SNVSAL1C December 2017 – June 2021 LP87702-Q1
The LP87702-Q1 device has programmable voltage monitoring for the BUCKx and BOOST converter output voltages and for VANA, VMON1, and VMON2 inputs. Monitoring of each signal is independently enabled in the PGOOD_CTRL register. Voltage monitoring can be under-voltage monitoring only (PGOOD_WINDOW = 0) or overvoltage and undervoltage monitoring (PGOOD_WINDOW = 1). This selection is common for all enabled monitorings. Section 18.104.22.168describes how the enabled monitoring signals are combined to generate power-good (PG0 and PG1) and interrupts. Monitoring comparators have a dedicated reference and bias block, which is independent of the main reference and bias block.
Nominal level for the output voltage of BUCKx converter is set with BUCKx_VSET in the BUCKx_VOUT register. Overvoltage and undervoltage detection levels, with respect to nominal level, are selected with BUCKx_WINDOW as ± 30 mV, ± 50 mV, ± 70 mV or ± 90 mV. Nominal level for the output voltage of the BOOST converter is set with BOOST_VSET in the BOOST_CTRL register. Available levels are 4.9 V, 5 V, 5.1 V, and 5.2 V. Overvoltage and undervoltage detection levels, with respect to nominal level, are selected with BOOST_WINDOW as ± 2%, ± 4%, ± 6% or ± 8%. Converter monitoring window selection bits are in the PGOOD_LEVEL_3 register.
Input voltage of LP87702-Q1 is monitored at the VANA pin. Nominal level can be selected as 3.3 V or 5 V with the VANA_THRESHOLD bit. Overvoltage and undervoltage detection levels are selected with VANA_WINDOW as ± 5% or ± 10% (nominal). VANA_THRESHOLD and VANA_WINDOW are set in the PGOOD_LEVEL_2 register.
VMON1 and VMON2 inputs can be used for monitoring external rails in the system. VMONx settings are defined in the PGOOD_LEVEL_1 and PGOOD_LEVEL_2 registers. Nominal value for the input level of VMONx is selected with VMONx_THRESHOLD, between 0.65 V to 1.8 V. Higher voltage levels or levels not directly supported can be monitored using an external resistor divider. In this case VMONx_THRESHOLD must be set as 0.65 V to have a high-impedance input, and the resistor divider must scale the monitored level down to 0.65 V at the VMONx pin. Overvoltage and undervoltage detection levels are selected with VMONx_WINDOW as ± 2%, ± 3%, ± 4% or ± 6%.
See Section 7 for more details on the accuracy of the monitoring windows and deglitch filtering.