MXL1014

To adjust the frequency digitally, connect a voltage-output DAC to ⅡN via a series resistor, as shown. The converter output ranges from 0 V at zero to 2.5(255/256) V at full scale. Current injected by the converter into ⅡN, therefore, ranges from 0 to 748 μA. The 2.5-V reference and 1.2-Ω resistor inject a constant 2μA, so (by superposition) the net current into ⅡN ranges from 2 μA (at a code of 00000000) to 750μA (at 1111 1111). The quad DAC IC operates from 5 V or ±5 V. As described below, it can also provide digital control of FADJ and DADJ. For fine adjustments (±70 percent), apply a control voltage in the range ±2.3 V to the frequency adjust (FADJ) terminal. Both FADJ and ⅡN have wide bandwidths that allow the output frequency to be modulated at a maximum rate of about 2 MHz. As the more linear input, ⅡN is preferred for open-loop frequency use in a phase-locked loop. For digital control of FADJ, conftgure a DAC and external op amp (as shown in the figure) to produce an output ranging from -2.3 V (00000000) to 2.3 V (1111 1111).

The Maxim MXL1013 is a precision dual op amp that upgrades the performance of popular devices such as the MC1458/MC1558, LM158 and OP221. The Maxim MXL1014 is a precision quad op amp that directly upgrades designs in the industry-standard 14-pin DIP configuration and has specifications similar to the LT1013. The MXL1013 and MXL1014 are pin compatible with industry standards such as the LT1013 and LT1014.

Precision specifications include: 40V offset voltage, 0.3V/ drift (TCVOS), 117dB CMRR, and 120dB PSRR. While supply current is typically only 350A per amplifier, the outputs can source and sink more than 20mA.

Both the MXL1013 and the MXL1014 can be operated from a single +5V power supply. The input voltage range includes ground and the outputs swing to within a few millivolts of ground.