2 Responses to “A/D Converter needed”

1. admin says:

   March 30 at 7:24 am

   In message <<01bc13b2$4c5b75a0$01000…@stargate20.sgi.net>> "Stanley Koontz" <st…@sgi.net> writes:

   > I need an A/D converter that has a minimum sample freq of 500 KHz.

   > I’m using the 10x rule so that no ailasing will occur in the 50 Khz sigmal
   > that is being converted.

   > Single channel
   > Prefer serial out but parallel out is ok two.

   One critical bit of info missing – the resolution 8,12,16 bits ??
   Maxim make a lot of good A/Ds. MAX 121 is a 14 bit 400ksps serial
   device.
   M
2. admin says:

   March 30 at 7:24 am

   Stanley Koontz wrote:

   > Hello

   > I need an A/D converter that has a minimum sample freq of 500 KHz.

   > I’m using the 10x rule so that no ailasing will occur in the 50 Khz sigmal
   > that is being converted.

   > Single channel
   > Prefer serial out but parallel out is ok two.

   I am not familiar with such a 10x rule.  The Nyquist criteria is 2x.
   With 2x however, the best you get is a square wave.  I have found
   that good reconstruction can be achieved with 6x to 7x the highest
   frequency component in the signal.

   You did not mention how many bits you need, the accuracy needed or
   if you need an input mux.  I will make a few general suggestions,
   all available from National Semiconductor:

                    MAX SAMP    SUPPLY
   DEVICE   BITS   RATE (KHz)  VOLTAGE   SER/PAR
   ADC0820    8       667         5      parallel
   ADC0831    8     1,000         5      serial
   ADC08231   8       500         5      serial
   ADC0852    8       400         5      serial
   ADC08061   8     2,000         5      parallel
   ADC08161   8     2,000         5      parallel
   ADC10154  10       166    5 or +/-5   parallel
   ADC10061  10       800         5      parallel
   ADC10662  10     1,500         5      parallel
   ADC12030  12       114         5      serial
   ADC12130  12       114         5      serial
   ADC12H030 12       182         5      serial
   ADC12041  12       278         5      parallel
   ADC1205   12     1,000         5      parallel
   ADC1225   12     1,000         5      parallel
   ADC12762  12     1,400         5      parallel
   ADC1241   12       500         5      parallel
   ADC1251   12        83         5      parallel

   Good luck.

   –
   Nick Gray
   Applications Engineer
   National Semiconductor Corporation
   email:  ng…@redwood.nsc.com
   National Data Sheets at http://www.national.com