TP4056

The TP4056 chip is a lithium Ion battery charger for a single cell battery, protecting the cell from over and under charging. It has two status outputs indicating charging in progress and charging complete. It also has a programmable charge current of up to 1A.

You can use it to charge batteries directly from a USB port since the working input voltage range is 4V ~ 8V.

There are two types of common breakout boards for this chip:

• One with only the charger chip on board.
• One with three chips on board.

Here you are looking at the 3 chip breakout board (TP4056, DWO1A and 8205A MOSFET).

What you can learn here:

• How to use the TP4056 breakout board.
• How to use the TP4056 safely.
• How the DWO1A works on the TP4056 breakout board.
• How to set temperature limits using the TP4056 TEMP input.
  

Note: You need to change the current programming resistor on the breakout board to match the lithium battery you are using - the default is 1.2k which is for a 1Ah (1000mAh) battery.

Note: Follow this link to learn how to use the DWO1A correctly.

Lithium batteries can be dangerous if not charged properly and that's why the TP4056 is useful as it stops over voltage and current charging at specific conditions.

TP4056 Features

• Constant Current / Constant voltage charging method.
• C/10 Charge termination.
• 2.9V trickle charge threshold (for deeply discharged batteries).
• Upper charge stop voltage : 4.2V.
  
• Soft start inrush current limit.
• Automatic recharge (keeps batteries optimally charged when connected to a charger).
  

TP4056 module Datasheet

Download the TP4056 Datasheet here.

TP4056 Specifications

            [trckl = Trickle charge, trhsy = Trickle Charge Hysteresis]

TP4056 Current Programming Resistor

TP4056 Status indicator LEDs

TP4056 Breakout Board Schematic

[ Source:www.sunrom.com/p/lithum-battery-charger-with-protection-microusb ]

When charging a battery using the above board connect the battery to B+ and B- and disconnect OUT+ and OUT- from your circuit. When using the battery disconnect the 5V input and take the output voltage from OUT+ and OUT- to your circuit.

TP4056 Connections

The following diagram shows a typical setup (from the datasheet).

TP4056 Block diagram

TP4056 reverse polarity protection

DWO1A Battery Protector Chip

On some breakout boards there are an extra 2 chips. One is the DWO1A and the other is a dual N Channel MOSFET required by the DWO1A chip.

Learn more about the DWO1A Battery protector here.

Note: Follow this link to learn how to use the DWO1A correctly.

This chip provides battery protection but it is not used in the right way on this board and so only provides short circuit protection (and over current protection).

It should provide all of the following:

Charger input protection

• Short Circuit detector.
• Over current detector.
• Charger Detector.
• Reverse charger detection (overstress high current?).
  

Battery monitoring

VCC and GND are connected across the battery where two voltages are detected:

• Overcharge Detector (battery voltage too high).
• Overdischarge Detector (battery voltage too low).

Follow this link for more details on the DWO1A operation and use.

DW01A and TP4056 breakout Board

• Stops discharging at voltages below 2.9V; Here trickle charge activates.
       The DWO1A threshold is ~ 2.4V; So it will never activate.
  
• Stops charging at voltages above 4.2V.
      The DWO1A threshold is  ~ 4.3V; So it will never activate.

The only function that will operate is the overcurrent protection and short circuit protection. These will activate at around 3A when using the 8205A dual Mosfet.

Follow this link for more details on the DWO1A operation and use.

TP4056 Power Sharing Problem

One problem with this circuit is that you must disconnect the load when charging. The reason is that the charging circuit detects when the charge rate falls below C/10 (Constant current charge mode near the end of the charging cycle). C is the battery capacity in mAh.

If you have a load connected to the battery then this will change the current detected so the TP4056 may never terminate the charging process.

Using 3 Components to achieve safe charging

A way around this problem is to use a switching circuit employing a P Channel MOSFET - this is sometimes called load sharing or automatic power path control. it is a controlled switch that disconnects the battery when external power is applied.

The idea is that when a power source is connected to the Battery charger chip, the PMOSFET disconnects the battery from the load. The TP4056 still charges the battery but without a load. Power to the load is supplied from the power source directly.

When the power source is disconnected, the PMOSFET is turned on connecting the load to the battery.

With this configuration the TP4056 can safely charge the battery with the load connected, as the battery is isolated from the load during external power application.

PMOSFET power Sharing

The following diagrams show how the PMOSFET is used for power sharing.

To turn ON the PMOSFET, the Gate must be negative (<V_GS(th)) w.r.t the Source.
To turn OFF the PMOSFET, the Gate must higher than V_GS(th) w.r.t the Source.

Note: V_GS(th) is the threshold voltage of the MOSFET.

PMOSFET ON (Just the battery)

Here the gate of Q1 is low (pulled down by R_PULL) and the PMOSFET is on, so current flows from the battery to the load.

State of D1 No Input Power

State of Q1 No Input Power

PMOSFET OFF (Power source connected)

[Source: Microchip application note AN1149]

Here the gate of Q1 is high and the PMOSFET is off. so the battery is isolated from the load. The power source drives current through the schottkey diode (D1) to the load.

    V_G = V_IN

    V_GS = V_{POWER -} V_D1FV

Conditions for the PMOSFET to be OFF are:

    The Gate is higher voltage than the Source : Vgs > V_GS(TH) i.e. more positive.

Since the Gate is equal to Vin (~5V) and the diode drops 0.4V, Vgs is positive by 0.4V, therefore the MOSFET is off.

Examples of P MOSFET Selection

Example of a Schottkey Diode

Note: The schottkey diode will heat up when the charger is externally powered. The Power used depends on the load attached to the output - current through it and voltage drop accross it.

An alternative to the schottkey diode is to use the 2^nd PMOSFET in the IRF7329 above to replace the diode. This would need controlling using a microcontroller or using the status outputs of the TP4056 (see the LTC4056 datasheet - which is a different chip but provides a design reference).

How to use the TP4056 TEMP control Input

Working out R1 and R2 for the TP4056

Recommended operating temperature

Battery University recommends charging only from 5°C to 45°C.

Note: Use these calculations at your own risk. Also you must use the battery manufacturer's data on the thermistor for operational use. Also other standards suggest charging at even tighter temperature limits.

Temperature Limit Design Calculations

Warning: This is just an example calculation. Always use the battery manufacturer data sheet for the thermistor inside the battery to ensure correct operation.

Found 4900 86200 Ratio1 0.450 Ratio2 0.803 

The closest Standard resistors (E48) are:

        (E48) R2 = 86600

        (E48) R1 = 4870

These standard values result in the following ratios:

r1 4780 r2 86600 Rntc1 4.2e3 Rntc2 26e3
Ratio1  0.4559
Ratio2  0.8071

These will stop the TP4056 charging below 5°C and above 45°C (approx).

Note: Remember to account for resistor tolerance and thermistor accuracy.

Program to calculate Ratios

This is a tcl program. You can download (the completely free) tcl language at Activestate.com.

Copy Sketch

# Inputs  for MF52 (B=3950)
set vratio1 0.45
set vratio2 0.80
set ratio_tol1 0.01
set ratio_tol2 0.05
set Rntc_min 4.2e3
set Rntc_max 26e3

# Stepping controls
set tpPriv(step) 100 ;# Step size
set tpPriv(startR)  100  ;#Step start
set tpPriv(maxR1R2) 250e3 ;# Step end
set tpPriv(stop) 0

console show

################################################################
proc get_ratio { Rntc r1 r2 } {
   set Rpara   [expr { ( 1.0* $Rntc * $r2 )/( $Rntc  + $r2)} ]
   set Vratio  [expr { ( 1.0* $Rpara      )/( $Rpara + $r1)} ]
   return $Vratio
}

################################################################
proc within_tol {num val tol} {
   if {$num >= ($val-$tol) && $num <= ($val+$tol)} {return 1}
   return 0
}

################################################################
proc  testTP4056Temp {Rntc1 Rntc2 Ratio1 Ratio2 tol1 tol2} {
global tpPriv
   set op {}
   set tpPriv(found) 0
   for {set r1 $tpPriv(startR)} {$r1<$tpPriv(maxR1R2)} {incr r1 $tpPriv(step)} {
   puts "$r1" ; update
       for {set r2 $tpPriv(startR)} {$r2<$tpPriv(maxR1R2)} {incr r2 $tpPriv(step)} {

          set VratioCalc1  [ get_ratio $Rntc1 $r1 $r2]

          if { [within_tol $VratioCalc1 $Ratio1 $tol1] } { ;# if this is ok check the other ratio

             set VratioCalc2 [ get_ratio $Rntc2 $r1 $r2]

             if { [within_tol $VratioCalc2 $Ratio2 $tol2] } {

                set frat1 [format "%2.3f" $VratioCalc1]
                set frat2 [format "%2.3f" $VratioCalc2]
                puts "Found $r1 $r2 Ratio1 $frat1 Ratio2 $frat2" ; update
                lappend op  "Found $r1 $r2 Ratio1 $frat1 Ratio2 $frat2\n"
                incr tpPriv(found)
             }
          }
          if {$tpPriv(stop)} {break}
       }
       if {$tpPriv(stop)} {break}
   }
   set fh [open op.txt w]
   puts $fh [ join $op ]
   close $fh
}

proc stop {} {set ::tpPriv(stop) 1}

pack [ button .b -text Stop -command stop ]

testTP4056Temp $Rntc_min $Rntc_max $vratio1 $vratio2 $ratio_tol1 $ratio_tol2

puts "\nFound: $tpPriv(found)\n\n"