Ultra-low-noise, high PSRR, 0.5A negative rail LDO

Ultra-low-noise, high PSRR, 0.5A negative rail LDO

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Analog Devices has added to its range of linear voltage regulator chips intended for stabilising supply rails to the most noise-sensitive active devices such as ADCs, DACs and precision/instrumentation amplifiers, that operate from negative voltage rails.
By Graham Prophet

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From the recently-posted details; ADP7185 is a 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 suitable for regulation of high performance analogue and mixed signal circuits operating from −0.5 V down to −4.5 V. Total integrated output noise is 4 μV rms independent of the output voltage, for high performance and noise sensitive applications. Shutdown current consumption is −7 μA (maximum). 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: −0.5V, −1.0V, −1.2V, −1.5V, −1.8V, −2.0V, −2.5V, −3.0V, and −3.3V. Additional voltages available by special order are −0.8V, −0.9V, −1.3V, −2.8V, −4.2V, and −4.5V. An adjustable version is also available which allows output voltages that range from −0.5V to −VIN + 0.5V with an external feedback divider (diagram, above). The enable logic feature is capable of interfacing with positive or negative logic levels for maximum flexibility.

The ADP7185 regulator output noise is 4 μV rms independent of the output voltage. The ADP7185 is available in an 8-lead, 2 × 2 mm LFCSP, making it not only a very compact solution but also providing excellent thermal performance. An evaluation board is available (pictured). Appropriately noise sensitive applications are anticipated in communications, medical and healthcare, and in industrial and instrumentation.

 

Analog Devices; www.analog.com/en/products/power-management/linear-regulators/adp7185.html

 

next page; feature listing…

 


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 μV rms 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

 

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