Automatic Programmable 4.2V Battery Charge, Current up to 500mA using LTH7R IC

Effortless Battery Charging: Build an Automatic Programmable 4.2V Charger with up to 500mA Current Using LTH7R IC and PCB

The LTH7R IC is a constant current or constant voltage base charger chip, mainly used for single cell lithium battery charging.

No external sensing resistor is needed, it has its internal power MOSFET structure, so no external reverse diode is needed.

The LTH7R IC has under temperature protection and control, it adjusts the charging current automatically to limit high temperature on the chip.

Its charging voltage is fixed at 4.2V, and the charging current can be adjusted by an external resistor.
When the float voltage is reached and the charging current drops to 1/10 of the defined circuit, the LTH7R IC automatically completes the charging process.

Fig. 2 - Pinout LTH7R IC

When the input source voltage is removed, the LTH7R IC automatically enters low current mode, drawing less than 2uA from the battery.

When the LTH7R IC enters standby mode, the supply current is less than 25uA. The LTH7R IC can also monitor charging current, has the features of voltage detection, auto-cycle charging, and has an indicator pin to indicate end-of-charge status and input voltage status.

Features

• Programmable charging current up to 500mA
• No need for external MOSFET, sensing resistor, reverse diode
• Constant current or constant voltage mode operation, with thermal protection function Preset charging voltage
• Standby current is 20uA
• 2.9V slow charge voltage
• Soft start limits the inrush current
• Adopt SOT23-5 package, application line
  

Product application

• Microphone Battery
• Light Camera
• Mobile Phones, PDAs, MP3 players
• Bluetooth headsets 

External programming of the load current:

PROG (pin 5): Constant current load current setting and load current monitoring terminal. The load current can be programmed by connecting an external resistor from the PROG pin to ground.

In the pre-charge phase, the voltage of this pin is modulated by 0.1V; in the constant current charging stage, the voltage of this pin is fixed at 1V.

In all charging state modes, measuring the voltage of this pin can estimate the charging current according to the following formula:

General Formula:

I_bat = 1000 / R_prog

To use, for example, in a charger whose required current is 300mA, we can use the formula as follows:

• I_bat = 1000/ R_prog
• R_prog = 1000 / I_bat
• R_prog = 1000 / 300
• R_Prog = 3.3K

To use, for example, in a charger whose current required is the maximum current, 500mA, we can use the formula as follows:

• I_bat = 1000/ R_prog
• R_prog = 1000 / I_bat
• R_prog = 1000 / 500
• R_Prog = 2K
  

We leave just below a small table ready with five models with the standard currents for the battery charger.

Model	R_prog	I_bat
1	10K	100mA
2	5K	200mA
3	3,3K	300mA
4	2,5K	400mA
5	2K	500mA

The Circuit Schematic

In Figure 3, below, we can see the schematic diagram of the Automatic Programmable 4.2V Battery Charge, Current up to 500mA using LTH7R IC.

All circuit components are SMD, the power supply input is done by soldering on the PCB. This type of miniaturized SMD circuit is great to be implemented in circuits with small spaces.

The capacitors are SMD electrolytic, but if you have tantalum capacitors, you can put them on, it will help with the plate height, but if you can't find them, you can use electrolytic.

The charger circuit supports voltage between 4.4V to 7V, the recommended is 5V, which is great news for us to be able to charge our battery in a PC USB port or even with cell phone chargers.

Fig. 3 - Automatic Programmable 4.2V Battery Charge, Current up to 500mA using TH7R IC

Printed Circuit Board

In Figure 4, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass.

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

Fig. 4 - PCB Automatic Programmable 4.2V Battery Charge, Current up to 500mA using TH7R IC

Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

I hope you enjoyed it!!!

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

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My Best Regards!!!

General  IC Description

The RT8289 is a step-down regulator with an internal Power MOSFET. It achieves 5A of continuous output current over a wide input supply range with excellent load and line regulation.

Current mode operation provides fast transient response and eases loop stabilization. The RT8289 provides protections such as cycle-by-cycle current limiting and thermal shutdown.

In shutdown mode, the regulator draws 25A of supply current. The  RT8289  requires  a  minimum  number  of  external components, to provide a compact solution. The  RT8289  is  available  in  a  SOP-8  (Exposed  Pad) package.

Features

• High Output Current up to 5A
• Internal Soft-Start
• 100mΩ Internal Power MOSFET Switch 
• Internal  Compensation  Minimizes  External  Parts Count
• High Efficiency up to 90%
• 25μA Shutdown Current
• Fixed 500kHz Frequency
• Thermal Shutdown Protection
• Cycle-by-Cycle Over Current Protection
• Wide 5.5V to 32V Operating Input Range
• Adjustable Output  Voltage from 1.222V to 26V
• Available in an SOP-8 (Exposed Pad) Package
• RoHS Compliant and Halogen Free
  

Output Voltage Setting

To define the output voltage, we use a voltage divider formed by 2 resistors, R1 and R2, this allows the FB pin of the integrated circuit to detect changes in the output voltage, and recalibrate the circuit keeping it stabilized.

To set this output voltage, we can calculate the external resistive divider, according to the equation formulated below:

• VOUT = VREF *(1 + (R1/R2))
• Where VREF is the reference voltage (type 1.222V).
• Where R1 = 10kΩ.

We exemplify in our circuit, the voltage divider is formed by R1 and R2.

General Formula:

• VOUT = VREF *(1 + R1/R2)
• Where VREF is the reference voltage (type 1.222V).
• Where R1 = 10kΩ.
  

For a 3.3V output, our formula would look like:

• Vout = 1,222 * (1+ (10/5.8))
• Vout = 3.328V

For a 5V output, our formula would look like:

• Vout = 1,222 * (1+ (10/3.16))
• Vout = 5,089V

For a 9V output, our formula would look like:

• Vout = 1,222 * (1+ (10/1.57))
• Vout = 9,005V

For a 12V output, our formula would look like:

• Vout = 1,222 * (1+ (10/1.13))
• Vout = 12,036V

For a 26V output, our formula would look like:

• Vout = 1,222 * (1+ (10/0.493))
• Vout = 26,009V
  

We may be using a trimpot instead of R2, this allows you to vary the output voltage through the Trimpot.

The Circuit Schematic

In Figure 2, below, we can see the schematic diagram of the Low Noise and High Frequency 5A DC-DC Step-Down Converter.

All circuit components are SMD, except the terminal blocks, “optional”, you can solder directly to the board. This type of SMD circuit is great to be implemented in miniaturized circuits.

It is preferable to use tantalum capacitors, but if you cannot find them, electrolytic capacitors can be used, but for more sensitive circuits, we recommend using tantalum.

The DC-DC converter supports input from 5.5V to 32V, and at the output it maintains the preset voltage completely stabilized.

Fig. 2 - Schematic 5A, 1.22V to 26V, 500kHz Step-Down Converter Using RT8289 IC

Printed Circuit Board

In Figure 3, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass.

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

The PCB tracks are doubled, the main ones have their tracks on the bottom and top of the PCB as the current is 5 amps.

Fig. 3 - PCB 5A, 1.22V to 26V, 500kHz Step-Down Converter Using RT8289 IC

Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

I hope you enjoyed it!!!

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

Subscribe to our blog!!! Click here - elcircuits.com!!!

My Best Regards!!!

The circuit

How it works

When turning on the electronic resistive load, a current passes through the Drain and Source taps, and this current flow is controlled by the Mosfet Gate.

For this control to happen properly, a stabilized voltage is needed at that point, which is done through the resistor R1, current limiting, in series with the zener diode, which stabilizes the voltage at the Gate.
This stabilized voltage ensures that the current not be variable when the input voltage undergoes some variation.

This stabilized voltage point is controlled by the potentiometer P1, which adjusts the voltage at the Gate of the Mosfet according to the required current.

It is worth remembering that the transistor used is a logic-type IRL44N Mosfet, not the well-known IRF44N. 

They differ in relation to the gate voltage, as the logic-type Mosfet triggers the Gate with low Vgs voltages from 4V, and the IRF44N does not work with such low voltages, the minimum Vgs is 7V.

The Circuit

The schematic diagram of the Electronic Resistive Load - Power Supply Test!, is shown in Figure 2 below, it is a simple circuit to assemble, there are few external components to solder, however it is a circuit of great quality and stability.

Fig. 2 - Electronic Resistive Load - 50A Power Supply Test

Fig. FM Transmitter 75 to 108MHz using BA1404 IC with PCB

Build Your Own FM Transmitter: Step-by-Step Guide with BA1404 IC & PCB

This is a Stereo FM Transmitter, based on the BA1404 Hi-Fi Integrated Circuit, which is a stereo FM modulator that creates composite stereo signals, with low consumption, maximum 3mA, and an operating voltage between 1.5 to 2V.

The FM modulator has carriers in the FM transmission band (75~108MHz). It develops signals composed of a MAIN signal (L+R), a SUB signal (L-R) and a pilot signal (19KHz) using 38KHz crystal oscillators.

Feature

• Available in DIP18 and SOP18 packages
• Low operating voltage range (1.0V ~ 2V)
• Low power consumption, typically 3mA
• Requires few external components

Applications

• FM stereo Transmitters
• Wireless Microphones
• FM PLL Oscillator 
  

ATTENTION!

For each Country, Region, State... There are Laws on broadcasting, telecommunications, audio and video transmission, etc.

Do not use telecommunications equipment without authorization from the entities responsible for transmitting Radio Frequencies.

Electronic Circuits teaches electronics applied to various segments, with the aim of improving knowledge, we do not support or take responsibility for any type of illegal operation.

For any operation with RF, we recommend looking for the competent regulatory agencies, seeking certification and/or legalization.

You might also be interested in:

• FM Transmitter 70MHz to 150MHz using MAX2606 IC with PCB
• 2.5KM FM transmitter, using transistor 2N3866 with PCB
  

The transmitter circuit

The schematic diagram of the FM Transmitter 75 to 108MHz using BA1404 IC, is shown in Figure 2 below, it is a simple circuit to assemble, there are few external components to solder, however it is a circuit of great quality and stability.

Fig. 2 - Diagram Schematic FM Transmitter 75 to 108MHz using BA1404 IC

The Coil

The L1 coil is a Model 750A3.5T Inductor, however, you can make your own inductor by winding 3 to 4 turns of 24 AWG copper wire, or 0.5 mm diameter copper wire, into a 5 mm diameter ferrite core.

The Antenna

The antenna can be used with a telescopic antenna purchased at electronics stores, if you don't have it, you can use approximately 30cm of rigid wire, which will work perfectly.

Component List

• Semiconductors
• CI1 ...... BA1404 Integrated Circuit
  
• Resistors
• R1, R2 .... 47KΩ resistor (yellow, violet, orange, gold)
• R3 ........... 270Ω resistor (red, violet, brown, gold)
• R4 ........... 150KΩ resistor (brown, yellow, green, gold)
• R5 ........... 5.6KΩ resistor (green, blue, red, gold)
• R6, R7 .... 27KΩ resistor (red, violet, orange, gold)
  
• Capacitors
• C1, C2, C6, C12, C13 .. 1nF Ceramic Capacitor
• C3, C4, C5, C14 .......... 10uF 16V Electrolytic Capacitor
• C7, C10 ....................... 10pF Ceramic Capacitor
• C8, C9, C11 ................. 15pF Ceramic Capacitor
• C15 .............................. 220pF Ceramic Capacitor
  
• Inductor
• L1 ......... 750A3.5T Inductor *see text
  
• Cristal
• CR1 ...... 38KHz Cristal
  

• Miscellaneous
• P1, P2 .... Screw Terminal Type 5mm 2-Pin Connector
• ANT1 .... Telescopic Antenna *See Text
• Others .... Printed Circuit Board, tin, wires, etc.
  

The PCB - Files to Download

In Figure 3, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass. 

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

Fig.3 - PCB FM Transmitter 75 to 108MHz using BA1404 IC

Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

I hope you enjoyed it!!!

If you have any questions, suggestions or corrections, please leave them in the comments, and we will answer them soon.

Subscribe to our blog! Click Here - elcircuits.com!

My Best Regards!

ATTENTION!

You might also be interested in:

• FM Transmitter 70MHz to 150MHz using MAX2606 IC with PCB
• FM Transmitter 75 to 108MHz using BA1404 IC with PCB
  

Characteristics!

• High sensitivity of audio pickup
• 12V to 16Vdc supply voltage
• Simple circuit to assemble
• Great range, about 2.5km
• Easy assembly
  

The transmitter frequency adjustment, is regulated through the CV1 trimmer, and the CV2 and CV3 trimmers, to regulate the antenna impedance matching, must be done with patience for a better use.

The coil L1, L2 and L3 must be made with enameled wire 22 AWG of 1 cm in diameter with air core, the number of turns is described in the component list.

L4 is a 10uH RF shock, and you could be building your own RF shock by winding 15 vols of thin enamel wire around a 1MΩ resistor, soldering to both ends of the copper wire, at each end of the resistor.

The antenna can be a length of rigid wire between 20 and 50 cm for short ranges, or use a 1/2 wave dipole antenna for long ranges.

The Power Supply

PCB - Printed Circuit Board

In Figure 3, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass. 

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

Fig. 3 - PCB - 2.5KM FM transmitter, using transistor 2N3866

Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

• High output power capability:
• 4 x 50W / 4Ω max.
• 4 x 30W / 4Ω @ 14.4 V, 1 kHz, 10 %
• 4 x 80W / 2Ω max.
• 4 x 55W / 2Ω @ 14.4V, 1 kHz, 10 %
• MOSFET output power stage
• Excellent 2Ω driving capability
• Hi-Fi class distortion
• Low output noise
• ST-BY function
• Mute function
• Auto mute at min. supply voltage detection
• Low external component count:
• Internally fixed gain (26 dB)
• No external compensation
• No bootstrap capacitors
• On board 0.35 A high side driver
  

In Figure 2 below, we have available the schematic diagram of the 14V 4 Channel 200W MOSFET power amplifier circuit, this circuit is quite simple to assemble.

As we can see there are very few external components, making the circuit very simple to assemble, even for a technician or hobbyist with little experience in electronics can assemble it without much difficulty. 

Fig. 2 - Diagram 14V 4 Channel 200W MOSFET Quad Bridge Power Amplifier using TDA7850

It is important to remember to be careful when assembling the circuit, as simple as the circuit is. We must be careful not to invert any components, such as capacitors, or invert the input voltage of the circuit, because the integrated circuit or other components can be damaged easily.

Components List

• Semiconductors
• U1 ............ TDA7850 Integrated Circuit 
  
  
• Resistors
• R1 ............ 47KΩ Resistor (yellow, violet, orange, gold)
• R2, R3 ..... 10K resistor (brown, black, orange, gold)
  
  
• Capacitors
• C1 to C4 ... 220nF Ceramic/Polyester Capacitor
• C5, C6 ...... 1μF Ceramic/Polyester Capacitor
• C7 ............. 470nF Ceramic/Polyester Capacitor
• C8 ............. 47μF / 25V Electrolytic Capacitor
• C9 ............. 2.200μF / 25V Electrolytic Capacitor
• C10 ........... 100nF Ceramic/Polyester Capacitor
  
  
• Miscellaneous
• P1 to P9 .... Screw Terminal Type 5mm 2-Pin Connector
• Other ........ PCB, Wires, Speaker, etc.
  

Power Supply

This amplifier is powered by unipolar source, with direct current, the maximum current required by the circuit is approximately 15 Amperes.

And you can connect it directly to a car battery, or a motorcycle battery, or a no-break battery, or a bench power supply... 

The power will be according to the power supply, and as already shown in the IC features above, to have 4 outputs of 50W we have to supply the circuit with 14.4V. 

Printed Circuit Board

In Figure 3, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass. 

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

Fig. 3 - PCB 14V 4 Channel 200W MOSFET Quad Bridge Power Amplifier using TDA7850

Files to Download, Direct Link: