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The universal battery charger using Lm317

Here comes very simple idea is the universal battery charger circuit.
When, an input power is applied to the circuit.
The SCR1 (Silicon controlled rectifier) turn off, then not has a bias current path to ground.
The LM317 acts as a current regulator, It is connected to the battery thought a one way diode D1, limiting resistor R1, and a bias resistor R2.
The D1 prevents the circuit from battery discharging, when the power out off from this circuit.
As the battery charges, the voltage across A point potentiometer R5 and some point rises, to turn on the SCR1.
Then current from the regulator LM317 can flow to ground, so now the IC1 is in functions the voltage-regulating mode.
The R6 be used to control the output voltage.
When the SCR1 turn on, it also provides LED1 through R3 with a path to ground.
But when LED1 is on, this circuit is in the voltage-regulating mode, while LED1 is off to be in the current-regulating mode.

Be the first to comment - What do you think? Posted by admin - February 4, 2012 at 3:51 am

Categories: Battery charger Tags: Linear Battery Charger, universal battery charger circuit

Lithium-Ion Linear Battery Charger with Thermistor Interface By LTC4050

Lithium-Ion Linear Battery Charger with Thermistor Interface LTC4050, pdf file

The LTC® 4050-4.1/LTC4050-4.2 are complete standalone constant-current/constant-voltage linear charge control-lers for lithium-ion (Li-Ion) batteries. Charge current is programmable and final float voltage has ±1% accuracy.
When the input supply is removed, the LTC4050 automatically enters a low quiescent current sleep mode, dropping the battery drain current to 5µA. An internal comparator detects the near-end-of-charge (C/10) condition while a
programmable timer, using an external capacitor, sets the total charge time. Fully discharged cells are automatically trickle charged at 10% of the programmed current until cell voltage exceeds 2.49V. The thermistor interface
suspends charging if the cell temperature is outside of a 0°C to 50°C temperature window.