Datasheet

µC

PWM

FAULT

3-PHASE

INPUT

ISO 5500

ISOLATIONBARRIER

ISO5500

SLLSE64C –SEPTEMBER 2011–REVISED JUNE 2013

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APPLICATION INFORMATION

TYPICAL APPLICATION

Figure 61 shows the typical application of a three-phase inverter using six ISO5500 isolated gate drivers. Three-

phase inverters are used for variable-frequency drives to control the operating speed of AC motors and for high

power applications such as High-Voltage DC (HVDC) power transmission.

The basic three-phase inverter consists of three single-phase inverter switches each comprising two ISO5500

devices that are connected to one of the three load terminals. The operation of the three switches is coordinated

so that one switch operates at each 60 degree point of the fundamental output waveform, thus creating a six-

step line-to-line output waveform. In this type of applications carrier-based PWM techniques are applied to retain

waveform envelope and cancel harmonics.

Figure 61. Typical Motor Drive Application

RECOMMENDED ISO5500 APPLICATION CIRCUIT

The ISO5500 has both, inverting and non-inverting gate control inputs, an active low reset input, and an open

drain fault output suitable for wired-OR applications. The recommended application circuit in Figure 62 illustrates

a typical gate drive implementation using the ISO5500.

The four 0.1 μF supply bypass capacitors provide the large transient currents necessary during a switching

transition. Because of the transient nature of the charging currents, low current (20 mA) power supplies for V

CC2

and V

EE-P

suffice. The 100 pF blanking capacitor disables DESAT detection during the off-to-on transition of the

power device. The DESAT diode and its 100 Ω series resistor are important external protection components for

the fault detection circuitry. The 10 Ω gate resistor limits the gate charge current and indirectly controls the IGBT

collector voltage rise and fall times. The open-drain fault output has a passive 3.3 kΩ pull-up resistor and a

330pF filtering capacitor. In this application, the IGBT gate driver will shut down when a fault is detected and will

not resume switching until the micro-controller applies a reset signal.

Product Folder Links :ISO5500