What the PSRR curve means for your rail
The ADP7142ARDZ-5.0 is a 200 mA low-dropout linear regulator from Analog Devices, fixed to a 5 V output, with a maximum input voltage of 40 V. Its headline spec is the power-supply rejection ratio: 88 dB at 10 kHz, rolling off to 50 dB at 1 MHz. That 88 dB at 10 kHz means the regulator attenuates switching noise from a typical 400 kHz–1 MHz buck converter by a factor of roughly 25,000 — so the 5 V rail feeding a sensitive ADC or PLL sees less than 10 µV of ripple from a 200 mVpp input ripple at that frequency.
Dropout margin and load regulation
Maximum dropout voltage is 420 mV at the full 200 mA load. The 140 µA quiescent current (Iq) holds steady even at light loads, so the regulator does not waste battery current in a sleep-mode application.
Industrial temperature range and protection
On-chip protection includes over-temperature shutdown and short-circuit current limiting — no external crowbar or thermal cutoff needed.
Package and thermal management
Housed in an 8-lead SOIC with exposed pad (8-SOIC-EP, 3.90 mm body width). For 200 mA at 5 V output from a 12 V input, the power dissipation is 1.4 W — a 1-inch-square copper pour on the top layer keeps the junction below 125°C in still air.
Control features and enable logic
The Enable pin lets a GPIO or supervisor sequence the 5 V rail on and off. The Soft Start pin programs the output ramp time with a single capacitor to ground — useful for limiting inrush current into a large bypass cap bank on the output.