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BQ25751

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Stand-alone or I²C controlled, 70V, buck-boost, lead acid battery charge controller with power path

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Data sheet

BQ25751

ACTIVE
Data sheet Order now

Product details

Rating Catalog Number of series cells 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 Cell chemistry Lead Acid Charge current (max) (A) 20 Features Adjustable switching frequency, BAT temp thermistor monitoring (JEITA profile), Bidirectional, IC thermal regulation, ICO (Input Current Optimization), IINDPM (Input current limit), Input OVP, Integrated ADC, Integrated LDO, Power Path, SYNC Pin, USB C/PD compatible, VINDPM (Input voltage threshold to maximize adaptor power) Vin (min) (V) 4.2 Vin (max) (V) 70 Absolute max Vin (max) (V) 85 Control topology Switch-Mode Buck-boost Battery charge voltage (min) (V) 0 Battery charge voltage (max) (V) 70 Control interface I2C TI functional safety category Functional Safety-Capable Operating temperature range (°C) -40 to 125
Rating Catalog Number of series cells 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 Cell chemistry Lead Acid Charge current (max) (A) 20 Features Adjustable switching frequency, BAT temp thermistor monitoring (JEITA profile), Bidirectional, IC thermal regulation, ICO (Input Current Optimization), IINDPM (Input current limit), Input OVP, Integrated ADC, Integrated LDO, Power Path, SYNC Pin, USB C/PD compatible, VINDPM (Input voltage threshold to maximize adaptor power) Vin (min) (V) 4.2 Vin (max) (V) 70 Absolute max Vin (max) (V) 85 Control topology Switch-Mode Buck-boost Battery charge voltage (min) (V) 0 Battery charge voltage (max) (V) 70 Control interface I2C TI functional safety category Functional Safety-Capable Operating temperature range (°C) -40 to 125
VQFN (RRV) 36 30 mm² (6 mm × 5 mm)
  • Wide input voltage operating range: 4.4V to 70V
  • Wide battery voltage operating range: up-to 70V
    • 6V up-to 48V lead-acid charging profile with bulk, absorb and float voltage charging phases
    • Charge voltage temperature compensation
  • Synchronous buck charge controller with NFET drivers
    • Adjustable switching frequency from 200kHz to 600kHz
    • Optional synchronization to external clock
    • Integrated loop compensation with soft start
    • Optional gate driver supply input for optimized efficiency
  • Bidirectional converter operation (Reverse Mode) supporting USB-PD Extended Power Range (EPR)
    • Adjustable input voltage (VAC) regulation from 3.3V to 65V with 20mV/step
    • Adjustable input current regulation (RAC_SNS) from 400mA to 20A with 50mA/step using 2mΩ resistor
  • Direct power path management for highest efficiency to power system
    • System power selection from adapter or battery
    • Dynamic power management
    • All N-channel FET drivers
  • High accuracy
    • ±0.5% charge voltage regulation
    • ±3% charge current regulation
    • ±3% input current regulation
  • I2C controlled for optimal system performance with resistor-programmable option
    • Hardware adjustable input and output current limits
  • Integrated 16-bit ADC for voltage, current, and temperature monitoring
  • Low battery quiescent current
  • High safety integration
    • Adjustable input overvoltage and undervoltage protection
    • Battery Overvoltage and overcurrent protection
    • Charging safety timer in CV Mode
    • Thermal shutdown
  • Status outputs
    • Adapter present status (PG)
    • Charger Operation status
  • Package
    • 36-pin 6mm × 5mm QFN
  • Wide input voltage operating range: 4.4V to 70V
  • Wide battery voltage operating range: up-to 70V
    • 6V up-to 48V lead-acid charging profile with bulk, absorb and float voltage charging phases
    • Charge voltage temperature compensation
  • Synchronous buck charge controller with NFET drivers
    • Adjustable switching frequency from 200kHz to 600kHz
    • Optional synchronization to external clock
    • Integrated loop compensation with soft start
    • Optional gate driver supply input for optimized efficiency
  • Bidirectional converter operation (Reverse Mode) supporting USB-PD Extended Power Range (EPR)
    • Adjustable input voltage (VAC) regulation from 3.3V to 65V with 20mV/step
    • Adjustable input current regulation (RAC_SNS) from 400mA to 20A with 50mA/step using 2mΩ resistor
  • Direct power path management for highest efficiency to power system
    • System power selection from adapter or battery
    • Dynamic power management
    • All N-channel FET drivers
  • High accuracy
    • ±0.5% charge voltage regulation
    • ±3% charge current regulation
    • ±3% input current regulation
  • I2C controlled for optimal system performance with resistor-programmable option
    • Hardware adjustable input and output current limits
  • Integrated 16-bit ADC for voltage, current, and temperature monitoring
  • Low battery quiescent current
  • High safety integration
    • Adjustable input overvoltage and undervoltage protection
    • Battery Overvoltage and overcurrent protection
    • Charging safety timer in CV Mode
    • Thermal shutdown
  • Status outputs
    • Adapter present status (PG)
    • Charger Operation status
  • Package
    • 36-pin 6mm × 5mm QFN

The BQ25751 is a wide input voltage, switched-mode buck-boost battery charge controller with direct power path control. The device offers high-efficiency battery charging over a wide voltage range with bulk, float and absorption charging for lead-acid batteries. The device integrates all the loop compensation for the buck-boost converter, thereby providing a high density solution with ease of use.

Besides the I2C host-controlled charging mode, the device also supports standalone charging mode via resistor programmable limits. Input current, charge current and charge voltage regulation targets can be set via the ILIM_HIZ, ICHG and FB pins, respectively.

The BQ25751 is a wide input voltage, switched-mode buck-boost battery charge controller with direct power path control. The device offers high-efficiency battery charging over a wide voltage range with bulk, float and absorption charging for lead-acid batteries. The device integrates all the loop compensation for the buck-boost converter, thereby providing a high density solution with ease of use.

Besides the I2C host-controlled charging mode, the device also supports standalone charging mode via resistor programmable limits. Input current, charge current and charge voltage regulation targets can be set via the ILIM_HIZ, ICHG and FB pins, respectively.
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Top documentation Type Title Format options Date
* Data sheet BQ25751: Standalone/I2C Controlled, 70V Bidirectional Buck-Boost Lead Acid Battery Charge Controller with Direct Power Path Control datasheet PDF | HTML Dec 8, 2024
Application note How To Implement External P&O Feature On BQ2575X PDF | HTML May 16, 2025

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Evaluation board

BQ25751EVM — BQ25751 evaluation module

The BQ25751EVM evaluation module (EVM) is a complete evaluation system for the BQ25751 IC, a buck-boost battery charge controller with a wide input range of 4.4V to 70V, a wide output voltage range of up to 70V, and bidirectional capabilities. The BQ25751EVM has a max input and output of 55V and a (...)
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Calculation tool

BQ25756-DESIGN-CALC — BQ25756 design calculator

BQ25756 design calculator is a calculation tool for BQ25756 which is a wide input voltage, switched mode buck-boost Li-Ion, Li-polymer, or LiFePO4 battery charge controller with bidirectional power flow support.
Supported products & hardware
Reference design

PMP31276 — 288W PFC, LLC and bidirectional battery charger reference design

This reference design is an AC/DC battery-backup charger with two outputs: system and battery. A 4-SW bidirectional buck-boost charges the battery and supplies system load. An optional microcontroller disables main power sections, reducing stand-by power while collecting parameters for telemetry.

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VQFN (RRV) 36 Ultra Librarian
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