Since the time I completed the first version of a 3V-to-9V converter I got quite a few feedback. It looks like people need a converter like that for various purposes. So I decided to make a new one with better parameters.
The new converter is based on TPS61040 IC manufactured by Texas Instruments. I just used a standard schematic from its datasheet. However, in my case the best results were obtained with 2200pF feedforward capacitor. With a smaller value of this capacitor one can hear an unpleasant whistle caused by pause bursts on an audio frequency.
| Schematic | Layout | PCB | ||
The previous converter drove about 50 mA from the battery even without load, which is unacceptable in many cases. This one draws just about 60 μA, which is about 3 orders less. I replaced the old converter in my multimeter with the new one by putting the PCB between two pinkish pieces of foam. When the multimeter is on, the drawn current from the battery went down to about 10 mA.
The only inconvenience that this design might cause is that the IC TPS61040 is only manufactured for surface mounting. Anyway, the PCB size is about 16.5x11.5 mm and it is designed with Eagle software, which offers a free version for small boards. Here is the parts list:
| Part | DigiKey reference | |
| Ceramic capacitor 10μF x 10v | 587-2562-1-ND | |
| Ceramic capacitor 1μF x 25v | 587-1434-1-ND | |
| Ceramic capacitor 2200pF | 399-5699-1-ND | |
| Inductor 10μH | 490-4059-1-ND | |
| DC/DC converter TPS61040 | 296-12685-1-ND | |
| Resistor 1M 1% | P1.00MHCT-ND | |
| Resistor 180K 1% | P180KHCT-ND |
Last modified:Mon, Jan 23, 2023.