OPA549: Current limit Tolerance & Offset.

Hello Louis,

The OPA549 datasheet provides one assurance regarding the current limit tolerance and that is  -  Current Limit Tolerance is ±200 mA typical, ±500 mA maximum, for VS = ±30V, RCL = 7.5kΩ, ILIM = ±5A, RL = 4Ω, in a high-speed test with TJ = +25°C. Thus, for a fast 5 Ampere output current test under these very specific conditions the tolerance is ±4% typical, ±10% maximum. However, this only applies to this specific 5 Ampere set of conditions and the tolerance may be tighter or looser under another other set of conditions. No assurances are provided as to what it will be for other cases.

The OPA549 datasheet does provide a Typical Characteristics curve showing Current Limit vs Supply Voltage that should be useful for approximating the current limit for the current levels that you are interested in using. It appears from the graph that the typical tolerance appears to be in the same range for each different current curve. The tolerance appears to tighten with higher supply voltage.

Do note however that the OPA549 datasheet states on Pg. 8 in the Adjustable Current Limit section "Operation of the OPA549 with current limit less than 1A results in reduced current limit accuracy. Applications requiring lower output current may be better suited to the OPA547 or OPA548." This is something to consider with your lower current levels.

Regards, Thomas

Precision Amplifiers Applications Engineering