Analog Devices AD7828UQ, AD7828UE, AD7824LN, AD7824KR, AD7824KN Datasheet

REV. D

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.

a

LC2MOS High Speed

4- & 8-Channel 8-Bit ADCs

AD7824/AD7828

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 2000

FUNCTIONAL BLOCK DIAGRAM

RDY

CS

RD

INT

DB3
DB2
DB1
DB0

DB7
DB6
DB5
DB4

THREE
STATE

DRIVERS

4-BIT

FLASH

ADC

(4LSB)

V

REF

(+)

16

TIMING AND CONTROL

CIRCUITRY

ADDRESS

LATCH

DECODE

AIN 1

AIN 4

AIN 8

MUX*

*AD7824 – 4-CHANNEL MUX
**AD7828 – 8-CHANNEL MUX

A2 – AD7828 ONLY

A0 A1 A2**

V

REF

(+)

V

REF

(–)

4-BIT

FLASH

ADC

(4MSB)

4-BIT

DAC

FEATURES
4- or 8-Analog Input Channels
Built-In Track/Hold Function
10 kHz Signal Handling on Each Channel
Fast Microprocessor Interface
Single 5 V Supply
Low Power: 50 mW
Fast Conversion Rate, 2.5 s/Channel
Tight Error Specification: 1/2 LSB

GENERAL DESCRIPTION

The AD7824 and AD7828 are high-speed, multichannel, 8-bit
ADCs with a choice of 4 (AD7824) or 8 (AD7828) multiplexed
analog inputs. A half-flash conversion technique gives a fast
conversion rate of 2.5 µs per channel and the parts have a built-
in track/hold function capable of digitizing full-scale signals of
10 kHz (157 mV/µs slew rate) on all channels. The AD7824 and
AD7828 operate from a single 5 V supply and have an analog
input range of 0 V to 5 V, using an external 5 V reference.

Microprocessor interfacing of the parts is simple, using standard
Chip Select (CS) and Read (RD) signals to initiate the conver­sion and read the data from the three-state data outputs. The
half-flash conversion technique means that there is no need to
generate a clock signal for the ADC. The AD7824 and AD7828
can be interfaced easily to most popular microprocessors.

The AD7824 and AD7828 are fabricated in an advanced, all
ion-implanted, linear-compatible CMOS process (LC

2

MOS)
and have low power dissipation of 40 mW (typ). The AD7824
is available in a 0.3" wide, 24-lead “skinny” DIP, while the
AD7828 is available in a 0.6" wide, 28-lead DIP and in 28­terminal surface mount packages.

PRODUCT HIGHLIGHTS

1. 4- or 8-channel input multiplexer gives cost-effective space­saving multichannel ADC system.

2. Fast conversion rate of 2.5 µs/channel features a per channel
sampling frequency of 100 kHz for the AD7824 or 50 kHz
for the AD7828.

3. Built-in track-hold function allows handling of 4- or 8­channels up to 10 kHz bandwidth (157 mV/µs slew rate).

4. Tight total unadjusted error spec and channel-to-channel
matching eliminate the need for user trims.

5. Single 5 V supply simplifies system power requirements.

6. Fast, easy-to-use digital interface allows connection to most
popular microprocessors with minimal external components.
No clock signal is required for the ADC.

REV. D

–2–

AD7824/AD7828–SPECIFICATIONS

(VDD = 5 V, V

REF

(+) = 5 V, V

REF

(–) = GND = O V unless otherwise

noted. All specifications T

MIN

to T

MAX

unless otherwise noted. Specifications apply for Mode 0.)

Parameter K Version1L Version B, T Versions C, U Versions Unit Conditions/Comments

ACCURACY

Resolution 8 8 8 8 Bits
Total Unadjusted Error

2

± 1 ± 1/2 ± 1 ± 1/2 LSB max

Minimum Resolution for which

No Missing Codes Are Guaranteed 8 8 8 8 Bits

Channel-to-Channel Mismatch ± 1/4 ± 1/4 ± 1/4 ± 1/4 LSB max

REFERENCE INPUT

Input Resistance 1.0/4.0 1.0/4.0 1.0/4.0 1.0/4.0 kΩ min/kΩ max
V

REF

(+) Input Voltage Range V

REF

(–)/ V

REF

(–)/ V

REF

(–)/ V

REF

(–)/ V min/V max

V

DD

V

DD

V

DD

V

DD

V

REF

(–) Input Voltage Range GND/ GND/ GND/ GND/ V min/V max

V

REF

(+) V

REF

(+) V

REF

(+) V

REF

(+)

ANALOG INPUT

Input Voltage Range V

REF

(–)/ V

REF

(–)/ V

REF

(–)/ V

REF

(– )/ V min/V max

V

REF

(+) V

REF

(+) V

REF

(+) V

REF

(+)
Input Leakage Current ± 3 ± 3 ±3 ± 3 µA max Analog Input Any Channel
Input Capacitance

3

45 45 45 45 pF typ 0 V to 5 V

LOGIC INPUTS

RD, CS, A0, A1 & A2

V

INH

2.4 2.4 2.4 2.4 V min

V

INL

0.8 0.8 0.8 0.8 V max

I

INH

111 1 µA max

I

INL

–1 –1 –1 –1 µA max

Input Capacitance

3

8 8 8 8 pF max Typically 5 pF

LOGIC OUTPUTS

DB0–DB7 & INT

V

OH

4.0 4.0 4.0 4.0 V min I

SOURCE

= 360 µA

V

OL

0.4 0.4 0.4 0.4 V max I

SINK

= 1.6 mA

I

OUT

(DB0–DB7) ± 3 ± 3 ±3 ± 3 µA max Floating State Leakage

Output Capacitance

3

8 8 8 8 pF max Typically 5 pF

RDY

V

OL

4

0.4 0.4 0.4 0.4 V max I

SINK

= 2.6 mA

I

OUT

± 3 ± 3 ±3 ± 3 µA max Floating State Leakage

Output Capacitance 8 8 8 8 pF max Typically 5 pF

SLEW RATE, TRACKING

3

0.7 0.7 0.7 0.7 V/µs typ

0.157 0.157 0.157 0.157 V/µs max

POWER SUPPLY

V

DD

5 5 5 5 Volts ± 5% for Specified

Performance

I

DD

5

16 16 20 20 mA max CS = RD = 2.4 V

Power Dissipation 50 50 50 50 mW typ

80 80 100 100 mW max

Power Supply Sensitivity ± 1/4 ± 1/4 ± 1/4 ± 1/4 LSB max ± 1/16 LSB typ

VDD = 5 V ± 5%

NOTES

1

Temperature ranges are as follows: K, L Versions; 0°C to 70°C

B, C Versions; –40°C to +85°C
T, U Versions; –55°C to +125°C

2

Total Unadjusted Error includes offset, full-scale and linearity errors.

3

Sample tested at 25°C by Product Assurance to ensure compliance.

4

RDY is an open drain output.

5

See Typical Performance Characteristics.

Specifications subject to change without notice.

AD7824/AD7828

REV. D

–3–

TIMING CHARACTERISTICS

1

(VDD = 5 V; V

REF

(+) = 5 V; V

REF

(–) = GND = 0 V unless otherwise noted)

Limit at Limit at

Limit at 25CT

MIN

, T

MAX

T

MIN

, T

MAX

Parameter (All Grades) (K, L, B, C Grades) (T, U Grades) Unit Conditions/Comments

t

CSS

0 0 0 ns min CS to RD Setup Time

t

CSH

0 0 0 ns min CS to RD Hold Time

t

AS

0 0 0 ns min Multiplexer Address Setup Time

t

AH

30 35 40 ns min Multiplexer Address Hold Time

t

RDY

2

40 60 60 ns max CS to RDY Delay. Pull-Up

Resistor 5 kΩ.

t

CRD

2.0 2.4 2.8 µs max Conversion Time, Mode 0

t

ACC1

3

85 110 120 ns max Data Access Time after RD

t

ACC2

3

50 60 70 ns max Data Access Time after INT, Mode 0

t

lNTH

2

40 65 70 ns typ RD to INT Delay
75 100 100 ns max

t

DH

4

60 70 70 ns max Data Hold Time

t

P

500 500 600 ns min Delay Time between Conversions

t

RD

60 80 80 ns min Read Pulsewidth, Mode 1
600 500 400 ns max

NOTES

1

Sample tested at 25°C to ensure compliance. All input control signals are specified with tr = tf = 20 ns (10 % to 90% of 5 V) and timed from a voltage level of 1.6 V.

2

CL = 50 pF.

3

Measured with load circuits of Figure 1 and defined as the time required for an output to cross 0.8 V or 2.4 V.

4

Defined as the time required for the data lines to change 0.5 V when loaded with the circuits of Figure 2.

Specifications subject to change without notice.

Test Circuits

Figure 1. Load Circuits for Data Access Time Test

Figure 2. Load Circuits for Data Hold Time Test

AD7824/AD7828

REV. D

–4–

Operating Temperature Range

Commercial (K, L Versions) . . . . . . . . . . . . . . 0°C to 70°C

Industrial (B, C Versions) . . . . . . . . . . . . . –25°C to +85°C

Extended (T, U Versions) . . . . . . . . . . . . –55°C to +125°C

Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C

Lead Temperature (Soldering, 10 secs) . . . . . . . . . . . . . 300°C

Power Dissipation (Any Package) to 75°C . . . . . . . . . 450 mW

Derates above 75°C by . . . . . . . . . . . . . . . . . . . . . . 6 mW/°C

*Stresses above 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 sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.

ABSOLUTE MAXIMUM RATINGS*

(TA = 25°C unless otherwise noted)

VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V, 7 V

Digital Input Voltage to GND

(RD, CS, A0, A1 & A2) . . . . . . . . . . . . –0.3 V, V

DD

+ 0.3 V

Digital Output Voltage to GND

(DB0, DB7, RDY & INT) . . . . . . . . . . –0.3 V, V

DD

+ 0.3 V

V

REF

(+) to GND . . . . . . . . . . . . . . . . . . V

REF

(–), VDD + 0.3 V

V

REF

(–) to GND . . . . . . . . . . . . . . . . . . . . . . . . 0 V, V

REF

(+)

Analog Input (Any Channel) . . . . . . . . . . –0.3 V, V

DD

+ 0.3 V

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 these devices feature 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.

PIN CONFIGURATIONS

DIP/SOIC/SSOP

PLCC

LCCC

ORDERING GUIDE

Total

Temperature Unadjusted Package

Model Range Error (LSBs) Option

AD7824KN 0°C to 70°C ±1 N-24
AD7824LN 0°C to 70°C ± 1/2 N-24
AD7824KR 0°C to 70°C ±1 R-24
AD7824BQ –40°C to +85°C ±1 Q-24
AD7824CQ –40°C to +85°C ±1/2 Q-24
AD7824TQ* –55°C to +125°C ± 1 Q-24
AD7824UQ* –55°C to +125°C ± 1/2 Q-24

AD7828KN 0°C to 70°C ±1 N-28
AD7828LN 0°C to 70°C ± 1/2 N-28
AD7828KP 0°C to 70°C ±1 P-28A
AD7828LP 0°C to 70°C ± 1/2 P-28A
AD7828BQ –40°C to +85°C ±1 Q-28
AD7828CQ –40°C to +85°C ±1/2 Q-28
AD7828BR –40°C to +85°C +1 R-28
AD7828BRS –40°C to +85°C +1 RS-28
AD7828TQ* –55°C to +125°C ± 1 Q-28
AD7828UQ* –55°C to +125°C ± 1/2 Q-28
AD7828TE* –55°C to +125°C ± 1 E-28A
AD7828UE* –55°C to +125°C ± 1/2 E-28A

*Available to /883B processing only. Contact our local sales office for military

data sheet. For U.S. Standard Military Drawing (SMD) see DESC Drawing
#5692-88764.

WARNING!

ESD SENSITIVE DEVICE