RAA271000 datasheet(28/105 Pages) RENESAS

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R16DS0051EU0101 Rev.1.01

Page 28

May 23, 2022

RAA271000 Datasheet

7.1.2

Buck Regulator Startup Ramp Rate

The rate at which the buck regulators ramp up during startup can be factory programmed to different options. This

ramp rate depends on the voltage range used for the buck regulator and therefore, the value of VOUTFBDIV.

Table 9 shows the factory programmable startup ramp rate options.

7.1.3

Buck 1 Additional Features

In addition to the specifications previously mentioned that are common to all buck channels, Buck 1 contains

some additional features. Buck 1 includes Dynamic Voltage Scaling (DVS) to quickly change between two

predetermined voltage levels. Buck 1 also uses an internal high-side NMOS device, so a bootstrap capacitor is

required and ties between pins BOOT and PH1.

7.1.4

Dynamic Voltage Scaling (DVS)

While all buck regulators can change output voltage by changing the DAC value, Buck 1 has several options to

achieve DVS. There are two independently programmable voltage settings for the Buck 1 controller, which can set

the output voltage. These settings are DVS0 and DVS1. By changing the DVS number selected, the

corresponding output voltage is selected. There are two methods to select the DVS output voltage.

▪ Method 1: Use internal registers to select DVS by writing to the BUCK1_DVSSELECT bit in the

BUCK1_DVSSEL register using SPI or I2C. To use this method, the BUCK1_DVSCTRL bit has to be set to 0b0

for the corresponding buck. The BUCK1DVSSELECT bit allows you to switch between the two different DVS

settings, each corresponding to a set of DVS registers holding the DVS information.

For example, DVS0 corresponds to BUCK1_DVS0VOUT92[7:0] and BUCK1_DVS0VOUT10[1:0]. The two

▪ Method 2: Using the GPIO3 pin to achieve DVS, there are five variations depending on the IO_PINMODE

Note: To use DVS using the GPIO/MPIO pins requires IO_PINMODE to be OTP programmed before a start-up

Table 9. Buck Regulator Ramp Rate Options

VOUTFBDIV Value

Option Number

Buck 1 Ramp Rate (mV/µs)

Buck 2-5 Ramp Rate (mV/µs)

1.0 Options

1.0

1.2

1.0

163

1.0

14.4

7.2

1.0

0.75 Options

0.75

1.6

0.75

3.2

0.75

6.4

0.5 Options

0.501.2

1.2

0.512.4

2.4

0.5

266

0.25 Options

0.25

1.2

0.25

2.4

0.25

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