IP5306 Power Management IC - DONE.LAND

The IP5306 is a fully integrated power bank system-on-chip (SOC) with a charger and a 2A discharger that works with single LiIon cells:

Charger
uses a buck converter at 750kHz switching frequency, and charges with a maximum current of 2.1A. Can be adjusted to 0.05-3.2A using I2C (when the IP5306 version supports I2C, see below for details).
Discharge:
uses a boost converter at 500kHz switching frequency and a 5V output at a maximum current of 2.4A (12W)

This chip—or one of its many Chinese clones, like the FM5324GA—is commonly used in modern DIY modules.

Overview

The IP5306 is found on affordable breakout boards like the X-150 and the MH-CD42.

These modules use IP5306-variants that are non-programmable, so you are limited to the chip defaults which are tailored to powerbank use-cases, not so much to power microcontroller projects:

High Charging Current: uses a maximum current of 2.1A (which may be too much for small LiIon/LiPo batteries).
Low Current Cut-Off: turn automatically off when the load current drops below 50mA for more than 32s (which can cause problems, i.e. with microcontroller projects that use deep sleep)

I2C to the rescue

There are more sophisticated versions of IP5306 that include a I2C interface. This interface allows microcontrollers to communicate with the chip, and change its settings.

The PB01 is an example of a very affordable breakout board (below €1.00) that comes with the I2C-enabled IP5306 and exposes the I2C pins.

Adjusting the IP5306 configuration provides immense flexibility:

Adjust Charge:
The maximum charging current can be adjusted in a wide range of 0.05-3.2A, i.e. you can lower it to match the requirements of small LiPo batteries you may be using.
Continuous Power:
You can tell the chip to keep its 5V output open continuously and not turn off after a while when the load drops below 50mA. This way, microcontrollers continue to receive power even when they switch to power-saving deep sleep modes.

There are many more things I2C can read or change, i.e. fine-tune discharge protection or battery specifics, determine whether the battery is fully charged, and even manually controlling the charger.

One thing the IP5306 isn’t able to do though is provide energy statistics such as actual battery voltage, or measuring currents.

Power While Charging

Devices can be powered continuously even during charging, with a small power gap occuring when charging ends and the internal boost converter is re-enabled, and an optional push button can be used to manually turn power on and off.

How simultaneous charge and discharge works

This chip either use its integrated boost converter to increase the battery voltage to 5V at a maximum of 2.4A output (12W 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 because it only has one external coil that is used either for boost or for buck operations.

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.

On Battery

Boost converter supplies 5V at 2.4A max (12W). The battery must be capable of supplying a peak current of 4A 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.

When Charging

Input voltage powers both the charger (at a maximum current of 2.1A at up to 4.2V) and the load (at a maximum of 12W).

The total power demand can reach 22W when accounting for conversion inefficiencies. The external 5V power supply must provide 4.2A to handle a combined maximum load. With charging only, a standard 5V 2A power supply is sufficient.

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.

Practical Use Cases

IP5306 was originally designed for power banks. You can use IP5306 either to build your own powerbank, or something related:

Charger
Battery Tester
“integrated” powerbank
(aka powering your project from a built-in LiIon/LiPo battery)

The most exciting use case probably is providing power to portable projects: by adding a IP5306, you can convert it into a rechargeable battery-driven solution - whether it is a microcontroller project, LED strips, DIY flashlights, etc.

Sample Projects for Inspiration

Here are a few example implementations that are all using a IP5306:

Using Basic IP5306

The basic IP5306 (without I2C interface) that is found on X-150 and MH-CD42 breakout boards is perfect if…

…your project is power-hungry and won’t drop below 50mA
…you use a LiIon or a large LiPo battery that can sustain up to 2.1A charging rate (i.e. 18650 LiIon).

Here is why:

By default, IP5306 turns off power automatically once current drops below 50mA for more than 32 seconds.
LiIon battery cells (like 18650) typically support 1-3C and can typically sustain the 2.1A default charging rate. However typical LiPo pouch cells have a nominal charging rate of just 0.3C: a 1000mAh LiPo cell needs a charging rate of just 350mA, not 2.1A (which can overcharge, heat up, and lead to fire hazards).

Using I2C-Enabled IP5306

The I2C-enabled IP5306 requires a microcontroller, so this version is suitable only when your project uses a microcontroller. I2C then lets you fine-tune IP5306 which is especially useful if…

…power consumption may drop below 50mA, i.e. when your microcontroller enters deep sleep states
…you are using a LiPo battery that requires reduced charging rates

Example Implementation

To get a first inspiration how microcontrollers can interface with IP5306, you may want to explore a commercial programmable power bank that uses an ESP32 microcontroller and IP5306:

I2C Programming: C++ code illustrating how the power bank’s ESP32 microcontroller communicates with the IP5306 registers via I2C.
Schematics: Circuitry showing the wiring and implementation, including the use of BSS138 MOSFETs used as a level shifter to translate between the battery voltage and the 3.3V used by the ESP32 microcontroller.

Next Steps

Get yourself an I2C-enabled IP5306 or purchase a breakout board that uses one (like the PB0A). Next, you can start building your own sophisticated microcontroller-operated power bank, charger, battery tester, or related.

Just keep in mind the inherent IP5306 limitations:

uses 1S LiIon battery
outputs 5V, no fancy USB PD standards
input and output connectors are separate

BMS and Protection

The IP5306 has the most important security features built in:

Output protection

Over-Current detection:
Output voltage <4.4V for over 30ms
Short-Circuit Protection:
Output current >4A for over 200us

Battery protection

Over-Discharge:
turns off battery when voltage <3.25V (may vary with internal configuration)
Over-Charge:
Charge termination at 4.2V, safety timer cuts off at <24h
Under-Voltage:
Trickle charge (100mA) when battery voltage <2.9V
Over-Voltage:
Turns off charging when battery voltage >4.2V
Over-Current:
Limits charging to 2.1A max., and limits further if charger voltage drops too much
Auto-Recharge:
Starts when battery voltage <4.1V

General protection

Thermal shutdown (at 125C)

Missing Protections

For a safe and robust power bank, IP5306 lacks these two protections:

Temperature Sensor:
No support for external temperature sensors. External temperature sensors typically detect catastrophic battery failures during charging.
Revers Battery Polarity:
Connecting the battery in reverse polarity destroys the chip. Since rechargeable batteries are typically not serviceable in portable devices and powerbanks, such a protection is normally not needed (with proper assembly).

To cover this:

Use an affordable Dallas temperature sensor (or similar). They can be connected directly to your microcontroller, and in case of excessive temperatures, your microcontroller can disable the charger via I2C.
Add an ideal diode if you do not hard-wire the battery (in which case there would be the risk of users not replacing the battery in correct polarity).

Operational Modes

IP5306 can be in four different operational modes:

Mode	When Active	LED(s)	5V Output	I2C Active	Can Charge	Description
0	remove power source	❌	❌	❌	❌	Chip is off, resets to default configuration
1	add power source	❌	❌	❌	✅	All configuration changes made by I2C are lost.
2	short-press button, or connect load	✅	✅	✅	✅	Disconnecting the load for >32s or double-pressing the push button switches to mode 1
3	setting bit `1` of I2C register `00`	❌	✅	❌	✅	IP5306 stays active and keeps all settings, power output is permanently on

Mode 3 is available only in I2C-enabled versions of IP5306.

Charging

Charging is a separate feature and can be utilized independently from other features if you wish.

You could, for instance, use the IP5306 solely for charging LiIon/LiPo cells, possibly as a replacement for a simple TP4056 if you want higher charging rates:

Item	Description
Input Voltage	5-5.5V
Charging Current	2.1A
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

If you are using the IP5306 as a simple charger, the lacking battery reverse polarity protection becomes an issue. Either make sure the battery connectors or bays are fool-proof, or add an ideal diode to the battery wiring.

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.

I2C-enabled breakout boards, like the PB01, use the status LED connectors as I2C interface. These boards use additional helper ICs to drive a WS2812 RGB LED which typically pulsates in changing color, indicating the charging state.

A new charging cycle is initiated automatically once the battery voltage drops below 4.1V.

“Dead” Batteries

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.

That’s why many chargers refuse to charge such batteries at all. Charging such a battery with normal charging rates would convert the excess energy into heat and can subsequently easily cause a fire or explosion.

IP5306 can deal with over-discharged batteries. When the battery voltage is too low for normal charging, its recovery charge mode reduces the charging rate and charges in intervals.

This is not guaranteed to work of course, it is just a best effort. If the battery was damaged beyond recovery, IP5306 aborts the recovery charge mode after 24 hours.

Supplying Power

IP5306 has a robust and efficient boost converter. It boosts the battery voltage to 5V at up to 2A. The boost converter is equipped with over-current and short circuit protection.

Item	Description
Output Voltage	5-5.15V (USB-A, 5V pads)
Output Voltage Ripple	50mV
Output Current	max. 2.4A
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

Automatic Load Detection

When a load is connected to the power output, the boost converter activates and begins supplying power. This requires the load to consume significant currents. Light loads may require to manually turn on the power output by pressing a push button (connected to pins K and GND on most breakout boards). This behavior is inline with typical powerbanks.

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.

The I2C-enabled versions of IP5306 can adjust all this. Specifically, IP5306 can be switched to an always-on mode that works also with light loads (I2C register 00, bit 1 set to 1). When always-on is enabled, the on-board LED still turns off after the designated time (32s by default, can be shortened via I2C to 8s), but the 5V output remains active, and the IP5306 preserves all other changes that have been made via I2C.

While power is being supplied, four LEDs indicate the battery’s state of charge in 25% increments. Each LED is supplied with 4mA. *I2

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

I2C-enabled breakout boards often use a single pulsating WS2812-RGB LED.

Power Consumption

Operating the boost converter requires approximately 100µA.

To save even more energy, the chip can minimize power consumption to just 30-50µA when disabling the power output (quiescent current).

That’s why by default, IP5306 has an active low load detection: once the load drops below 50mA for more than 32 seconds, the chip switches off the boost converter and cuts power output.

Like mentioned before, if this power-savings feature causes problems because your load requires low current (i.e. deep sleep), you have two options:

Manual:
pull pin K low every 30 seconds, either by external discrete logic, or by waking up your MCU every 30 seconds.
Reconfigure:
if you use an I2C-enabled IP5306, set bit 1 of register 00 to keep the boost converter turned on all the time. Be aware that the power LED(s) on the board will turn off, yet the power output stays enabled.

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.

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 Controlling Power Output

This can be done by grounding pin K:

Turn On:
Short press (30ms-2000ms).
- resets the light load detection timer
  by issuing impulses every 30 seconds, you can manually keep the power output active.
Turn Off:
- genuine IP5306: long press (>2000ms)
- Clones: two short presses

This controls the boost converter only.

When IP5306 is connected to a charger, the power output is always active because during charging, the power output is supplied by the charger, not the boost converter.

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):

Implementation Details

IP5306 is a highly compact IC with just 8 pins. External components are minimal.

Inductor for Switching

Both boost and buck converter share the same external inductor which should be 1uH. The inductor needs to be rated for at least 4.5A.

A push button can be connected to K/KEY and GND. It should be protected by a 10K resistor because when “torch mode” is active, K/KEY can supply considerable current.

Status LEDs

In basic (non-I2C) variants of IP5306, pins L1, L2, and L3 connect to the status LED:

Optionally, less than 4 LEDs can be connected:

I2C Interface

For I2C-enabled variants of IP5306, pins L1, L2, and L3 host the I2C interface:

IP5306 is running on battery voltage, so a level shifter mechanism is required to translate the voltages and logic levels to the levels required by the external microcontroller.

IRQ indicates whether IP5306 is active. This does not necessarily mean that the I2C interface is active. If I2C does not respond, you may have to send a short impulse to K/KEY (30ms-2000ms).

Examples

Materials

IP5306 Datasheet
IP5306 I2C Register Map
FM5324GA (IP5306 Clone) Translated English (translated)
FM5324GA (IP5306 Clone) Chinese Original (Chinese original)
ESP32-controlled Powerbank Schematics (image)

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