Sealed Lead Acid Battery Charger Using LT3755

This Sealed Lead Acid Battery Charger is deigned using the LT3755 DC DC controller. The LT3755 is a DC DC controller designed to operate as a constant-current source and supports a wide input voltage range from 4.5 up to 40 volts and a can provide a maximum output voltage of 70 volts.

Sealed Lead Acid Battery Charger Circuit Diagram:

Charger Circuit Diagram

Also the LT3755 is a DC/DC controller can be used for any other applications where is needed a high efficiency ( like LED drivers ).

The main features of this Sealed Lead Acid (SLA) Battery Charger circuit are : adjustable frequency 100kHz to 1MHz ,low shutdown current:

The Sealed Lead Acid (SLA) Battery Charger based on the LT3755 require an input voltage between 8V to 40V and has VFLOAT = 13.5V and VCHARGE.


USB-Chargeable Emergency Inspection Light

Described is one USB-chargeable Emergency Inspection Light for in-lab use, wired around a hi-efficiency 5mm-white LED. The power-bank of this circuit is a 1F/5.5v (yes, 1 Farad!) super capacitor. Just connect your finished circuit to an active usb port, and push switch S1 when necessary. The result is a short-time white light from LED1, generated by the charge stored in C1. Fuse F1 in the circuit is added for usb port protection, and diode D1 works as a “one-way” switch. Resistor R1 limits the current (and hence the light output) through LED1.

USB-chargeable Emergency Inspection Light Circuit Diagram:

Light Circuit Diagram

In the prototype, 1F/5.5V super capacitor took up from an old video cassette recorder was used. If you are using the commonly-available 1F/2.5v type super capacitor, you should connect two of them in series as shown here. Note that, this reduces the total capacitance, but doubles the voltage rating. Only one drawback of this idea is the undepicted price of the super capacitor; 1F/2.5v super capacitor in an Indian online store costs about 300 Indian Rupee (~ $5)!

Inspection Light Circuit Diagram

(author’s prototype realized using cannibalized parts)

 Emergency Inspection Light Circuit Diagram

(1 farad super capacitor)

Note: Super capacitor is a special capacitor (electrochemical double layer capacitor) offers ultra-high capacitance and ultra-low equivalent series resistance. Super capacitors hold up power for long duration, and that’s why the LED in our circuit works for a finite duration even after it’s unplugged from the USB port.



Digital-DC Step-Down DC-DC Converter with ZL2106

The ZL2106 is an innovative power conversion and management IC that combines an integrated synchronous step-down DC/DC converter with key power management functions. The power supply circuit build around the ZL2106 IC can provide an output voltage from 0.54 volts up to 5.5 volts  from an input voltage range between 4.5 volts and 14 volts.

Digital-DC Step-Down DC-DC Converter Circuit Diagram:

Converter Circuit Diagram

DC-DC Converter Circuit Diagram

Internal low RDS(ON) synchronous power MOSFETs enable the ZL2106 to deliver continuous loads up to 6A with high efficiency. The ZL2106 also supports phase spreading to reduce system input capacitance. This power supply circuit diagram will provide a 3.3 volts output from an 12volts input.

Main features of this converter are:Integrated MOSFET switches, 6A continuous output current, ±1% output voltage accuracy, Snapshot™ parametric capture, I2C/SMBus interface, PMBus compatible, Internal non-volatile memory (NVM).


Simple Battery Charger Controller Using UC3906

This UC3906 battery charger circuit controller contains all of the necessary circuitry to control the charge and hold cycle for sealed lead-acid batteries. The UC3906 battery charger circuit is specifically designed to provide the proper charging voltage and current determined by the temperature and state of charge of the battery.

Simple Battery Charger Controller Circuit Diagram:


The UC3906 battery charger circuit controller monitor and control both the output voltage and current of the charger through three separate charge states .

UC3906 has separate voltage loop and current limit amplifiers which regulate the output voltage and current levels in the charger by controlling the onboard driver.The charger circuit requires 18 to 22 volts DC input. Three optical ( LED ) indicators show the charge state . This IC is configured to provide three charge states:

  • Bulk charge – the charger operates in a constant-current charge mode until the battery reaches the programmed full-charge voltage.
  • Overcharge – when the voltage reaches the programmed full-charge voltage, the charger switches to overcharge mode to ‘top-off’ the battery.
  • Float charge – when the current decreases to the minimum overcharge current, the charger enters the float charge mode.


Universal Battery Charger Using by LM317

A very simple universal battery charger electronic project can be designed using the LM317 voltage regulator and some other electronic components . As you can see in this schematic circuit this charger has extreme few components , but is doing a very good job . When power is applied to the circuit the SCR1 is off, so there is no bias-current path to ground.

Universal Battery Charger Circuit Diagram:

Universal Battery Charger Circuit Diagram

The LM317 is connected to the battery through diode D1, limiting resistor R1, and bias resistor R2. The D1 diode is used to prevent the battery from discharging through the LED and the SCR when power is removed from the circuit. When LED1 is on, the circuit is in the voltage-regulating mode and when LED1 is off, the circuit is in the current-regulating mode.

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