SLVSFT8F February 2023 – December 2023 TPS7H1111-SEP , TPS7H1111-SP
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
For this design, it is desired that the power good pin asserts when VOUT reaches 90% of its final value (1.62 V).
By using Equation 7 and selecting an RFBPG_BOT value 10 kΩ, the RFBPG_TOP resistor is calculated as shown in Equation 18.
A standard value 44.2 kΩ resistor is selected for RFBPG_TOP. The worst case (highest) VIN(assert_threshold) threshold is then calculated in order to ensure PG is asserted (and the fast charge current is turned-off) before VOUT reaches its desired value. This is determined using Equation 7 along with the maximum VFB_PG(rising) threshold of 313 mV. The VOUT(assert_threshold), max value is determined to be 1.70 V. This is 94% of the final VOUT value which is sufficient margin.
Finally, the typical value of the VOUT(deassert_threshold) is calculated to know when PG will deassert. This is determined using Equation 8 along with the VFB_PG(hysteresis) value of 14 mV. The VOUT(deassert_threshold) value is determined to be 1.58 V. This means that if VOUT falls to 88% of its nominal value, the PG pin will deassert.