1. Li-ion Battery Charging Chip CHK0501
CHK0501’s internal circuit is composed of the reference voltage circuit, sampling circuit
and short circuit protection circuit and so on. Chart 1 is its pin indication, where PIN 1 is
the power negative input; PIN 2 is the LED driver output control; PIN 3 is the power
positive input; PIN 4 is the charging tube control output; PIN 5 is the temperature compare
input; PIN 6 is the undervoltage compare input; PIN 7 is the battery positive voltage input ;
PIN 8 is the current detection input and power negative.

2. Charger’s Operation Principle
(1) Switch-mode stabilized voltage power
switch-mode stabilized voltage power is grid JP12 AC voltage directly rectified by D61,
D62, D63, D64, filtered into a high-voltage DC, and transformed by the high-frequency
transformer TR44 and power switching transistors U52 into low-voltage AC, and then
rectified by the D44 low-voltage , filter output DC voltage. If remove diode D12, through
the diode D11 and DC Block JK11 connect charger ( adapter).