CKCS PB0A

The PB0A module is one of the most affordable programmable charger/dischargers for single-cell (1S) LiIon batteries. It supports I2C.

The module features a DATA through-hole pin and a separate solder pad on the front side, both providing access to its internal I2C programming interface.

Overview

The PB0A breakout board is a sophisticated version of the basic X-150. Both boards are based on the power management chip IP5306, which comes in two different versions:

• No I2C (non-programmable):
  Basic versions (like the chip used on X-150) are pre-programmed and have no built-in I2C interface.
• I2C (programmable):
  PB0A (discussed here) uses a more advanced version of IP5306 that includes an I2C Interface.

Feature	X-150	PB0A
I2C Interface	❌	✔️
LEDs	4 (monochrome)	1 (RGB)
Charging Current	2.1A	2.1A (default), 0.05-3.2A (configurable)
Auto-Shutoff	<50mA for >32s	<50mA for >32s (default) 8s/16s/32s/no Auto-Shutoff (configurable)

You may want to familiarize yourself with this comprehensive IP5306 guide before reading on. The article you are currently reading focuses exclusively on the specific details and nuances of the PB0A breakout board.

Why Use I2C?

If you are satisfied with the default specs of the IP5306 or your project does not use a microcontroller, simpler breakout boards like X-150 or MH-CD42 are easier to use and slightly cheaper. In fact, the PB0A behaves exactly like those by default.

However, when working with IP5306-based charger/dischargers, you may encounter some common issues:

• Too much charging current:
  By default, the IP5306 delivers a maximum charging current of 2.1A. For small batteries, especially affordable LiPo pouches with capacities of 400-3000mAh, this current is too high and may damage the battery or create a fire hazard. The typical safe charging current for these batteries is 0.3C (100-900mA).
• Auto-Shutdown:
  IP5306 was designed for power banks and, by default, shuts down when output current drops below 50mA for more than 32s. For low-power projects or microcontrollers that occasionally enter deep sleep, this can cause unexpected power cuts.

With a programmable IP5306, you can re-configure the chip to:

• Raise or lower the maximum charging current
• Enable or disable the automatic shutdown feature

To do this, you need a microcontroller that can communicate with the I2C interface.

Caveats

Before working with PB0A and its I2C interface, consider the following:

Unmarked Chips

Many PB0A breakout boards use unmarked chips. It is not always clear whether these are original IP5306 chips or clones, and whether they truly have an enabled I2C interface.

All boards acquired from various sources on AliExpress worked flawlessly.

Confusing Labels

The battery output pins are marked with a battery symbol and lack distinct BAT+ and BAT- labels. The small “pin” on the battery symbol marks the positive (BAT+) pin.

Make sure you connect the battery correctly. There is no reverse polarity protection, and connecting the battery in reverse will destroy the board.

Several additional pins and solder pads are unmarked, and one pin is labeled DATA (which really is the SDA pin for the I2C interface). The unmarked solder pads provide access to the remaining I2C pins (see below for clear pin labels).

I2C vs Default Configuration

Some sellers claim the PB0A board delivers 3.2A charging current (compared to 2.1A for “normal” boards). This is only partly true: while the board can deliver up to 3.2A, in its default configuration it is identical to X-150 and MH-CD42:

• Charging: 2.1A max.
• Discharging: 12W (max 2.4A at 5V)

To unlock special PB0A features (like adjustable charging currents), you must use the I2C interface, and you need to do this every time the board powers up (it has no memory for persistent configuration).

Key conclusions:

• If your project does not use a microcontroller, choose the more affordable X-150 or MH-CD42. Without I2C configuration, they behave exactly like the PB0A.
• If your project does use a microcontroller with I2C, PB0A is an excellent choice for portable power solutions. You can precisely adjust the charging current and avoid unwanted power cuts during microcontroller deep sleep.

Understanding Power Output Paths

All IP5306-based boards, including PB0A, use different connectors for input and output. The USB-C connector is only for charging and does not supply power. It does not work bi-directional.

PB0A supplies 5V at 12W/2.4A output via its 5V+ and 5V- solder pads and (optionally) the USB-A connector (solder pads on the module’s backside).

Power While Charging

This module can supply 5V power to an external device while running from a single cell LiIon battery, even during charging via the USB-C connector.

However, unplugging the charging cable may cause a brief power interruption that can reboot microcontrollers (unless large-enough capacitors are used to bridge the gap). The reason:

• Battery Operation:
  Uses its boost converter to raise battery voltage to 5V.
• Charging:
  Disables the boost converter and supplies 5V USB-C input to both the charger and the external device.

When charging stops (USB-C unplugged), the module must re-enable its boost converter, causing a brief power gap.

This power path can draw up to 5A during charging:

• Charging:
    Up to 3.2A at 4.2V (14W) to charge the battery
• Device:
    Up to 2.4A at 5V (12W) to the output
• Total:
    Combined output power is 26W.
    The USB-C power supply must deliver up to 26W/5.2A at 5V for maximum performance.

Push Button

An optional push button can be connected to the K and GND solder pads with a 10kΩ resistor in series. The button is used to manually power an external device on or off.

Default behavior:

• Short press (>30ms but <2s): Turns on indicator LEDs and enables power output.
• Double short press: Turns off indicator LEDs and disables power output.

Button behavior can be adjusted via I2C (e.g., customizing which presses control on/off functions).

Charging Mode

The built-in charger activates automatically when a power supply is connected to the USB-C port, charging the battery at up to 2.1A (default) or 0.05-3.2A (when configured via I2C).

Supplying Power

The module provides 5V output on demand, similar to a power bank:

• Auto Power On:
  When a load is connected to the USB-A connector (may not be soldered; see solder pads on the backside) or the 5V+/5V- pins, the module enables its boost converter and supplies up to 10W at 5V.
• Auto Power Off:
  If the load draws less than 50mA for 32s, the module cuts power, disables the boost converter, and enters standby.

Disabling Auto Power Off

The power supply behavior can be reconfigured via I2C. For microcontroller projects that are always connected, manual power control is often preferable:

• Manual Power On and Off:
  The Auto Power On When Load Connected feature can be disabled via I2C (Register 0x00, set bit 2 to 0). Power must then be enabled manually using a push button on pin K.

  The module will no longer cut power automatically, even if current drops below 50mA.

  To power off, double-press the push button on K.

• Continuous Operation for Microcontrollers:

  1. Default: Board powers on automatically when a load is detected (e.g., microcontroller connected).
  2. Disable Auto Power On: The microcontroller can disable “Auto Power On When Load Connected” via I2C, ensuring the power supply remains active even at low current draw.
       Now, the microcontroller can safely enter deep sleep without losing power.
  3. Permanent Off: To turn off battery power, the microcontroller can re-enable “Auto Power On When Load Connected” via I2C and enter deep sleep. The board will detect <50mA current and turn off battery power until manually reactivated by the push button.

Missing I2C Documentation

If you are curious to start using I2C to customize your PB0A now, there is one hurdle to take: lack of documentation.

Although sellers often mention a mysterious PB0A Configuration Tool Instructions.doc document, such a tool or document does not exist.

Fortunately, you don’t need this. Here are the facts:

• No Configuration Tool:
  There is no specific “configuration tool” because it would not make sense anyway: IP5306 has no built-in memory and cannot be permanently re-programmed by any external tool. Instead, it must be configured at each power-on by a microcontroller that is part of your project.
• Standard I2C Interface:
  The board exposes a standard I2C interface on pins DATA (SDA) and SCL (via an unmarked solder pad). The I2C device address is 0x75.

Whenever IP5306 starts supplying power, it also powers on your microcontroller. Your firmware should send the required configuration data via I2C each time the microcontroller is powered on.

• Level Shifter Required:
  I2C logic levels are tied to the IP5306 internal voltages, which vary with battery charge (2.8-4.2V). For I2C to work, your microcontroller must be powered by the battery (not the 5V output), or you must use a level shifter.

  Powering the microcontroller directly from the battery is usually infeasible, as most MCUs are incompatible with 2.8-4.2V. Voltage regulators are also unsuitable, as they alter logic levels.

  Use a level shifter that supports independent voltages on both sides, since the battery voltage can be lower or higher than the MCU voltage. Most chip-based level shifters (like TXS0108) are unsuitable. Use one with discrete MOSFETs (like the BSS138).

  For testing only, you can power both the PB0A board and your microcontroller from a lab bench power supply set to 3.3V, using BAT+ and GND to simulate a suitable battery voltage.

• Strong Pull-Ups Required:
  Both SDA and SCK/SCL must be pulled up to VDD (BAT+) with 2.2K resistors. Due to the relatively high 400kHz I2C speed and design, strong pull-ups are required. 10K and higher resistors may not work.

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