USB2524 datasheet(39/58 Pages) MICROCHIP

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 2013 - 2016 Microchip Technology Inc.

DS00001588B-page 39

USB2524

7.3.8.2

Reserved Registers

Unless otherwise instructed, only a ‘0’ may be written to all reserved registers or bits.

7.4

Default Strapping Option

The USB2524 can be configured via a combination of internal default values and pin strap options.

The strapping option pins only cover a limited sub-set of the configuration options. The internal default values will be

used for the bits & registers that are not controlled by a strapping option pin.

The LED_A[4:1]_N pins are sampled after RESET_N negation, and the logic values are used to configure the hub if the

internal default configuration mode is selected. The implementation shown in Figure 7-1, "LED Strapping Option" shows

a recommended passive scheme. When a pin is configured with a “Strap High” configuration, the LED functions with

active low signaling, and the PAD will “sink” the current from the external supply. When a pin is configured with a “Strap

Low” configuration, the LED functions with active high signaling, and the PAD will source the current to the external LED.

7.5

Default Configuration

When configured for Internal Defaults only, the Default ROM values in Table 7-1, "Internal EEPROM & SMBus Register

Memory Map" lists the values which will be used to configure the various hub features.

FIGURE 7-1:

LED STRAPPING OPTION

HUB

100K

Strap Low

LED

100K

Strap High

LED

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