®
®
ADS-931
THERMAL REQUIREMENTS
All DATEL 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
N
START
CONVERT
100ns typ.
Acquisition Time
730ns typ.
N+1
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 DATEL's HS Series heat sinks.
See Ordering Information for the assigned part number. See
page 1-183 of the DATEL Data Acquisition Components Catalog
for more information on the HS Series. Request DATEL
Application Note AN-8, "Heat Sinks for DIP Data Converters," or
contact DATEL directly, for additional information.
N+2
N+3
20ns typ.
INTERNAL S/H
Hold
270ns typ.
60ns typ.
EOC
55ns typ.
280ns typ.
Conversion Time
20ns typ.
OUTPUT
DATA
Data N-4 Valid
Data N-3 Valid
60ns typ.
Invalid
Data
940ns typ.
Data N-2 Valid
Invalid
Data
Data N-1 Valid
Notes: 1. Scale is approximately 50ns per division. fs = 1MHz.
2. This device has three pipeline delays. Four start convert pulses (clock cycles) must be applied for valid data
from the first conversion to appear at the output of the A/D.
3. The start convert positive pulse width must be between either 40 and 175nsec or 280 and 460nsec
(when sampling at 1MHz) to ensure proper operation. For sampling rates lower than 1MHz, the start pulse
can be wider than 460nsec, however a minimum pulse width low of 40nsec should be maintained. A 1MHz
clock with a 100nsec positive pulse width is used for all production testing.
Figure 3. ADS-931 Timing Diagram
0
–10
–20
Amplitude Relative to Full Scale (dB)
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
–130
–140
–150
–160
–170
0
50
100
150
200
250
300
350
400
450
500
Frequency (kHz)
(fs = 1MHz, fin = 480kHz, Vin = –0.5dB, 16,384-point FFT)
Figure 4. FFT Analysis of ADS-931
6
MURATA-PS [ MURATA POWER SOLUTIONS INC. ]
