UVLO function is implemented for V_CC and V_EE pins to prevent an under-driven condition on IGBTs and MOSFETs. When V_CC is lower than UVLO_R at device start-up or lower than UVLO_F after start-up, the voltage-supply UVLO feature holds the effected output low, regardless of the input forward current as shown in Table 8-2. The V_CC UVLO protection has a hysteresis feature (UVLO_hys). This hysteresis prevents chatter when the power supply produces ground noise which allows the device to permit small drops in bias voltage, which occurs when the device starts switching and operating current consumption increases suddenly.

When V_CC drops below UVLO_F, a delay, t_{UVLO_rec} occurs on the output when the supply voltage rises above UVLO_R again.

UVLO is referenced to COM on the UCC23514E, and to V_EE in all other versions.

Figure 8-8 UVLO functionality