8.3.2 Typical Application for Powering the Negative Rail of an ADC or DAC

Typically, the input voltage to the inverter in applications powering the negative supply of an ADC or DAC is about 5 V. The circuit therefore was optimized for this input voltage range, because the size and amount of capacitors depends on the voltage applied to the capacitors. In order not to over-design, the input voltage range was set to the range required to set a limit for the dc bias of the capacitors. Figure 42 shows a, for an input voltage of 5-V, optimized design. The minimum input voltage to support the full output current is 4.5 V. The maximum input voltage is defined by the dc bias characteristic of the input and C_CP capacitors. If a higher input voltage is required, these capacitors have to be adjusted accordingly.

Figure 42. Typical Application for V_IN ≈ 5 V