RT9451GQW

Overview

The RT9451GQW is a switch-mode single-cell Li-ion battery charger IC manufactured by Richtek USA Inc. It integrates a synchronous 375kHz PWM controller with built-in power MOSFETs, supporting USB and AC adapter input sources. The device provides a maximum charge current of 4A and a charge voltage of 4.44V, operating within an input voltage range of 4.3V to 12V. It features On-The-Go (OTG) support, D+D- detection, and a 50mA LDO regulator in a WQFN4x4-32 package.

Feature Summary

• Integrates high-efficiency USB-friendly switch-mode charging with synchronous PWM control
• Supports On-The-Go (OTG) functionality for host power delivery
• Includes built-in bootstrap switch and internal compensation for simplified design
• Features cycle-by-cycle current limit and programmable charge termination

Applications

• Single-cell Li-ion and Li-polymer battery charging systems
• USB-powered portable electronic devices requiring OTG capability
• Mobile phones and smartphones with integrated fast-charging solutions
• Tablets and handheld gaming devices utilizing AC adapter or USB inputs

Procurement Notes

Verify the specific suffix 'GQW' against the manufacturer's official datasheet to confirm pinout compatibility and thermal pad configuration. Ensure that the ordering documentation explicitly references the RT9451 series specifications, particularly regarding the 4.44V charge voltage setting and 4A current limit parameters. Cross-reference the package type WQFN4x4-32 with PCB footprint libraries to prevent assembly errors during procurement validation.

Selection Notes

Select this component for applications requiring integrated USB OTG capabilities alongside standard battery charging functions. The internal bootstrap switch simplifies the external bill of materials compared to discrete solutions. Consider the 375kHz switching frequency when designing EMI-sensitive layouts. Verify that the system's input source can sustain the required 4A peak current without triggering undervoltage lockout conditions during the constant-charge phase.

Part Context

The RT9451 belongs to Richtek's family of single-cell lithium-ion battery chargers designed for mobile consumer electronics. Unlike linear chargers, this switch-mode device offers higher efficiency during charging, reducing heat dissipation in compact enclosures. The integration of an LDO regulator and OTG controller allows it to serve as a comprehensive power management solution for small form-factor devices where space and component count are critical constraints.

Replacement Considerations

Public confirmed substitute part numbers: None identified in provided documentation.