XRP7714_1009 Datasheet, PDF (24/29 Pages) Exar Corporation – Quad Channel Digital PWM Step Down Controller

XRP7714
Quad Channel Digital PWM Step Down Controller
Fault and Warning Indication
The GPIOs can be configured to signal Fault or Warning conditions when they occur in the chip.
Each GPIO can be configured to signal one of the following:
• OCP Fault on Channel 1 - 4
• OCP Warning on Channel 1 - 4
• OVP Fault on Channel 1 - 4
• UVLO Fault on VIN1 or VIN2
• UVLO Warning on VIN1 or VIN2
• Over Temperature Fault or Warning
I²C COMMUNICATION
The I²C communication is standard 2-wire communication available between the Host and the IC.
The communication has the option of enabling Packet Error Checking in order to deal with noisy
environments where bit-errors could occur in the communication. This packet error checking is a
CRC-8 code appended to all communication between the Host and the IC.
Each XRP7714 in an I²C -bus system is activated by sending a valid address to the device. The
address always has to be sent as the first byte after the start condition in the I²C -bus protocol
MSB
LSB
6
5
4
3
2
1
0 R/W
Fig. 30: Alignment of I2C address in 8 bit byte
There is one address byte required since 7-bit addresses are used. The last bit of the address byte
is the read/write-bit and should always be set according to the required operation. This 7-bit I²C
address is stored in the NVM. One can program a blank device with the 7-bit Slave address or
select one of the preprogrammed options. The 7-bit address plus the R/W bit create an 8-bit data
value that is sent on the bus.
The XRP7714ILB-0X10-F has an I²C address of 0x10. The internal registers are written by sending
a data value of 0x20 and read by sending a data value of 0x21. This reflects the address being
shifted one bit to the left and the least significant bit being set to reflect a read or write operation
in order to stuff the byte correctly.
The second byte sent to the XRP7714 is the location of a specific register.
Using GPIO3 to select I²C Address
GPIO3 may be used to change the LSB of the 7-bit address. This option can be enabled within the
PowerArchitect^TM software by checking the “Use GPIO3 to control LSB of I2C address” box at the
top right of the “Digital Design” tab. More about the use of this option and other methods of
changing the default I2C address of the part are available in ANP-31 “Power^XR Configuration and
Programming”.
© 2010 Exar Corporation
24/29
Rev. 1.1.4