BQ738 Datasheet PDF – Battery SMBus Charge Controller

Part Number: BQ738 ( = BQ24738 )

Function : 1-4 Cell Li+ Battery SMBus Charge Controller

Package: QFN-20 Type

Manufacturer: Texas Instruments

Image

BQ738 datasheet

Description

The BQ738 device is a high-efficiency, synchronous battery charger, offering low component count for space-constrained, multichemistry battery charging applications. The BQ738 device supports turbo boost by allowing battery discharge energy to the system when system power demand is temporarily higher than the adapter maximum power level so the adapter will not crash.

Pinout

BQ738 pinout BQ24738

Features

1. Adapter and Battery Provide Power to System Together to Support Intel CPU Turbo Boost Mode

2. SMBus Host-Controlled NMOS-NMOS Synchronous Buck Converter With Programmable 615-, 750-, and 885-kHz Switching Frequencies

3. Programmable Battery Depletion Threshold, and Battery LEARN Function

4. Programmable Adapter Detection and Indicator

5. Integrated Loop Compensation and Soft Start

Applications

1. Portable Notebook Computers, UMPC, Ultra-Thin Notebooks, and Netbooks

2. Handheld Terminals

3. Portable Equipment

4. Industrial and Medical Equipment

Design Considerations

  • Select external MOSFETs with appropriate RDS(on) and current rating for charger efficiency.
  • Inductor value must be chosen based on switching frequency and desired ripple current.
  • Proper layout of high-current switching paths is critical to minimize EMI and losses.
  • Use SMBus interface to configure charging voltage, current limits, and system power management.
  • Thermal management of MOSFETs and inductor should be considered in compact notebook designs.

Selection Guidance

  • Recommended when SMBus-controlled smart charging is required.
  • Suitable for systems needing adapter and battery power sharing.
  • Useful in designs where high transient CPU loads must be supported.
  • Appropriate for compact designs requiring low external component count.
  • Compatible with multichemistry rechargeable battery systems.

Other data sheets are available within the file: BQ24738

BQ738 Datasheet

BQ738 pdf

BQ735 Datasheet

BQ735 pdf

BQ24728 Datasheet – Battery SMBus Charge Controller – TI

Part Number: BQ24728, BQ728, BQ24728RGRT

Function: Battery SMBus Charge Controller ( Power management , System Charge Power IC )

Package: QFN 20 Pin

Manfacturers: Texas Instruments

Image:

BQ24728 image

Description

The bq24728 is a high-efficiency, synchronous battery charger, offering low component count for space-constraint, multi-chemistry battery charging applications. The device uses two charge pumps to  separately drive n-channel MOSFETs (ACFET, RBFET and BATFET) for automatic system power source selection. SMBus controlled input current, charge current, and charge voltage DACs allow for high regulation accuracies that can be programmed by the system power management micro-controller.

Features

  • SMBus programmable charging parameters (voltage/current/input limit)
  • High-efficiency synchronous charging architecture
  • Automatic power source selection (adapter ↔ battery)
  • Supports multi-chemistry battery systems (primarily Li-ion/Li-polymer)
  • Low external component count
  • High regulation accuracy via internal DACs
  • Dual charge pump for full NMOS drive (no P-channel needed)

Pinout

BQ24728 Datasheet, Pinout

Typical Circuit Usage

  • Adapter input → ACFET/RBFET → system rail
  • Synchronous buck stage → battery charging path
  • BATFET controls battery connection/disconnection
  • SMBus connected to EC (Embedded Controller)

Design Notes (Critical Points)

  • Accurate current sensing resistor selection is essential for charge precision
  • External MOSFET selection impacts efficiency and thermal performance
  • SMBus firmware must properly configure charging profiles
  • PCB layout must minimize switching loop inductance
  • Thermal design critical for high-current charging scenarios

Applications

  • Notebook / ultrabook / netbook platforms
  • Handheld and portable terminals
  • Industrial battery-powered equipment
  • Medical portable systems
  • Embedded battery charging modules

Advantages

  • Highly flexible and programmable
  • Efficient power-path control
  • Reduced component count
  • Suitable for smart battery systems

Alternative / Equivalent Products

  • BQ24727 (closely related variant)
  • BQ24725A
  • ISL6255
  • MAX8734
  • LTC4012

BQ24728 Datasheet

BQ24728 pdf

BQ24725 Datasheet

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