STEP_VREF_MARGIN_HIGH is a paged register. The STEP_VREF_MARGIN_HIGH command sets the target voltage which the reference voltage changes to when the OPERATION command is set to "Margin High". The contents of this register can be stored to non-volatile memory using the STORE_USER_ALL command.

The actual reference voltage commanded by a margin high command can be found by:

Equation 17.

The margin high range is 0% to 10% of the nominal reference voltage (600 mV) in 2-mV steps. Permissible values range from 0 mV to 60 mV. If a value outside this range is given with this command, the TPS4022 device sets the reference voltage to the upper or lower limit depending on the direction of the setting, asserts SMBALERT and sets the CML bit in STATUS_BYTE and the invalid data bit in STATUS_CML.

Including settings from both VREF_TRIM and STEP_VREF_MARGIN_x commands, the net permissible reference voltage adjustment range is -180 mV to 60 mV (-30% to 10%). If a value outside this range is given with this command, the TPS4022 device sets the reference voltage to the upper or lower limit depending on the direction of the setting, asserts SMBALERT and sets the CML bit in STATUS_BYTE and the invalid data bit in STATUS_CML.

The reference voltage transition occurs at the rate determined by the TON_RISE command if the transition is executed during soft-start. Any transition in the reference voltage after soft-start is complete occurs at the rate determined by the highest programmable TON_RISE.

The default value of STEP_VREF_MARGIN_HIGH is 30 (dec). This corresponds to a default margin high voltage of 60 mV (±10%) .