The TPS2410 uses an internal linear error amplifier to keep the external MOSFET from saturating at light load. This feature has the benefits of setting a turn-off above 0 V, providing a soft turn-off for slowly decaying input voltages, and helps droop-sharing redundancy at light load.
Although the control loop has been designed to accommodate a wide range of applications, there are a few guidelines to be followed to assure stability.
Symptoms of stability issues include V(AC) undershoot and possible fast turn-off on large-transient recovery, and a worst-case situation where the gate continually cycles on and off. These conditions are solved by following the rules above. Loop stability should not be confused with tripping the fast comparator due to V(AC) tripping the gate off.
Although not common, a condition may arise where the dc/dc converter transient response may cause the GATE to cycle on and off at light load. The converter experiences a load spike when GATE transitions from OFF to ON because the ORed bus capacitor voltage charges abruptly by as much as a diode drop. The load spike may cause the supply output to droop and overshoot, which can result in the ORed capacitor peak charging to the overshoot voltage. When the supply output settles to its regulated value, the ORed bus may be higher than the source, causing the device to turn the GATE off. While this may not actually cause a problem, its occurrence may be mitigated by control of the power supply transient characteristic and increasing its output capacitance while increasing the ORed load to capacitance ratio. Adjusting the TPS2410 turn-off threshold or using STAT if possible to desensitize the redundant ORing device may help as well. Careful attention to layout and charge-pump noise around the device helps with noise margin.
The linear gate driver has a pull-up current of 290 μA and pull-down current of 3 mA typical.