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AD7828CQ

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
AD7824/AD7828
–4–
REV. F
Operating Temperature Range
Commercial (K, L Versions) . . . . . . . . . . . . . . 0°C to 70°C
Industrial (B, C Versions) . . . . . . . . . . . . . –40°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*
(T
A
= 25°C, unless otherwise noted.)
V
DD
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V, 7 V
Digital Input Voltage to GND
(RD, CS, A0, A1, and A2) . . . . . . . . . –0.3 V, V
DD
+ 0.3 V
Digital Output Voltage to GND
(DB0, DB7, RDY, and INT) . . . . . . . –0.3 V, V
DD
+ 0.3 V
V
REF
(+) to GND . . . . . . . . . . . . . . . . . V
REF
(–), V
DD
+ 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 AD7824/AD7828 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
TOP VIEW
(Not to Scale)
24
23
22
21
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
9
10
11
12
AD7824
NC = NO CONNECT
AIN4 V
DD
AIN3 NC
AIN2 A0
AIN1 A1
NC DB7
DB0 DB6
DB1 DB5
DB2 DB4
DB3
CS
RD
RDY
INT
V
REF
(+)
GND V
REF
(–)
TOP VIEW
(Not to Scale)
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
AD7828
NC = NO CONNECT
AIN6
AIN7
AIN5
AIN8
AIN4
V
DD
AIN3
A0
AIN2
A1
AIN1
A2
NC
DB7
DB0
DB6
DB1
DB5
DB2
DB4
DB3
CS
RD
RDY
INT
V
REF
(+)
GND
V
REF
(–)
WARNING!
ESD SENSITIVE DEVICE
PLCC
25
24
23
22
21
20
19
5
6
7
8
9
10
11
4 3 2 1 28 27 26
PIN 1
IDENTIFIER
TOP VIEW
(Not to Scale)
12 13 14 15 16 17 18
A0
AIN2
V
DD
RD
NC = NO CONNECT
AD7828
A1
AIN1
A2
NC
DB7
DB0
DB6
DB1
DB5
DB2
DB4
DB3
AIN8
AIN7
AIN6
AIN5
AIN4
AIN3
INT
GND
V
REF
(–)
V
REF
(+)
RDY
CS
LCCC
TOP VIEW
(Not to Scale)
28 271
2
3426
25
21
22
23
24
19
20
5
6
7
8
9
10
11
12
13 14 15 16 17 18
AD7828
AIN2
A0
V
DD
RD
AIN1
A1
NC A2
DB0 DB7
DB1
DB6
DB2
DB5
DB3 DB4
AIN8
AIN7
AIN6
AIN5
AIN4
AIN3
INT
GND
V
REF
(–)
V
REF
(+)
RDY
CS
NC = NO CONNECT
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
AD7828LRS 0°C to 70°C ±1/2 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.
Typical Performance Characteristics–AD7824/AD7828
REV. F
–5–
T
A
– AMBIENT TEMPERATURE – ⴗC
3
2
1
–100 150–50
t
CRD
– CONVERSION TIME – ␮s
050100
V
DD
= 5V
TPC 1. Conversion Time vs. Temperature
V
REF
– V
2.0
1.0
0
051
LINEARITY ERROR – LSB*
234
1.5
0.5
V
DD
= 5V
T
A
= 25ⴗC
*1LSB =
V
REF
256
TPC 2. Accuracy vs. V
REF
[V
REF
= V
REF
(+) – V
REF
(–)]
INPUT FREQUENCY – kHz
–36
–44
–52
51
SNR – dB
234
–40
–48
–38
–46
–42
–50
20 30 40 50 70 100710
ENCODE RATE = 400kHz
INPUT SIGNAL = 5V p-p
MEASUREMENT BANDWIDTH = 80kHz
TPC 3. Signal Noise Ratio vs. Input Frequency
T
A
– AMBIENT TEMPERATURE – ⴗC
14
12
10
–100 150–50
I
DD
– SUPPLY CURRENT – mA
050100
13
11
9
8
V
DD
= 5.25V
V
DD
= 4.75V
V
DD
= 5V
TPC 4. Power Supply Current vs. Temperature
(Not Including Reference Ladder)
t
P
– ns
2.0
1.0
0
300
LINEARITY ERROR – LSB
1.5
0.5
V
DD
= 5V
V
REF
= 5V
T
A
= 25
ⴗ
C
400 500 600 700 800 900
TPC 5. Accuracy vs. t
P
T
A
– AMBIENT TEMPERATURE – ⴗC
8
4
–100 150–50
OUTPUT CURRENT – mA
050100
10
6
2
0
I
SOURCE
, V
OUT
= 2.4V
V
DD
= 5V
I
SINK
, V
OUT
= 0.4V
TPC 6. Output Current vs. Temperature
AD7824/AD7828
–6–
REV. F
OPERATIONAL DIAGRAM
The AD7824 is a 4-channel 8-bit ADC and the AD7828 is an
8-channel 8-bit ADC. Operational diagrams for both of these
devices are shown in Figures 3 and 4. The addition of just a 5 V
reference allows the devices to perform the analog-to-digital function.
24
23
22
21
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
9
10
11
12
AD7824
NC = NO CONNECT
AIN4
V
DD
AIN3
NC
AIN2
A0
AIN1
A1
NC
DB7
DB0
DB6
DB1
DB5
DB2
DB4
DB3
CS
RD
RDY
INT
V
REF
(+)
GND
V
REF
(–)
ANALOG INPUTS
0V TO 5V
␮
P 4LSB
DATA BUS
␮
P CONTROL INPUT
STATUS OUTPUT
␮
P ADDRESS
BUS
␮
P 4MSB
DATA BUS
␮
P CONTROL INPUT
STATUS OUTPUT
5V
5V
Figure 3. AD7824 Operational Diagram
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
AD7828
NC = NO CONNECT
AIN6
AIN7
AIN5
AIN8
AIN4
V
DD
AIN3
A0
AIN2
A1
AIN1
A2
NC
DB7
DB0
DB6
DB1
DB5
DB2
DB4
DB3
CS
RD
RDY
INT
V
REF
(+)
GND
V
REF
(–)
ANALOG INPUTS
0V TO 5V
␮P 4LSB
DATA BUS
␮P CONTROL INPUT
STATUS OUTPUT
ANALOG INPUTS
0V TO 5V
␮P ADDRESS
BUS
␮P 4MSB
DATA BUS
␮P CONTROL INPUT
STATUS OUTPUT
5V
5V
Figure 4. AD7828 Operational Diagram
CIRCUIT INFORMATION
BASIC DESCRIPTION
The AD7824/AD7828 uses a half-flash conversion technique
whereby two 4-bit flash ADCs are used to achieve an 8-bit result.
Each 4-bit flash ADC contains 15 comparators that compare
the unknown input to a reference ladder to get a 4-bit result.
For a full 8-bit reading to be realized, the upper 4-bit flash, the
most significant (MS) flash, performs a conversion to provide
the four most significant data bits. An internal DAC, driven by
the four MSBs, then recreates an analog approximation of the
input voltage. This analog result is subtracted from the input,
and the difference is converted by the lower flash ADC, the least
significant (LS) flash, to provide the four least significant bits of
the output data. The most significant flash ADC also has one
additional comparator to detect overrange on the analog input.
APPLYING THE AD7824/AD7828
REFERENCE AND INPUT
The two reference inputs on the AD7824/AD7828 are fully differ-
ential and define the zero to full-scale input range of the ADC.
As a result, the span of the analog input voltage for all channels
can easily be varied. By reducing the reference span, V
REF
(+) to
V
REF
(–), to less than 5 V, the sensitivity of the converter can be
increased (e.g., if V
REF
= 2 V then 1 LSB = 7.8 mV). The input/
reference arrangement also facilitates ratiometric operation.
This reference flexibility also allows the input channel voltage
span to be offset from zero. The voltage at V
REF
(–) sets the
input level for all channels, which produces a digital output of
all zeroes. Therefore, although the analog inputs are not them-
selves differential, they have nearly differential input capability
in most measurement applications because of the reference
design. Figures 5 to 7 show some of the configurations that are
possible.
AD7824*
AD7828*
AIN1
GND
V
DD
V
REF
(+)
V
REF
(–)
47␮F0.1␮F
V
IN
(–)
V
IN
(+)
5V
ADDITIONAL PINS OMITTED FOR CLARITY.
ONLY CHANNEL 1 SHOWN.
*
Figure 5. Power Supply as Reference
AD7824*
AD7828*
AIN1
GND
V
DD
V
REF
(+)
V
REF
(–)
47␮F0.1␮F
V
IN
(–)
V
IN
(+)
5V
ADDITIONAL PINS OMITTED FOR CLARITY.
ONLY CHANNEL 1 SHOWN.
*
AD580
0.1␮F
10␮F
Figure 6. External Reference Using the AD580, Full-Scale
Input is 2.5 V
AD7824*
AD7828*
AIN1
GND
V
DD
V
REF
(+)
V
REF
(–)
47␮F0.1␮F
V
IN
(+)
5V
ADDITIONAL PINS OMITTED FOR CLARITY.
ONLY CHANNEL 1 SHOWN.
*
DB7
DB0
DATA
V1
V2
DATA = ⴛ 256 (FOR ALL CHANNELS)
V
IN
(+)
V1 – V2
Figure 7. Input Not Referenced to GND
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

AD7828CQ

Mfr. #:
Buy AD7828CQ
Manufacturer:
Analog Devices Inc.
Description:
Analog to Digital Converters - ADC High Spd 8-Ch 8-Bit CMOS
Lifecycle:
New from this manufacturer.
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