I’m charging a Li-ion 3.7 V, 3500 mAh using a TP4056 charge controller IC and feeding a 6 V, 9 W monocrystalline solar panel to charge it.

When I connect the solar panel at good sun light at 2 PM in the noon, though what ever the programmable resistor I connect Rprog, 1k, 2k, 3k or 4.7k, the 4056 IC is heating very badly, at times my skin got peel off. What is the mistake we are doing?enter image description here

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    \$\begingroup\$ Post schematic or it didn’t happen. \$\endgroup\$ – winny Jun 19 '18 at 9:29
  • \$\begingroup\$ Schematic with Problem at the point is uploaded \$\endgroup\$ – Shiv Jun 19 '18 at 10:08
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    \$\begingroup\$ Better, but what's behind your "speaking boubble"? \$\endgroup\$ – winny Jun 19 '18 at 10:27
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    \$\begingroup\$ It is a linear regulator so power loss is in the nature of this thing. Datasheet is lacking to say the least, but your average SO8 capsule is in the 100 K/W range so it will heat up badly if you don't have a PCB heatsink for it. \$\endgroup\$ – winny Jun 19 '18 at 10:31
  • \$\begingroup\$ What is the voltage at the BAT pin when no battery is connected? \$\endgroup\$ – Umar Jun 19 '18 at 10:35

As @winny says, there is no place for the heat to go without a heat sink, so the temperature will rise. This device detects its own junction temperature, and will automatically reduce its output current to maintain the junction temperature at 145 Celsius. So with no heat sink, the chip will reach this temperature regardless of Rprog.


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