Specifications
| Full Charge Vmax |
8.2, 8.4 Volt |
| Input Min Voltage |
Undefined Volt |
| Input Max Voltage |
20 Volt |
| Battery Cells |
2 cell |
| Battery Chemistry |
Li-Ion |
| Charge Modes |
CC, CV |
| On/Off Pin |
No |
| Special Features |
1% tolerance, 0.5% tolerance |
| Full Charge Vmin |
8.2, 8.4 Volt |
| Error Flag |
No |
| Adjustable Output |
Yes |
| Voltage Fault Protection |
No |
| Output Current |
Undefined mA |
| RegType |
Linear/LDO Controller |
| Temperature Min |
-40 deg C |
| Temperature Max |
125 deg C |
| View Using Catalog |
DescriptionThe LM3420 is available in a sub-miniature 5-lead SOT23-5 surface mount package thus allowing very compact designs.The LM3420 series of controllers are monolithic integrated circuits designed for charging and end-of-charge control for Lithium-Ion rechargeable batteries. The LM3420 is available in five fixed voltage versions for one through four cell charger applications (4.2V, 8.2V/8.4V, 12.6V and 16.8V respectively).
Features of the LM3420 are:(1)voltage options for charging 1, 2, 3 or 4 cells; (2)tiny SOT23-5 package; (3)precision (0.5%) end-of-charge control; (4)drive capability for external power stage; (5)low quiescent current, 85 A (typ.).Included in a very small package is an (internally compensated)op amp,a bandgap reference,an NPN output transistor, and voltage setting resistors. The amplifier's inverting input is externally accessible for loop frequency compensation. The output is an open-emitter NPN transistor capable of driving up to 15 mAof output current into external circuitry.
The absolute maximum ratings of the LM3420 can be summarized as:(1)input voltage:20V;(2)storage temperature:-65 to 150;(3)junction temperature:150;(4)lead temperature:200;(5)power dissipation:300mW;(6)output current:20 mA.Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed.Some performance characteristics may degrade when the device is not operated under the listed test conditions.controlling the ADJ. pin of the LM317 which begins to regulate the voltage across the battery and the constant voltage portion of the charging cycle starts. Once the charger is in the constant voltage mode, the charger maintains a regulated 8.4V across the battery and the charging current is dependent on the state of charge of the battery.As the cells approach a fully charged condition, the charge current falls to a very low value.
LM3420 Data Sheet
