ST7538 - Datasheet problems

krapf · ‎2005-05-12

Posted on May 13, 2005 at 03:54

krapf · ‎2005-04-01

Posted on April 01, 2005 at 11:58

HEY GUYS!!!!!

The ST7538 datasheet at page 7 (Electrical Characteristics) display Linear Regulation Current Limitation -I(Vdc)- as a value in VOLTS????

I am calculating my system taking into account the values in mA.

Rafael Krapf

BRASIL

reinhard_larch · ‎2005-05-11

Posted on May 12, 2005 at 07:03

I have a problem with the AN1714 regarding the receiving circuit. It says on page 13 that the passive filters of the demo board have been dimensioned for the 132.5kHz channel. Looking at Figure 12 on page 11 the values for L7 and C36 are 330uH and 4.7nF

But Table 1 on page 18 suggests 6.8nF for C36 and 220uH for L7.

If I use the formula on page 17 to calculate the center frequency fo, I get a value of 127.8kHz with 330uH and 4.7nFn which is further away from the 132.5kHz than the value of 130.1kHz in Table1.

My question: Will there be a major improvement, when using the 132.5kHz channel, changing the values for C36 and L7 from 4.7nF/330uH to 6.8nF/220uH.

Best Regards

Reny

boicuflorin · ‎2005-05-12

Posted on May 13, 2005 at 03:54

Hi Reny,

For L=330uH, C=4.7nF the Quality factor Q = 2.83

For L=220uH, C=6.8nF the Quality factor Q = 4.16

In AN1714 at 17 page it say: ''A Q value betweens 2 and 3 is acceptable''. :|