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
interfacedtomicroprocessors. Allactivecircuitryiscontained
on-chip including a clock generator and stable 2.5V bandgap
reference, control logic and double buffered latches with
reference.
BUSY (END OF CONVERSION)
RD (OUTPUT ENABLE)
CLOCK
1
2
3
4
18 DB
17 DB
16 DB
15 DB
0
(LSB)
1
2
3
WR (START CONVERSION)
Only a reference resistor and capacitor, clock resistor and
capacitor and input resistors are required for operation with
either unipolar or bipolar input voltage.
R
EXT
IN
REF IN
REF OUT
5
6
7
14 DB
13 DB
12 DB
4
5
6
V
V
V
8
9
11 DB
7
(MSB)
FEATURES
■
Easy Interfacing to Microprocessor, or operates as a
GROUND
10 +VCC (+5V)
'Stand-Alone' Converter
ZN448/9E (DP18)
■
■
■
■
■
■
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
BUSY (END OF CONVERSION)
1
2
3
4
18
17
16
15
DB
DB
DB
DB
0
(LSB)
RD (OUTPUT ENABLE)
CLOCK
1
2
3
Commercial Temperature Range
WR (START CONVERSION)
ORDERING INFORMATION
R
EXT
IN
REF IN
REF OUT
5
6
7
14
13
12
DB
DB
DB
4
5
6
Linearity
error (LSB) temperature
Operating
V
Device type
Package
V
ZN448E
ZN449D
ZN449E
0.5
1
0°C to +70°C
0°C to +70°C
0°C to +70°C
DP18
MP18
DP18
V
8
9
11
10
DB
7
(MSB)
GROUND
+VCC (+5V)
1
ZN449D (MP18)
Fig.1 Pin connection - top view
COMPARATOR
5
6
7
ANALOGUE
+
R
EXT
INPUT
-
8-BIT DAC
V
IN
REF
8
V
OUT
REF
3
CLOCK
CK RC OR
2.5V
REFERENCE
GENERATOR
EXT CLOCK
4
1
INTERFACE
AND
CONTROL
LOGIC
WR
SUCCESSIVE
APPROXIMATION REGISTER
9
GROUND
BUSY
10
V
(+5V)
CC
2
3-STATE BUFFERS
RD
11
7
12
13
14
15
16
17
18
0
DB
DB
Fig.2 System diagram