LAN9250 datasheet(38/421 Pages) MICROCHIP

38 / 421 page

LAN9250

DS00001913A-page 38

 2015 Microchip Technology Inc.

6.2

Resets

The device provides multiple hardware and software reset sources, which allow varying levels of the device to be reset.

All resets can be categorized into three reset types as described in the following sections:

• Chip-Level Resets

- Power-On Reset (POR)

- RST# Pin Reset

• Multi-Module Resets

- DIGITAL RESET (DIGITAL_RST)

• Single-Module Resets

- PHY Reset

- Host MAC Sub-System Reset

- 1588 Reset

The device supports the use of configuration straps to allow automatic custom configurations of various device param-

eters. These configuration strap values are set upon de-assertion of all chip-level resets and can be used to easily set

the default parameters of the chip at power-on or pin (RST#) reset. Refer to Section 6.3, "Power Management," on

page 44 for detailed information on the usage of these straps.

Table 6-1 summarizes the effect of the various reset sources on the device. Refer to the following sections for detailed

information on each of these reset types.

TABLE 6-1:

RESET SOURCES AND AFFECTED DEVICE FUNCTIONALITY

Module/

Functionality

POR

RST#

Digital

Reset

25 MHz Oscillator

(1)

Voltage Regulators

(2)

Host MAC sub-system

PHY

PHY Common

(3)

Voltage Supervision

(3)

PLL

(3)

1588 Clock / Event Gen.

1588 Timestamp Unit 0

1588 Timestamp Unit 1

1588 Timestamp Unit 2

SPI/SQI Slave

Host Bus Interface

Power Management

Device EEPROM Loader

I2C Master

GPIO/LED Controller

General Purpose Timer

Free Running Counter

System CSR

Config. Straps Latched

YES

NO(4)

EEPROM Loader Run

YES

Reload Host MAC Addr.

(5)(5)(5)

Tristate Output Pins(

YES

Note

POR is performed by the XTAL voltage regulator, not at the system level

POR is performed internal to the voltage regulators

POR is performed internal to the PHY

Strap inputs are not re-latched, however Soft-straps are returned to their previously latched pin defaults before they

are potentially updated by the EEPROM values.

Part of EEPROM loading

Only those output pins that are used for straps

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