特徴

入力電圧範囲：2.3 V～6.5 V

最大負荷電流：2 A

低ノイズ：出力電圧に依存しない5 µV rms（100 Hz～100 kHz時

高速過渡応答：1mAから1.5Aの負荷ステップに対して1.5μs

60 dB PSRR（100 kHz時

低入出力電圧：172mV（2A負荷時、VOUT = 3 V

初期精度-0.5%（最小）、+1%（最大）

ライン、負荷、温度に対する精度：±1.5%

静止電流、IGND = 0.7 mA、無負荷時

低シャットダウン電流：0.25 μA（VIN = 5 V時

小型の4.7 µFセラミック出力コンデンサで安定化

調整可能および固定出力電圧オプション1.2 V～5.0 V

1.2VからVINまで出力調整可能 - VDO

プレシジョン・イネーブル

調整可能なソフトスタート

8-lead 3 mm × 3 mm LFCSP package

Supported by ADIsimPower™ tool

 

アプリケーション

レギュレーションからノイズに敏感なアプリケーションまで：ADCおよびDAC回路、高精度アンプ、PLL/VCO、クロックIC

通信とインフラ

医療・ヘルスケア

工業用および計測機器

 

概要

The ADM7172 is a CMOS, low dropout linear regulator (LDO) that operates from 2.3 V to 6.5 V and provides up to 2 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 1.5 A load step.

The ADM7172 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 to VIN − VDO with an external feedback divider.

The ADM7172 regulator output noise is 5 μV rms, independent of the output voltage. The ADM7172 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 2 A of output current in a small, low profile footprint.

 

動作理論

The ADM7172 is a low quiescent current, low dropout linear regulator that operates from 2.3 V to 6.5 V and provides up to 2 A of load current. Drawing a low 4.8 mA of quiescent current (typical) at full load makes the ADM7172 ideal for portable equipment. Typical shutdown current consumption is 0.25 μA at room temperature.

Optimized for use with small 4.7 μF ceramic capacitors, the ADM7172 provides excellent transient performance.

Internally, the ADM7172 consists of a reference, an error amplifier, a feedback voltage divider, and a PMOS pass transistor. Output current is delivered via the PMOS pass device, which is controlled by the error amplifier. The error amplifier compares the reference voltage with the feedback voltage from the output and amplifies the difference. When the feedback voltage is lower than the reference voltage, the gate of the PMOS device is pulled lower, allowing more current to pass and increasing the output voltage. When the feedback voltage is higher than the reference voltage, the gate of the PMOS device is pulled higher, allowing less current to pass and decreasing the output voltage.

The ADM7172 is available in 17 fixed output voltage options, ranging from 1.2 V to 5 V. The ADM7172 architecture allows any fixed output voltage to be set to a higher voltage with an external voltage divider.

Use a value of less than 200 kΩ for R2 to minimize errors in the output voltage caused by the SENSE pin input current. For example, when R1 and R2 each equal 200 kΩ and the default output voltage is 1.2 V, the adjusted output voltage is 2.4 V. The output voltage error introduced by the SENSE pin input current is 0.1 mV or 0.004%, assuming a typical SENSE pin input bias current of 1 nA at 25°C.