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POWER MANAGEMENT

SC905

Analog LDO Voltage Table B

The bit code controls the output voltage of each LDO. The LSB size at the output is 50mV. Output voltage can be set

by writing the proper code to the desired LDO register. See Table B for the bitcodes and their corresponding voltages.

TABLE B - Output Voltage Code Bits for LDOs VANA, VTCXO, VTX, VRX, VPLL

LDO Output

Voltage

2.55V

2.60V

2.65V

2.70V

2.75V

2.80V

2.85V

2.90V

The I2C General Speciﬁcation

The SC905 is a read-write slave-mode I2C device and complies with the Philips I2C standard Version 2.1 dated January,

2000. The SC905 has eight user-accessible internal 8-bit registers. The I2C interface has been designed for program

ﬂexibility, in that once the slave address has been sent to the SC905 enabling it to be a slave transmitter/receiver, any

the SC905 I2C logic, a tight software loop can be designed to randomly access the next register independent of which

allowed if necessary.

SC905 Limitations to the I2C speciﬁcations:

Seven bit addressing is used and ten bit addressing is not allowed. Any general call address will be ignored by the SC905.

The SC905 is not CBUS compatible. The SC905 can operate in standard mode (100kbit/s) or fast mode (400kbit/s).

Supported Formats:

Direct Format - Write

The simplest format for an I2C write is given below. After the start condition [S], the slave address is sent, followed

by an eighth bit indicating a write. The SC905 I2C then acknowledges that it is being addressed, and the master re-

sponds with an 8 bit data byte consisting of the register address. The slave acknowledges and the master sends the

appropriate 8 bit data byte. Once again the slave acknowledges and the master terminates the transfer with the stop

condition [P].

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