Description and precautions for the protection scheme of 4--14 series lithium batteries

The resistance value of Rvm is selected in the 4--7 series lithium battery protection scheme, the resistance value of Rvm should not be selected too large, and Rvm*Ivm should be less than 3V. If the Rvm is too large, the discharge protection cannot be locked. Rvm resistance is recommended to use 100K, the range is 0---1000K. In the protection scheme of lithium batteries in series with more than 8 cells, Rvm needs to be set appropriately according to the user's own application requirements. When the value of Rvm is larger, the current consumption of batteries above the 7th section is smaller, but the corresponding over-discharge protection release time will be longer. Conversely, the greater the current consumption, the shorter the release time of the over-discharge protection. It is recommended to use 1M for Rvm resistance. Rcgs resistance selection

If the Vgs withstand voltage of the Mcd tube you choose is much higher than the Vcc voltage of TH2132, you don’t need to connect Rcgs. The advantage of this is that the power consumption of the entire solution will be reduced during normal operation. Decrease the value of Icout to about 5uA. If the Vgs withstand voltage of the Mcd tube you choose is close to or lower than the Vcc voltage value of TH2132, you need to connect Rcgs to limit the Vgs voltage value of the Mcd tube (Vgsu003dIcout*Rcgs). The value of Rcgs can be set according to the user's application. ZD1 voltage regulation value selection ZD1 voltage regulation value needs to be higher than the Vcc voltage value when TH2132 is working, but not higher than the limit withstand voltage value of TH2132; because when the voltage across the voltage regulator tube is close to the voltage regulation value, the voltage regulator tube Will produce power consumption, so the voltage regulation value should be selected according to the actual situation. Make the power consumption as small as possible, while keeping the voltage regulation value as close as possible to the Vcc operating voltage value. The reverse withstand voltage value of D1 and D2 must be greater than the total voltage of the battery pack. The reverse withstand voltage value of D3 and D4 must be greater than 'the total voltage of the battery pack minus Vcc'. The Vce withstand voltage value of Q1 must be greater than Icout*Rcgs or Vcc voltage value (when Rcgs is not connected). The Vce withstand voltage value of Q2 must be greater than the charger voltage. (The charger voltage refers to the maximum voltage across the charger when the charging MOS tube is turned off) The Vec withstand voltage value of Q3 must be greater than the 'charger voltage minus the total voltage of the battery pack'. Mcd is a charging MOS tube, and its Vgs withstand voltage value must be greater than Icout*Rcgs or Vcc voltage value (when Rcgs is not connected); Vds withstand voltage must be greater than 'charger voltage minus total battery voltage'. Mfd is a discharge MOS tube, and its Vgs withstand voltage must be greater than 18V; Vds withstand voltage must be greater than the total voltage of the battery pack.