Management of the STCC50x1 attach detector

AN4308

10/14

DocID024781 Rev 1

The truth table for this case is following:

It results to simple logical function: 5V_SMPS_EN = SLP_S4 + CHARGING/ATTACH.

This function can be realized either using single gates or simply using discrete MOSFETs

4.1

EN and ATTACH_EN controlled by GPIOs

This is the most flexible case consuming most GPIOs, thus not applicable in many

applications. The functionality can be programmed exactly as demanded by the application.

4.2

ATTACH_EN = CTL3, CTLx pins controlled by SLP_Sx

signals from Intel chipset

The 2 signals SLP_S3 and SLP_S4 can be used to control CTLx pins: the CTL1 tied to the

SLP_S3 and the CTL2 tied to the SLP_S4. Thus using only 1 GPIO from embedded

controller (again the CTL3 pin can be user-configurable (BIOS, etc.) to enable/disable the

charging feature) and implementing Table 10: Truth table for 5 V SMPS described above,

we can control the following modes:

Table 11. 5 V SMPS truth table for SLP_S4 and CHARGING/ATTACH control

Power state

SLP_S4

CHARGING/ATTACH

5V_SMPS_EN

S0

1

X

ON

S3

1

X

ON

S4/S5

0

1 (attach not detected)

OFF

S4/S5

0

0 (attach detected)

ON

Table 12. STCC50x1 truth table for SLP_Sx and GPIO control

Power state

CTL1 =

SLP_S3

CTL2 =

SLP_S4

ATTACH_EN = CTL3

= GPIO from EC

Mode

S0

1

1

0

SDP

S0

1

1

1

CDP

S3

0

1

0

SDP full remote wakeup

S3

0

1

1

CDP LS remote wakeup /

FS, HS DCP auto.

S4/S5

0

0

1

EN = 0: Attach detection.

EN = 1: DCP auto.

S4/S5

0

0

0

OFF