MP2731 USB PD Reference Design: 4.5A, NVDC Single-Cell Charger with OTG


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1.1 Description

The MP2731 USB power delivery (PD) reference design provides a complete solution for USB PD applications that comply with USB PD3.0 specifications. The major components of this reference design include the MP2731 — a 4.5A, narrow voltage DC (NVDC) single-cell Li-ion battery charger — and a CCG3PA (USB PD controller).

The reference design offers a bidirectional DRP Type-C port. When a USB input is present, the port functions as an upstream-facing port (UFP) to charge the battery. When a USB PD sink is connected to the Type-C port, the reference design functions as a downstream-facing port (DFP), and can provide a 5V USB On-the-Go (OTG) for the sink device. This reference design provides NVDC architecture with power path management functionality, which makes the solution well-suited for smartphones, tablets, and various portable charging applications.

1.2 Features

  • 5V to 16V Operating Input Voltage Range Supporting Common Fixed PDO Voltages
  • Up to 22V Maximum Sustainable Voltage
  • High-Efficiency, 4.5A, 1.35MHz Buck Charger
  • Support USB PD 3.0 and BC 1.2 Protocols
  • USB On-the-Go (OTG) Function to Power USB Port from Battery Power
  • Up to 9A Battery Discharge Current
  • Narrow Voltage DC (NVDC) Power Path Management Functionality
  • I2C Interface for Configurable System Parameter Settings
  • High-Accuracy: ±0.5% Charge Voltage Regulation, ±5% Charge Current Regulation
  • Configurable JEITA Thresholds for Battery Temperature Protection
  • Provide Thermal Regulation Loop and Thermal Shutdown Protection
  • Input and System Over-Voltage Protection (OVP)

Figure 1: Solution Module for USB PD

1.3 Applications

  • Tablets
  • Smartphones
  • Mobile Devices

Reference Design

2.1 Block Diagram

The MP2731 USB PD reference design offers a cost-effective solution to achieve up to 18W PD fast charging by pairing a highly integrated MP2731 charger with a universal PD controller (CCG3A). A universally available Type-C connector on the board serves as a bidirectional input. The back-to-back input FET configuration is optional because the MP2731 also provides an internal input-blocking FET, which helps to further reduce PCB size and BOM cost (see Figure 2).

Figure 2: MP2731 USB PD Charger System Block Diagram

2.2 Related Solutions

This reference design is based on the following MPS solution:

Table 1: System Specifications

MPS Integrated Circuit Description
MP2731GQC-0000 4.5A, NVDC single-cell charger with USB On-the-Go (OTG)

System Specifications

Table 2: System Specifications

Parameter Specification
Input voltage range  5 to 16V
Charge-full voltage  4.2V, I2C-configurable
Charge current 3.0A, I2C-configurable
Input voltage regulation  4.6V, I2C-configurable
Input current regulation 0.5A, I2C-configurable
OTG voltage regulation 5.1V, I2C-configurable
OTG current limit 2.4A, I2C-configurable
Board form factor  78mmx63mmx12mm 
Efficiency >90%

Test Results

3.1 Charge Efficiency

VIN = 5V, 9V, or 12V, VBATT = 3.8V, RL_DCR = 21mΩ, not including the external blocking FET (Q1, Q2)Image 3

Efficiency vs. Charge Current

3.2 Thermal Measurements

Conditions: VIN = 12V, VBATT = 3.8V, IBATT = 3A, TA = 24°C.

Figure 6: Thermal Performance