8.3.9.1 Dynamic Voltage Scaling

The device has a dynamic voltage scaling (DVS) function which lets you change the output voltage in a controlled way during operation. Figure 16 shows a simplified block diagram of the DVS function. The VSEL pin controls a multiplexer which selects either the VOUT1 register or the VOUT2 register to control the set voltage. The ramp control block detects when the target output voltage is different from the actual output voltage and ramps the output voltage to the target voltage in 25-mV steps. You can use the 2-bit SLEW parameter in the Control register to select one of four slew rates from 0.5 V/ms to 10 V/ms.

The device starts a DVS ramp when you change the logic level on the VSEL pin or program to a new value in the active VOUT register.

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Figure 16. Dynamic Voltage Scaling Block Diagram

Note that if you change the contents of the active VOUT register or change the state of the VSEL pin during start-up (that is, before the end of the soft start), the converter uses the new value immediately and does not ramp gradually to the final value.

Figure 17 shows the timing diagram when you use the VSEL pin to change between the output voltage values in the VOUT1 and VOUT2 registers.

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Figure 17. DVS Timing Diagram Using the VSEL Pin

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Figure 18 shows the timing diagram when you use the I²C interface to change the output voltage value in one of the VOUT registers.

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Figure 18. DVS Timing Using the I²C Interface