XRP7704

REV 1.1.0

Quad-Output Digital PWM Buck Controller

Output Voltage Setting and Monitoring

The Output Voltage setting is controlled by the SET_VOUT_TARGET_CHx register. This register allows the user

to set the output voltage with a resolution of 50mV for output voltages between 0 and 2.5V and with a resolution

of 100mV for output voltages between 2.6V and 5.1V. Output voltages higher than 5.1V can be achieved by

adding an external voltage divider network. The output voltage of a particular channel can be read back using the

READ_VOUTx register.

Output Voltage from 0.9V to 5.1V

Per the equation below, for values between 0.9V and 5.1V the output voltage is equal to the binary number stored

in the SET_VOUT_TARGET_CHx register multiplied by 50mV. When programming an output voltage from 2.6V

to 5.1V, odd binary values should be avoided. As a result, the set resolution for an output voltage higher than

2.5V is 100mV.

Output VOUT Higher Than 5.1V

To set the output voltage higher than 5.1V, the user needs to add an external voltage divider. The resistors used

in the voltage divider should be below 10kΩ. The SET_VOUT_TARGET_CHx register should be set to 0x32

which is equivalent to an output voltage of 2.5V without the external divider network. The output voltage regulation

in this case might exceed 2% due to extra error from the resistor divider. R1 and R2 follow the definition below.

External divider network for high output voltage

Output Voltage Lower Than 0.9V

The XRP7704 can be programmed to regulate an output voltage lower than 0.9V. However, in this case the

specification of +-2% output voltage accuracy may be exceeded.

EXAR CONFIDENTIAL. PROPRIETARY. DO NOT DISTRIBUTE OR COPY.

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