EC9529A

Lithium Battery Protection

Integrated Circuit

E-CMOS Corp. (www.ecmos.com.tw)

5L16N-Rev. F003

6/10

Overcurrent Condition

When the discharging current becomes equal to or higher than a specified value (the VM pin voltage is equal to

or higher than the overcurrent detection voltage) during discharging under normal condition and the state

continues for the overcurrent detection delay time or longer, the EC9529A turns off the discharging

control FET to stop discharging. This condition is called overcurrent condition. (The overcurrent includes

overcurrent, or load short-circuiting.) The VM and GND pins are shorted internally by the RVMS resistor

under the overcurrent condition. When a load is connected, the VM pin voltage equals the VDD voltage

due to the load. The overcurrent condition returns to the normal condition when the load is released and the

impedance between the B+ and B- pins becomes higher than the automatic recoverable impedance.

When the load is removed, the VM pin goes back to the GND potential since the VM pin is shorted the GND pin

with the RVMS resistor. Detecting that the VM pin potential is lower than the overcurrent detection voltage

(VIOV1), the IC returns to the normal condition.

Abnormal Charge Current Detection

If the VM pin voltage drops below the charger detection voltage (VCHA) during charging under the normal

condition and it continues for the overcharge detection delay time (tCU) or longer, the EC9529A turns

the charging control FET off and stops charging. This action is called abnormal charge current detection.

Abnormal charge current detection works when the discharging control FET is on and the VM pin voltage

drops below the charger detection voltage (VCHA). When an abnormal charge current flows into a

battery in the over-discharge condition, the EC9529A consequently turns the charging control FET off

and

stops

charging

after

the

battery

voltage becomes the over-discharge detection voltage and the

overcharge detection delay time (tCU) elapses. Abnormal charge current detection is released when the voltage

difference between VM pin and GND pin becomes lower than the charger detection voltage (VCHA) by

separating the charger. Since the 0 V battery charging function has higher priority than the abnormal charge

current detection function, abnormal charge current may not be detected by the product with the 0 V battery

charging function while the battery voltage is low.

Load Short-circuiting condition

If voltage of VM pin is equal or below short circuiting protection voltage (VSHORT), the EC9529A will stop

discharging and battery is disconnected from load. The maximum delay time to switch current off is tSHORT.

This status is released when voltage of VM pin is higher than short protection voltage (VSHORT), such as when

disconnecting the load.

0V Battery Charging Function

This function enables the charging of a connected battery whose voltage is 0 V by self-discharge. When a

charger having 0 V battery start charging charger voltage (V0CHA) or higher is connected between B+ and B-

pins, the charging control FET gate is fixed to VDD potential. When the voltage between the gate and

the source of the charging control FET becomes equal to or higher than the turn-on voltage by the charger

voltage, the charging control FET is turned on to start charging. At this time, the discharging control FET is

off and the charging current flows through the internal parasitic diode in the discharging control FET. If

the battery voltage becomes equal to or higher than the over-discharge release voltage (VDU), the

normal condition returns.

Note:

(1) Some battery providers do not recommend charging of completely discharged batteries. Please refer

to battery providers before the selection of 0 V battery charging function.

(2)

The

0V

battery

charging

function

has

higher

priority

than

the

abnormal

charge

current

detection

function. Consequently, a product with the 0 V battery charging function charges a battery and

abnormal charge current cannot be detected during the battery voltage is low (at most 1.8 V or lower).

(3) When a battery is connected to the IC for the first time, the IC may not enter the normal

condition in which discharging is possible.

In this case, set the VM pin voltage equal to the GND voltage

(short the VM and GND pins or connect a charger) to enter the normal condition.