foreword
USB PD is currently the mainstream fast charging protocol. With the release of USB PD3.1, the transmission power can reach up to 240W. With the popularity of the USB Type-C interface, most electronic products begin to use the Type-C interface for power transmission. When mentioning the Type-C interface, it is often associated with USB PD fast charging. Among them, Type-C is a new interface specification, and USB PD is a fast charging protocol, because the Type-C interface has a dedicated communication line CC (channel configure) that can be used to transmit the USB PD protocol, so it is often used USB PD and Type-C are divided together, but there is an essential difference between the two.
1. What is PD fast charging?
It can be seen from the above figure that USB PD communication is the data interaction between Host (Source) and Power Brick (Sink).
1. When the Sink is connected (the host detects the access of the 5.1K pull-down resistor), the host (Source) will send the Source Cap (including the PDO that can provide the voltage range) within 100ms~200ms.
2. When the device receives the message from the host, it will reply Good CRC to respond, and reply Request (request the required voltage and current) within 24ms.
3. The host will reply Good CRC to respond to the Request sent by the device, and check whether its own PDO supports the device Request. If it supports it, it will reply Accept within 24ms. If it does not support it, it will reply Reject.
4. When the device receives the Accept/Reject from the host, it will respond with a Good CRC.
5. If the host supports the device request, it will adjust the voltage within 450ms, send PS_RDY after the voltage adjustment is completed, and then wait for the device to reply Good CRC to respond.
2. The function of ECP5701 receiving chip
1. Provide a boost
ECP5701 series single chip supports boost fast charging protocol such as PD3.0/2.0, and provides single resistor configuration mode and level configuration mode to request voltage gear.
2. Adaptive function.
Summarize
ECP5701 is used as a power-receiving sink chip, which can be widely used in terminal equipment with lithium batteries, such as electric tools, lighting fixtures, speaker equipment, photographic equipment, small household appliances such as fascia guns, etc. The power supply of the protocol requests the maximum or specified voltage. For example, the PD charger can support 5V, 9V, 12V, 15V, and 20V charging. Devices equipped with ECP5701 circuits can obtain 5V9V12V, 15V, and 20V voltage signals from the adapter to achieve fast charging. Function.