The post elaborately explains a single chip CC/CV or constant current, constant voltage Li-Ion battery charger circuit, using the IC TP4056.
The TP4056 is a comprehensive constant-current (CC), constant-voltage (CV) linear charger IC specially designed for safely charging single cell lithium-ion batteries.
It comes with a SOP package and hardly any external component count making the IC TP4056 specially applicable for portable Li-Ion chaging applications.
In addition, the TP4056 can also work with USB and wall socket based adapter supplies.
The design does not depend on any blocking diode due to the presence of an internal PMOSFET architecture which is configured to prevent any sort of negative Charge Current in the Circuit.
A special Thermal feedback loop is included in order to regulate the charge current to limit the body temperature while using in high power operation mode or with high ambient temperatures.
The full charge voltage is fixed at 4.2V, while the charge current can be adjusted externally through a given single resistor.
The IC TP4056 is featured to automatically shut down the charging cycle as soon as the charge current has dropped to 1/10th the set value, after the final float voltage is accomplished.
Some of the other mains features of this IC TP4056 include a built-in current monitor circuitry, an under voltage lockout, an automatic recharge resumption, and a couple of status pinouts to indicate full-charge cut off and the supply input voltage switch ON.
IC TP4056 image and pinout arrangement
FEATURES and SPECIFICATIONS
·Charge Current may be programmed to a max 1000mA
·The circuit can be free of power devices, Sensing Resistor or a Blocking Diode
·A full fledged Linear Charger in SOP-8 Package for charging applications of Single Cell Lithium-Ion Batteries.
·Designed to Produces a Constant-Current/Constant-Voltage Output
·Capable of Charging Single Cell Li-Ion Batteries through Direct USB Port plugin
·Internally set 4.2V constant Charge Voltage with +/-1.5% Accuracy
·Includes an Automatic Recharge initialization.
·A double LED compatible Charge Status Output Pins for indication purpose
·C/10 Charge Termination or auto shut down feature
·Trickle charge is initiated as soon as a 2.9V threshold is reached.
·An Internal Soft-Start processor Limits and inhibits Inrush surge Current
·Comes with a 8-Lead SOP Package, The Radiator needs to be connected to GND.
ABSOLUTE MAXIMUM RATINGS
Pinout specification and functioning details of TP4056 IC
TEMP(Pin 1) :Temperature Sense Input
Hooking up TEMP pin with an NTC thermistor's output in Lithium ion battery pack. If TEMP pin’s voltage goes under 45% or over 80% of supply voltage VIN exceeding 0.15S, this indicates that
battery’s temperature is simply too high or overly reduced, charging at this position is stopped. The temperature detection feature could be disabled by joining the TEMP pinto the ground rail.
PROG(Pin 2): is associated with the Constant Charge Current Setting and may be set by attaching a resistor RISET from this pin2 to GND.
While in the precharge mode, the ISET pin’s voltage is regulated to around 0.2V. and in constant charge current mode, the ISET pin’s voltage is regulated to around 2V. Within all modes and in the process of charging, the voltage on ISET pin could be utilized to monitor the charge current through a meter.
GND(Pin3): Ground Terminal
Vcc(Pin 4): Positive Input Supply Voltage
VIN is the power supply input for the internal circuit to operate. Any time VIN falls at around 30mv below the BAT pin voltage, TP4056 goes into low power sleep mode, reducing BAT pin’s current below 2uA.
BAT(Pin5): Battery Connection Pin.
Link the positive terminal of the battery to BAT pin. BAT pin consumes lower than 2uA current whenever the chip is in the disable mode or in sleep mode. BAT pin offers charge current for the connected battery and presents it with a voltage regulation of precise 4.2V.
(Pin6): Open Drain Charge Status Output, Whenever the battery reaches the Charge Termination shut off point, this pinout is dragged low through an in-built switch, but normally this pin remains in high impedance status.
(Pin7): Open Drain Charge Status Output Once the battery is connected and begins charging, this pinout is taken low by an in-built switch, in any other case the pin is held at high impedance condition.
CE(Pin8): Chip Enable Input. A high input here enables the unit to be in the typical operating mode.
Towing the CE pin to a logic low level will force the TP4056 chip into a disable or shut down mode.
The CE pin is compatible and could be associated wit TTL or CMOS logic triggers.
Li-Ion Battery charger circuit using TP4056
The following design represents the typical Li-ion battery charger circuit with constant current and constant voltage features and with auto termination at 4.2V.
The following figure shows the LED status indication details for the above discussed CV, CC Li-Ion battery charger circuit.
Courtesy: NanJing Top Power ASIC Corp.