 256 × f
768 × f

Conceptually, the AD1895 interpolates the serial input data by
a rate of 2

for both input and output serial ports.

S

20

and samples the interpolated data stream by the
output sample rate. In practice, a 64-tap FIR filter with 2
polyphases, a FIFO, a digital servo loop that measures the time
difference between input and output samples within 5 ps, and a
digital circuit to track the sample rate ratio are used to perform
the interpolation and output sampling. Refer to the Theory of
Operation section. The digital servo loop and sample rate ratio
circuit automatically track the input and output sample rates.

*

SDATA_O
SCLK_O
LRCLK_O

TDM_IN

SMODE_OUT_0
SMODE_OUT_1

WLNGTH_OUT_0
WLNGTH_OUT_1

20

*Patents pending.

REV. B

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 that
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: [phone] www.analog.com
Fax: [phone] © Analog Devices, Inc., 2002

AD1895–SPECIFICATIONS

TEST CONDITIONS, UNLESS OTHERWISE NOTED.

Supply Voltages

VDD_CORE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 V

VDD_IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.0 V or 3.3 V

Ambient Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25°C

Input Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.0 MHz

Input Signal . . . . . . . . . . . . . . . . . . . . . . . . . . 1.000 kHz, 0 dBFS

Measurement Bandwidth . . . . . . . . . . . . . . . . . . 20 to f

Word Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Bits

Load Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 pF

Input Voltage High . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 V

Input Voltage Low . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.8 V

DIGITAL PERFORMANCE (VDD_CORE = 3.3 V  5%, VDD_IO = 5.0 V  10%)

Parameter Min Typ Max Unit

RESOLUTION 24 Bits

SAMPLE RATE @ MCLK_IN = 30 MHz 6 215 kHz

SAMPLE RATE (@ OTHER MASTER CLOCKS)

SAMPLE RATE RATIOS

Upsampling 1:8
Downsampling 7.75:1

DYNAMIC RANGE
(20 Hz to f

S_OUT

2

/2, 1 kHz, –60 dBFS Input) A-Weighted

44.1 kHz: 48 kHz 128 dB
48 kHz: 44.1 kHz 128 dB
48 kHz: 96 kHz 128 dB

44.1 kHz: 192 kHz 128 dB
96 kHz: 48 kHz 127 dB
192 kHz: 32 kHz 127 dB

(20 Hz to f

/2, 1 kHz, –60 dBFS Input) No Filter

S_OUT

44.1 kHz: 48 kHz 125 dB
48 kHz: 44.1 kHz 125 dB
48 kHz: 96 kHz 125 dB

44.1 kHz: 192 kHz 125 dB
96 kHz: 48 kHz 124 dB
192 kHz: 32 kHz 124 dB

TOTAL HARMONIC DISTORTION + NOISE
(20 Hz to f

Worst-Case (48 kHz: 96 kHz)

/2, 1 kHz, 0 dBFS Input) No Filter

S_OUT

3

2

44.1 kHz: 48 kHz –120 dB
48 kHz: 44.1 kHz –119 dB
48 kHz: 96 kHz –118 dB

44.1 kHz: 192 kHz –120 dB
96 kHz: 48 kHz –122 dB
192 kHz: 32 kHz –122 dB

INTERCHANNEL GAIN MISMATCH 0.0 dB

INTERCHANNEL PHASE DEVIATION 0.0 Degrees

MUTE ATTENUATION (24 BITS WORD WIDTH)(A-WEIGHT) –127 dB

NOTES

1

Lower sampling rates than those given by this formula are possible, but the jitter rejection will decrease.

2

Refer to the Typical Performance Characteristics section for DNR and THD + N numbers over a wide range of input and output sample rates.

3

For any other ratio, minimum THD + N will be better than –115 dB. Please refer to detailed performance plots.

Specifications subject to change without notice.

S_OUT

1

/2 Hz

MCLK_IN/5000 ≤ f

< MCLK_IN/138 kHz

S_MAX

–115 dB

–2–

REV. B

DIGITAL TIMING (–40C < TA < +105C, VDD_CORE = 3.3 V  5%, VDD_IO = 5.0 V  10%)

Parameter

t

MCLKI

f

MCLK

t

MPWH

t

MPWL

1

Min Max Unit

MCLK_IN Period 33.3 ns
MCLK_IN Frequency 30.0
MCLK_IN Pulsewidth High 9 ns
MCLK_IN Pulsewidth Low 12 ns

INPUT SERIAL PORT TIMING
t

LRIS

t

SIH

t

SIL

t

DIS

t

DIH

LRCLK_I Setup to SCLK_I 8 ns
SCLK_I Pulsewidth High 8 ns
SCLK_I Pulsewidth Low 8 ns
SDATA_I Setup to SCLK_I Rising Edge 8 ns
SDATA_I Hold from SCLK_I Rising Edge 3 ns

OUTPUT SERIAL PORT TIMING
t

TDMS

t

TDMH

t

DOPD

t

DOH

t

LROS

t

LROH

t

SOH

t

SOL

t

RSTL

NOTES

1

Refer to Timing Diagrams section.

2

The maximum possible sample rate is: FS

3

f

of up to 34 MHz is possible under the following conditions: 0°C < TA < 70°C, 45/55 or better MCLK_IN duty cycle.

MCLK

Specifications subject to change without notice.

TDM_IN Setup to SCLK_O Falling Edge 3 ns
TDM_IN Hold from SCLK_O Falling Edge 3 ns
SDATA_O Propagation Delay from SCLK_O, LRCLK_O 20 ns
SDATA_O Hold from SCLK_O 3 ns
LRCLK_O Setup to SCLK_O (TDM Mode Only) 5 ns
LRCLK_O Hold from SCLK_O (TDM Mode Only) 3 ns
SCLK_O Pulsewidth High 10 ns
SCLK_O Pulsewidth Low 5 ns
RESET Pulsewidth Low 200 ns

= f

MCLK

/138.

MAX

2, 3

AD1895

MHz

TIMING DIAGRAMS

LRCLK_I

I

SCLK

SDATA

I

O

LRCLK

SCLK

O

t

DOPD

SDATA

O

O

LRCLK

O

SCLK

IN

TDM

t

t

LROS

t

TDMS

LRIS

t

DIS

t

LROH

MCLK IN

t

SIH

RESET

t

t

MPWH

RSTL

RESET

t

MPWL

Timing

t

SIL

Figure 2.

t

DIH

t

SOH

t

SOL

t

DOH

Figure 3. MCLK_IN Timing

t

TDMH

Figure 1. Input and Output Serial Port Timing (SCLK_I/O,
LRCLK_I/O, SDATA_I/O, TDM_IN)

REV. B

–3–

AD1895

DIGITAL FILTERS (VDD_CORE = 3.3 V  5%, VDD_IO = 5.0 V  10%)

–SPECIFICATIONS

Parameter Min Typ Max Unit

Pass Band 0.4535 f

S_OUT

Hz

Pass-Band Ripple ±0.016 dB
Transition Band 0.4535 f
Stop Band 0.5465 f

S_OUT

S_OUT

0.5465 f

S_OUT

Hz

Hz
Stop-Band Attenuation –125 dB
Group Delay Refer to the Group Delay Equations Section

Specifications subject to change without notice.

DIGITAL I/O CHARACTERISTICS (VDD_CORE = 3.3 V  5%, VDD_IO = 5.0 V  10%)

Parameter Min Typ Max Unit

Input Voltage High (V
Input Voltage Low (V
Input Leakage (I
Input Leakage (I

IH

IL

) 2.4 V

IH

) 0.8 V

IL

@ VIH = 5 V) +2 µA

@ VIL = 0 V) –2 µA
Input Capacitance 5 10 pF
Output Voltage High (VOH @ IOH = –4 mA)
Output Voltage Low (VOL @ IOL = +4 mA)
Output Source Current High (I

)–4mA

OH

VDD_CORE – 0.5 VDD_CORE – 0.4 V

0.2 0.5 V

Output Sink Current Low (IOL)+4mA

Specifications subject to change without notice.

POWER SUPPLIES

Parameter Min Typ Max Unit

SUPPLY VOLTAGE

VDD_CORE 3.135 3.3 3.465 V
VDD_IO* VDD_CORE 3.3/5.0 5.5 V

ACTIVE SUPPLY CURRENT

I_CORE_ACTIVE

48 kHz: 48 kHz 20 mA
96 kHz: 96 kHz 26 mA
192 kHz: 192 kHz 43 mA

I_IO_ACTIVE 2 mA

POWER-DOWN SUPPLY CURRENT: (ALL CLOCKS STOPPED)

I_CORE_PWRDN 0.5 mA
I_IO_PWRDN 10 µA

*For 3.3 V tolerant inputs, VDD_IO supply should be set to 3.3 V; however, VDD_CORE supply voltage should not exceed VDD_IO.

Specifications subject to change without notice.

–4–

REV. B

AD1895

POWER SUPPLIES (VDD_CORE = 3.3 V  5%, VDD_IO = 5.0 V  10%)

Parameter Min Typ Max Unit

TOTAL ACTIVE POWER DISSIPATION

48 kHz: 48 kHz 65 mW
96 kHz: 96 kHz 85 mW
192 kHz: 192 kHz 132 mW

TOTAL POWER-DOWN DISSIPATION (RESET LOW)

Specifications subject to change without notice.

TEMPERATURE RANGE

Parameter Min Typ Max Unit

Specifications Guaranteed 25 °C
Functionality Guaranteed –40 +105 °C
Storage –55 +150 °C
Thermal Resistance, θJA (Junction to Ambient)

Specifications subject to change without notice.

ABSOLUTE MAXIMUM RATINGS*

Parameter Min Max Unit

POWER SUPPLIES

VDD_CORE –0.3 +3.6 V
VDD_IO –0.3 +6.0 V

DIGITAL INPUTS

Input Current ±10 mA
Input Voltage DGND – 0.3 VDD_IO + 0.3 V

AMBIENT TEMPERATURE (OPERATING) –40 +105 °C

*Stresses greater than those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; 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.

2mW

109 °C/W

ORDERING GUIDE

Model Temperature Range Package Description Package Option

AD1895AYRS –40°C to +105°C 28-Lead SSOP RS-28
AD1895AYRSRL –40°C to +105°C 28-Lead SSOP RS-28 on 13" Reel

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 AD1895 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.

WARNING!

ESD SENSITIVE DEVICE

REV. B

–5–

AD1895

PIN FUNCTION DESCRIPTIONS

Pin No. IN/OUT (I/O) Mnemonic Description

1 IN NC No Connect
2 IN MCLK_IN Master Clock or Crystal Input
3 OUT MCLK_OUT Master Clock Output or Crystal Output
4 IN SDATA_I Input Serial Data (at Input Sample Rate)
5 IN/OUT SCLK_I Master/Slave Input Serial Bit Clock
6 IN/OUT LRCLK_I Master/Slave Input Left/Right Clock
7 IN VDD_IO 3.3 V/5 V Input/Output Digital Supply Pin
8 IN DGND Digital Ground Pin
9 IN BYPASS ASRC Bypass Mode, Active High
10 IN SMODE_IN_0 Input Port Serial Interface Mode Select Pin 0
11 IN SMODE_IN_1 Input Port Serial Interface Mode Select Pin 1
12 IN SMODE_IN_2 Input Port Serial Interface Mode Select Pin 2
13 IN RESET Reset Pin, Active Low
14 IN MUTE_IN Mute Input Pin—Active High Normally Connected to MUTE_OUT
15 OUT MUTE_OUT Output Mute Control—Active High
16 IN WLNGTH_OUT_1 Hardware Selectable Output Wordlength—Select Pin 1
17 IN WLNGTH_OUT_0 Hardware Selectable Output Wordlength—Select Pin 0
18 IN SMODE_OUT_1 Output Port Serial Interface Mode Select Pin 1
19 IN SMODE_OUT_0 Output Port Serial Interface Mode Select Pin 0
20 IN TDM_IN Serial Data Input* (Only for Daisy-Chain Mode). Ground when not used.
21 IN DGND Digital Ground Pin
22 IN VDD_CORE 3.3 V Digital Supply Pin
23 OUT SDATA_O Output Serial Data (at Output Sample Rate)
24 IN/OUT LRCLK_O Master/Slave Output Left/Right Clock
25 IN/OUT SCLK_O Master/Slave Output Serial Bit Clock
26 IN MMODE_0 Master/Slave Clock Ratio Mode Select Pin 0
27 IN MMODE_1 Master/Slave Clock Ratio Mode Select Pin 1
28 IN MMODE_2 Master/Slave Clock Ratio Mode Select Pin 2

*Also used to input matched-phase mode data.

NC

MCLK_IN

MCLK_OUT

SDATA_I

SCLK_I

LRCLK_I

VDD_IO

DGND

BYPASS

SMODE_IN_0

SMODE_IN_1

SMODE_IN_2

RESET

MUTE_IN

PIN CONFIGURATION

1

2

3

4

AD1895

TOP VIEW

5

(NOT TO SCALE

6

7

8

9

10

11

12

13

14

NC = NO CONNECT

28

MMODE_2

27

MMODE_1

26

MMODE_0

25

SCLK_O

24

LRCLK_O

)

23

SDATA_O

22

VDD_CORE

21

DGND

TDM_IN

20

19

SMODE_OUT_0

18

SMODE_OUT_1

17

WLNGTH_OUT_0

16

WLNGTH_OUT_1

15

MUTE_OUT

–6–

REV. B

Typical Performance Characteristics–A

D1895

0

–20

–40

–60

–80

–100

dBFS

–120

–140

–160

–180

–200

0

2.5 5.0 7.5 10.0 12.5
FREQUENCY – kHz

15.0

17.5 20.0 22.5

TPC 1. Wideband FFT Plot (16 k Points) 0 dBFS 1 kHz
Tone, 48 kHz: 48 kHz (Asynchronous)

0

–20

–40

–60

–80

–100

dBFS

–120

–140

–160

–180

–200

0

2.5

5.0 7.5 10.0 12.5
FREQUENCY – kHz

15.0

17.5 20.0 22.5

0

–20

–40

–60

–80

–100

dBFS

–120

–140

–160

–180

–200

0102030405060708090

FREQUENCY – kHz

TPC 4. Wideband FFT Plot (16 k Points) 44.1 kHz: 192 kHz,
0 dBFS 1 kHz Tone

0

–20

–40

–60

–80

–100

dBFS

–120

–140

–160

–180

–200

0 2.5

5.0 7.5 10.0 12.5 15.0 17.5 20.0
FREQUENCY – kHz

TPC 2. Wideband FFT Plot (16 k Points) 0 dBFS 1 kHz
Tone, 44.1 kHz: 48 kHz (Asynchronous)

0

–20

–40

–60

–80

–100

dBFS

–120

–140

–160

–180

–200

05

10 15 20 25 30 35 40 45

FREQUENCY – kHz

TPC 3. Wideband FFT Plot (16 k Points) 48 kHz: 96 kHz,
0 dBFS 1 kHz Tone

TPC 5. Wideband FFT Plot (16 k Points) 48 kHz: 44.1 kHz,
0 dBFS 1 kHz Tone

0

–20

–40

–60

–80

–100

dBFS

–120

–140

–160

–180

–200

0

2.5 5.0 7.5 10.0 12.5

FREQUENCY – kHz

15.0

17.5 20.0 22.5

TPC 6. Wideband FFT Plot (16 k Points) 96 kHz: 48 kHz,
0 dBFS 1 kHz Tone

REV. B

–7–

AD1895

0

–20

–40

–60

–80

–100

dBFS

–120

–140

–160

–180

–200

0

2.5 5.0 7.5 10.0 12.5
FREQUENCY – kHz

15.0

17.5 20.0 22.5

TPC 7. Wideband FFT Plot (16 k Points) 192 kHz: 48 kHz,
0 dBFS 1 kHz Tone

–50

–60

–70

–80

–90

–100
–110

–120

–130

dBFS

–140

–150

–160

–170

–180

–190

–200

0

2.5 5.0 7.5 10.0 12.5
FREQUENCY – kHz

15.0

17.5 20.0 22.5

TPC 8. Wideband FFT Plot (16 k Points) 48 kHz: 48 kHz
–60 dBFS 1 kHz Tone (Asynchronous)

–50

–60

–70

–80

–90

–100
–110

–120

–130

dBFS

–140

–150

–160

–170

–180

–190

–200

051015 20 25 30 35 40 45

FREQUENCY – kHz

TPC 10. Wideband FFT Plot (16 k Points) 48 kHz: 96 kHz,
–60 dBFS 1 kHz Tone

–50

–60

–70

–80

–90

–100

–110

–120

–130

dBFS

–140

–150

–160

–170

–180

–190

–200

010203040

50 60 70 80 90

FREQUENCY – kHz

TPC 11. Wideband FFT Plot (16 k Points) 44.1 kHz: 192 kHz,

–60 dBFS 1 kHz Tone

–50

–60

–70

–80

–90

–100
–110

–120

–130

dBFS

–140

–150

–160

–170

–180

–190

–200

0

2.5 5.0 7.5 10.0 12.5
FREQUENCY – kHz

15.0

17.5 20.0 22.5

TPC 9. Wideband FFT Plot (16 k Points) 44.1 kHz: 48 kHz,
–60 dBFS 1 kHz Tone

–50

–60

–70

–80

–90

–100

–110

–120

–130

dBFS

–140

–150

–160

–170

–180

–190

–200

0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0

FREQUENCY – kHz

TPC 12. Wideband FFT Plot (16 k Points) 48 kHz: 44.1 kHz,

–60 dBFS 1 kHz Tone

–8–

REV. B