Very simple scheme, great option! Allows you to charge a current of up to 800 mA (see the description of the datasheet ). True, it tends to become very hot, but in this case, the built-in overheating protection reduces the current.
The scheme can be significantly simplified by throwing out one or even both LEDs with a transistor. Then it will look like this (you see, there is no place to be easier: a pair of resistors and one connector):
One of the options for the PCB is available at this link . The board is designed for items of size 0805.
The charge current (in amperes) is computed using the formula I = 1000 / R . Immediately it is not necessary to expose a large current, first see how much the chip will be heated. For my own purposes, I took a 2.7 kΩ resistor, and the charge current turned out to be about 360 mA.
The radiator is unlikely to adapt to this microcircuit, and it is not a fact that it will be effective due to the high thermal resistance of the crystal-body transition. The manufacturer recommends to make the heat sink “through the findings” – to make as thick as possible tracks and leave the foil under the microchip body. And in general, the more “ground” foil is left, the better.
By the way, most of the heat is removed through the 3rd leg, so you can make this path very broad and thick (fill it with excessive amount of solder).
The chip came out very successful, so it has some analogues parts: STC4054, MCP73831, TB4054, QX4054, TP4054, SGM4054, ACE4054, LP4054, U4054, BL4054, WPM4054, IT4504, Y1880, PT6102, PT6181, VS6102, HX6, 2008, 2010, 2010, LC LC, LC,, 18,,, 4040 EC49016, CYT5026, Q7051. Before using any of these analogues, check the datasheets.