UCC23511 is a single channel, isolated gate driver with opto-compatible input for power semiconductor devices, such as MOSFETs, IGBTs, or SiC MOSFETs. It is intended for use in applications such as motor control, industrial inverters, and switched-mode power supplies. It differs from standard opto isolated gate drivers as it does not have an LED input stage. Instead of an LED, it has an emulated diode (e-diode). To turn the e-diode "ON", a forward current in the range of 7mA to 16mA should be driven into the Anode. This will drive the gate driver output High and turn on the power FET. Typically, MCU's are not capable of providing the required forward current. Hence a buffer has to be used between the MCU and the input stage of UCC23511. Typical buffer power supplies are either 5V or 3.3V. A resistor is needed between the buffer and the input stage of UCC23511 to limit the current. It is simple, but important to choose the right value of resistance. The resistor tolerance, buffer supply voltage tolerance and output impedance of the buffer, have to be considered in the resistor selection. This will ensure that the e-diode forward current stays within the recommended range of 7mA to 16mA. Detailed design recommendations are given in the Section 9.1. The current driven input stage offers excellent noise immunity that is need in high power motor drive systems, especially in cases where the MCU cannot be located close to the isolated gate driver. UCC23511 offers best in class CMTI performance of >150kV/us at 1500V common mode voltages.

The e-diode is capable of 25mA continuous in the forward direction. The forward voltage drop of the e-diode has a very tight part to part variation (1.8V min to 2.4V max). The temperature coefficient of the forward drop is <1.35mV/°C. The dynamic impedance of the e-diode in the forward biased region is ~1Ω. All of these factors contribute in excellent stability of the e-diode forward current. To turn the e-diode "OFF", the Anode - Cathode voltage should be <0.8V, or I_F should be <I_FLH. The e-diode can also be reverse biased up to 13V (14V abs max) in order to turn it off and bring the gate driver output low. The large reverse breakdown voltage of the input stage provides system designers the flexibility to drive the input stage with 12V PWM signals without the need for an additional clamping circuit on the Anode and Cathode pin.

The output power supply for UCC23511 can be as high as 33V (35V abs max). The output power supply can be configured externally as a single isolated supply up to 33V or isolated bipolar supply such that V_CC-V_EE does not exceed 33V, or it can be bootstrapped (with external diode & capacitor) if the system uses a single power supply with respect to the power ground. Typical quiescent power supply current from V_CC is 1.2mA (max 2.2mA).