Intel PXA250 and PXA210 Applications Processors

I2C
7.1.2 Digital-to-Analog Converter (DAC)
Figure 7-1 shows the schematic for connecting the I 2 C interface to a Linear Technology
micropower DAC. The DAC output is connected to the buck converter feedback path and is
controlled by the I 2 C bus interface unit. The DAC can modify the voltage of the feedback path,
which effects the processor core voltage.
Figure 7-1. Linear Technology DAC with I 2 C Interface
DC3P3V
R165 1.00M
U30
4
VCC
LTC1663
SA_I2C_SDA
1
SDA
VOUT
3
SA_I2C_SCL
5
SCL
GND
2
LTEP
LTC1663C35
A8752-01
The signals SA_I2C_SDA and SA_I2C_SCL correspond to the applications processor signals
SDA and SCL, respectively.
7.1.3 Other Uses of I 2 C
Figure 7-2 shows the I 2 C signals passing through an analog switch to a compact flash socket. Since
the CF socket has all of the signals to support two CF cards, and this design only uses one CF card,
the signals meant for a second card are being used for alternate functions. If you decide not to use a
CF card, a different application using a CF card socket could be designed to utilize the I 2 C bus
interface unit. If this alternate function is used, the I 2 C bus can be enabled to the CF socket by
asserting the signal SA_I2C_ENAB shown in the diagram. If the user decides to use a CF Card,
negate the SA_I2C_ENAB signal so the I 2 C bus traffic does not interfere with the CF card.
Note:
The CF card socket is disabled if a device is inserted in the expansion bus.
7-2 PXA250 and PXA210 Applications Processors Design Guide