7820
Microprocessor-compatible 8-Bit ADC
TABLE 1. PIN DESCRIPTION
PIN
SYMBOL
DESCRIPTION
1
2
3
4
5
6
7
V
Analog Input Range: VREF(-) to V
.
IN
REF(+)
DB0
DB1
DB2
DB3
Data Output. Three State Output, bit 0 (LSB)
Data Output. Three State Output, bit 1
Data Output. Three State Output, bit 2
Data Output. Three State Output, bit 3
WR/RDY WRITE control input/READY status output.
Mode
Mode Selection Input. It determines whether the device operates in the
WR-RD or RD mode. It is internally tied to GND through a 50 µA current
source.
8
9
RD
INT
READ Input. RD must be low to access data from the part.
INTERUPT Output. INT going low indicates that the conversion is com-
plete INT returns high on rising the edge of RD or CS.
10
11
12
13
GND
Ground
V
Lower limit of reference span. Range: GND < VREF(-) < V
REF-
REF(+)
V
Upper limit of reference span. Range: GND < VREF(-) < VREF(+) < V
REF+
DD
CS
Chip Select Input. CS, the decoded device address, must be low for RD
or WR to be recognized by the converter.
14
15
16
17
18
DB4
DB5
DB6
DB7
OFL
Data Output. Three State Output, bit 4
Data Output. Three State Output, bit 5
Data Output. Three State Output, bit 6
Data Output. Three State Output, bit 7 (MSB)
Overflow Output. If the analog input is higher than (VREF(+) - 1/2LSB),
OFL will be low at the end of conversion. It is a non three state output
which can be used to cascade 2 or more devices to increase resolution.
19
20
NC
No Connection.
V
Power supply voltage, +5V
DD
1
TABLE 2. 7820 ABSOLUTE MAXIMUM RATINGS
PARAMETER
MIN
MAX
UNIT
V
DD to GND
-0
7.0
V
V
V
V
V
Digital Input Voltage to GND (Pins 6-80, 13)
-0.3
0.3
0
V
DD +0.3
DD +0.3
DD +0.3
REF (+)
Digital Output Voltage to GND (Pins 2-5, 9, 14-18)
V
VREF (+) to GND
V
VREF (-) to GND
V -0.3
V
SS
09.09.03 Rev 3
All data sheets are subject to change without notice
2
©2003 Maxwell Technologies
All rights reserved.
MAXWELL [ MAXWELL TECHNOLOGIES ]
