| The lithium-ion (Li-ion) battery is a new type of high-energy batterysuccessfully developed by the energy experts with there unremitting efforts in thelast century. Compared with other nickel-cadmium batteries, Lithium battery is withlarge capacity, high operating voltage, long cycle life, low power consumption, nomemory, etc. As the lithium battery is very sensitive to the charging voltage, ambienttemperature and other factors, good intelligent lithium battery protection systemplays a vital role in extending the service life of the lithium battery.This paper mainly uses the intelligent protection system with the battery cellcharge and discharge control. The whole process of the lithium intelligent protection:Trickle pre-charge-constant current charge-constant voltage charge-dischargecontrolled. Therefore, the key of the circuit design is to, prevent over-current/shortcircuit, fully charge, automatically monitor and control. Li-ion battery protection ICis a system on-chip (SOC). It consists of microcontrollers (MCU), DC/DCdifferential amplifier, the voltage loop error amplifier, voltage acquisition, voltagecomparators, temperature sensing comparator, LED Signal-driven benchmark power.Many different functions IC are integrated on a chip. The multiplexer, the voltagedetector of battery, the MOSFET control circuit, high-precision reference, andprogrammable I/O are designed in the analog front end (AFE) chip in the paper.In this paper, the design innovation of the lithium battery protection circuit isthat the intelligent management of the4-cell battery protection circuit can beprecision measurement, and at the same time precision control of the smart way tocontrol voltage detection circuit can be used on per-cell battery unit to check andselect the appropriate cell voltage or offset voltage output; in battery energy storagesystem charging and discharging of the battery cell are essential. The protectionsystem, which combined with conditioning mode circuit and middle TAP un-connectdetection circuit, can charge and discharge per-cell battery unit. The equalizationcircuit of the battery cell plays the role in balancing per-cell battery unit andextending the battery life while the middle TAP un-connect detection circuit is usedto detect, the leakage current of each node of the battery, to judge whether to exist the open-circuit phenomenon and further determine the location of the open-circuitpoints.Especially important core is the AFE internal integrated linear regulator.3.3Vstable voltage output is used to drive LED and provide the voltage of the AFEinternal analog circuit modules. Its drive capability is set to20mA (max) andrequired accuracy is10%. The LDO driver makes use of the PMOS. The chipintegrates a large number of TIMMING circuit to self-calibrate the output voltage, sono additional on-chip adjustable resistor. Large filter capacitor (0.47μF) need toconnect the output of the regulator to prevent large ripple when the input voltage orload changes. To detect AFE-supplying linear regulator’s output voltage VDDA33,VDDD18and VDDD33, the reset circuit plays a role in regulating the voltage signalwhen any LDO output is too low, whose delay time is completely determined by theexternal RC, and can prevent the battery power too low in the long time..The design based on TSMC0.5umHV40V process. The Cadence tools are usedfor circuit design layout design and simulation verification. The following issimulation results: the logical front end (AFE): the maximum pressure DC-30V;normal operating current (Isup)30~115uA; power-down mode current (Ipd)0.5uA.battery detection circuit: input offset voltage Voff31~385mV; battery detectioncircuit: voltage threshold0.396~0.404(the Vreg=2.5V). |
PDF Full Text Request