LM139JB datasheet by Texas Instruments

LM139JB Frequently Asked Questions (FAQs)

• What is the maximum voltage that can be applied to the input pins?
  The maximum voltage that can be applied to the input pins is the supply voltage (VCC) + 0.3V. Exceeding this voltage can cause damage to the device.
• How do I ensure that the comparator output is not oscillating?
  To prevent oscillation, ensure that the input signals are properly filtered and decoupled, and that the output is properly loaded. Additionally, consider adding hysteresis to the comparator by connecting a resistor and capacitor between the output and the non-inverting input.
• What is the minimum input voltage required for the comparator to function correctly?
  The minimum input voltage required for the comparator to function correctly is typically around 1.5V to 2V below the supply voltage (VCC). Operating the comparator at input voltages closer to the supply voltage can result in incorrect operation.
• Can I use the LM139JB as an amplifier?
  No, the LM139JB is a comparator, not an amplifier. It is designed to compare two input voltages and output a digital signal indicating which input is higher. It is not suitable for amplifying small signals.
• How do I choose the correct pull-up resistor value for the output?
  The pull-up resistor value depends on the load current required and the output voltage swing. A general rule of thumb is to choose a resistor value that limits the output current to 1-2mA. A higher value resistor may be required for higher output voltage swings.