 |
| TP5000 charger circuit diagram with pinout, wiring, charging current, Li-ion ও LiFePO4 modes, PCB test points, NTC, LEDs and repair tips. |
TP5000 Battery Charger Module: Circuit Diagram, Pinout, Wiring, Charging Current and Repair Guide
The TP5000 is a switching-mode battery charger IC designed for single-cell 4.2V lithium-ion/manganese lithium batteries and single-cell 3.6V LiFePO4 batteries. It uses an internal power MOSFET and a buck-converter architecture, allowing relatively high charging current with fewer external components than a linear charger.
According to the manufacturer information, the TP5000 supports programmable charging current from approximately 0.1A to 2A, operates from an input supply of up to 9V, provides three-stage charging, and includes functions such as battery temperature monitoring, overcurrent protection, undervoltage protection, short-circuit protection, overtemperature protection and reverse-battery protection.
This guide focuses on the TP5000 battery charging circuit, pinout, wiring, charging-current selection, practical PCB checking and common repair problems.
TP5000 Battery Charger Specifications
The TP5000 is supplied in a compact QFN16, 4 mm × 4 mm package. Its switching operation works at approximately 800 kHz, allowing the use of a relatively small external inductor. The manufacturer's information specifies an inductor range of approximately 2.2 µH to 10 µH.
| Parameter | TP5000 Specification |
|---|---|
| IC Package | QFN16, 4 mm × 4 mm |
| Battery Type | Single-cell Li-ion/Manganese Lithium or LiFePO4 |
| Li-ion Charge Voltage | 4.2V |
| LiFePO4 Charge Voltage | 3.6V |
| Input Operating Range | 4.5V–9V |
| Programmable Charge Current | 0.1A–2A |
| Switching Frequency | Approximately 800 kHz |
| Inductor Range | Approximately 2.2 µH–10 µH |
| Pre-charge Current | Programmable, approximately 10%–100% |
| Status Outputs | CHRG and STDBY |
| Temperature Monitoring | TS input with NTC support |
| Package | QFN16 |
The exact electrical limits should always be checked against the datasheet for the specific TP5000 device being used. The values above describe the published device/application information rather than every third-party TP5000 module.
TP5000 Pinout and Pin Functions
Understanding the pinout is essential when testing a damaged charging board because several pins belong to the switching power path, while others are control, sensing or status pins.
| Pin | Name | Function |
|---|---|---|
| 1, 2, 16 | VIN | Positive input supply |
| 3, 4, 5 | LX | Switching output to the inductor |
| 6, 7 | GND | Power ground |
| 8 | VS | Charge-current sense input |
| 9 | BAT | Battery voltage sensing/output node |
| 10 | VREG | Internal regulated supply |
| 11 | TS | Battery temperature sensing input |
| 12 | RTRICK | Pre-charge current setting |
| 13 | CS | Battery chemistry/control selection |
| 14 | STDBY | Charge-complete status output |
| 15 | CHRG | Charging-status output |
The TP5000 datasheet identifies VIN, LX, GND, VS, BAT, VREG, TS, RTRICK, CS, STDBY and CHRG as the main functional pins. CHRG and STDBY operate as status outputs, while TS is used for battery temperature monitoring.
TP5000 Circuit Diagram Explained
A typical TP5000 circuit contains the input supply section, switching section, current-sensing network, battery output section and status-indicator circuit.
The basic power path can be understood as:
Input Supply → VIN → Internal Switching MOSFET → LX → Inductor → Current-Sense Network → BAT → Battery
The actual component arrangement varies between reference designs and commercial modules, so a module should not be repaired by assuming that every TP5000 board uses exactly the same circuit.
Input Supply and VIN Section
The VIN pins receive the external DC supply. Published TP5000 documentation specifies an operating supply range that reaches 9V, while typical application circuits commonly use around 5V–6V input.
A 10 µF input capacitor is commonly used close to VIN to reduce supply ripple and support stable switching operation. The reference designs also emphasize keeping the capacitor physically close to the IC.
For practical testing, measure directly between VIN and GND instead of relying only on a connector reading. A broken trace, cracked solder joint or damaged input component can produce a correct voltage at the connector but an incorrect voltage at the IC.
LX Pin and Inductor Section
The LX pins 3, 4 and 5 form the switching node. This node connects to the external power inductor.
A 4.7 µH inductor is used in the published reference/demo circuits, although the manufacturer indicates that inductors in the approximate 2.2 µH–10 µH range can be used depending on the design.
The LX waveform is normally a high-frequency switching waveform rather than a fixed DC voltage. Therefore, checking LX with a normal multimeter can be misleading. For advanced circuit repair, an oscilloscope is much more useful for confirming whether the switching stage is operating.
A damaged or open inductor can cause a no-charge condition, while a shorted or physically damaged inductor can create excessive current and heating.
Charge Current Sense Resistor
The TP5000 controls charging current through an external Rs current-sense resistor connected around the VS/BAT charging path.
Typical published values are:
| Rs Value | Approximate Charge Current |
|---|---|
| 1.0 Ω | 100 mA |
| 0.2 Ω | 500 mA |
| 0.1 Ω | 1000 mA |
| 0.067 Ω | 1500 mA |
| 0.05 Ω | 2000 mA |
The relationship can be approximated from the datasheet table as:
Charge Current ≈ 0.1 / Rs
where Rs is in ohms and the resulting current is in amperes.
For example:
Rs = 0.1 Ω
Charge current ≈ 0.1 / 0.1 = 1A
Similarly:
Rs = 0.067 Ω
Charge current ≈ 0.1 / 0.067 ≈ 1.5A
These are nominal design values; resistor tolerance, PCB layout, thermal conditions and IC characteristics can affect the real charging current. Published TP5000 documentation specifically lists 0.067 Ω for approximately 1.5A and 0.05 Ω for approximately 2A.
BAT Pin and Output Capacitors
The BAT pin monitors the battery voltage and connects to the battery positive node.
The reference circuits use output capacitors such as 10 µF capacitors, with a 0.1 µF ceramic capacitor also used in the application design for high-frequency decoupling. The exact capacitor technology and voltage rating should be selected according to the circuit requirements rather than copied blindly from a module.
For repair work, check for:
Shorted output capacitor
Cracked MLCC capacitor
Open PCB track between BAT and the battery connector
Incorrect battery polarity
Excessive leakage on the BAT line
A short directly on BAT can prevent normal charging and may make the IC appear defective even when the IC itself is still functional.
TS Pin and Battery Temperature Protection
The TS pin is intended for battery temperature monitoring through an NTC-based circuit.
According to the datasheet information, charging is suspended when the TS voltage indicates a temperature outside the permitted window. The published electrical information gives approximately 45% of VIN as the low-side threshold and 80% of VIN as the high-side threshold.
Some reference circuits disable temperature monitoring by connecting TS to ground. That configuration should not be treated as equivalent to having actual battery temperature protection.
For a safer design, a suitable NTC thermistor and the correct sensing network should be used according to the intended battery pack and charger design.
RTRICK Pin and Pre-Charge Current
The RTRICK pin controls the pre-charge current.
When a lithium battery is deeply discharged, the charger does not necessarily begin with the maximum programmed charging current. The TP5000 provides a lower-current pre-charge stage before entering higher-current charging.
Published application data shows that the pre-charge current can be configured from approximately 10% to 100% of the programmed charging current using the RTRICK network.
This function is especially important when dealing with a battery whose voltage has fallen significantly below its normal operating range.
CS Pin: Li-ion and LiFePO4 Selection
The CS pin is important because the TP5000 supports different single-cell battery chemistries.
The published TP5000 documentation describes:
CS high: 4.2V lithium-ion/manganese lithium charging mode
CS floating: 3.6V LiFePO4 charging mode
CS low: shutdown condition
The exact board configuration should therefore be checked before changing a resistor, jumper or solder bridge.
This distinction is critical. A 4.2V Li-ion cell and a 3.6V LiFePO4 cell are not interchangeable charging targets.
CHRG and STDBY LED Indicators
The TP5000 provides two status outputs:
CHRG indicates active charging.
STDBY indicates charge termination/standby status.
Many TP5000 modules use a red and green LED arrangement with a resistor such as 1 kΩ in the indicator circuit. This is a common reference-board implementation, not a universal requirement for every TP5000 module.
An LED that stays permanently on does not automatically mean the battery is charging correctly. The actual battery voltage, charging current and TP5000 status pins should be measured before diagnosing the indicator circuit.
How the TP5000 Charging Process Works
Stage 1: Pre-Charge
When the battery is deeply discharged, the TP5000 can use a reduced charging current. For 4.2V Li-ion charging, the published threshold is approximately 2.9V, while the LiFePO4 threshold is around 2.5V in the documented electrical characteristics.
The purpose is to bring a deeply discharged cell toward a safer operating voltage before applying the normal programmed charge current.
Stage 2: Constant Current
After the battery reaches the appropriate threshold, the charger enters the constant-current phase.
The selected Rs resistor determines the approximate charging current. For example, a 0.1 Ω sense resistor corresponds to approximately 1A, while 0.067 Ω corresponds to approximately 1.5A.
Stage 3: Constant Voltage
Near the end of charging, the TP5000 regulates the battery voltage rather than continuing to force the maximum current.
The documented charge-termination voltage is approximately 4.2V for the Li-ion mode and 3.6V for the LiFePO₄ mode.
The charging current then falls as the battery reaches full charge. Once the termination condition is met, the charger enters standby and can later perform an automatic recharge cycle when the battery voltage falls sufficiently.
Problem: TP5000 Module Has No Charging
Check the Input Voltage
Measure VIN directly at the TP5000 circuit.
A useful first test is:
VIN to GND → approximately 5V–6V on a typical application board
The TP5000's operating range extends to 9V, but the correct supply for the particular module should always be verified before testing.
If VIN is missing, inspect the USB/DC input connector, PCB tracks, fuse or protection components before replacing the TP5000 IC.
Check the battery voltage.
Measure BAT to GND with the battery connected.
If the battery is severely discharged, the charger may remain in the pre-charge stage for some time. However, an abnormal battery voltage, reversed polarity or a battery with internal damage can prevent normal charging.
Check the Current-Sense Resistor
Measure the resistance of Rs with the board powered down.
A cracked or incorrect-value sense resistor can cause an incorrect charging current or stop the charger from operating correctly.
A board designed for 1.5A charging may use approximately 0.067 Ω, while a 1A design commonly uses approximately 0.1 Ω.
Check the Inductor
Inspect the 4.7 µH inductor for cracks, overheating or an open winding.
For a switching charger, the inductor is part of the main energy-transfer path. A damaged inductor can make the board appear completely dead even when VIN reaches the IC.
Check the LX Switching Node
For professional repair, an oscilloscope can be used to inspect the LX pin.
No switching waveform with the correct VIN and a suitable battery connection can indicate a problem involving the TP5000, current-sense network, control configuration, or a shorted load.
Avoid using an oscilloscope probe casually on a high-frequency switching node. The probe ground connection and measurement technique must be appropriate for the circuit.
Problem: TP5000 IC or Inductor Gets Hot
Check for a Short on the battery line.
Power off the board and measure resistance between BAT and GND.
A very low resistance can indicate a shorted ceramic capacitor, damaged battery, solder bridge or another failed component.
Do not immediately replace the TP5000. A shorted external component can destroy a new replacement IC as well.
Inspect the Inductor and PCB
Check the inductor value, current rating and solder joints.
The manufacturer's application guidance recommends an inductor with sufficient current capability and emphasizes proper PCB routing of the high-current path.
Improve Thermal Design
At higher charging currents, PCB copper area and thermal management become increasingly important.
The TP5000 contains an internal power MOSFET, which reduces external component count but does not remove the need for good PCB heat dissipation. The published design notes specifically recommend proper PCB thermal management for high-current operation.
Problem: Charging LED Shows the Wrong Status
Check CHRG and STDBY
Check the CHRG and STDBY connections before replacing the LEDs.
Because these are status outputs, an incorrect LED circuit can create misleading indications even when the charger itself is working normally.
Also check the LED resistor and solder joints. A reference design may use a 1 kΩ LED resistor, but the exact LED circuit can differ between module manufacturers.
Problem: Battery Does Not Reach Full Voltage
Verify the Battery Chemistry
First confirm whether the board is configured for 4.2V Li-ion or 3.6V LiFePO4 operation.
An incorrect CS configuration can result in the wrong charging target.
Check the Sense and Feedback Path
Inspect the Rs resistor, VS connection, BAT trace and nearby capacitors.
A poor solder joint on the sensing path can cause inaccurate regulation or unstable charging.
Test With a Known-Good Battery
A battery with high internal resistance, excessive self-discharge or internal protection problems can appear to have a charger fault.
Using a known-good cell with the correct chemistry is one of the simplest ways to separate a charger-side problem from a battery-side problem.
TP5000 PCB Repair and Design Tips
For reliable repair and board design, the switching loop deserves more attention than ordinary low-current signal connections.
Keep the input capacitor close to VIN and GND, keep the high-current switching traces short, and use sufficiently wide copper for the VIN, LX and battery-current paths. The manufacturer's design guidance also recommends concentrated, low-impedance grounding and appropriate thermal management.
Use capacitors with suitable voltage ratings, an inductor with adequate saturation/current capability and a current-sense resistor with an appropriate power rating.
A very low-value resistor such as 0.067 Ω can dissipate meaningful power at high charging current. Therefore, its package, tolerance and power rating matter during continuous operation.
Important TP5000 Repair Notes
The S495 Schottky diode appears in some TP5000 reference/demo circuits, but it should not automatically be assumed to be mandatory on every TP5000 design. The manufacturer states that the IC has an internal anti-reverse-current function and does not require an external anti-intrusion Schottky diode for that purpose.
Commercial TP5000 modules can also differ in LED arrangement, NTC implementation, jumper configuration, capacitor values and battery connector layout. Always trace the actual PCB before replacing components.
Most importantly, never select the charging voltage simply from the module label. Confirm the battery chemistry and the TP5000 configuration first.
TP5000 Safety and Protection Functions
The TP5000 integrates several protection functions intended to improve charger reliability, including input overcurrent protection, undervoltage protection, chip overtemperature protection, short-circuit protection, battery temperature monitoring and reverse-battery protection.
The documented chip thermal protection threshold is around 145°C in the electrical characteristics. This is a protection feature of the IC, not an indication that the board should normally operate anywhere near that temperature.
It is also important not to describe the TP5000 as having a general-purpose input overvoltage cutoff at exactly 9V. The manufacturer's information specifies the supported operating/input range and protection features, but the 9V figure should not be treated as a guaranteed overvoltage protection threshold.
Official TP5000 Information and Datasheet
For component identification and the latest manufacturer-published information, refer to the Top Power ASIC TP5000 product page and the corresponding TP5000 datasheet rather than relying only on third-party module listings. The manufacturer identifies the TP5000 as a QFN16 switching charger for single-cell 4.2V lithium and 3.6V LiFePO4 applications.
Official manufacturer: Top Power ASIC — TP5000
Official TP5000 Product Information — Top Power ASIC
Note Point: Always verify the actual TP5000 PCB, battery chemistry, component values and datasheet before performing circuit repair or modification.
Disclaimer: This guide is for technical reference and troubleshooting; lithium battery repair can be hazardous, so use appropriate instruments, correct components and safe battery-handling procedures.
