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This design of laptop battery
Since the volume density of lithium dell 5081P battery, energy density, and up to 4.2V single-cell voltage, so mobile phones, PDA and digital cameras and other portable electronic products to obtain a wide range of applications. In order to ensure the safety of the use of lithium batteries in the application must have a corresponding battery management circuitry to prevent battery overcharge, over discharge and over-current. Lithium Battery Protection IC ultra-small package and very little need for external components to make it a single lithium battery protection circuit design has been widely adopted.
Currently, however, whether it is positive (independently developed) or reverse (imitation development) designed to protect the domestic lithium dell laptop battery IC due to technical, technological reasons, the actual parameter is usually associated with standard parameters are very different, in the forward design of IC is particularly prominent, therefore, lithium battery protection IC test the actual working parameters has become a necessity. Currently on the market there have been a dedicated lithium battery protection board tester, but the price is generally high, and the test must first IC soldering the circuit board. Therefore, this paper designed a simple test circuit, using an ordinary electronic equipment can be completed on the lithium battery protection IC testing.
Lithium laptop battery Protection IC works
Single Li-ion battery protection IC for the application circuit is very simple, only two external resistors, two capacitors and two MOSFET, the typical application circuit shown in Figure 1.
Figure 1 Lithium Battery Protection IC Typical Application Circuit
Lithium Battery Protection IC Test Circuit Design
Figure 2 Lithium Battery Protection IC Test Circuit
According to Li-ion dell Inspiron 700m battery Protection IC design of the working principle of the test circuit shown in Figure 2, Figure 3 details the module B in Figure 2 circuit. A in the test over-current protection module when CS pin voltage, analog Figure 1 in the CS pin of the detected voltage. Adjusting the variable potentiometer module for CS pin to provide a variable power supply, control of them hopping switches available for CS mutation voltage. Module B for power, analog voltage for the IC to provide work. Adjustment circuit variable potentiometer R7 may be for the entire circuit to provide a variable voltage test Overcharge protection voltage and over-discharge protection voltage is used. Control module in the switch S1, is closed for the test circuit to provide a transition power supply IC in the test over-charge, over discharge and over-current delay time to use. Jumper Port P1, P2, when the test IC operating current use, the other parameters in the test switch S2 turn-on when it can be. Test IC operating current, it will ammeter connected to the P1, P2, move the switch S2 off. Module C is made of two MOSFET micro-current source, in the test OD, OC output high and low to the pin when the suction, irrigationdell Inspiron 710m battery currents, as long as the MOSFET choose appropriate to meet the testing needs. Module D is a two MOSFET integrated chip, equivalent to Figure 1 of the M1, M2, one of the two ports in the test leakage current when the MOSFET used in testing the other parameters to these two ports shorted. Module E is an IC socket, the socket will be placed under test IC, can be placed up to 4 IC (the test can only put an IC), after testing End IC can be removed without leaving any trace, does not affect the sales of IC and re-testing.
Figure 3 Module B of the circuit
In the test circuit design, the choice of the resistance to be careful. In the module A, B, C because of the existence of a variable potentiometer, if other resistance selection of inappropriate and likely to cause burning of the circuit, especially the module A and B, the choice of the variable potentiometer for testing a variety of voltage accuracy of a significant influence. The circuit in two dell F5136 battery variable potentiometers are 1K/10 circle high precision. Module C of the MOSFET selection should pay attention to its operating current range, the current in the test need to use only two levels, one for tenths of microamps, a dozens of microamps, so the general requirements to provide microampere level following current. In addition, the power stability of the entire IC test parameters have a great impact, therefore, in testing to make full use of the stability of a good power supply.
The design features
This design has the following three features.
● test IC overcharge, over-discharge and over-current delay time switch will be used to achieve resistance short-circuit or open circuit the power of the mutations, and use the oscilloscope at the same time grasping power and OC, OD hopping waveforms to measure the delay time.
● In order to achieve test OC, OD high, low suction to the pin, sink current, the circuit with the MOSFET to do two simple micro-current source, selected MOSFET model TN0201T, the use of gate-level voltage-controlled drain, source-level current, in order to drain, source-level current of current source, precision can reach 0.1μA, essential to meet the testing needs.
● Test voltage over-current protection, that is tested to make dell 312-0306 battery OD pin from a high jump into the CS pin voltage is low. Short-circuiting protection voltage much higher than the overcurrent protection voltage, when the voltage over-current protection circuit voltage when the transition has taken place, OD output has been low, so conventional methods can not identify short-circuiting protection voltage, therefore, this article uses an indirect approximation method. IC for over-current protection delay time to approximately a few dozen milliseconds, while the short-circuiting delay time at around 10 a few microseconds, it can over-current delay time and short-circuiting the different dell 312-0305 battery delay time to approximate test short-circuiting the protection voltage. This parameter using a dedicated lithium battery protection board testers, can not be measured.
This test circuit there are also some drawbacks. First, the accuracy of the IC testing and power stability, accuracy of the meter, which tests the accuracy of various voltages with the precision of the variable potentiometer; second short-circuiting protection voltage measured is an approximation.
Summary
Although the current market there are many lithium battery protection board tester, but are expensive, and the test parameters fixed, can not meet the actual test requirements. In practical applications, customers of the most Li-ion dell Inspiron 500m battery protection IC focus in several key parameters are: over-charge, over discharge and over-current protection voltage, quiescent current and shutdown current, over charge, over discharge and over-current protection delay , and OD, OC pin output high, low. This article provides test methods can be accurately measured by the above parameters, has gone beyond the lithium battery protection board tester can test parameters. Thus, in some of the lithium battery protection IC parameters required to be comprehensive or conditions are restricted occasions, this article provides a test circuit and test method is a better dell Inspiron 510m battery choice.
The test circuit and test methods have been put into use, has been successfully tested more than a thousand film lithium battery protection IC. From the test results, in addition to short-circuiting protection voltage is similar to testing outside the other parameters tested with special test equipment measured results are very consistent; reflect the situation from the customer point of view, the test circuit parameters measured accurately, to meet the customer needs. Since the test circuit does not package (plus housing), according to customer's need to increase the appropriate circuit test more parameters (such as the test mentioned in this article dell Inspiron 600m battery MOSFET leakage current size).