33702 Datasheet, PDF (19/24 Pages) Motorola, Inc – 3.0 A Switch-Mode Power Supply with Linear Regulator

Freescale Semiconductor, Inc.
I²C BUS OPERATION
Introduction
The 33702 device is compatible with the I²C interface
standard. SDA and SCL pins are the Serial Data and Serial
Clock pins of the I²C bus.
I²C Command and Data Formats
Communication Start
Communication starts with a START condition, followed by
the slave device unique address. Figure 13 illustrates the data
transfer beginning an I²C communication for a 7-bit slave
address.
S
7-Bit Address
R/W Ack
Figure 13. Communication Using 7-Bit Address
Slave Address Definition
33702 has the two LSB’s address bits defined by the state of
the CLKSEL pin and the ADDR pin.
Note The state of the CLKSEL pin also defines the
configuration of the oscillator synchronization CLKSYN pin.
This feature allows up to four 33702 ICs to communicate in
the same I²C bus, all of them sharing the same high-order
address bits. A different combination of bits A1 and A0 is
assigned to each individual part to assure its unique address.
Figure 14 illustrates the flexible addressing feature for a 7-bit
address. Table 3 provides the definition of the selectable
portion of the device address.
Bits 6 5 4 3 2 1 0
1 1 1 0 1 A1 A0
Fixed Address Selectable
Address
Figure 14. Address Bit Definition for 7-Bit Address
Table 3. Definition of Selectable Portion of Device Address
CLKSEL Pin ADDR Pin
A1
A0
Low
Low
0
0
Low
Open
0
1
Open
Low
1
0
Open
Open
1
1
Writing Data Into the Slave Device
After the address acknowledgment by the slave, DATA can
be written into the slave registers. The R/W bit must be set to 0
so DATA will be read. Figure 15 shows the data write
sequence. Actions performed by the slave device are grayed.
S 7-Bit Address
0 Ack
DATA
Ack
Figure 15. Data Transfer for Write Operations
Data Definition
For the sake of 33702 acting as a slave device, the master
writes a Command Byte and writes one Data Byte. The
Command Byte identifies the kind of operation required by the
master and has two fields, as illustrated in Figure 16:
1. Address field
2. Value field
The address field is selected from the list in Table 4.
Bits 7 6 5 4 3 2 1 0
D7 D6 D5 D4 D3 D2 D1 D0
Address Field Value Field
Figure 16. Command Byte
Table 4. Address Field Definitions
Code
001
010
011
Operation
Voltage Margining
Not Used
Watchdog
Write
W
–
W
Refer to Table 5, page 20, which summarizes the value field
definitions for the entire set of operation options.
MOTOROLA ANALOG INTEGRATED CI_FRC_oU_rIT_MD_oE_rV_eICE_InD_fA_oT_rA_{mation On This Product,}
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33702
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