2. Hardware
In fact, in order to apply the principles of the hysteresis actual battery system, but also consider the question of a reference voltage. Reference voltage UREF not change or the threshold voltage up and down will change. And the reference voltage is generated by the voltage of the battery, it should be much lower than the voltage of the battery and low energy consumption. Dell Inspiron 1720 battery Dell Latitude D620 battery
Specific hardware circuit, reference voltage of shunt regulator LM285Z product 2.5, which requires only 10μA of the minimum, can be output by the current stable reference voltage 2.5V, which can significantly reduce energy consumption battery in the state lockout, low voltage. ST TS393I compare selected companies, it is a comparison of micro-hydro, so that any partial pressure of resistance can choose a great addition to reducing power consumption. Comparison of production control P-channel MOSFET, VT3 connects or disconnect the load. When the battery voltage drops to a certain extent VT2 off, making the composition of the protection by the comparator circuit and the battery is disconnected, the battery is greatly reduced energy consumption, the battery is a kind similar to the natural discharge of the state, where the recovery time of battery voltage, VT2 natural circuit protection conduction to resume work.
3 Parameter calculations
We 9V battery as an example to calculate the parameters.
Step 1: fixed according to the characteristics of the battery voltage threshold UTHH = 7.8V = 6V and UTHL. Dell Vostro 1000 battery Dell Studio 1555 battery
Step 2: To ensure that when the battery voltage reaches the low voltage lockout control of partial pressure of 2.5 LM285Z can still work, they must ensure LM285Z 2.5 on the elite present, but also shunt regulator separate the current to the resistance network with others, leaving twice the margin, so that the real must ensure Iref> 20μA, which can be obtained R6 = 175kΩ, take R6 = 125kΩ.
Step 3: As the battery voltage exceeds the reference voltage, the battery voltage by R4 and R5 should divider network formed after the partial pressure of the reference voltage divider with a benchmark for comparison. Set = 1.25 V UL (UL Uref take half the size, in order to R1, R2, R3 resistance is relatively close, of course, can choose a value other than Uref), then R4 and R5 ratio partial pressure Q = UL / UTHL, you can Q = R4 / (R4 + R5) R4 and R5 calculated the ratio, but can also be UH = Q = 4.625V × UTHH. Dell Vostro 1710 battery Dell Latitude D510 battery
Step 4: Let R1 = 9lkΩ, according to equation (4) can be obtained by R2 = 91kΩ.
Step 5: According to equation (3) to calculate R3 = 78kΩ.
When the battery voltage below 5V, VT2 was disconnected, the resistance is essentially the sum of the resistance of 385kΩ energy consumption of battery discharge current is only 10μA or more.
The Series 6 1.2V Ni-MH, the use of the above parameters for the test. After the battery is completely discharged when the voltage is less than 6V the UTHL, the load is disconnected, the battery voltage rises quickly to about 7.4V, but does not meet 7.8V UTHH with the load disconnected, then no oscillation circuit. dell inspiron 9400 battery dell inspiron b120 battery
4 Conclusion
This simple circuit protection system of the battery, the use of hoses. Just select a higher voltage comparators, voltage can be applied to any level of the circuit, just change the resistor value can be set anywhere turn around and the threshold Judgement, which may have a wide safety margin. In addition, during the battery protection through the use of all chips ultra-low power consumption and greater resistance value, the power consumption of so little. When the battery voltage is reduced further, the system automatically disconnects the protected circuit, the battery is natural in a similar state of discharge, the discharge current of only a few microamps. dell inspiron 9200 battery dell inspiron 9300 battery