New Industry Products

High-Current IGBT Gate Driver with Active Miller Clamp

December 11, 2018 by Paul Shepard

The NCD5702 from ON Semiconductor is a high-current, high-performance, stand-alone IGBT driver for high power applications that include solar inverters, motor control and uninterruptible power supplies. The device offers a cost-effective solution by eliminating many external components.

Typical applications are expected to include solar inverters, motor controls, uninterruptible power supplies, rapid shutdown for photovoltaic systems, and so on.

Device protection features include Active Miller Clamp, accurate UVLO, EN input, DESAT protection and Active open-drain FAULT output. The driver also features an accurate 5.0 V output and separate high and low (VOH and VOL) driver outputs for system design convenience.

The driver is designed to accommodate a wide voltage range of bias supplies including unipolar and bipolar voltages. It is available in a 16-pin SOIC package.

Features include:

  • High Current Output (+4/-6 A) at IGBT Miller Plateau Voltages
  • Low Output Impedance of VOH & VOL for Enhanced IGBT Driving
  • Short Propagation Delays with Accurate Matching
  • Direct Interface to Digital Isolator/Opto-coupler/Pulse Transformer for Isolated Drive, Logic Compatibility for Non-isolated Drive
  • Active Miller Clamp to Prevent Spurious Gate Turn-on
  • DESAT Protection with Programmable Delay
  • Enable Input for Independent Driver Control
  • Tight UVLO Thresholds for Bias Flexibility
  • Wide Bias Voltage Range including Negative VEE Capability
  • This Device is Pb-Free, Halogen-Free and RoHS Compliant

The NCD5702 driver family is equipped with many features which facilitate a superior performance IGBT driving circuit. Foremost amongst these features is the high drive current capability. The drive current of an IGBT driver is a function of the differential voltage on the output pin.

The drive current tends to drop off as the output voltage goes up (for turn-on event) or goes down (for turn-off event). The most critical phase of IGBT switching event is the Miller plateau region where the gate voltage remains constant at a voltage (typically in 9- to 11-V range depending on IGBT design and the collector current), but the gate drive current is used to charge/discharge the Miller capacitance.

By providing a high drive current in this region, a gate driver can significantly reduce the duration of the phase and help reducing the switching losses. The NCD5702 addresses this requirement by providing and specifying a high drive current in the Miller plateau region. Most other gate driver ICs merely specify peak current at the start of switching - which may be a high number, but not very relevant to the application requirement. It must be remembered that other considerations such as EMI, diode reverse recovery performance, etc., may lead to a system level decision to trade off the faster switching speed against low EMI and reverse recovery.

However, the use of NCD5702 does not preclude this trade−off as the user can always tune the drive current by employing external series gate resistor. Important thing to remember is that by providing a high internal drive current capability, the NCD5702 facilitates a wide range of gate resistors. Another value of the high current at the Miller plateau is that the initial switching transition phase is shorter and more controlled.

Finally, the high gate driver current (which is facilitated by low impedance internal FETs), ensures that even at high switching frequencies, the power dissipation from the drive circuit is primarily in the external series resistor and more easily manageable. Experimental results have shown that the high current drive results in reduced turn−on energy (EON) for the IGBT switching.

Summary of benefits:

  • Reduced switching losses and short switching times
  • Full enhancement of IGBT
  • Prevents Spurious Gate Turn-on
  • Enhanced programmable protection