SNVAA33 December   2021 LM61460 , LM61460-Q1 , LM61495 , LM61495-Q1

 

  1.   Trademarks
  2. 1USB Type-C Specifications
  3. 2Popular AC Adapter Design
  4. 3Dynamic Output Voltage Control Methods
    1. 3.1 Method 1: Feedback Resistor Switch Network
    2. 3.2 Method 2: Feedback Current Injection Network
  5. 4Schematic
  6. 5Lab Measurements
    1. 5.1 Bench Measurement (VOUT = 5 V)
    2. 5.2 Bench Measurement (VOUT = 9 V)
    3. 5.3 Bench Measurement (VOUT = 15 V)
    4. 5.4 Bench Measurement (VOUT = 20 V)
  7. 6Summary
  8. 7References

1 USB Type-C Specifications

For most USB applications, the USB port is used to charge personal electronic devices. With the demand for more processing power comes the need for more power in a highly efficient and thermally cool solution. In order to meet the ever-growing trend of increased maximum power for USB applications, the system end equipment must be designed to accommodate the newly specified USB Type-C 1.2 (15 W) and USB PD 3.0 (100 W) power requirements detailed in Table 1-1 and illustrated in Figure 1-1.

Table 1-1 USB Specification and Maximum Voltage, Current, and Power
Specification Maximum voltage Maximum Current Maximum Power
USB 2.0 5 V 500 mA 2.5 W
USB 3.0 and USB 3.1 5 V 900 mA 4.5 W
USB BC 1.2 5 V 1.5 A 7.5 W
USB Type-C 1.2 5 V 3 A 15 W
USB PD 3.0 20 V 5 A 100 W
GUID-20211115-SS0I-R23Q-DNH9-QJXX4X4WJ8K8-low.jpg Figure 1-1 USB Source Power Demand Progression

The USB Type-C application is then further segmented into different power and data roles as shown in Figure 1-2. This application note focuses on a no data/source only USB Type-C end equipment with the use of a high-efficiency switching buck converter as the intermediary DC/DC conversion for a well-regulated output voltage rail.

GUID-20211115-SS0I-LH1N-DXQ8-BNVKSXXJT0GT-low.jpg Figure 1-2 USB Type-C Application Examples