1A step-down regulators + LDO reduces footprint & EMI

16th August 2018

Analog Devices

Enaie Azambuja

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Datasheet

Analog Devices has announced the Power by Linear ADP5138, automotive qualified, high efficiency, 3.2MHz synchronous quad output buck regulators, incorporating a fixed frequency, peak current mode, PWM control architecture that reduces conducted and radiated emissions. The device’s high efficiency buck regulators improve thermal management, operate down to 0.8V outputs and deliver up to 1A of continuous output current from each channel.

Also integrated is a 250mA low output noise (20µVRMS from 10Hz to 100kHz), high PSRR (61dB at 1kHz) low dropout linear regulator (LDO) for powering noise-sensitive devices.

This high level of integration and combination of features, in addition to the compact 4mm x 4mm LFCSP package, make it ideal for automotive, industrial and instrumentation systems, as well as DC to DC point-of-load applications where space is at a premium.

The ADP5138 runs at a fixed PWM switching frequency of 3.2MHz, or can be synchronised to the external clock from 2.8MHz to 3.5MHz, which is outside the amplitude modulation (AM) band.

Furthermore, this high switching frequency reduces the size of external components, enabling a smaller solution footprint. The four buck regulators run 90° out-of-phase to each other, reducing the input ripple current and the input capacitor size and lowering the system’s electromagnetic interference (EMI).

Integrated internal compensation simplifies design, and the device’s internal soft-start circuitry and power-up sequencing reduce input inrush current. The ADP5138 monitors the input voltage and provides input overvoltage lockout (OVLO), undervoltage monitor (UVM), and undervoltage lockout (UVLO) features.

The device also monitors the undervoltage and overvoltage of the outputs. The power-on reset (POR) signal is asserted when the input or output voltage fault occurs. Additional protection includes overcurrent protection (OCP) and thermal shutdown (TSD).

The ADP5138 and the automotive qualified version, the ADP5138W, are offered in a low profile (0.75mm), compact 28-lead 4mm x 4mm LFCSP package with backside exposed metal pad for excellent thermal performance. The devices operate from –40°C to 125ºC (junction temperature).