The BQ25601 is a highly integrated switch-mode battery charge management IC designed for single-cell Li-Ion and Li-polymer batteries. It efficiently manages battery charging, power path management, and USB input compatibility, making it ideal for smartphones, ePOS systems, and portable internet devices.
Explore the BQ25601 IC boot sequence schematic and pinout. Download the PDF for essential information and enhance your understanding of this component.
1. Features Breakdown
The bq25601 includes several key features for efficient battery charging and power management.
1.1 High-Efficiency
1.5-MHz, Synchronous Buck Charger
92% charge efficiency at 2A from a 5V input.
Optimized for USB voltage input (5V).
Selectable Low Power Pulse Frequency Modulation (PFM) Mode for light-load operations.
1.2 USB On-The-Go (OTG) Support
Functions as a boost converter with up to 1.2A output.
Provides 92% boost efficiency at 1A output.
Soft-start capability for capacitive loads up to 500µF.
Includes output short circuit protection.
1.3 Wide Input Voltage Range
Supports input voltage range of 3.9V to 13.5V.
Absolute maximum input voltage rating: 20V.
Programmable input current limit (100mA to 3.2A) with 100mA resolution.
Input voltage-based maximum power tracking (VINDPM).
VINDPM threshold automatically tracks battery voltage.
1.4 High Battery Discharge Efficiency
18mΩ Battery Discharge MOSFET ensures minimal power loss.
1.5 Narrow VDC (NVDC) Power Path Management
Enables Instant-On operation, even without a battery or with a deeply discharged battery.
Ideal Diode operation supports battery supplement mode.
1.6 Advanced Control Modes
BATFET Control supports Ship Mode, Wake-Up, and Full System Reset.
Can operate in Autonomous Mode or I²C Mode for flexible system integration.
Integrated MOSFETs, Current Sensing, and Loop Compensation simplify system design.
1.7 Low Power and Safety Features
17µA low battery leakage current supports Ship Mode for energy savings.
High Accuracy:
±0.5% charge voltage regulation.
±5% charge current regulation at 1.5A.
±10% input current regulation at 0.9A.
Multiple safety features:
Battery temperature sensing (for charge and boost mode).
Thermal regulation and thermal shutdown.
Input Undervoltage Lockout (UVLO) and overvoltage protection.
2. Operations
The bq25601 operates in several phases for battery charging and system power management. Let's go through each step in detail.
2.1 Powering the IC
Connect the USB input (5V) or high-voltage adapter (up to 13.5V).
The internal power path determines the best distribution between system load and battery charging.
2.2 Input Voltage Regulation (VINDPM)
The IC monitors the input voltage to prevent voltage drops below a defined threshold.
Automatically adjusts charge current to maintain stable input voltage.
2.3 Battery Charging Process
The charging process follows three main phases:
(1) Pre-Charge Phase
If the battery voltage is too low (<3V), the IC supplies a small pre-charge current to safely bring the battery up to a chargeable level.
(2) Fast-Charge Phase
Once the battery reaches a safe threshold, the IC switches to constant current (CC) mode, supplying a higher current (e.g., 2A) for rapid charging.
(3) Constant Voltage (CV) Phase
When the battery reaches the target charge voltage (typically 4.2V), the IC switches to constant voltage mode, gradually reducing the charge current.
This prevents overcharging and extends battery life.
2.4 USB On-The-Go (OTG) Boost Mode
When enabled, the bq25601 functions as a boost converter, delivering 5V output to external devices.
Supports up to 1.2A output current with soft-start for handling large capacitive loads.
2.5 Battery Discharge & System Load Sharing
If the adapter is disconnected, the IC automatically switches to battery power.
The Narrow VDC (NVDC) power path ensures a smooth transition between the adapter and the battery.
The Ideal Diode feature helps minimize power losses.
2.6 Safety Protections
Overvoltage & Undervoltage Protection: Prevents damage from incorrect input voltages.
Short-Circuit Protection: Shut down the system if a short circuit is detected.
Thermal Shutdown: Protects the IC from overheating.
2.7 Communication via I²C Interface
The bq25601 can be controlled via an I²C bus, allowing software-based configuration of parameters such as:
Charge voltage & current.
Input current limit.
Power path control.
OTG mode activation.
3. Applications of bq25601
Due to its high efficiency and flexibility, the bq25601 is widely used in:
3.1 Smartphones & Portable Devices
Efficient battery charging for Li-Ion/Li-Polymer batteries.
Supports USB charging (USB 2.0/3.0 and high-voltage adaptors).
3.2 ePOS Systems
Provides stable power management for point-of-sale devices.
Ensures reliable battery operation with protection mechanisms.
3.3 Portable Internet Devices & Accessories
Ideal for wireless routers, IoT gadgets, and Bluetooth accessories.
Boost mode allows USB OTG functionality.