The TPS737 internal current limit helps protect the regulator during fault conditions. Foldback current limit helps protect the regulator from damage during output short-circuit conditions by reducing current limit when V_OUT drops below 0.5 V. See Figure 5-17 in the Typical Characteristics section.

From Figure 5-17, approximately –0.2 V of V_OUT results in a current-limit of 0 mA. Therefore, if OUT is forced below –0.2 V before EN goes high, the device can possibly not start up. In applications that work with both a positive and negative voltage supply, the TPS737 must be enabled first.