Philips ST7SB - Manual (Page 8)

3 - Configuring and Connecting to Your Socket Board ST7SB Socket Board User Guide
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Configure for other VDD
To configure your socket board to use a VDD other than 3.3V or 5V, you will have
to calculate the required serial resistance and install the necessary resistors in the
area labelled OTHER that is provided on your socket board. To do this:
1 Calculate the serial resistance for the voltage you want, using the formula:
R
VDD . OTHER
= (50 / V
VDD . OTHER
) -10
R
VDD . OTHER
: is the serial resistance in K
Ω to be installed in the OTHER area on
the socket board.
V
VDD . OTHER
: is the desired VDD voltage.
2 Install the necessary resistors in the OTHER area on the socket board. Figure 3
shows one possible solution for the example in Step 1.
3 Set the VDD jumper to the OTHER position (see Figure 2 ).
Figure 3: Installing serial resistors
Example to obtain a V
VDD . OTHER
of 4V:
R
VDD . OTHER
= (50 / 4) - 10 = 2.5 K
Ω