SLVS503F November 2003 – February 2020 TPS2490 , TPS2491
PRODUCTION DATA.
An integrating capacitor, CT, connected to the TIMER pin provides a timing function that controls the fault-time for both versions and the restart interval for the TPS2491. The timer charges at 25 µA whenever the TPS249x is in power limit or current limit and discharges at 2.5 µA otherwise. The charge-to-discharge current ratio is constant with temperature even though there is a positive temperature coefficient to both. If TIMER reaches 4 V, the TPS2490 pulls GATE to ground, latch off, and discharge CT. The TPS2491 pulls GATE to ground and attempt a restart (reenable GATE) after a timing sequence consisting of discharging CT down to 1 V followed by 15 more charge and discharge cycles. The TPS2490 can be reset by either cycling the EN pin or the UVLO (for example, power cycling). TIMER discharges when EN is low or UVLO or POR are active. The TIMER pin should be tied to ground if this feature is not used.