For Automotive Applications
For Industrial Applications
For IoT Devices
The short circuit current protection cuts off discharge current as soon as a short circuit current is detected. Short-circuit between external electrodes causes battery cells to discharge to the limit of their capacity and generate heat. If the temperature increases and the battery becomes overheated, the internal structure (especially a separator) can be damaged, leading to dangerous situations such as emitting toxic fumes, fire and explosion.
The short circuit current protection cuts off discharge current after the detection of short circuit current within 1 ms. Though it is functionally similar to discharge overcurrent protection, the short circuit current protection features its fast response against large discharge current.
Adopted Products:：all the 1-/2-/multi-cell protection ICs except the R5433 series
Whether recharge of 0 V cells (fully discharged cells) is accepted or not is determined by the product version.
0 V charge prohibited Version:
Charging operation is prohibited if the cell voltage decreases to a voltage level below the overdischarge voltage threshold.
0 V charging of Li-ion batteries without guarantee may worsen the condition of the battery, such as liquid leakage. Choosing the 0 V charge-prohibited version prevents such a risk.
0 V Charge Acceptable Version:
Recharge of 0 V cells is permitted.
This version is suitable for battery cells guaranteeing a secure 0 V charge. The 0 V charge acceptable version can restore to the original battery voltage as good as possible.
・ selectable： R5405 Series, R5494 Series, R5487 Series, R5497 Series, R5471 Series
・ Prohibited Only： R5463 Series
Cell balancing equalizes the cell voltages of multi-cell batteries. A cell voltage equalizing process is achieved by a charge current bypass or by discharging cells with a higher voltage.
Cell voltages of multi-cell batteries become out of balance due to individual differences such as capacity, leak current, etc. The unbalance causes the charging operation to stop when the cell with a higher voltage reaches its charge-end voltage regardless of the state of lower cell voltages. On the other hand, the cells with a lower-voltage reaches the discharge-end voltage faster than the higher-voltage cells. The unbalancing state narrows the specification range substantially, reduces the actual capacity of the battery, and causes deterioration of the lifetime of the system or battery cells.
The cell balancing prevents a cell voltage unbalance and reduction of actual capacity of the battery.
Cascade connection refers to connecting multi-cell battery protection ICs in series.
By connecting two five-cell Li-ion battery protection ICs with their cascade connection pins COUT and DOUT, those ICs are able to protect a ten-cell Li-ion series battery. Cascade connection enables protection ICs to support multi-stage batteries even though there are no ICs available of monitoring those batteries with a single chip.
Besides, in some cases, ICs with cascade connection can be more cost-efficient than multi-cell battery protection ICs with high-voltage resistance.
Temperature protection detects abnormal temperature increase of the Li-ion battery and stops the charging / discharging operation to prevent dangerous situations.
The protection is achieved by connecting an NTC thermistor and a resistor in series as a voltage divider.
When a cell voltage exceeds the alarm threshold, an alarm signal will appear on AOUT pin. If the detection temperature of thermistor exceeds 45℃, the alarm detect voltage threshold shifts to VALMH. (The detection temperature is user-selectable.)
Li-ion batteries generate more heat by continuing the charging operation at high temperature. In order to prevent the batteries from becoming overheated, providing an alarm signal is important.
In Japan, Li-ion batteries must be equipped with two-step overcharge protection circuits, which is regulated by Electrical Appliance and Material Safety Act*. The alarm circuit makes it possible to construct a two-step overcharge protection in a single chip.
* Other countries have similar regulations.
Adopted Products： R5461K Series, R5464K Series, (R5466K Series), Part of 2-cell protection ICs
Open-wire detection detects an open-wire between the cells and protection circuits in a multi-cell battery.
As for products such as electric power tools, there is a risk of an open-wire caused by the vibration of the tools. In case of an open-wire, the protection ICs cannot monitor the state of battery cells and therefore cannot judge whether the battery is safe or not.
The open-wire detection monitors the connection between the battery cells and the protection IC periodically. When detecting open-wire, the protection circuit prohibits charging / discharging operation to avoid dangerous situations.