The BQ25785 is a synchronous NVDC buck-boost battery charge controller to charge a 2cell to 5cell battery from a wide range of input sources including USB adapter, extended power range (EPR) USB-C Power Delivery (PD) sources, standard power range (SPR) USB-C Power Delivery (PD) sources and traditional adapters. The device offers a low component count, high efficiency design for space-constrained, 2cell to 5cell battery charging applications.
The NVDC configuration allows the system to be regulated based on battery voltage, but not drop below system minimum voltage. The system keeps operating even when the battery is completely discharged or removed. When load power exceeds input source rating, the battery goes into supplement mode and prevents the system from crashing.
During power up, the charger sets the converter to a buck, boost, or buck-boost configuration based on the input source and battery conditions. The charger seamlessly transits between the buck, boost, and buck-boost operation modes without host control. The TI-patented quasi-dual phase converter can interleave dual phase under high power buck mode helping thermal distribution and reduce each inductor size. Simultaneously, the device only needs two boost side switching MOSFETs to save overall system area and cost due to limited power operation under boost mode.
In the absence of an input source, the BQ25785 supports the USB On-the-Go (OTG) function.
When only a battery powers the system and no external load is connected to the USB OTG port, the BQ25785 implements the latest Intel Vmin Active Protection (VAP) feature, in which the device charges up the VBUS voltage from the battery to store some energy in the input decoupling capacitors. During a system peak power spike, the energy stored in the input capacitors supplements the system, to prevent the system voltage from dropping below the minimum system voltage and causing a system crash.
The BQ25785 monitors adapter current, battery current, and system power. The flexibly programmable PROCHOT output goes directly to the CPU for throttling back when needed.
The latest version of the USB-C PD specification includes Fast Role Swap (FRS) to provide power role swapping occurs in a timely fashion so that the devices connected to the dock can avoid experiencing momentary power loss or glitching. This device integrates FRS in compliance with the PD specification.
TI-patented switching frequency dithering pattern can significantly reduce EMI noise over the whole conductive EMI frequency range (150kHz to 30MHz). Multiple dithering scale options are available and provide flexibility for different applications. The dithering feature greatly simplify EMI noise filter design.
The charger operates with the TI-patented Pass Through Mode (PTM) to improve efficiency over the full load range. In PTM, input power directly pass through the charger to the system. Switching losses of the MOSFETs and inductor core loss can be saved thus achieving high efficiency operation.
The BQ25785 is available in a 36-pin 4mm × 5mm WQFN package.
| Top documentation | Type | Title | Format options | Date |
|---|---|---|---|---|
| * | Data sheet | BQ25785 40V, SMBus, 2- to 5Cell, Narrow VDC Quasi Dual Phase Buck-Boost Battery Charge Controller With System Power Monitor and Processor Hot Monitor datasheet | PDF | HTML | 03 Mar 2026 |
For additional terms or required resources, click any title below to view the detail page where available.
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| WQFN (REE) | 36 | Ultra Librarian |
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