NXP Semiconductors
UMxxxxx
Install Guide
All information provided in this document is subject to legal disclaimers.
Preliminary 1
— September 6, 2013
© NXP B.V. 2013. All rights reserved.
57 of 70
7.2.1 Bus1 Bus Buffer (PCA9617A)
I2C signals from the Fm+ Development Board (OM13260), called SCL1 and SDA1, are applied to the
high voltage or ‘B’ Side of IC1 (PCA9617A). The required pull up resistors on this section of Bus1 are on
the Fm+ Development Board (OM13260).
Signals on the low voltage or ‘A’ Side of IC1 are connected to a selection of pull up resistors selected by
either JP5 (for SCL) or JP3 (for SDA), and the low voltage or ‘A’ Side of the second PCA9617A, IC3.
Loading capacitors, C31 for SCL and C51 SDA, can be placed on the low voltage section of the bus. To
accommodate two different footprints IC1 (TSSOP8) and IC2 (HWSON8) are connected in parallel, but
only one part is installed. Installing JP4 disables the Bus Buffer. See figure 7.4
Fig 7.4 Bus1 Bus Buffer
7.2.2 Bus2 Bus Buffer (PCA9617A)
I2C signals on the low voltage bus are also connected to the A side of the second PCA9617A Bus Buffer
device, IC3. To accommodate two different footprints IC3 (TSSOP8) and IC4 (HWSON8) are connected
in parallel, but only one device is installed. Installing JP6 disables the Bus Buffer. See figure 7.5
I2C signals from the high voltage or ‘B’ Side of IC3 (PCA9617A) are passed back to the Fm+
Содержание OM13260
Страница 71: ......