Avago Technologies has announced the 2,5 A peak-output drive ACPL-H342 and ACPL-K342 optically isolated IGBT gate drivers that feature a built-in Miller clamp, rail-to-rail output voltage, under-voltage lockout (UVLO) circuitry and protection against IGBT cross-conduction and current ‘shoot-through’ for safe and efficient power inverter and motor control applications.
A Miller clamp allows the control of the Miller current during high dV/dt output transition. It can also eliminate the need for a negative power supply to ensure safe IGBT turn-off by quickly discharging the IGBT’s large gate capacitance to a low level without affecting the IGBT turn-off characteristics. In addition, Avago’s new gate drive optocouplers feature common-mode transient immunity of 40 kV/μs at a 1,5 kV common mode voltage for reliable operation in noisy environments.
The UVLO function causes the output to be clamped whenever there is insufficient power supply voltage for safe operation. The under-voltage lockout protection circuitry ensures that there is sufficient gate drive voltage to switch the IGBTs completely on, therefore minimising IGBT power dissipation. Once the supply voltage exceeds the positive-going UVLO threshold, the UVLO clamp is released, allowing the device output to turn on in response to an input signal.
Efficiency has been a key design goal of the new ACPL-H342 and ACPL-K342 gate drives. Their rail-to-rail output voltage swing and the low output dead time, made possible by low propagation time, minimise driver dissipation and increase efficiency.
Propagation delay is specified to prevent cross conduction of the IGBTs in the high- and low-side half-bridge IGBT configuration that is commonly used in power inverters. Propagation delay difference between two devices is -10 ns minimum to -200 ns maximum. Hence, shoot-through is prevented, thus eliminating a major condition that can cause IGBT damage and shorten operating life.
The devices are available in RoHS-compliant, 8-lead stretched SO-8 packages that are 40% smaller than conventional 8-pin DIP packages. All devices operate over a very wide temperature range of -40°C to +105°C.
For more information contact Marian Ledgerwood, Future Electronics, +27 (0)21 421 8292, [email protected], www.futureelectronics.com
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