Introduction

The Texas Instruments product range has thousands of interesting power supply and related integrated circuits. I thought it could be interesting to review a few designs I’ve experimented with, and discuss what particular devices were used.

 

Powering an iPod/iPhone for Automotive Use

This is a snippet of a schematic from an in-car project – this is the iPod/iPhone charger portion of the circuit using the TPS40200TPS40200 as a step-down controller. I’ve used it for many years, it has survived many winters in the car. It has survived a failing alternator, and several jump-starts and so on during this time. It has lasted longer than both my iPod and Alpine in-car amplifier, and come to think of it has lasted longer than the existing electrical wiring connections (RCA connectors are awful, I wish they would be phased out of consumer electronics gear).

 

I used the ‘soft start’ (SS) pin to control the power supply, so that it could be remotely switched on.

 

Building a LiPo Battery Charger

I thought the BQ2409X series of battery charger ICs were awesome. Some earlier generation devices from other manufacturers had limited safety features. In contrast the TI BQ2409X series of devices have lots of in-built features such as a timer, external thermistor for the cell, and even over-voltage protection if the input source goes faulty.

 

For my design, I added a MOSFET on the ISET2 pin, so that the charge current was under computer control.

 

Building a Solar Charger

I’ve blogged about this in more detail here: Building a Solar Charger . The BQ24650BQ24650 is particularly useful because of its flexibility. It allows a user to start the circuit design even if the final solar panel and final cell/battery and cell chemistry has not been selected yet. I was highly impressed at the flexibility of this integrated circuit.

 

Wide Input Range Step-Down Power Supply

I love that TI seem to have a solution for everything. In this situation, I wanted to have a device that could be powered from a 12V or a 24V source normally (e.g. industrial applications), but I also wanted the ability for a user to disconnect it from the power source, and run it from a PC, using the USB connection (5V) for troubleshooting or firmware upgrades, etc. The TPS54540TPS54540 allows for inputs from 4.5V to 42V, which met and exceeded my needs!

 

 

Using DC-DC Converter Modules

Sometimes it is just easier to trust the TI experts and use off-the-shelf DC-DC converter modules that they have designed. I used two of them in a project: RIoTboard: Building a TFT LCD Display and Digitizer - Part 2: Circuit

I used them to connect a laptop TFT screen to a RIoTboard computer. The use of off-the-shelf modules means that the PCB doesn’t need to be a multi-layer board; one or two layers is fine!

 

The DC-DC converter modules that were used have an adjustable output controlled by a single resistor. I used two resistors in parallel to allow me to select popular resistance values. The PTH04000WAHPTH04000WAH is a step-down converter that I used to obtain 3.3V from a 5V supply, and the PTN04050CAHPTN04050CAH is a step-up converter that I used to power the screen backlight.

 

Summary

A small selection of power supply circuits and their use-cases were presented. I hope it was interesting. It would be great to hear from people about their tips for interesting power supply ICs and what use that they were put to!