The TPS542A50 output voltage can be adjusted in ~0.028% increments from –20% to +10% of the set output voltage. This function can only be performed after PGOOD goes high. During programming mode, these registers are read only.

For positive margin, write to 0x02 and 0x03 registers. Writing only to the 0x02 register does not adjust the output voltage. Writing to both registers, 0x02 and 0x03, does adjust the output voltage. Bits [7:3] of register 0x02 must be equal to 0000 for a positive output voltage adjustment. Bits [7:3] of register 0x02 must be 1111 for a negative output voltage adjustment.

• Writing 0x01 to 0x02 register and 0x66 to 0x03 register will margin the output voltage +10%. The output voltage will transition with a slew rate of soft start.
• Writing 0xFD to 0x02 register and 0x34 to 0x03 register will margin the output voltage -20%.
• Writing 0x01 to the 0x03 register will step the output voltage margin by one positive step. The 0x02 register does not have to be written for small positive steps.