Automotive The LM1949 Switching Application Circuit in Figure 7 shows a darlington connection but only one of the driving transistors is identified. What is the unidentified transistor? Q1 in figures 1, 5, and 7 refers to the two transistors shown, this is a single Darlington Power transistor. Both transistors are included inside the TIP121 and the 2N6044 package. It would have been more obvious if we had shown a dotted box around the two transistors to let you know the unidentified transistor is part of the darlington pair. The TIP121 is a 5 Amp darlington transistor available from ON Semiconductor and the 2N6044 is an 8 Amp darlington transistor available from several suppliers Relevant Part: LM1949 How can the LM2907 be used to measure input frequency if there are variations in the V+ power supply voltage? Proper and repeatable operation of the LM2907/17 series demands a stable supply voltage, as all functions have some relationship to the V+ voltage (see the formulae in the data sheet). If a stable power supply voltage is not available the LM2917 should be used, since the LM2917 has an internal zener diode that gives a reasonably constant voltage at the V+ pin. However, the LM2917 does require an additional current limiting resistor to be used between the external power supply and the V+ pin to protect the zener Relevant Part: LM2907 What is the temperature coefficient of the frequency-to-voltage transfer function of the LM2907? The temperature coefficient of the transfer function is negative. For a given frequency, the output voltage drops about 0.5% with a temperature increase from 25 degrees C to 85 degrees C. For more details please refer to our datasheet Relevant Part: LM2907 Are the LM9040 or LM9044 devices suitable for use with ''wide band'' or ''narrow band'' lambda sensors? The LM9040 and LM9044 devices are suitable for use only with Narrow Band Lambda Sensors that provide an output voltage between 0.0Vdc and 1.0Vdc Relevant Part: LM9044;LM9040