UG167: Si8281-EVB User s Guide This document describes the operation of the Si8281-EVB. KEY POINTS The Si8281 Evaluation Kit contains the following items: Discusses hardware overview and setup, Si8281-EVB including: Si8281CD-IS installed on the evaluation board. Si8281 low voltage side connections. DC-DC operation. Si8281 isolated gate drive connections. Offers alternative configurations. Demonstrates driver functionality. Shows Si8281-EVB schematics and silkscreen/copper layout. Includes the bill of materials and ordering guide. Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 1 Rev. 0.1 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice December 20, 2021 1UG167: Si8281-EVB User s Guide Overview and Setup 1. Overview and Setup 1.1 Hardware Si8281-EVB can be used to demonstrate the isolated gate drive capabilities of the installed Si8281CD-IS. The Si8281 includes a DC-DC converter used to supply isolated power to the gate driver. Si8281 Low Voltage Side Connections Supply power to the input side of Si8281 by applying 5.0 V to VIN at terminal block J1. LED D4 above terminal block J1 illuminates to DC show power applied. A jumper must be installed at JP2 as VDDA is powered by the same supply as VIN. J6J10 single pin headers provide access to the IN+, IN, RSTb inputs, and FLTb and RDY outputs of the Si8281. These signals can be brought out to an external microcontroller using a ribbon cable (not supplied). FLTb is an open drain output and has a weak pull-up resistor and LED D11 in series to VDDA. The open drain output allows multiple gate drivers FLTb outputs to share the same microcontroller input. Driver functionality can be exercised without microcontroller by applying a GNDA referenced PWM signal from a function generator to the IN+ and IN inputs. Maximum input voltage is VDDA. DC-DC Operation The isolated DC-DC converter is set to generate (with respect to VMID) 15 V for VDDB and 11 V for VSSB. LED D5 illuminates when VDDB is powered. A jumper must be installed at JP1 to power VDDB from the DC-DC output. Si8281 Isolated Gate Drive Connections There are four different load options for Si8281 gate driver: 1. Through holes for a MOSFET or an IGBT in a TO-247 package (not supplied) at Q1. 2. Through holes for a MOSFET or an IGBT in a TO-220 package (not supplied) at Q2. 3. Through holes for a capacitor (not supplied) at C17. 4. Pads for a 1206-size surface mount capacitor (not supplied) at C11. From top to bottom, the through holes for the transistor leads are Source, Drain, and Gate. Load transistors are biased by applying voltage across VPWR and VMID terminals of J2. This voltage should not exceed the rated V of the transistor or 300 V, whichever is DS lower. Supply voltage constraints are summarized in the table below. Note: Si8281 can drive the gate of either high-side or low-side MOSFET or IGBT in a bridge configuration. When used as a high-side gate driver, VMID is connected to the load. When used as a low-side gate driver, VMID is the return for the load. For capacitive loads, capacitor value should be chosen to match the gate capacitance of the desired transistor. Supply voltage constraints are summarized in the table below. Table 1.1. Supply Voltage Constraints 3.0 V VIN GNDA = VDDA GNDA 5.5 V VSSB VMID < VDDB UVLO+ < VDDB VSSB < 30 V VPWR < V (Q) DS VPWR < 300 V GNDA VSSB < 5 kV Note: 1. UVLO+ for the Si8281CD-IS is 12.3 V typically. Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 2 Rev. 0.1 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice December 20, 2021 2