ADM7170ACPZ-4.2-R7

Overview

The ADM7170ACPZ-4.2-R7 is a fixed-output CMOS low dropout linear regulator (LDO) manufactured by Analog Devices Inc., providing a regulated 4.2 V output with a maximum load current of 500 mA. It operates from an input voltage range of 2.3 V to 6.5 V and features ultralow noise performance, delivering 5 µV rms in the 100 Hz to 100 kHz bandwidth. The device achieves high power supply rejection ratio (PSRR) of 60 dB at 100 kHz and fast transient response of 1.5 μs for a 1 mA to 500 mA load step. Initial accuracy is ±0.75%, expanding to ±1.25% over line, load, and temperature conditions. Quiescent current is 0.7 mA at no load, dropping to 0.25 μA in shutdown mode. It requires only a small 4.7 µF ceramic output capacitor for stability.

Feature Summary

• Ultralow noise architecture delivers 5 µV rms output noise independent of the output voltage setting.
• High power supply rejection ratio (PSRR) of 60 dB at 100 kHz ensures effective suppression of input supply ripple.
• Fast transient response capability settles within 1.5 μs during significant load steps using minimal external capacitance.
• Precision enable pin allows precise control of regulator startup and shutdown states.

Applications

• Regulation for noise-sensitive analog circuits such as ADC and DAC interfaces
• Powering precision amplifiers and PLL/VCO circuits
• Clocking IC regulation in communications and infrastructure systems
• Medical and healthcare equipment requiring stable low-noise rails

Procurement Notes

Verify the specific ordering suffix -R7 indicates reel packaging when sourcing components. Confirm that the fixed 4.2 V output variant matches the design requirement, as the ADM7170 family also offers adjustable versions and other fixed voltages. Ensure compatibility with the required 8-lead LFCSP footprint and thermal management strategy for the target application environment.

Selection Notes

Select this component when a fixed 4.2 V rail is needed with high PSRR and low noise characteristics. Consider the 500 mA current limit and 2.3 V minimum input voltage for headroom calculations. Evaluate thermal dissipation requirements based on the difference between input and output voltage at maximum load. Verify that the 4.7 µF ceramic capacitor requirement aligns with board space and cost constraints.

Part Context

The ADM7170 belongs to a family of high-performance CMOS LDOs designed for portable and battery-powered applications. It shares architectural similarities with the ADM7171 (1 A) and ADM7172 (2 A) variants, offering comparable noise and PSRR performance scaled for different current demands. All devices utilize the same compact 8-lead LFCSP package and support similar operating voltage ranges.

Replacement Considerations

Direct functional substitutes within the same package include the ADM7171ACPZ-4.2-R7 and ADM7172ACPZ-4.2-R7, which offer higher current capabilities (1 A and 2 A respectively) while maintaining identical output voltage and pinout configurations. Other fixed-voltage options within the ADM7170 series may be used if the 4.2 V requirement can be adjusted via the SENSE pin in adjustable mode.