Charge/discharge protection circuit utilizing a charger connection recovery circuit that cycles a discharge control transistor on and off while a battery is over-discharged during charging
View Patent ↗A charge/discharge protection circuit that protects a secondary battery from overcharge, over-discharge, charge over-current, and discharge over-current is disclosed. The charge/discharge protection circuit includes an overcharge detection circuit, an over-discharge detection circuit, a charge over-current detection circuit, a discharge over-current detection circuit, a charge control FET that is turned off when overcharge is detected and when charge over-current is detected, a discharge control FET that is turned off when over-discharge is detected and when discharge over-current is detected, and a charger connection recovery circuit that controls on/off operations of the discharge control FET. When connection with a charger is established at a time over-discharge is detected and the discharge control FET is turned off, the discharge control FET is forcefully turned on after a first predetermined time elapses.
1. A charge/discharge protection circuit that protects a secondary battery from overcharge, over-discharge, charge over-current, and discharge over-current, said charge/discharge protection circuit comprising:
an overcharge detection circuit;
an over-discharge detection circuit;
a charge over-current detection circuit;
a discharge over-current detection circuit;
a charge control FET that is turned off when overcharge is detected by the overcharge detection circuit and when charge over-current is detected by the charge over-current detection circuit;
a discharge control FET that is turned off when over-discharge is detected by the over-discharge detection circuit and when discharge over-current is detected by the discharge over-current detection circuit; and
a charger connection recovery circuit that controls on/off operations of the discharge control FET such that when connection with a charger is established at a time over-discharge is detected and the discharge control FET is turned off, the discharge control FET is forcefully turned on after an over-discharge recovery delay time elapses,
wherein the discharge control FET is turned off after an over-discharge detection delay time elapses from the time the discharge control FET is forcefully turned on.
2. The charge/discharge protection circuit as claimed in claim 1 , wherein
when a battery cell voltage is less than or equal to an over-discharge detection voltage, operations of turning on the discharge control FET after the elapse of the over-discharge recovery delay time and turning off the discharge control FET after the elapse of the over-discharge detection delay time are repeated.
3. The charge/discharge protection circuit as claimed in claim 1 , wherein
the over-discharge recovery delay time and the over-discharge detection delay time are determined according to variations in internal circuit temperature characteristics, charger temperature characteristics, over-discharge recovery delay time temperature characteristics, and over-discharge detection delay time temperature characteristics.
4. A battery pack comprising the charge/discharge protection circuit as claimed in any one of claims 1 , 2 or 3 .
5. An electronic apparatus comprising a battery pack, said battery pack including a charge/discharge protection circuit that protects a secondary battery from overcharge, over-discharge, charge over-current, and discharge over-current, said charge/discharge protection circuit comprising:
an overcharge detection circuit;
an over-discharge detection circuit;
a charge over-current detection circuit;
a discharge over-current detection circuit;
a charge control FET that is turned off when overcharge is detected by the overcharge detection circuit and when charge over-current is detected by the charge over-current detection circuit;
a discharge control FET that is turned off when over-discharge is detected by the over-discharge detection circuit and when discharge over-current is detected by the discharge over-current detection circuit; and
a charger connection recovery circuit that controls on/off operations of the discharge control FET such that when connection with a charger is established at a time over-discharge is detected and the discharge control FET is turned off, the discharge control FET is forcefully turned on after an over-discharge recovery delay time elapses,
wherein the discharge control FET is turned off after an over-discharge detection delay time elapses from the time the discharge control FET is forcefully turned on.
6. A mobile phone comprising a battery pack, said battery pack comprising:
a charge/discharge protection circuit that protects a secondary battery from overcharge, over-discharge, charge over-current, and discharge over-current, said charge/discharge protection, circuit comprising:
an overcharge detection circuit;
an over-discharge detection circuit;
a charge over-current detection circuit;
a discharge over-current detection circuit;
a charge control FET that is turned off when overcharge is detected by the overcharge detection circuit and when charge over-current is detected by the charge over-current detection circuit;
a discharge control FET that is turned off when over-discharge is detected by the over-discharge detection circuit and when discharge over-current is detected by the discharge over-current detection circuit; and
a charger connection recovery circuit that controls on/off operations of the discharge control FET such that when connection with a charger is established at a time over-discharge is detected and the discharge control FET is turned off, the discharge control FET is forcefully turned on after an over-discharge recovery delay time elapses,
wherein the discharge control FET is turned off after an over-discharge detection delay time elapses from the time the discharge control FET is forcefully turned on.