2.5-A isolated gate driver offers 40-percent faster propagation delays for industrial applications

October 02, 2012 // By Paul Buckley
Texas Instruments Incorporated has introduced an isolated gate driver for insulated-gate bipolar transistors (IGBTs) and MOSFETs that is 40 percent faster than equivalent optical gate drivers.

The input TTL logic and output power stage in the ISO5500 are separated by a capacitive, silicon dioxide (SiO2) isolation barrier that doubles the lifetime of the device compared to optocouplers and magnetic isolators. When used with isolated power supplies, the device provides for safer, more reliable electronics by blocking high voltages, isolating ground and preventing noise currents from entering the local ground and interfering with or damaging sensitive circuitry.                                                                 

The ISO5500 provides over-current protection, while an under-voltage lockout circuit monitors the output power supply to ensure sufficient gate drive voltage in motor control, motion control, industrial inverter and switch-mode power supply applications. If the output supply drops below 12 V, the gate driver outputs transitions to a logic-low state, turning off the power transistor. This prevents the device from overheating and damage. The new gate driver is qualified for operating at extended temperatures from –40 to +125C.

To provide secondary power supply to the ISO5500, the SN6501 transformer driver can be used in conjunction with a transformer, rectifier and a regulator. The result is a small, low-cost, high-efficiency, low electro-magnetic interference (EMI), solution for generating the isolated power to the system.

The ISO5500 offers a maximum propagation delay of 300 ns enables faster control of the motor.

Maximum device-to-device skew is 45 ns, which is 80 percent better compared to optical gate drivers. This is essential for H-bridge applications, such as motor control and power inverters, to ensure accurate switching performance.              

The device offers 4 kV electrostatic discharge (ESD) on all pins to ensure high reliability, preventing damage to the device in harsh environments.

The device also supports 3.3-V and 5-V supplies, enabling the use of a single device across 3.3-V and 5-V applications. It also eliminates the need for a level translator, reducing system cost and device count.

The ISO5500 complements TI’s microcontroller portfolio for various motor and digital power control applications allowing for isolation of