Burr Brown Corporation ADS7808P, ADS7808UB-1K, ADS7808UB, ADS7808U-1K, ADS7808U Datasheet

1

®

ADS7808

12-Bit 10µs Serial CMOS Sampling
ANALOG-to-DIGITAL CONVERTER

FEATURES

● 100kHz SAMPLING RATE

● 72dB SINAD WITH 45kHz INPUT

●

±1/2 LSB INL AND DNL

● SIX SPECIFIED INPUT RANGES

● SERIAL OUTPUT

● SINGLE +5V SUPPLY OPERATION

● PIN-COMPATIBLE WITH 16-BIT ADS7809

● USES INTERNAL OR EXTERNAL

REFERENCE

● 100mW MAX POWER DISSIPATION

● 20-PIN 0.3" PLASTIC DIP AND SOIC

● SIMPLE DSP INTERFACE

ADS7808

DESCRIPTION

The ADS7808 is a complete 12-bit sampling analog­to-digital using state-of-the-art CMOS structures. It
contains a 12-bit capacitor-based SAR A/D with S/H,
reference, clock, and a serial data interface. Data can
be output using the internal clock, or can be synchro­nized to an external data clock. The ADS7808 also
provides an output synchronization pulse for ease of
use with standard DSP processors.

The ADS7808 is specified at a 100kHz sampling rate,
and guaranteed over the full temperature range. Laser­trimmed scaling resistors provide various input ranges
including ±10V and 0V to 5V, while an innovative
design operates from a single +5V supply, with power
dissipation under 100mW.

The 20-pin ADS7808 is available in a plastic 0.3" DIP
and in an SOIC, both fully specified for operation over
the industrial –40°C to +85°C range.

10kΩ

CDAC

4kΩ

20kΩ

5kΩ

Internal

+2.5V Ref

Clock

BUSY

Data Clock

Serial Data

Successive Approximation Register and Control Logic

Serial

Data

Out

Comparator

Buffer

20kΩ

R/C

CS

R1IN

R2

IN



R3

IN

REF

Power Down

CAP

ADS7808

ADS7808



®

International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: [phone] • Twx: 910-952-1111

Internet: http://www.burr-brown.com/ • FAXLine: [phone] (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: [phone] • Immediate Product Info: [phone]

©

1992 Burr-Brown Corporation PDS-1155B Printed in U.S.A. January 1997

®

ADS7808

2

SPECIFICATIONS

ELECTRICAL

At TA = –40°C to +85°C, fS = 100kHz, V

DIG

= V

ANA

= +5V, using internal reference and fixed resistors as shown in Figure 4, unless otherwise specified.

ADS7808P, U ADS7808PB, UB

PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS

The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN
assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject
to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not
authorize or warrant any BURR-BROWN product for use in life support devices and/or systems.

RESOLUTION 12 ✻ Bits
ANALOG INPUT

Voltage Ranges ±10V, 0V to 5V, etc. (See Table I)
Impedance See Table I
Capacitance 35 ✻ pF

THROUGHPUT SPEED

Conversion Time 5.7 8 ✻✻µs
Complete Cycle Acquire and Convert 10 ✻ µs
Throughput Rate 100 ✻ kHz

DC ACCURACY

Integral Linearity Error ±0.9 ±0.45 LSB

(1)

Differential Linearity Error ±0.9 ±0.45 LSB
No Missing Codes Guaranteed ✻
Transition Noise

(2)

0.1 ✻ LSB

Full Scale Error

(3,4)

±0.5 ±0.25 %
Full Scale Error Drift ±7 ±5 ppm/°C
Full Scale Error

(3,4)

Ext. 2.5000V Ref ±0.5 ±0.25 %
Full Scale Error Drift Ext. 2.5000V Ref ±2 ✻ ppm/°C
Bipolar Zero Error

(3)

Bipolar Ranges ±10 ✻ mV
Bipolar Zero Error Drift Bipolar Ranges ±2 ±2 ppm/°C
Unipolar Zero Error

(3)

0V to 10V Range ±5 ✻ mV

0V to 4V Range ±3 ✻ mV

0V to 5V Range ±3 ✻ mV
Unipolar Zero Error Drift Unipolar Ranges ± 2 ✻ ppm/°C
Recovery to Rated Accuracy 1µF Capacitor to CAP 1 ✻ ms

after Power Down

Power Supply Sensitivity +4.75V < V

D

< +5.25V ±0.5 ✻ LSB

(V

DIG

= V

ANA

= VD)

AC ACCURACY

Spurious-Free Dynamic Range f

IN

= 45kHz 80 90 ✻✻ dB

(5)

Total Harmonic Distortion f

IN

= 45kHz –90 –80 ✻✻dB

Signal-to-(Noise+Distortion) f

IN

= 45kHz 70 73 72 ✻ dB

Signal-to-Noise f

IN

= 45kHz 70 73 72 ✻ dB

Full-Power Bandwidth

(6)

250 ✻ kHz

SAMPLING DYNAMICS

Aperture Delay 40 ✻ ns
Aperture Jitter Sufficient to meet AC specs ✻ ns
Transient Response FS Step 2 ✻ µs
Overvoltage Recovery

(7)

150 ✻ ns

REFERENCE

Internal Reference Voltage No Load 2.48 2.5 2.52 ✻✻✻ V
Internal Reference Source Current 1 ✻ µA

(Must use external buffer)

External Reference Voltage Range 2.3 2.5 2.7 ✻✻✻ V

for Specified Linearity

External Reference Current Drain Ext. 2.5000V Ref 100 ✻ µA

DIGITAL INPUTS

Logic Levels

V

IL

–0.3 +0.8 ✻✻V

V

IH

+2.0 VD +0.3V ✻✻V

I

IL

VIL = 0V ±10 ✻ µA

I

IH

VIH = 5V ±10 ✻ µA

3

®

ADS7808

DIGITAL OUTPUTS

Data Format
Data Coding
Pipeline Delay
Data Clock

Internal EXT/INT LOW 2.3 ✻ MHz

(Output Only When
Transmitting Data)

External EXT/INT HIGH 0.1 10 ✻✻MHz

(Can Run Continually)

V

OL

I

SINK

= 1.6mA +0.4 ✻ V

V

OH

I

SOURCE

= 500µA+4 ✻ V

Leakage Current High-Z State, ±5 ✻ µA

V

OUT

= 0V to V

DIG

Output Capacitance High-Z State 15 15 pF

POWER SUPPLIES

Specified Performance

V

DIG

Must be ≤ V

ANA

+4.75 +5 +5.25 ✻ **V

V

ANA

+4.75 +5 +5.25 ✻ **V

I

DIG

0.3 * mA

I

ANA

16 * mA

Power Dissipation: PWRD LOW V

DIG

= V

ANA

= 5V, fS = 100kHz 100 * mW

PWRD HIGH 50 * µW

TEMPERATURE RANGE

Specified Performance –40 +85 * * °C
Derated Performance –55 +125 * * °C
Storage –65 +150 * * °C
Thermal Resistance (

θ

JA

)
Plastic DIP 75 * °C/W
SOIC 75 * °CW

NOTES: (1) LSB means Least Significant Bit. For the ±10V input range, one LSB is 4.88mV. (2) Typical rms noise at worst case transitions and temperatures. (3)
As measured with fixed resistors in Figure 4. Adjustable to zero with external potentiometer. (4) For bipolar input ranges, full scale error is the worst case of –Full
Scale or +Full Scale untrimmed deviation from ideal first and last code transitions, divided by the transition voltage (not divided by the full-scale range) and includes
the effect of offset error. For unipolar input ranges, full scale error is the deviation of the last code transition divided by the transition voltage. It also includes the
effect of offset error. (5) All specifications in dB are referred to a full-scale ±10V input. (6) Full-Power Bandwidth defined as Full-Scale input frequency at which Signal­to (Noise + Distortion) degrades to 60dB. (7) Recovers to specified performance after 2 x FS input overvoltage.

ELECTROSTATIC
DISCHARGE SENSITIVITY

Electrostatic discharge can cause damage ranging from per­formance degradation to complete device failure. Burr-Brown
Corporation recommends that this integrated circuit be handled
and stored using appropriate ESD protection methods.

SPECIFICATIONS (CONT)

ELECTRICAL

At TA = –40°C to +85°C, fS = 100kHz, V

DIG

= V

ANA

= +5V, using internal reference and fixed resistors shown in Figure 4, unless otherwise specified.

ADS7808P/U ADS7808PB/UB

PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS

Analog Inputs: R1IN.......................................................................... ±25V

R2

IN

.......................................................................... ±25V

R3

IN

.......................................................................... ±25V

CAP .....................................V

ANA

+0.3V to AGND2 –0.3V

REF ....................................... Indefinite Short to AGND2,

Momentary Short to V

ANA

Ground Voltage Differences: DGND, AGND2 .................................±0.3V

V

ANA

...................................................................................................... 7V

V

DIG

to V

ANA

....................................................................................... +0.3

V

DIG

....................................................................................................... 7V

Digital Inputs .............................................................–0.3V to V

DIG

+0.3V

Maximum Junction Temperature .................................................. +165°C

Internal Power Dissipation ............................................................700mW

Lead Temperature (soldering, 10s) .............................................. +300°C

ABSOLUTE MAXIMUM RATINGS

ORDERING INFORMATION

MINIMUM

MAXIMUM SIGNAL-TO- SPECIFICATION

LINEARITY (NOISE + DISTORTION) TEMPERATURE

PRODUCT ERROR (LSB) RATIO(dB) RANGE (

°C) PACKAGE

ADS7808P ±0.9 70 –40°C to +85°C 20-Pin Plastic DIP
ADS7808PB ±0.45 72 –40°C to +85°C 20-Pin Plastic DIP
ADS7808U ±0.9 70 –40°C to +85°C 20-Pin SOIC
ADS7808UB ±0.45 72 –40°C to +85°C 20-Pin SOIC

PACKAGE INFORMATION

PACKAGE DRAWING

PRODUCT PACKAGE NUMBER

(1)

ADS7808P 20-Pin Plastic DIP 222
ADS7808PB 20-Pin Plastic DIP 222
ADS7808U 20-Pin SOIC 221
ADS7808UB 20-Pin SOIC 221

NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.

Serial 12 bits

Binary Two's Complement or Straight Binary

Conversion results only available after completed conversion.

Selectable for internal or external data clock