DESIGN OF A CUSTOM ASIC INCORPORATING CAN™ AND 1 ...

Figure 2.7 UART/RS232 Serial Port Interface [8].
For those applications that already use an I 2 C [9] bus, the implementation in Figure 2.8 is
most convenient to establish a 1 – Wire® Master. This design makes use of an existing I 2 C bus
controller, such as a microcontroller, or ASIC/FPGA, and some spare space in the program
memory. The advantages to this implementation are its relatively low cost for the features
provided, and the fact that the 1 – Wire® timing is generated by hardware. The DS2482
supports a strong pullup as well as an active pullup. On the downside, the DS2482 cannot drive
as many 1 – Wire® slave devices as the DS2490 or DS2480B. The single-channel version, the
DS2482-100 as shown in Figure 2.8, has a control output for an additional strong pullup (Q1)
circuit as shown in Figures 2.3 through 2.6 [13 – 15].
16