OPA548 Power handling capability

Hello Visakh,

The OPA548 will internally limit the current output to about 5 Amperes peak so it will not be possible to achieve a current level higher even when in pulse operation. The SOA curve shown on Fig 2 of data sheet page 8 does make mention of pulse operation. The dashed lines define the SOA for pulse operation. The maximum P_D is a function of voltage across the particular output transistor | V_S | - | V_O | and the output current. According to this figure the maximum P_D is 50 W and with 10 V across the output transistor the current is the maximum of 5 Amperes and that is with T_C = 25 C. The maximum allowable P_D decreases with higher T_C. Also, do observe the note on Fig 2 stating "Pulse operation only - Limit RMS current to <= 3 A."

Regards, Thomas

PA - Linear Applications Engineering

Visakh,

The thermal characteristics of OPA548 are strong function of the choice of IC package and the type of heat sink used - see below and on page 10 of the datasheet - therefore, there is no way to provide a single peak pulse power vs time graph to cover the op amp maximum power handling capabilities; actually, with proper external heat sink OPA548 may be able to handle continuous maximum power of 180W (P=Vsupply_max * Iout_max= 60V*3A).

Having said that, however, OPA548 has a programmable current limit range of up to +/-5A and an integrated thermal shutdown that will protect the amplifier from damage - the current limit sets the maximum short circuit output current while the the thermal protection circuitry disables the output (it becomes high impedance) when the junction temperature reaches approximately 160 deg C, allowing the device to cool down, enabling it again when the junction temperature reaches around 140 deg C.