LM139-N, LM239-N, LM2901-N, LM3302-N, LM339-N

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SNOSBJ3E – NOVEMBER 1999 – REVISED DECEMBER 2014

9 Power Supply Recommendations

Even in low-frequency applications, the LM139-N can have internal transients which are extremely quick. For this

reason, bypassing the power supply with 1.0 µF to ground will provide improved performance; the supply bypass

capacitor should be placed as close as possible to the supply pin and have a solid connection to ground. The

bypass capacitors should have a low ESR.

10 Layout

10.1 Layout Guidelines

Try to minimize parasitic impedances on the inputs to avoid oscillation. Any positive feedback used as hysteresis

should place the feedback components as close as possible to the input pins. Take care to ensure that the

output pins do not couple to the inputs. This can occur through capacitive coupling if the traces are too close and

lead to oscillations on the output.

The optimum bypass capacitor placement is closest to the V+ and ground pins. Take care to minimize the loop

area formed by the bypass capacitor connection between V+ and ground. The ground pin should be connected

to the PCB ground plane at the pin of the device. The feedback components should be placed as close to the

device as possible minimizing strays.

10.2 Layout Example

Figure 38. Layout Example

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Product Folder Links: LM139-N LM239-N LM2901-N LM3302-N LM339-N