ADS 949
14 Bit, 12.8MHz
Sampling A/D Converters
THERMAL REQUIREMENTS
All MPS sampling A/D converters are fully characterized and
specified over operating temperature (case) ranges of 0 to +70°C
and –55 to +125°C. All room temperature (T
A
= +25°C) production
testing is performed without the use of heat sinks or forced air
cooling. Thermal impedance figures for each device are listed in
their respective specification tables.
These devices do not normally require heat sinks, however,
standard precautionary design and layout procedures should be
used to ensure devices do not overheat. The ground and power
planes beneath the package, as well as all pcb signal runs to and
from the device, should be as heavy as possible to help conduct
heat away from the package.
Electrically-insulating, thermally-conductive "pads" may be
installed underneath the package. Devices should be soldered to
boards rather than socketed, and of course, minimal air flow over
the surface can greatly help reduce the package temperature.
in more severe ambient conditions, the package/junction
temperature of a given device can be reduced dramatically
(typically 35%) by using one of MPS's HS Series heat sinks. See
ordering information for the assigned part number. See page
1-183 of the MPS Data Acquisition Components Catalog for more
information on the HS Series. Request MPS Application Note
AN8, "Heat Sinks for DiP Data Converters", or contact Murata
Power Solutions directly, for additional information.
Table 3. Output Coding
STRAIGHT BIN.
UNIPOLAR
SCALE
INPUT VOLT.
0 TO +5V
MSB
LSB
OUTPUT CODING
MSB
LSB
INPUT VOLT.
±2.5V
BIPOLAR
SCALE
+FS – 1 LSB
+7/8 FS
+3/4 FS
+1/2 FS
+1/4 FS
+1/8 FS
+1 LSB
0
+4.999695
+4.375000
+3.75000
+2.500000
+1.250000
+0.625000
+0.000305
0.000000
11 1111 1111 1111
11 1000 0000 0000
11 0000 0000 0000
10 0000 0000 0000
01 0000 0000 0000
00 1000 0000 0000
00 0000 0000 0001
00 0000 0000 0000
OFF. BINARY
01 1111 1111 1111
01 1000 0000 0000
01 0000 0000 0000
00 0000 0000 0000
11 0000 0000 0000
10 1000 0000 0000
10 0000 0000 0001
10 0000 0000 0000
TWO'S COMP.
+2.499695
+1.875000
+1.250000
0.000000
–1.250000
–1.875000
–2.499695
–2.500000
+FS – 1LSB
+3/4FS
+1/2FS
0
–1/2FS
–3/4FS
–FS+1LSB
–FS
–5V
+15V
4.7µF
+
4.7µF
+
+5VA
+5VD
4.7µF
+
4.7µF
+
0.1µF 0.1µF
0.1µF
0.1µF
+5V
GAIN
ADJUST
20K
–5V
UNIPOLAR
ANALOG
INPUT
+5V
ZERO/
OFFSET
ADJUST
20k
–5V
START
CONVERT
5
3
RANGE REF
➀
–5V
1VIN A
2 VIN B
31 GAIN ADJUST
28
30
29
+15V AGND +5VA
27
26
+5VD DGND
23 BIT 1 (MSB)
22 BIT 2
21 BIT 3
20
19
18
17
16
15
14
13
12
11
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
BIT 9
BIT 10
BIT 11
BIT 12
BIT 13
ADS-949
4 OFFSET ADJUST
20k�½
32 RANGE
➀
6 2.5V REF
➀
7 START CONVERT
9 ENABLE
10 BIT 14 (LSB)
8 EOC
Figure 3. Typical ADS-949 Unipolar Connection Diagram
➀
Bypass Pins 5, 6, 32 with a 4.7µF to Analog Ground.
www.murata-ps.com
32 (Range) sets the input voltage range of the ADS-949
Technical enquiries
email: sales@murata-ps.com, tel:
+1 508 339 3000
Note: The Voltage Value at Pin
MDC_ADS-949.B01 Page 5 of 8
eg: If Pin 6 (2.5V Reference Out) is tied to the Range Pin 32 (20k Pot is shorted), then
the input range of the ADS-949 becomes 0 to 5V
If the 20k Pot is set at midrange then the input range of the ADS-949 becomes 0 to 2.5V
MURATA-PS [ MURATA POWER SOLUTIONS INC. ]
