The control of the multi-phase regulator settings is done using the control registers of the primary BUCK regulator in the multi-phase configuration. The TPS6593-Q1 ignores settings in the following registers of the secondary and, if used, the tertiary and quaternary BUCK regulators :

• BUCKn_CTRL register, except BUCKn_VMON_EN
• BUCKn_CONF register
• BUCKn_VOUT_1 and BUCKn_VOUT_2 registers
• BUCKn_PG_WINDOW register
• Interrupt bits related to the secondary and, if sued, the tertiary and quaternary BUCK regulator, except BUCKn_ILIM_INT, BUCKn_ILIM_MASK and BUCKn_ILIM_STAT

Table 8-2 shows the supported Multi-Phase BUCK regulator configurations and the assigned primary BUCK regulator in each configuration.

When the BUCK regulators are configured in 3-phase or 4-phase configurations, there are exceptions to the above list of registers that the TPS6593-Q1 ignores. The configuration registers are user-configurable for the voltage monitor function on BUCK3 and BUCK4 in a 4-phase configuration and BUCK3 in a 3-phase configuration. The UV/OV voltage monitors of these BUCK3 and BUCK4 regulators can be used to monitor external supply rails, by connecting these external rails to the FB_Bn pins of these BUCK3 and BUCK4 regulators. The following list of registers and register bits for BUCK3 and BUCK4 can be used to enable and set the target voltage for the external voltage monitoring function under such configuration:

• BUCKn_VMON_EN bit
• BUCKn_VSEL bit
• BUCKn_SLEW_RATE
• BUCKn_VOUT_1 and BUCKn_VOUT_2 registers
• BUCKn_PG_WINDOW register

Customers are responsible for the values set in these registers when using BUCK3 or BUCK4 to monitor an external supply under the 3-phase or 4-phase configuration. If the voltage monitor function is not used under such a scenario, the FB_Bn pins must be connected to the reference ground, and the BUCKn_VMON_EN bits must be set to '0'.