Analog Devices AD1876JN Datasheet

AGND

V

REF

COMP

A CHIP

V

IN

8

10

11

9

LEVEL TRANSLATORS

LOGIC TIMING

16-BIT

DAC

INPUT

BUFFERS

CAL
DAC

CLK

SAMPLE

D CLK

OUT

D CHIP

D

OUT

3

14

AD1876

2

16

1 RAM

ALU

SAR

AGND

SENSE

CAL

15 BUSY

MICROCODED
CONTROLLER

16-Bit 100 kSPS

a

FEATURES
Autocalibrating

0.002% THD
90 dB S/(N+D)
1 MHz Full Power Bandwidth
On-Chip Sample & Hold Function
23 Oversampling for Audio Applications
16-Pin DIP Package
Serial Twos Complement Output Format
Low Input Capacitance–typ 50 pF
AGND Sense for Improved Noise Immunity

PRODUCT DESCRIPTION

The AD1876 is a 16-bit serial output sampling A/D converter
which uses a switched capacitor/charge redistribution architecture
to achieve a 100 kSPS conversion rate (10 µs total conversion
time). Overall performance is optimized by digitally correcting
internal nonlinearities through on-chip autocalibration.

The circuitry of the AD1876 is partitioned onto two monolithic
chips, a digital control chip fabricated with Analog Devices’
DSP CMOS process and an analog ADC chip fabricated with
the BiMOS II process. Both chips are contained in a single
package.

The serial output interface requires an external clock and
sample command signal. The output data rate may be as high
as 2.08 MHz, and is controlled by the external clock. The twos
complement format of the output data is MSB first and is di­rectly compatible with the NPC SM5805 digital decimation fil­ter used in consumer audio products. The AD1876 is also
compatible with a variety of DSP processors.

The AD1876 is packaged in a space saving 16-pin plastic DIP
and operates from +5 V and ±12 V supplies; typical power con­sumption is 235 mW. The digital supply (V
the linear supplies (V
Separate analog and digital grounds are also provided.

and VCC) for reduced digital crosstalk.

EE

) is isolated from

DD

Sampling ADC

AD1876

FUNCTIONAL BLOCK DIAGRAM

REV. A

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: [phone] Fax: [phone]

AD1876–SPECIFICA TIONS

(T

to T

MIN

, VCC = +12 V 6 5%, VEE = –12 V 6 5%, VDD = +5 V 6 10%)

MAX

1

AD1876J

Parameter Min Typ Max Units

TEMPERATURE RANGE 0 70 °C
TOTAL HARMONIC DISTORTION (THD)

2

–0.05 dB Input –95 –88 dB

0.002 0.004 %

–20 dB Input –78 dB

0.01 %

–60 dB Input –40 dB

1.0 %
D-RANGE, –60 dB, A-WEIGHTED 92 dB
SIGNAL-TO-NOISE AND DISTORTION (S/(N+D)) RATIO

3

–0.05 dB Input, A-Weighted 92 dB
–0.05 dB Input, 48 kHz Bandwidth 83 90 dB
–20 dB Input, A-Weighted 73 dB
–20 dB Input, 48 kHz Bandwidth 70 dB
–60 dB Input, A-Weighted 34 dB

–60 dB Input, 48 kHz Bandwidth 31 dB
PEAK SPURIOUS OR PEAK HARMONIC COMPONENT –99 –89 dB
INTERMODULATION DISTORTION (IMD)

4

2nd Order Products –102 dB

3rd Order Products –98 dB
FULL POWER BANDWIDTH 1 MHz
VOLTAGE REFERENCE INPUT RANGE5 (V
ANALOG INPUT

6

Input Range (VIN) ±V

)3510.0 V

REF

REF

V
Input Impedance *
Input Capacitance During Sample 50* pF
Aperture Delay 6ns
Aperture Jitter 100 ps

POWER SUPPLIES

Operating Current

I

CC

I

EE

I

DD

912mA
912mA
312mA

Power Consumption 235 350 mW

NOTES

1

V

= 5.00 V; conversion rate = 96 kSPS; fIN = 1.06 kHz; VIN = –0.05 dB unless otherwise noted. All measurements referred to a 0 dB (10 V p-p) input signal.

REF

Values are post calibration.

2

Includes first 19 harmonics.

3

Minimum value of S/(N+D) corresponds to 5.0 V reference; typical values of S/(N+D) correspond to 10.0 V reference.

4

fa = 1008 Hz; fb = 1055 Hz. See Definition of Specifications section and Figure 14.

5

See Applications section for recommended voltage reference circuit and Figure 11 for performance with other reference voltage values.

6

See Applications section for recommended input buffer circuit.

*For explanation of input characteristics, see “Analog Input” section.
Specifications subject to change without notice.
Specifications shown in boldface are tested on all devices at final electrical test at worst case temperature. Results from those tests are used to calculate outgoing

quality levels. All min and max specifications are guaranteed, although only those shown in boldface are tested.

ORDERING GUIDE

Temperature THD Package Package

Model Range dB Description Option*

AD1876JN 0°C to +70°C –95 Plastic 16-Pin DIP N-16

*N = Narrow Plastic DIP.

–2–

REV. A

AD1876

WARNING!

ESD SENSITIVE DEVICE

(T

to T

DIGITAL SPECIFICATIONS

MIN

Parameter Test Conditions Min Typ Max Units

LOGIC INPUTS

V

IH

V

IL

I

IH

I

IL

C

IN

High Level Input Voltage 2.4 V
Low Level Input Voltage –0.3 0.8 V
High Level Input Current VIH = V
Low Level Input Current VIL = 0 V –10 +10 µA
Input Capacitance 10 pF

LOGIC OUTPUTS

V

OH

V

OL

Specifications subject to change without notice.
Specifications shown in boldface are tested on all devices at final electrical test at worst case temperature. Results from those tests are used to calculate outgoing qual-

ity levels. All min and max specifications are guaranteed, although only those shown in boldface are tested.

High Level Output Voltage IOH = 0.1 mA VDD – 1 V V
Low Level Output Voltage IOL = 1.6 mA 0.4 V

ABSOLUTE MAXIMUM RATINGS*

VCC to VEE . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +26.4 V

V

to DGND . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V

DD

V

to AGND . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +18 V

CC

V

to AGND . . . . . . . . . . . . . . . . . . . . . . . . –18 V to +0.3 V

EE

AGND to DGND . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.3 V

Digital Inputs to DGND . . . . . . . . . . . . . . . . . . . 0 V to 5.5 V

Analog Inputs, V

to AGND . . . . . . . . . . . (VCC + 0.3 V) to

REF

, VCC = +12 V 6 5%, VEE = –12 V 6 5%, VDD = +5 V 6 10%)

MAX

DD

I

= 0.5 mA 2.4 V

OH

–10 +10 µA

Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C, 10 sec

Storage Temperature . . . . . . . . . . . . . . . . . . –60°C to +100°C

*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

(V

– 0.3 V)

EE

reliability.

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 AD1876 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.

TIMING SPECIFICATIONS

Parameter Symbol Min Typ Max Units

Sampling Rate
Sampling Period
Acquisition Time (Included in t
Calibration Time t
CLK Period t
CAL to BUSY Delay t
CLK to BUSY Delay t
CLK to D
CLK HIGH t
CLK LOW t
D

OUT

SAMPLE LOW to 1st CLK Delay t
CAL HIGH Time t
CLK to D
SAMPLE LOW t

NOTES

1

See Figure 1 and Figure 2 and the Conversion Control and Autocalibration sections for detailed explanations of the above timing.

2

Depends upon external clock frequency; includes acquisition time and conversion time. The minimum sampling rate/maximum sampling period is specified to

account for droop of the internal sample/hold. Operation at slower rates than specified may degrade performance.

REV. A

1

(T

to T

MIN

MAX

2

2

)t

S

Hold Time t

OUT

CLK LOW t

CLK t

OUT

, VCC = +12 V 6 5%, VEE = –12 V 6 5%, VDD = +5 V 6 10%, V

fS = 1/t

S

tS = l/f

S
A
CT
C
CALB
CB
CD
CH
CL
DCL
SC
CALH
CDH
SL

1 100 kSPS
10 1000 µs
2 µs

480 ns
0ns
50 120 175 ns
10 ns
160 ns
50 ns
30 80 200 ns
50 ns
4t
150 200 275 ns
50 ns

–3–

= 5.00 V)

REF

5000 t

C

C

AD1876

CAL

BUSY

CLK

SAMPLE

BUSY

D

OUT

CLK

D

OUT

CLK

t

CALB

t

A

PREVIOUS LSB

t

CT

t

C

tCHt

CL

Figure 1. AD1876 Calibration Timing

tS (=1/fs)

t

SL

t

C

t

tCHt

1

t

CDH

CB

t

CD

X

t

SC

CL

2

MSB

t

3

DCL

t

CB

t

A

t

CB

16

17

LSB

Figure 2. Recommended AD1876 Conversion Timing

Definition of Specifications

NYQUIST FREQUENCY

An implication of the Nyquist sampling theorem, the “Nyquist
Frequency” of a converter is that input frequency which is one­half the sampling frequency of the converter.

TOTAL HARMONIC DISTORTION

Total harmonic distortion (THD) is measured as the ratio of the
rms sum of the first nineteen harmonic components to the rms
value of a 1 kHz full-scale sine wave input signal and is ex­pressed in percent (%) or decibels (dB). For input signals or
harmonics that are above the Nyquist frequency, the aliased
component is used.

SIGNAL-TO-NOISE PLUS DISTORTION RATIO

Signal-to-noise plus distortion (S/N+D) is defined to be the ra­tio of the rms value of the measured input signal to the rms sum
of all other spectral components below the Nyquist frequency,
including harmonics but excluding dc.

D-RANGE DISTORTION

D-range distortion is the ratio of the distortion plus noise to the
signal at a signal amplitude of –60 dB. In this case, an A-weight
filter is used. The value specified for D-range performance is the
ratio measured plus 60 dB.

BANDWIDTH

The full power bandwidth is that input frequency at which the
amplitude of the reconstructed fundamental is reduced by 3 dB
for a full-scale input.

INTERMODULATION DISTORTION (IMD)

With inputs consisting of sine waves at two frequencies, fa and
f

, any device with nonlinearities will create distortion products,

b

of order (m+n), at sum and difference frequencies of mf

± nfb,

a

where m, n = 0, l, 2, 3. . . . Intermodulation terms are those for

which m or n is not equal to zero. For example, the second or­der terms are (f
(2f

+ fb), (2fa – fb), (fa + 2fb) and (fa – 2fb). The IMD products

a

+ fb) and (fa – fb), and the third order terms are

a

are expressed as the decibel ratio of the rms sum of the mea­sured input signals to the rms sum of the distortion terms. The
two signals applied to the converter are of equal amplitude, and
the peak value of their sum is –0.05 dB from full scale. The
IMD products are normalized to a 0 dB input signal.

APERTURE DELAY

Aperture delay is the time required after SAMPLE is taken
LOW for the internal sample-hold of the AD1876 to open, thus
holding the value of V

.

IN

APERTURE JITTER

Aperture jitter is the variation in the aperture delay from sample
to sample.

–4–

REV. A