Week 12 (Nov. 14, 2018): Regulator-Amplifier IC (Integrated Chip) Selection

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Today, we received some assistance regarding power electronics from Dan, one of the coaches.

We explained to him our plan regarding induction charging. Basically, we narrowed our search for an induction charger module (consisting of a transmitter and receiver) to two possibilities: 12V at 600 mA, or 5V at 2 A. In the case of the former (12V, 500mA), we must buck down (step down) the voltage to around 7.4V, the battery voltage, and increase the current to at least 1.5A to achieve a decent charging rate (“fast-charging” cell phone adapters are rated at 2.1A). In the case of the latter (5V, 2A), we must simply boost up (step up) the voltage to around 7.4V, the battery voltage.

Dan recommended buying the 12V at 600mA induction charging module, and then getting an IC (Integrated Chip, which is basically an electronic chip containing a very tiny circuit) that will step down the voltage to around 7.4V, and another IC that will amplify current to 1.5A. He also said that there are chips that can do both regulate voltage and amplify current. He suggested sites, such as Texas Instruments (TI) and Analog Devices.

While we were not able to discuss, in detail, battery selection due to his services being required elsewhere, we do appreciate Dan’s time, especially suggesting looking into an IC that can do both regulate voltage and amplify current. For now, we will continue using the 7.4V, 2600 mAh, 2S, 90C, 192 Wh LiPo battery used by last year’s team.

Later that day, we were eventually able to find an IC that indeed does both regulate voltage and amplify current! 2 for the price of 1! Thanks to TI’s Component Parametric Comparison Tool, we selected the “TPS53313 6-A Step-Down Regulator With Integrated Switcher”. The notable features of this chip are as follows: a 4.5V to 16 V input voltage range, an adjustable output voltage ranging from 0.6V to 70% of the input voltage, and a continuous 6A output current or a selectable 5A, 6A, or 9A peak output current. With this chip, we can step down the voltage from 12V to a maximum of 8.4V (70% of 12V) and amplify the current from 600mA to a maximum of 9A! Therefore, this chip will be connected between the induction charger receiver and the LiPo battery charger. The portion of the datasheet containing this information is shown below.

We also ordered both types of induction chargers (12V, 600mA and 5V, 2A), just in case the former would not work. However, we will try out the 12V, 600mA charger first.

UPDATE: Calculations for the induction charging and battery are found in the Week 14 and Week 15 blog posts.
 

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