The IP5306 is a fully integrated power bank system-on-chip with a 2.4A charger and a 2A discharger. This chip—or one of its many Chinese clones, like the FM5324GA—is commonly used in modern DIY modules.
For highly integrated chips like this one, it is essential to understand their concepts and functionality before use. Some of its features - like its optional torch mode - may not be immediately apparent and could lead to unintended risks.
Overview
The IP5306 is found on affordable breakout boards like the X-150 and the MH-CD42.
Modules utilizing this chip are highly compact (typically 15-20x25mm) yet surprisingly powerful. With a single Li-Ion cell, they can deliver up to 2A at 5V.
This compactness is made possible by a clever architecture that uses a single inductor for both charging and discharging operations.
How simultaneous charge and discharge really work
Power Paths
This chip can either use its integrated boost converter to increase the battery voltage to 5V at a maximum of 2A output (10W total), or it can step down an external 5V input to a charging voltage suitable for Li-Ion or Li-Po batteries. However, the chip can only perform one of these conversions at a time.
Despite this limitation, the chip supports simultaneous discharging and charging. This means you can operate a connected device both while the chip is charging and when the device is powered by the battery alone.
Understanding the involved switching between different power paths is critical.
Battery Operation
When the chip operates solely on battery power, its boost converter supplies 5V at a maximum of 2A to the output, providing up to 10W of power. The battery must be capable of supplying a peak current of 3.5A to support this load. Be aware that smaller batteries or low-cost, low-current Li-Po batteries may not be sufficient to meet this demand.
Charging
When an external 5V power supply is connected, the chip dynamically switches internal power paths:
- The input voltage is stepped down to a suitable charging voltage for the battery, with a maximum charging current of 2.4A.
- The internal boost converter is deactivated.
- The power output is now directly supplied by the 5V input.
This allows the device to continue operating while the battery is being charged. However, during this mode:
- If the connected device draws the full 10W output while the battery is simultaneously charged at the maximum rate, the total power demand can reach 21W when accounting for conversion inefficiencies.
- The external 5V power supply must provide at least 4.2A to handle this combined maximum load.
- If no device is connected to the output during charging, a standard 5V 2A power supply is sufficient for charging the battery alone.
Temporary Power Cut
When an external power supply is connected or disconnected, the chip actively switches power paths. During this transition, there may be a brief power interruption at the output. This can cause connected devices, such as microcontrollers, to reboot. To prevent this, you can add an appropriately sized capacitor to the output line, which will smooth out any voltage dips during these transitions.
Use Cases
This chip is ideal for adding battery power to external 5V devices such as microcontrollers, WS2812 LED strips, DIY flashlights, and more. It is also suitable for building simple power banks.
Permanently Connected Devices
This chip is especially suited for adding battery support to 5V devices:
- a push button can be used to control power to the connected device, so it can be turned on and off as needed.
- Only the device connected to the power output can draw energy from the battery.
- The power input is exclusively reserved for charging the battery and does not allow external devices to deplete the battery.
Power Bank
When designing a power bank, the goal is to provide power on demand to various USB devices. To achieve this, you can add one or more USB connectors (of your chosen type) to the chip’s power output.
Key considerations for power bank design with this chip:
- The chip provides a fixed 5V output voltage only. This limitation is a direct consequence of the chip targeting 1S batteries (single-cell configurations).
- Boosting the voltage beyond 5V would require higher battery currents, larger physical components (e.g., coils), and lead to inefficiencies.
As a result:
- This chip does not support quick charge protocols, which rely on multiple output voltages such as 9/12/15/20V.
- Devices connected to the power bank will charge at standard speeds, limited to a fixed 5V output at a maximum current of 2A (10W).
In a nutshell, this chip is excellent for building physically very small power banks.
No Temperature Sensor
The IP5306 features several built-in protection mechanisms, including over-temperature protection, but there is no support for external temperature sensors.
External temperature sensors can detect catastrophic battery failures during charging.
Such sensors, though, are more commonly integrated into power management chips designed for higher-capacity battery systems, where the risk of thermal issues is higher due to larger energy storage and discharge rates.
Battery Requirements
The IP5306 supports 1S battery configurations (Li-Ion and Li-Po). You can use a single cell or connect multiple cells in parallel to increase capacity while maintaining the required 1S voltage.
Battery Voltage
This chip is designed for Li-Ion and Li-Po batteries with a maximum voltage of 4.2V. It also includes optional support for high-voltage cells with a maximum voltage of 4.35V. However, LiFePO₄ batteries are incompatible, and using them can be hazardous.
Some users have reported that the 4.35V setting is ineffective, with the maximum charging voltage remaining at 4.2V. Batteries must explicitly support 4.35V to utilize this setting. Many standard Li-Ion batteries with built-in BMS will cut off power above 4.2V. Additionally, their internal resistance increases sharply beyond this voltage, causing the charging current to taper naturally. To use the 4.35V setting, ensure your batteries are specifically designed for 4.35V operation.
Selecting Appropriate Battery Capacity
Given the high performance of the IP5306, selecting a suitable battery is critical. Batteries that are too small can lead to overcharging and/or over-discharging, increasing the risk of fire hazards.
Generally, you will need a battery with a minimum capacity of around 3,500mAh.
Key Considerations:
-
High Charging Current:
The charging current is fixed at 2.4A. At a 1C charge rate, the battery must have a capacity of at least 2,400mAh to safely handle this current. -
High Power Output:
The chip can supply up to 10W to its power output. When the battery voltage drops to 3V near depletion, a 10W output at 90% conversion efficiency requires approximately 3.5A. At a 1C discharge rate, the battery must have a capacity of at least 3,500mAh. - Minimum Capacity:
Due to the fixed charging current, at 1C charge rate, your battery must have a capacity of at least 2.400mAh. Assuming a 1C discharge rate as well, at this capacity the battery could deliver a maximum output current of 2.4A. When the battery is close to depletion at 3V, this allows for a maximum of 6.5W power output (1.3A at 5V output). - Recommended Minimum Capacity:
To take advantage of the maximum 2A output (10W) that this chip supports, your battery capacity must be at least 3.500mAh at an assumed 1C discharge rate.
If the chip stops charging after only a few minutes and reports the battery as fully charged when it is not, this might indicate that the battery is too small for the 2.4A charging current. Overcharging a small battery can cause its voltage to temporarily rise too quickly, triggering the chip’s early cut-off protection.
Risk: Low-Performance Batteries
Low-performance Li-Ion/Li-Po batteries, such as the one shown below, can be a perfect and affordable choice for projects requiring only small currents.
However, it is essential to understand their limitations before using them with high performance chips like the IP5306.
In the calculations discussed earlier, a default 1C charge and discharge rate was assumed. This means the current can reach the same value as the battery’s total capacity. For example, with a 3000mAh battery like the one depicted, a 1C rate would allow for a charge or discharge current of 3A.
However, low-performance batteries often fall short of the 1C standard. For the battery shown:
- Maximum charge current: 0.2C (600mA)
- Maximum discharge current: 0.5C (1,500mA)
If this battery were connected to the IP5306, the chip’s fixed charging current of 2,400mA would exceed the battery’s maximum safe charge current by four times, potentially damaging the battery and creating safety hazards.
Charging
Charging and discharging are separate features, and you can use the IP5306 for charging only, possibly as a replacement for a simple TP4056, simply to achieve higher charging currents.
| Item | Description |
|---|---|
| Input Voltage | 5-5.5V |
| Charging Current | 2.4A |
| Charge Switching Freq. | 750kHz |
| Charging Cut-Off Voltage | 4.2V or 4.35V (configurable) |
| Charging Efficiency | 91% |
| Short Circuit Protection | Yes |
| Low Voltage Recovery | Yes |
| Battery Reverse Polarity Prot. | No |
| Charging While Discharging | Yes |
The chip lacks battery reverse polarity protection. Use an ideal diode or other suitable protection if reverse polarity is a risk, i.e. because you are using battery holders where a user could be intreagued to insert a battery in wrong position.
Initiating Charging
Charging starts automatically when a power supply is connected, and the battery voltage is >2.8V and <4.2V. The external power supply must provide 5V at 2A minimum.
During charging, the indicator LED show charging progress in 25% increments, and one LED is blinking at 1Hz.
Charging phases:
- Deep Discharge Recovery: If battery voltage is below 2.8V, the chip supplies 180mA until safe voltage levels are reached.
- Constant Current: For voltage between 2.8V and the cut-off, the chip charges at 2.4A.
- Constant Voltage: Once the battery reaches 4.2V, current tapers off until it falls below 100mA or 24 hours elapse.
Once charging has completed, all four indicator LEDs light solidly.
A new charging cycle is initiated automatically once the battery voltage drops below 4.1V.
When a battery has accidentally been deeply discharged (i.e. by keeping it in storage for too long so that normal self-discharge could cause a voltage drop below 2.8V), it can no longer absorb the normal amount of energy. Charging such a battery with a normal charge current would convert the excess energy into heat and might cause a fire or explosion. The recovery charge mode is taking this into account. Whether or not it will be successful in recovering such a battery is not certain. However, if the battery isn’t fully charged after a maximum of 24 hours, the charging cycle is aborted.
Supplying Power
The chip includes a robust and efficient boost converter capable of supplying 5V at up to 2A. It is equipped with over-current and short circuit protection mechanisms.
| Item | Description |
|---|---|
| Output Voltage | 5-5.15V (USB-A, 5V pads) |
| Output Voltage Ripple | 50mV |
| Output Current | max. 2.1A |
| Indicator LED Current | 4mA each |
| Off Current | <50µA |
| Standby Current | <100µA |
| Load Removal Detection | <45mA for 32s |
| Boost Switching Freq. | 500kHz |
| Boost Efficiency | 92.5% |
| Short Circuit Prot. | Yes |
| Other Protections | Over-Current, Over-Voltage |
When a load is connected to the power output, the boost converter activates and begins supplying power. When the load is removed (or the load drops below 45mA for more than 32s), the boost converter automatically shuts down to conserve battery power.
While power is being supplied, four LEDs indicate the battery’s state of charge in 25% increments. Each LED is supplied with 4mA.
When the battery’s state of charge drops below 3%, one LED will blink at 2Hz to alert the user. If the battery voltage falls further, below 2.8-2.9V, the over-discharge protection feature turns off the power output to prevent damage to the battery.
| LED | On at battery voltage (V) |
|---|---|
| 1 | >3.36 |
| 2 | >3.57 |
| 3 | >3.65 |
| 4 | >3.91 |
Automatic Load Detection
The automatic load detection feature is essential for preserving battery life.
Operating the boost converter requires approximately 100µA. If the boost converter remained active continuously—even without an active load—it could deplete the battery unnecessarily.
To address this, both the boost converter and the indicator LEDs are activated only when required. In inactive states, the chip minimizes power consumption, reducing quiescent current to 30-50µA.
Two operational modes manage this behavior:
| Mode | Boost Converter | Indicator LED | Power Supply | Quiescent Power |
|---|---|---|---|---|
| Standby Mode | on | on | available | 100µA |
| Off Mode | off | off | not available | 30-50µA |
The chip automatically transitions between these modes:
- Load Detection: The chip continuously monitors the power output. When it detects a load, it activates Standby Mode to supply power to the connected device.
- Load Removal Detection: If the load drops below 45mA for a continuous period of at least 32 seconds, the chip shuts off the boost converter and switches to Off Mode.
A user once reported that the chip worked properly but stopped after exactly 33 seconds. This behavior was due to the automatic load removal detection. The user’s load was too small to sustain Standby Mode. To prevent this, you can increase the load above 45mA (e.g., by adding a small LED or resistor). Alternatively, you can enable the power output manually using the push button connector in regular intervals to reset the load removal timer (see below).
Automatic Power-off
The chip automatically cuts off power in the following scenarios (when operating on battery power):
- Low Load: If the load drops below 45mA for at least 32 seconds, the chip assumes the load is disconnected and turns off the boost converter.
- High Load: If the load exceeds 4A, the chip performs an emergency shutdown within 200µs to prevent damage.
- Battery Empty: If the battery voltage falls below 2.8-2.9V, the chip disables the boost converter to protect the battery from over-discharge.
- Manual: Using a push button signal (see below), the chip turns off the boost converter, even with the load still connected. This is useful for turning off permanently connected devices.
While charging, the output is always active.
Push Button Support
An optional push button can be connected to the K and GND solder pads on most boards. While not mandatory, it allows manual control over power output and can access a special “torch mode”.
Always use a resistor in series with the push button to limit potential current flow:
-
In some chip configurations, an optional flashlight function may be present. In this setup, an LED is connected in parallel with the push button. Pressing the button in such configurations effectively short-circuits the LED, which can result in high currents. These currents may damage the button, the LED, or the board itself.
-
To prevent such issues, use a resistor with a value of 2kΩ or 10kΩ in series with the button. Some chips can actively differentiate between these two resistor values. Depending on the resistance used, the chip may either activate or deactivate the flashlight function.
A user reported that pressing the push button produced a cloud of smoke. It turned out this user had taken two breakout boards and connected both push button wires to one push button to control both boards at the same time. While this is perfectly ok to do, the user did not add 10kΩ resistors. So when the push button was pressed, a temporary short circuit occured in both boards, resulting in high currents flowing across the push button. Since DIY push buttons typically are for logic levels only, they can easily burn up when exposed to such high currents. You now know that with this board, it is crucial to limit current flow with at least a 2kΩ resistor.
Types of Button Presses
All chip variants distinguish three fundamental key press patterns:
- Short press: >30ms but <=2s
- 2x Short press
- Long press: >2s
Manually Control Output Power
A short press (>30ms impulse) enables power output in all chip variants. Use a short press to turn on a device, or to reset the load removal detection timer before it can kick in on light loads <45mA.
With low loads (<50mA), your logic could send an impulse (<30ms <2s, simulated short press) in <30s intervals to prevent unintentional power off.
Manually turning off the boost converter varies between chip variants. With the original IP5306, this requires a long press, whereas clones like the FM5324GA may require two short presses instead.
Button presses only control the internal boost converter. The power output remains always active when the chip is connected to an external power supply (i.e., during charging).
Torch Mode
A less commonly noticed feature of this chip is its ability to support an external flashlight LED. When present, the LED is connected in parallel with the push button.
This torch mode is the reason why the push button must always be used with a 2kΩ or 10kΩ resistor in series. Without this resistor, activating the torch mode—either intentionally or accidentally—can result in large currents, as pressing the push button would effectively short-circuit the flashlight LED.
On certain chip models, the torch mode may either be permanently disabled or configurable by using a 2kΩ resistor instead of a 10kΩ in series with the push button.
| Variant | Short Press | 2x Short Press | Long Press | Remark |
|---|---|---|---|---|
| 1 | turns on power output and indicator LEDs | toggles flashlight | turns off power | IP5306 |
| 2 | turns on power output and indicator LEDs | turns off power output | toggles flashlight | FM5324GA: use 10kΩ in series with push button |
| 3 | turns on power output and indicator LEDs | turns off power output | no function | FM5324GA: use 2kΩ in series with push button |
Keep in mind that chips are often manufactured to meet specific customer requirements. If your chip has a different marking, it may function similarly to the IP5306 but exhibit slight variations, such as different push button actions or modified indicator LED behavior.
Issues
Here are the top issues with this chip and the boards that are using it:
- User Errors:
- Battery: when you add a battery that is too small and cannot handle the high charge and discharge currents, charging the battery may not work, and there is a fire hazard.
- Push Button: when you add a push button and omit a 10kΩ series resistor, when you press the button, high currents can flow and damage the button.
- Design Issues:
- Load Removal Discovery: with small loads <50mA, the unit cuts power after 32s. This is by design. To work around this, you can have your microcontroller ground the push button key (via a 10kΩ resistor, or you might ruin your microcontroller) in intervals of <30s. This resets the load removal discovery timer. Make sure you ground the pin for at least 50ms in order to be considered a short press. Alternatively, you can keep the pin permanently to ground as described below.
- Various Chip Variants: the fact that boards are produced with a variety of generic and cloned chips instead of the original IP5306 can cause issues due to slight variations in behavior.
-
Wake-Up Issues: there are reports with boards using the FM5324GA, that after prolonged operation for 24-48hrs, the board may not automatically wake up from standby anymore when a new load is connected.
The reason is not yet clear. A remidy is to manually short press the push button or cause a reset of power paths by supplying a charging power. You might be able to work around this by keeping the chip active all the time (preventing Off mode) at the expense of a slightly higher quiescent power consumption via the following circuit (which may also help with continuously operating low loads <50mA):
Keeping Power Output Active
One of the top design issues is the load removal detection that kicks in once the load drops below <50mA for more than 32s.
Whether you want to work around this load removal detection, or whether you want to generally prevent the board from entering Off mode, i.e. to work around wake-up problems, here are two suggestions you may want to try (at own risk) to keep the power output active:
-
MH-CD42 breakout board:
-
X-150 breakout board:
By keeping the boards’ boost converter active all the time, this will increase quiescent current consumption by approximately 50uA.
As always on this site, use all information including suggested circuitry entirely at your own risk.
Materials
IP5306 Power Management SoC Datasheet
FM5324GA Power Management SoC (Chinese Clone) Datasheet (translated)
FM5324GA Power Management SoC (Chinese Clone) Datasheet (Chinese original)
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(content created Jan 12, 2025 - last updated Jan 15, 2025)