Li-ion Battery Monitoring chip set (for NMOS-FET)
MK5208
Provides the high accuracy and total cost-down of the battery protection circuit


The MK5208 is a chip-set consisting of an analog front-end IC and a controller IC which supports 5 to 13 cells lithium-ion battery pack protection systems.
MK5208 measures the voltage more accurate than MK5207 and is improved so that NMOS-FET can be driven for the externally connected charge/discharge control. It can provide the more accuracy and the total cost-down of the battery protection circuit of multipe cells serial connection.
This chip set consists of the following two ICs.

  • ML5208 Analog Front End IC for voltage measurement
  • ML5227 Controller and embedded firmware


This chip set achieved the accuracy of ±10mV(Typ) overcharge/disovercharge voltage detection and measures the voltage of the battery cell with high accuracy.
Also, used with the current measurement, battery remainder measurement, and external thermistor, it measures the nearby battery and internal IC temperature and then detects the irregular operation of each battery cell and protects them.


  • Electrically assisted bicycles
  • Battery storage device


Chip Set Name MK5208
IC part number ML5208 / ML5227
The number of compatible cells 5 to 13 cells
FET driver for charge/discharge NMOS-FET
Overcharge/overdischarge voltage detection accuracy ±10mV (Typ.)
The detection range*1 Overcharge detection 3.6V to 4.4V
Overcharge release 3.4V to 4.4V
Overdischarge detection 2.0V to 3.0V
Overdischarge release 2.0V to 3.0V
Temperature measurement function ML5208internal 65 to 90°C
External (Max. 3 inputs) 65 to 85°C
System protection to deal with the irregular operation Short detection
Irregular SPI clock detection
Current consumption (typ) Under normal operation 250µA
Under power save mode 105µA
Under power-down mode 51µA
Power supply voltage*2 +8 to +80V
Operating temperature range -40 to +85°C
Package QFP44 / TQFP48


Block Diagram of chip set

  • ML5208 is analog front-end IC for the li-ion battery pack protection system of 5 to 13 cells. The li-ion battery pack protection system is organized by using it with the controller. It is possible to detect an overcuurent by connencting the sensing resistance externally, besides the overcharge and overdischarge of each cell. Moreover, ML5208 supports N-MOS FET as the external FET for switching charge and discharge.
  • ML5227 is the controller for ML5208 control. It can store the control program code and the parameter such as overcharge/overdischarge detection voltage into its internal Flash memory. It can be used according to the characteristics of li-ion battery cell without the nonvolatile memory.