AD7821
ABSOLUTE MAXIMUM RATINGS*
Industrial (B Version) . . . . . . . . . . . . . . . . –40°C to +85°C
Extended (T Version) . . . . . . . . . . . . . . . –55°C to +125°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . .+300°C
Power Dissipation (Any Package) to +75°C . . . . . . . 450 mW
Derates above +75°C by . . . . . . . . . . . . . . . . . . . . . 6 mW/°C
VDD to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V, + 7 V
VSS to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3 V, + 7 V
Digital Input Voltage to GND
(Pins 6–8, 13) . . . . . . . . . . . . . . . . . . . –0.3 V, VDD + 0.3 V
Digital Output Voltage to GND
(Pins 2–5, 9, 14–18) . . . . . . . . . . . . . . . –0.3 V, VDD + 0.3 V
VREF(+) to GND . . . . . . . . . . . . . . . VSS – 0.3 V, VDD + 0.3 V
VREF(–) to GND . . . . . . . . . . . . . . . VSS – 0.3 V, VDD + 0.3 V
VIN to GND . . . . . . . . . . . . . . . . . . . VSS – 0.3 V, VDD + 0.3 V
Operating Temperature Range
*Stresses above 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 sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Commercial (K Version) . . . . . . . . . . . . . . –40°C to +85°C
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 AD7821 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
PIN CONFIGURATIONS
DIP AND SOIC
LCCC
PLCC
PIN FUNCTION DESCRIPTIONS
Pin
Mnemonic Description
1
2
VIN
DB0
Analog Input: Range VREF(–) ≤ VIN ≤ VREF(+)
Three-State Data Output (LSB)
3–5
6
7
DB1–DB3
WR/RDY
MODE
Three-State Data Outputs
WRITE control input/READY status output. See Digital Interface section.
Mode Selection Input. It determines whether the device operates in the WR-RD or RD mode. This input is internally
pulled low through a 50 µA current source. See Digital Interface section.
8
9
RD
INT
READ Input. RD must be low to access data from the part. See Digital Interface section.
INTERRUPT Output. INT going low indicates that the conversion is complete. INT returns high on the rising
edge of CS or RD. See Digital Interface section.
10
11
GND
Ground
V
REF(–)
Lower limit of reference span.
Range: VSS ≤ VREF(–) ≤ VREF(+).
12
V
REF(+)
Upper limit of reference span.
Range: VREF(–) < VREF(+) ≤ VDD
.
13
14–16
17
CS
DB4–DB6
DB7
Chip Select Input. The device is selected when this input is low.
Three-State Data Outputs
Three-State Data Output (MSB)
18
OFL
Overflow Output. If the analog input is higher than (VREF(+) – 1/2 LSB), OFL will be low at the end of conversion. It
is a non-three-state output which can be used to cascade two or more devices to increase resolution.
19
20
VSS
Negative Supply Voltage
V
V
SS = 0 V; Unipolar Operation
SS = –5 V; Bipolar Operation
VDD
Positive Supply Voltage, +5 V
–4–
REV. B
ADI [ ADI ]
