IP2326

IP2326 from Injonic is a highly efficient boost converter that takes 5V USB input and boosts it to 8.4 (2S) or 12.6V (3S) at a maximum of 15W. It includes balancing (for 2S batteries, not for 3S configuration) and can charge 2S or 3S batteries from USB power supplies.

Use Cases:

• Charging:
  Add USB-C charging capabilities to any LiIon battery pack in 2S or 3S configuration (with support for fast charge protocols).

  

• Boost-Converter:
  Use the chip to boost an input voltage of 4.5-9.5V to 8.4V or 12.6V. Here is a use case where a single LiIon 18650 drives a professional 12V emergency light.

  

Overview

At its heart, IP2326 is a highly efficient synchronous boost converter with a 500kHz switching frequency and a built-in power MOSFET. It accepts a voltage in the range of 4.5-9.5V and boosts it to 8V or 12V output voltage.

Since it is a LiIon charger (and not just a boost converter), it supports CC/CV charging features and includes fundamental battery protection features (such as over-current and over-discharge protection).

Efficiency

IP2326 exemplifies modern power management ICs with significantly better efficiency than classic boost converters, resulting in much lower heat generation.

The efficiency is 94% at 8V/1A output and drops slightly to 92% at 1.5A. Generally, conversion efficiency is in the range of 91–94%, depending on charging current, voltage difference, and state of charge:

• The higher the voltage difference between input and output, the lower the efficiency.
• The higher the output current, the lower the efficiency.

Even at 5V input and 8.2V/2A (16.4W) and 12.4V/1.2A (14.9W) output, the efficiency remains better than 90%, which is quite remarkable. With higher input voltages, efficiency increases:

Input Voltage	Output	Efficiency
5V	12.4V/1.0A	90.5%
7V	12.4V/1.0A	93%
9V	12.4V/1.0A	94.5%

The datasheet provides detailed graphs.

94% is typical at 8V/1A when input voltage and thermal design are favorable. The 15W budget includes conversion losses; sustained 1.5A at 12.6V generally requires elevated input voltage via QC/PD (e.g., 7–9V), not 5V alone.

Important Pins

IP2326 can be configured via external resistors. Optionally, the chip also supports I2C and can be configured by a microcontroller, overriding any existing external configuration resistors.

Here are the most important pins:

• 2S/3S:
  With its pin CON_SEL, it can be switched from 2S to 3S configuration.
• LED:
  Pin LED connects to an optional charging indicator LED, and BAT_STAT provides a digital signal for the charging state.

• Standby:
  The enable pin EN can be pulled to ground to temporarily disable the charger:

  State	Power Consumption
  EN=LOW	3uA
  EN=HIGH	20mA

Creative Use-Cases

Since IP2326 at its core is a highly efficient boost converter, it enables surprisingly capable boost solutions.

For example, to run 12V devices (up to 12W) from a single LiIon cell, here is a simple and very affordable combination:

• X-150:
  Handles all the charging and discharging for 1S LiIon cells and provides strong and stable 5V output. It is based on IP5306.
• LX-LISC:
  This popular board uses the IP2326. In 3S configuration, it boosts the 5V from X-150 to 12V 1A output.

Caveats

Using a boost converter implies high input current for a given output power.

• Example: Delivering 12 V at 1 A (12 W) requires about 12 W / 5 V ≈ 2.4 A from a 5 V source; including losses, plan for roughly 3 A input current.
• Higher current magnifies every milliohm: wiring, connectors, and battery holders cause voltage drops that can destabilize operation.
• Boost stages are especially sensitive to input/source resistance, so minimize it.

Quick checks: IIN ≈ POUT/(η·VIN). For wiring, Vdrop ≈ 2·I·R·L (round-trip).

Practical wiring guidance

• Use short, adequately thick power leads to keep resistance and voltage drop low. For expected 3A, this should be at least AWG 22 as a lower bound; AWG 20 is a practical minimum, and AWG 18 gives extra margin—especially once connector and holder resistance are included.
• Avoid spring-based battery holders; their contact resistance is often high and variable under load. Prefer solid contacts or welded connections.

Symptoms of excessive voltage drop

• Input side:
  If the source voltage sags below the converter’s valid range, the controller may refuse to start or enter a fault state (e.g., blinking LED).
• Output side:
  Voltage drop in output wiring can make the controller “see” less battery voltage than actual, prematurely terminating or throttling charging.

Recommended connections

• For charging packs with IP2326-based boards, solder power connections directly. For cell assemblies, use nickel strips with spot welding, then solder the strip ends to the board.
• If removable packs are required, use low-resistance connectors such as XT30 or XT60 that can sustain the expected current with minimal loss.

Thermal tip: Achieving the stated efficiency depends on layout, inductor selection (low DCR, adequate Isat/Irms), and ceramic capacitors with sufficient voltage rating and low ESR.

Input

IP2326 accepts any voltage in the range of 4.5-9.5V.

USB 5V is just one of many options. You can also connect an ordinary power supply (and not use the charging feature). The chip is smart enough to request higher voltages from USB PD when available.

The large input voltage range is important because IP2326 is a boost converter (raises the input voltage): boosting works most efficiently when the input and output voltage differences are small.

Fast Charge Input

If you connect a USB power source with fast charge capabilities, IP2326 requests higher voltages in these scenarios:

Battery Voltage	Configuration	Action
<6.2V	2S	use 5V
<6.8V	2S	request 5.4V input
<7.8V	2S	request 6V input
<7.8V	2S	request 6V input
>7.8V	2S	request 7V input
<9V	3S	use 5V
<10.5V	3S	request 7V input
>10.5V	3S	request 9V input

When IP2326 is powered on, it first tests the input power supply for fast charge capabilities. This is why there is a brief delay of 3-4 seconds before IP2326 starts supplying power. If the input does not respond to fast charge protocol requests, IP2326 uses the supplied input voltage. The negotiation delay occurs at startup or when input is reattached; on sources without QC/PD, operation proceeds after the brief attempt.

Over-Current Protection

If the input voltage drops (i.e. due to a weak input power supply), IP2326 reduces the output current to prevent overloading the input supply.

This way, in a classic powerbank scenario, anything from weak and cheap 5V wall warts to powerful USB PD supplies can be used, and IP2326 dynamically adjusts its current to the input supply capabilities.

IP2326 has a number of additional protections built-in, i.e. over-voltage and short-circuit protection.

Output

The output voltage is available through two dedicated pins. Whether IP2326 delivers 8V or 12V is defined by pin CON_SEL. This way you can configure 2S and 3S battery packs. If you use IP2326 solely as boost converter for non-charging purposes, make sure you configure it to the appropriate output voltage.

8V or 12V?

There are breakout boards like LX_LISC that provide a solder bridge so you can configure the output voltage yourself. And there are other breakout boards that are preconfigured for 2S or 3S.

For LX_LISC boards, here is how you configure the output voltage:

Configuration	Changes on the board
2S	- clear the large solder bridge - add a 180 kΩ resistor to the solder pad next to the large solder bridge
3S	- close the large solder bridge with a blob of solder - remove the 180 kΩ SMB resistor next to it

Since it is much easier to remove a SMB resistor than to add one, it is best to stock the LX_LISC 2S variant unless you already know which configuration you need.

Output Current

The maximum output current is 1.5A; however, this current is limited by the maximum input power (15W):

• Input Voltage:
  The higher the input voltage, the more efficient the conversion, and the more current you can draw.
• Output Voltage:
  Likewise, a 2S configuration (8V) typically needs less boosting than a 3S configuration, so in a 2S configuration you again get closer to the maximum 1.5A output.

Even in demanding scenarios (boosting 5V input to 12V output), you can expect to receive an output of around 1A.

Battery Balancing

IP2326 comes with built-in balancing capabilities for 2S battery configurations. There is no balancing for 3S batteries.

• 3S Balancing:
  You may come across schematics that show balancing for 3S batteries, with an additional balancer wire connected to the configuration solder pad. This is dangerous nonsense and can damage the board.

  For 3S batteries, you need to add a dedicated 3S BMS board that takes care of balancing. IP2326 can only balance 2S batteries.

• Balancing Current:
  The balancing current of the built-in 2S balancing is in the range of 20-40mA. That is enough for maintaining balance between two equal batteries at equal state-of-charge.

  However, if you connect two batteries with substantially different charging state (one full, one empty), or even different capacities, it may take a very (very) long time until IP2326 has balanced the cells.

  The balancing current is determined by Rcb (should be >100 Ohm). Icb = Vcb / Rcb.

YouTube videos claiming that IP2326 balancing does not work show a lack of understanding—either because the author tried to balance 3S configurations (which aren’t supported), or by attempting to balance cells with absurdly different state-of-charge and capacities. If you pre-balance cells and match capacities (as is recommended) balancing works great.

Temperature Protection

The chip monitors its temperature and turns off when it exceeds 135C.

NTC Probe

An external 100K NTC thermistor can be connected to monitor the battery pack temperature.

• If no thermistor is used, NTC is pulled low via a 51K resistor.
• If a suitable thermistor is connected, IP2326 sends a 20 µA sensing current and analyzes the voltage drop:

NTC pin voltage	Action
<0.43V	stop charging, high temperature
<0.56V	hot battery, reduce charging rate by 50%
<1.32V	normal
>1.32V	stop charging, freezing

To enable an external NTC thermistor, the default 51K resistor must be replaced with a resistor that matches the thermistor in use; i.e., a 100K thermistor (B=4100) requires an 82K replacement resistor.

On the LX-LISC board, the resistor that needs to be replaced is labeled NTC:

Just connecting the thermistor and leaving the default 51K resistor unchanged is not an option: the sensed temperatures would be shifted to the lower end by around 10-20C. IP2326 would likely invoke freezing protection at low room temperature.

Pins and Adjustments

2S / 3S-Charging

CON_SEL	Mode	Output Voltage
floating/unconnected	2S	6.0-8.2V
via a 1K resistor to GND	3S	9.0-12.4V

Charging

Charging can be adjusted via external resistors:

Adjustment	Pin	Default (floating)	Adjustments
CC Current	ISET		120K-60K= 0.75A-1.5A
CV Voltage	VSET	8.4/12.6V	1K-120K= 8.1/12.3V-8.3/12.5V
Charging Voltage Range	CON_SEL	2S	1K to GND for 3S
Input Undervoltage Threshold	VIN_UVSET	4.65V	120K-1K= 4.45-4.25V
Input Overvoltage Threshold	VIN_OVSET	8.75V	120K-68K= 8.4-8.0V 1K=disabled
Charging Timeout	TIME_SET	24h	68K=4h 120K=12h 1K=no timeout

On the LX-LISC board, the relevant resistors are clearly labeled:

LX-LISC Label	Pin	Description
ISET	ISET	sets the maximum constant current charge rate
VSET	VSET	sets the battery voltage
RUV	VIN_UVSET	defines the input voltage drop threshold that triggers reducing the charging current
ROV	VIN_OVSET	defines the input voltage threshold that stops charging due to over-voltage
ROT	TIME_SET	sets the charging timeout or disables it

Charging Details

If the charger is left connected to the battery after it is fully charged, the charger automatically resumes charging when the battery voltage drops below 8.0V (2S) or 12.0V (3S).

Battery Configuration	Dead Battery	Undervoltage	Constant Current (ISET)	Constant Voltage
2S	<3.7V	<6V	6.0-8.3V	8.4V (VSET)
3S	<3.7V	<9V	9.0-12.5V	12.6V (VSET)

Charging Mode	Charging Current
Dead Battery	50mA
Undervoltage	100mA
Constant Current	defined by ISET
Constant Voltage	<200mA: pauses 30s, then tests whether stop charging voltage is reached

Materials

IP2326 Datasheet

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