STMEC001 datasheet(5/19 Pages) STMICROELECTRONICS

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STMEC001

Pin description

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1.1

Pin functional description

Table 3.

Pin detailed descriptions

Symbol

Description

CPPE

A logic low level on this input indicates that the card present supports PCI Express

functions. This input pin connects to the 3.3 VAUX input through a 150 kΩ internal pull up.

When inserted, the card physically connects this input to ground if the card supports PCI

Express functions.

CPUSB

A logic low level on this input indicates that the card present supports USB functions. The

input pin CPUSB connects to the 3.3 VAUX input through a 150 kΩ internal pull up. When

inserted, the card physically connects CPUSB to ground if the card supports USB

functions.

SHDN

When asserted (logic low), this input instructs the STMEC001 to turn off all voltage

outputs and the discharge FETs at the 3 outputs are activated.

STBY

When asserted (logic low), this input places the power switch in Standby Mode by turning

off the 3.3 V and 1.5 V power switches and keeping the 3.3 VAUX switch on.

RCLKEN

This pin serves as both an input and an output. On power up, the power switch keeps this

signal at a low state as long as any of the output power rails are out of their tolerance

range. Once all output power rails are within tolerance, the power switch releases

RCLKEN allowing it to transition to a high state (internally pulled up to 3.3 VAUX). The

transition of RCLKEN from a low to a high state starts an internal timer for the purpose of

de-asserting /PERST. As an input, RCLKEN can be kept low to delay the start of the

/PERST internal timer. RCLKEN can be used by the host system to enable a clock driver.

PERST

On power up, this output remains asserted. Once all power rails are within tolerance,

RCLKEN is asserted and /PERST is de-asserted after a time delay. On power down, this

output is asserted whenever any of the power rails drop below their voltage tolerance.

SYSRST

This input is driven by the host system and directly affects /PERST. Asserting /SYSRST

(logic level: low) forces /PERST to assert.

The OC pin is an open drain output for over-current indication. Output does not turn off

during over-current condition. The output voltage decreases as the output current

exceeds over-current limit. Only if the temperature increases above the limit the output is

turned off completely. Over-current in one output does not affect the other outputs.

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