After the disastrous error 5 weeks ago, with the LiPo IC, the revised Design arrived from JLCPCB. I did not notice the error when I downloaded the part Library from SnapEDA.s3.amazonaws, which I have no idea where I got this link from.
Recap – Or what does it do?
In summary, this board was designed to be the main distribution point for powering the rest of the circuit boards inside the Tricorder. This PCB would be mounted inside the slanted part where its soldered reed switch would detect the magnet located in the Lower Interface flap. When the flap is opened, this PCB will supply power to all the other boards (OK, I want to call them sub-systems) within the Tricorder.
The 3.3v Power requirement
I got this AMD31117 Voltage Regulator quite some time ago for another Project which did not materialise. Anyway, when I measured the output voltage, it gave me 2.882v instead. The original Project uses a 5v source which the AMS1117 performed ideally. But for the TR-595E Tricorder, it is using a 3.7v LiPo battery. Coupled with the 1.3v voltage dropout, the multimeter was correct. So, just to be able to sleep at night, I decided to choose another Voltage Regulator, which is the Texas Instrument TPS73733DCQR. It’s Datasheet claims to have a very low voltage dropout and also has a reverse polarity protection while giving a maximum current of 1000mA. So, yeah, v04C it is, then.
The HM1160
Basically, this tiny sot23-6 IC is a miracle. With just a capacitor and some resistors for the four LEDs, it displays the charge status of the LiPo battery. I am not too sure what happens when it is being charged via the Qi Wireless charger though. Still, (assuming) each LED represents a 25% segment this is as good as it gets for one little chip. I always wanted to have the four green leds (top left of the MKVIII to MKX Tricorders next to the red indicator) to show the status of the Tricorder.
From the Datasheet, it only needs a single 1uF capacitor and either a single 100R resistor for all the four (green) LEDs. I wonder what would happen if I changed the value of the 1uF capacitor to say, a 10uF capacitor? Most of these sot23 ICs such as candle flicker, flashers, etc, have it.
Initially, following the Datasheet’s spec of using the 100R resistor, the four green LEDs were quite bright.
How Bright is it?
From the Datasheet, each output port gives out about a maximum voltage of (Vss+0.3)v and 30mA. In other words (I presume), it is 4.0v. 30mA. Therefore, from the Ohm’s law calculation with the resistor of 100R, The LED would be rated at 18mA. So, by soldering a 200R resistor, I should be getting 9mA. In the image below, the lower PCB has a dimmer set of green LEDs.
