ZHCSH45B June 2017 – October 2021 TPS7A83A
PRODUCTION DATA
PSRR is a measure of how well the LDO control loop rejects signals from VIN to VOUT across the frequency spectrum (usually 10 Hz to 10 MHz). Equation 9 gives the PSRR calculation as a function of frequency for the input signal [VIN(f)] and output signal [VOUT(f)].
Even though PSRR is a loss in signal amplitude, PSRR is shown as positive values in decibels (dB) for convenience.
Figure 9-6 shows a simplified diagram of PSRR versus frequency.
An LDO is often employed not only as a dc/dc regulator, but also to provide exceptionally clean power-supply voltages that exhibit ultra-low noise and ripple to sensitive system components. This usage is especially true for the TPS7A83A.
The TPS7A83A features an innovative circuit to boost the PSRR from 200 kHz to 1 MHz; see Figure 7-1. To achieve the maximum benefit of this PSRR boost circuit, use a capacitor with a minimum impedance in the 100-kHz to 1-MHz band.