Reference Design for 27-Watt Class A Charger meeting Qualcomm Quick Charge 4 Spec.

November 01, 2017 by Paul Shepard

Diodes Incorporated and Weltrend Semiconductor Inc. today announced a joint reference design for a 27W, Class A charger that is one of the industry's first chargers to support Qualcomm® Quick Charge™ 4 specification for the fast charging of mobile devices.

Quick Charge 4 is the latest fast-charging specification from Qualcomm Technologies, Inc., a subsidiary of Qualcomm Incorporated, offering up to 20% faster charging, up to 30% greater efficiency, and running 5% cooler when compared to Quick Charge 3.0.

Quick Charge 4 also supports USB PD and PPS (programmable power supply), helping to standardize the capabilities of adaptors using these technologies, while being designed to deliver headline-making charging performance that provides five hours of talk time from just five minutes of charging, along with comprehensive safety features.

Evaluation board.

"Diodes' key corporate strength is rooted in its integrated device manufacturing (IDM) operations model. Leveraging our vertical integration manufacturing strength in conjunction with a platform solution approach provides the relevant active components required for target systems, especially as Diodes has a well-established business in providing primary- and secondary-side power regulation products for chargers and power adapter applications", said Ernest Lin, Division Manager, AC-DC Power and Lighting Division.

"Diodes recognized Weltrend's core competency in MCU-based power management applications and its established market position in protocol decoding products for quick charging, which made for a logical partnership for developing a reference design to meet the demanding requirements of the Qualcomm Quick Charge 4 specification," concluded Lin.

Evaluation board schematic. (click on schematic to enlarge)

The reference design uses Diodes' AP3302 peak-current control, quasi-resonant (QR) PWM controller, which is optimized for high performance, low standby power and cost-effective offline flyback conversion, and its APR345 secondary-side MOSFET synchronous rectification driver that directly supports CCM, DCM and QR flyback topologies.

Weltrend provides the highly integrated WT6615F programmable protocol decoder that supports the latest programmable power supply specification for Quick Charge protocols and USB PD, and consequently fully implements all the requirements of the Quick Charge 4 specification.

Tony Lin, Executive Assistant to the CEO and Acting VP of Marketing at Weltrend, said, "Working closely with Qualcomm Technologies, our expertise lies in understanding fast charge protocols and we are excited to be one of the first in our industry to provide a Quick Charge 4 compatible chipset.

"The joint development of this 27W Quick Charge 4 Class A reference design with Diodes provides a cost-effective, ready-to-go charger design that enables a rapid time-to-market solution for our mutual customer bases," continued Lin.

System key features

  • SSR Topology Implementation with an Opto-coupler for Accurate Step Voltage Controlling
  • QC4+ Offers QC3.0/QC2.0 Backward Compliance
  • Supports the USB PD3.0 Function and PPS ([email protected])
  • Meet DOE6 and CoC Tier 2 Efficiency Requirements
  • <75mW No-Load Standby Power

AP3302A key features

  • Quasi-Resonant Operation with Valley Lock under all Lines and Load Conditions
  • Switching Frequency: 22kHz-120kHz
  • Non-audible-noise QR Controlling
  • Soft Start Process during the Start-up Turn-on Moment
  • During the burst mode operation and Low start-up operating quiescent currents, 75mW standby power can be achieved
  • Built-in Jittering Frequency Function which is the EMI emission can be improved
  • Internal Auto Recovery OCP, OVP, OLP, OTP Power Protection, cycle by cycle current limit, also with DC polarity & transformer short and Brown out Protection

APR345 key features

  • Synchronous Rectification Working at DCM, CCM and QR Flyback
  • Eliminate Resonant Ringing Interference
  • Fewest External Components used

WT6615F key features

  • Type-C Source
  • USB PD 3.0 v1.1 (PPS)
  • 2 DCP
  • Qualcomm Quick Charge 4/4+
  • Built in Shunt Regulator for Constant Voltage and Constant Current
  • Programmable OVP/UVP/OCP/OTP
  • Internal Discharge MOS
  • Internal Vbus Load Switch Driver
  • 3V- 30V Operation Voltage without External Regulator

Weltrend's WT6615F Qualcomm Quick Charge 4 Controller is certified by GRL. The reference design supports Quick Charge 4 Class A (18-27W) and also provides optional Quick Charge 2.0 and Quick Charge 3.0 compliance to support the Quick Charge 4+ program. It provides support for USB PD 3.0 and PPS, including PDO at 5V and 9V, ADPO from 3V to 11V in 20mV steps, and current from 0A to 3A in 50mA steps.

Its safety management capability provides monitoring of voltage, current, and temperature, with reporting and protection features. The charger design supports low standby current consumption and meets Energy Star DOE VI and CoC Tier II efficiency requirements.