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TLV9062: Triangular wave generator

Part Number: TLV9062
Other Parts Discussed in Thread: TINA-TI, TLV9052, TLV9002

Hi Team,

A customer simulated a triangular wave generator in TINA-TI based on the circuit from SLAU508 document. Please refer to the waveform and schematic diagram below. His target output frequency range is 5-25 KHz. He used the potentiometers in the circuit to adjust the amplitude and frequency of the triangle wave. Aside from the TLV9062, can you please suggest a better opamp for this application.

Regards,

Danilo

  • Hello Danilo,

    From SLAU508, the necessary slew rate and GBW can be found.  Assuming a signal amplitude of 2.5V, which is conservative as you should not rail the outputs, and a signal frequency of 25kHz, you would need an op amp with a slew rate of 0.25V/us (equation 11).  Similarly, from equation 12 you would need a GBW of at least 475kHz.  Let's call it 1MHz with margin.  Additionally, you need an amplifier with rail-to-rail output capabilities.  Finally, it would be a good idea to have an amplifier with FET inputs to avoid bias current issues.  For this, look for an amplifier with bias current in the pA or fA range.

    The TLV9062 meets all these requirements.  In fact, you could probably use a slower device, such as the TLV9052 or the TLV9002.  However, I would warn you that the propagation delay of the amplifier is not specified.  The propagation delay will be set by the slew rate plus the internal propagation time of the device.  This internal time is not specified for an op amp.  So, it may be wise to consider using a true push-pull comparator here.

    One more word to the wise: avoid railing the output of the amplifier.  This will cause output overload recovery issues, which slow things down.

    Regards,
    Daniel