6.5 V, 1 A, Ultralow Noise, High PSRR,

Fast Transient Response CMOS LDO

Data Sheet

ADM7171

Rev. C

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FEATURES

Input voltage range: 2.3 V to 6.5 V

Maximum load current: 1 A

Low noise: 5 µV rms independent of output voltage at

100 Hz to 100 kHz

Fast transient response: 1.5 μs for 1 mA to 500 mA load step

60 dB PSRR at 100 kHz

Initial accuracy: −0.5% (minimum), +1% (maximum)

Accuracy over line, load, and temperature: ±1.5%

Stable with small 4.7 µF ceramic output capacitor

Adjustable and fixed output voltage options: 1.2 V to 5.0 V

Precision enable

Adjustable soft start

8-lead, 3 mm × 3 mm LFCSP package

Supported by ADIsimPower tool

APPLICATIONS

Regulation to noise sensitive applications: ADC and DAC

circuits, precision amplifiers, PLLs/VCOs, and clocking ICs

Communications and infrastructure

Medical and healthcare

Industrial and instrumentation

GENERAL DESCRIPTION

The ADM7171 is a CMOS, low dropout linear regulator (LDO)

that operates from 2.3 V to 6.5 V and provides up to 1 A of output

current. This high output current LDO is ideal for regulation of

high performance analog and mixed signal circuits operating

from 6 V down to 1.2 V rails. Using an advanced proprietary

architecture, the device provides high power supply rejection and

low noise, and achieves excellent line and load transient response

with just a small 4.7 µF ceramic output capacitor. Load transient

response is typically 1.5 μs for a 1 mA to 500 mA load step.

The ADM7171 is available in 17 fixed output voltage options.

The following voltages are available from stock: 1.3 V, 1.8 V,

2.5 V, 3.0 V, 3.3 V, 4.2 V, and 5.0 V. Additional voltages that are

available by special order are: 1.5 V, 1.85 V, 2.0 V, 2.2 V, 2.7 V,

2.75 V, 2.8 V, 2.85 V, 3.8 V, and 4.6 V. An adjustable version is

also available that allows output voltages that range from 1.2 V

Inrush current can be controlled by adjusting the start-up time

via the soft start pin. The typical start-up time with a 1 nF soft

start capacitor is 1.0 ms.

TYPICAL APPLICATION CIRCUIT

Figure 1. ADM7171 with Fixed Output Voltage, 3.3 V

The ADM7171 regulator output noise is 5 μV rms independent

of the output voltage. The ADM7171 is available in an 8-lead,

3 mm × 3 mm LFCSP, making it not only a very compact solution,

but also providing excellent thermal performance for applications

requiring up to 1 A of output current in a small, low profile

footprint.

Figure 2. Transient Response (Trace 2), 1mA to 500 mALoad Step in 400ns (Trace1)

Table 1. Related Devices

Device

Input Voltage

Output Current

Package

ADM7170

2.3 V to 6.5 V

500 mA

8-lead LFCSP

ADM7172

2.3 V to 6.5 V

2 A

8-lead LFCSP

VOUT

SENSE

SS

VIN

EN

ADM7171

GND

VIN

VOUT

1nF

4.7µF

4.7µF

OFF

ON

100mV

1

2

T