Microchip USB3503 Manual de Usario

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2013 Microchip Technology Inc. DS00001586A-page 1
INTRODUCTION
The USB3503 is the industry's first HSIC-based USB 2.0 hub controller designed specifically for portable consumer
electronics products such as smartphones, tablets and e-readers. The USB3503 features one HSIC upstream port, 3
downstream USB 2.0 ports, and is designed to deliver the low-power and ultra-small footprint that portable product
designers demand.
Minimizing power consumption, thus extending portable device battery life, is crucial for maintaining a competitive edge
in the portable device market. This document contains information for portable product designers looking to minimize
suspended state power consumption in designs containing the USB3503.
This document includes the following topics:
Low Power Modes Overview
Standard Suspend Mode
Reset Suspend Mode
Suspend Mode with Clock Power-Down
Audience
This document is written for developers who are familiar with USB/HSIC protocol and the various features of the
USB3503 hub. The goal of this application note is to familiarize the reader with low power options for the USB3503 and
to assist the developer with choosing the most appropriate configuration for their design.
AN1586
USB3503 Low Power Configurations
Author: Andrew Rogers,
Microchip Technology Inc.
DS00001586A-page 2 2013 Microchip Technology Inc.
AN1586
LOW POWER MODES OVERVIEW
The USB3503 is designed to handle USB communication within a personal device, such as a mobile phone or tablet
device. The low power configurations detailed in this application note are presented as if the hub was designed into a
personal device, where battery consumption is a primary concern. In a typical application, the HSIC upstream
connection will interface with the personal device’s microprocessor/controller. A downstream port may be connected to
a device such as a modem which may be used to send and receive calls. To conserve power consumption while there
is no modem activity, it is desirable to place the USB hub into low-power, suspended state. It may also be desirable that
hub be able to rapidly exit the suspended state when data is ready to be sent to the hub from the downstream port. This
document presents three different options for minimizing hub power consumption while the hub is not in use:
1. Standard Suspend Mode
2. Reset Suspend Mode
3. Suspend Mode with Clock Power-Down
Table 1 describes the primary trade-offs associated with these configuration options.
TABLE 1: LOW POWER CONSUMPTION MODES QUICK COMPARISON
Mode Pros Cons
Standard Suspend Mode Fastest resume/wakeup
Simplest implementation
Highest power consumption
Reset Suspend Lowest power consumption Slow resume/wakeup due to re-
enumeration
Suspend Mode with Clock
Power-Down
Fast resume/wakeup
Reduced power consumption
over standard suspend mode due
to suspension of clock
Non-default hub configuration and
additional chip-to-chip signaling
required
2013 Microchip Technology Inc. DS00001586A-page 3
AN1586
STANDARD SUSPEND MODE
For standard suspend configuration, the hub may be left in its default configuration. While the hub is in a suspended
state, the downstream USB 2.0 D+ line is kept high and the D- line is kept low. When a downstream device attempts to
wake up the hub from suspend to prepare upstream devices for data transmission, the downstream D+ line is switched
low and D- line is switched high. This signaling is interpreted by the hub and passed upstream via the HSIC lines to
signal the upstream device to prepare for data transmission. A screen capture of a standard wakeup event on the
USB3503 is shown in Figure 1.
While this method is fast, the hub must be kept in a low power suspended state while there is no USB activity. The clock
signal is not interrupted when switching between states and thus continuously consumes power during the suspended
state.
FIGURE 1: STANDARD WAKE-UP EVENT

Especificaciones del producto

Marca: Microchip
Categoría: No categorizado
Modelo: USB3503

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