PB Fortich

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  • Basic Buck-Boost DC-DC Converter using MAX1408 ADC

  • Created: Feb 23, 2017

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Small power storage such as coin battery plays an important role in electronics. Due to its size, it makes electronic devices more compact and handy. There are a lot of power-supply designs that continue to evolve and develop in response to the requirement of the technology development. The design features a buck-boost DC-DC converter circuit in which it improves the operation of the power supply.

The circuit is powered by a battery that it can be 2-3 button cells, li+ coin, 2-3 alkaline, or 2-3 button cells. The supply source is regulated by a MAX1759 which is a buck/boost regulating charge pump. It secures 3.3V output that the charge pump operates as a step-up voltage doubler or step-down gated switch depending on the battery supplied. The capacitor C1 and R’s act as low pass filter for an analog input to IN0 pin of MAX1408. The MAX1408 is a low-power, 16-bit multichannel DAS or Data-Acquisition Systems in which it handle the power supply circuit for run mode or sleep mode. The /SHDN pin is for shutdown output function that is connected also to the buck/boost regulating charge pump that synchronizes the shutdown function. The POK pin is connected and synchronized with the reset pins of the MCU and DAS. The AVDD and DVDD pins are connected together provided that the power is applied to the device before the analog input signals to avoid latch-up. The CPLL is for the integrated PLL in the DAS that generates 2.4576MHz signal, an 18nF capacitor C4 is connected in between the CPLL and AVDD that serves as filter. The /WU1 pin is for the wake up from sleep mode to standby mode of the DAS in which signal is sent by the MCU. The capacitor C5, C6, and C7 are also filters that stabilize the supply signal.

Small power supply circuit has a lot of applications especially on portable equipment. It can be part of a larger system that optimizes power management. It is applicable to medical instruments, industrial control systems, data-acquisition system, automatic testing, and robotics.