原标题：ADI ADP7185低压降(LDO)线性稳压器解决方案

　　ADI公司的ADP7185是CMOS低压降(LDO)线性稳压器,工作电压从-2.0V到-5.5V,提供高达-500mA输出电流,固定输出电压从-0.5V到-4.5V,可调输出电压从-0.5V到VIN+0.5V, 100 Hz - 100 kHz输出噪音4 μVrms, 10 kHz - 1 MHz噪音频谱密度20 nV/√Hz,在-500A负载时的压降为-190mV,主要用在对噪音要求高的稳压应用如ADC,DAC,精密放大器,通信和基础设备,医疗和健康设备以及工业和仪表.本文介绍了ADP7185主要特性,固定输出和可调输出内部框图,应用电路以及ADP7183和ADP7185评估板主要特性,电路图,材料清单和PCB设计图.

　　The ADP7185 is a complementary metal oxide semiconductor (CMOS), low dropout (LDO) linear regulator that operates from −2.0 V to −5.5 V and provides up to −500 mA of output current. This high output current LDO is ideal for regulation of high performance analog and mixed signal circuits operating from −0.5 V down to −4.5 V. Using an advanced proprietary architecture, the ADP7185 provides high power supple rejection ratio (PSRR) and low noise, and it achieves excellent line and load transient response with a small 4.7 μF ceramic output capacitor. The ADP7185 is available in 15 fixed output voltage options. The following voltages are available from stock: −0.5 V, −1.0 V, −1.2 V, −1.5 V, −1.8 V, −2.0 V, −2.5 V, −3.0 V, and −3.3 V. Additional voltages available by special order are −0.8 V, −0.9 V, −1.3 V, −2.8 V, −4.2 V, and −4.5 V. An adjustable version is also available which allows output voltages that range from −0.5 V to −VIN + 0.5 V with an external feedback divider. The enable logic feature is capable of interfacing with positive or negative logic levels for maximum flexibility. The ADP7185 regulator output noise is 4 μVrms independent of the output voltage. The ADP7185 is available in an 8-lead, 2 mm × 2 mm LFCSP, making it not only a very compact solution but also providing excellent thermal performance for applications requiring up to −500 mA of output current in a small, low profile footprint.

　　ADP7185主要特性:

　　Input voltage range: −2.0 V to −5.5 V

　　Maximum output current: −500 mA

　　Fixed output voltage options: −0.5 V to −4.5 V

　　Adjustable output from −0.5 V to −VIN + 0.5 V

　　Low output noise: 4 μVrms from 100 Hz to 100 kHz

　　Noise spectral density: 20 nV/√Hz, 10 kHz to 1 MHz

　　PSRR at −500 mA load

　　68 dB at 10 kHz

　　50 dB at 100 kHz

　　40 dB at 1 MHz

　　Low dropout voltage: −190 mV typical at −500 mA load

　　Initial output voltage (VOUT) accuracy: ±0.5%

　　Output voltage accuracy over line, load, and temperature: ±2.2%

　　Operating supply current (IGND): −0.6 mA typical at no load

　　Low shutdown current: −2 μA typical at VIN = −5.5 V

　　Stable with small 4.7 μF ceramic input and output capacitor

　　Positive or negative enable logic

　　Current-limit and thermal overload protection

　　8-lead, 2 mm × 2 mm LFCSP package

　　Supported by ADIsimPOWER voltage regulator design tool

　　ADP7185应用:

　　Regulation to noise sensitive applications:

　　analog-to-digital converters (ADCs), digital-to-analog converters (DACs),

　　precision amplifiers

　　Communications and infrastructure

　　Medical and healthcare

　　Industrial and instrumentation

　　图1.固定输出电压内部框图

　　图2.可调输出电压内部框图

　　图3.ADP7185固定输出电压-3.3V电路图

　　图4.ADP7185可调输出电压电路图:VOUT=-2.5V

　　ADP7183和ADP7185评估板

　　The ADP7183 and ADP7185 evaluation boards demonstrate the functionality of the ADP7183 and ADP7185 series of linear regulators.

　　Simple device measurements such as line and load regulation, dropout voltage, and ground current can be demonstrated with only a single voltage supply, a voltmeter, an ammeter, and load resistors.

　　For full details on the ADP7183 and ADP7185 linear regulators, see ADP7183 and ADP7185 data sheet, which must be con-sulted in conjunction with this user guide when using these evaluation boards.

　　ADP7183和ADP7185评估板主要特性:

　　Input voltage range: −2.0 V to −5.5 V

　　Output current range

　　ADP7183: 0 mA to −300 mA

　　ADP7185: 0 mA to −500 mA

　　Output voltage accuracy

　　ADP7183: ±2.6%

　　ADP7185: ±2.2%

　　Operating temperature range: −40℃ to +125℃

　　Adjustable option voltage set with two external resistors (R1 and R2), VOUT = −0.5 V × (1 + R1/R2)

　　图5.ADP7183和ADP7185固定输出评估板外形图

　　图6.ADP7183和ADP7185可调输出评估板外形图

　　ADP7183和ADP7185评估板材料清单: