SLVS736C February 2008 – October 2023 TPS2550 , TPS2551
PRODUCTION DATA
The TPS2550/51 responds to an overcurrent condition by limiting its output current to the IOC and IOS levels shown in Figure 9-1. Three response profiles are possible depending on the loading conditions and are summarized in Figure 8-3.
One response profile occurs if the TPS2550/51 is enabled into a short-circuit. The output voltage is held near zero potential with respect to ground and the TPS2550/51 ramps the output current to IOS (see Figure 7-3).
A second response profile occurs if a short is applied to the output after the TPS2550/51 is enabled. The device responds to the overcurrent condition within time tIOS (see Figure 8-2). The current-sense amplifier is over-driven during this time and momentarily disables the internal current-limit MOSFET. The current-sense amplifier gradually recovers and limits the output current to IOS.
A third response profile occurs if the load current gradually increases. The device first limits the load current to IOC. If the load demands a current greater than IOC, the TPS2550/51 folds back the current to IOS and the output voltage decreases to IOS x RLOAD for a resistive load, which is shown in Figure 8-3.
The TPS2550/51 thermal cycles if an overload condition is present long enough to activate thermal limiting in any of the above cases. The device turns off when the junction temperature exceeds 135°C (typ). The device remains off until the junction temperature cools 15°C (typ) and then restarts. The TPS2550/51 cycles on/off until the overload is removed (see Figure 7-5 and Figure 7-7) .