News Article
Avago’s Reveals Sophisticated Isolated Gate Drivers
The ACPL-H342 and ACPL-K342 contain an AlGaAs LED which is optically coupled to an integrated circuit with a power output stage and the module is suited to power inverter and motor control applications.
Avago Technologies, a supplier of analog interface components for communications, industrial and consumer applications, has unveiled its latest optically isolated IGBT gate drivers. The 2.5 A peak-output drive ACPL-H342 and ACPL-K342 drivers feature a built-in Miller clamp, Rail-to-Rail output voltage, and under-voltage lockout (UVLO) circuitry. They offer protection against IGBT cross-conduction and current “shoot-through” for safe and efficient power inverter and motor control applications.
Having started to look at the total cost of ownership of their power converter and motor drive systems, developers are concentrating on reducing potential maintenance and field repair costs. As such, system designers now demand isolated gate drivers with integrated features like Active Miller clamp and Rail-to-Rail output for reliable IGBT and power MOSFET operation and protection, especially important in motor drives and renewable energy inverters where downtime cannot be tolerated and field repairs are very costly.
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 says its new gate drive optocouplers feature an industry-best, 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 minimizing 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, minimize 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 (tphl - tplh) 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 ACPL-H342 and ACPL-K342 gate driver key features include
* Built-in IGBT protection
o Active Miller clamp
o UVLO with hysteresis
o No cross conduction between parts: tphl - tplh < 0 guarantee
* High peak output drive current: 2.0 A minimum, 2.5 A maximum
* 15 to 30 V supply voltage operation with rail-to-rail output drive
* High maximum working insulation voltage per IEC/EN/DIN EN 60747-5-5
o ACPL-H342-x60: 891 Vpeak
o ACPL-K342-x60: 1140 Vpeak
* High momentary withstand voltage per UL 1577
o ACPL-H342: 3750 Vrms for 1 minute
o ACPL-K342: 5000 Vrms for 1 minute
* High common-mode transient immunity: 40 kV/µs at 1.5 kV common mode voltage
* Fast propagation delay reduces dead time and increases system efficiency
* 8-lead SSO-8 package (stretched SO-8) is 40% smaller than 8-pin DIP
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 to +105° C.
Avago’s ACPL-H342-000E is priced at $1.45 each in 10,000 piece quantities and the ACPL-K342-000E is priced at $1.60 each in 10,000 pieces.
Samples and production quantities are available now through Avago’s direct sales channel and worldwide distribution partners.
