The OPA690 provides output voltage and current capabilities that are unsurpassed in a low-cost monolithic op amp. Under no-load conditions at 25°C, the output voltage typically swings closer than 1 V to either supply rail. Into a 15-Ω load (the minimum tested load), the device delivers more than ±160 mA.

The specifications described previously, though familiar in the industry, consider voltage and current limits separately. In many applications, the voltage × current, or V-I product is more relevant to circuit operation. See also Figure 6-55, the output voltage and current limitations plot in Section 6.11. The X- and Y-axes of this graph show the zero-voltage output current limit and the zero-current output voltage limit, respectively. The four quadrants give a more detailed view of the OPA690 output drive capabilities, noting that the graph is bounded by a safe operating area of 1-W maximum internal power dissipation. Superimposing resistor load lines onto the plot shows that the OPA690 can drive ±2.5 V into 25 Ω or ±3.5 V into 50 Ω without exceeding the output capabilities or the 1-W dissipation limit. A 100-Ω load line (the standard test circuit load) shows the full ±3.9-V output swing capability; see also Section 6.11.

The minimum specified output voltage and current specifications over temperature are set by worst-case simulations at the cold temperature extreme. Only at cold start-up do the output current and voltage decrease to the numbers shown in Section 6.5 and Section 6.7. As the output transistors deliver power, the junction temperatures increase, decreasing the V_BEs (increasing the available output voltage swing) and increasing the current gains (increasing the available output current). In steady-state operation, the available output voltage and current is always greater than that shown in the overtemperature specifications because the output stage junction temperatures is greater than the minimum specified operating ambient.

To protect the output stage from accidental shorts to ground and the power supplies, output short-circuit protection is included in the OPA690. The circuit acts to limit the maximum source or sink current to approximately 250 mA.