In case of accidental polarity inversion, due to improper batteries are installed in its proper "compartment", very likely is damage charge leg device (ZU). In [1] was a diagram of protective device for ZOU.
The scheme of memory protection is shown in Fig.1. В ней зарядка аккумулятора Li-ion производится от интегральной микросхемы типа MAX1551. Эта микросхема работает в линейном режиме зарядки указанного типа аккумуляторов от внешнего источника, подключаемого к входу «Адаптер 3.7…7 В» или от USB входа.
Figure. 1
When connected to the power source and the compliance with the agreed scheme Fig.1 polarity of the rechargeable battery (Li-ion), output voltage of the comparator MAX9001 approaches the potential of the power source. Accordingly, field effect transistor type JRF7201 opened, the load is powered on and the battery is charging.
When installing the battery in the wrong polarity of output voltage comparator is equal to 0, the transistor type JRF7201 is locked up, and for in-line current through the battery leaking. It will save from damage both battery and charger ICS MAX1551 type.
The scheme has current protection level MAX1551 chip 50 Ma. Protection response time not exceeding 200 ns.
To protect the inverse log of the comparator chip had to limit the current flowing through the integrated diode at the entrance of the MI kroshemy. This function performs the resistor R1. His denomination on a diagram about 50 kΩ. Resistor R2 performs a similar current protection the other input of the comparator.
MAX9001 chip can also be used as battery charger with AK kumuljatorov. Only it is necessary to watch, that do not exceed the planned watch settings.
Literature
- РЕ-AR. – 2016. – №2. – S. 19.
Author: Andrei Nikolaev, Zaporozhye
Source: Radioamator No. 4/2017
