DS3013 - 2.2
ZN448/ZN449
8-BIT MICROPROCESSOR COMPATIBLE A-D CONVERTER
The ZN448 and ZN449 are 8-bit successive
approximation A-D converters designed to be easily
interfaced to microprocessors. All active circuitry is contained
on-chip including a clock generator and stable 2.5V bandgap
reference, control logic and double buffered latches with
reference.
Only a reference resistor and capacitor, clock resistor and
capacitor and input resistors are required for operation with
either unipolar or bipolar input voltage.
BUSY (END OF CONVERSION)
RD (OUTPUT ENABLE)
CLOCK
WR (START CONVERSION)
R
EXT
V
IN
V
REF
IN
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
DB
0
(LSB)
DB
1
DB
2
DB
3
DB
4
DB
5
DB
6
DB
7
(MSB)
+V
CC
(+5V)
FEATURES
s
s
s
s
s
s
s
Easy Interfacing to Microprocessor, or operates as a
'Stand-Alone' Converter
Fast: 9 microseconds Conversion time Guaranteed
Choice of Linearity: 0.5 LSB - ZN448, 1 LSB - ZN449
On-Chip Clock
Choice of On-Chip or External Reference Voltage
Unipolar or Bipolar Input Ranges
Commercial Temperature Range
V
REF
OUT
GROUND
ZN448/9E (DP18)
BUSY (END OF CONVERSION)
RD (OUTPUT ENABLE)
CLOCK
WR (START CONVERSION)
R
EXT
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
DB
0
(LSB)
DB
1
DB
2
DB
3
DB
4
DB
5
DB
6
DB
7
(MSB)
+V
CC
(+5V)
ORDERING INFORMATION
Device type
ZN448E
ZN449D
ZN449E
Linearity
error (LSB)
0.5
1
1
Operating
temperature
0擄C to +70擄C
0擄C to +70擄C
0擄C to +70擄C
Package
DP18
MP18
DP18
V
IN
V
REF
IN
V
REF
OUT
GROUND
ZN449D (MP18)
Fig.1 Pin connection - top view
COMPARATOR
ANALOGUE
INPUT
VREF IN
6
+
5
REXT
7
8-BIT DAC
-
VREF OUT
8
2.5V
REFERENCE
CLOCK
GENERATOR
3
CK RC OR
EXT CLOCK
GROUND
9
SUCCESSIVE
APPROXIMATION REGISTER
INTERFACE
AND
CONTROL
LOGIC
4
WR
1
BUSY
VCC (+5V)
10
3-STATE BUFFERS
2
RD
11
DB7
12
13
14
15
16
17
18
DB0
Fig.2 System diagram