In order to pass information through the reinforced isolation barrier, the e-diode must be forward biased and requires between 7mA to 16mA of forward current to operate. Input resistors are paired with buffers or a discrete NMOS transistor to set the forward current IF . The input stage can be reverse biased with a second UCC23513 for interlock functionality by connecting anode to cathode, and cathode to anode. The output stage has a 33V max output drive with a peak current rating of 3A which can drive IGBTs, MOSFETs and SiC FETs. The six pin SO6 package provides greater than 8.5 mm of creepage and clearance and it makes the UCC23513 a drop in replacement for most single channel opto-coupled gate drivers. This application report will present an overview of three configurations in order to drive the input stage of the UCC23513. Different configurations include: operating with one discrete NMOS driving the cathode, single buffer and dual buffers to drive the input.
For the different configurations presented in Figure 2, Figure 3 and Figure 4, the following assumptions have been made:
- VSUP = 5V (5% tolerance)
- VF = 1.8 ~ 2.2V
- RM1 = 0.25 ~ 1.0Ω
- Manufacture's tolerance for REXT = +/- 3%
- Target current for IF = 11mA