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Management of the STCC50x1 attach detector

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Management of the STCC50x1 attach detector

The attach detector is controlled by the combination of EN and ATTACH_EN inputs

according to Table 9:

The goal of the attach detector is to allow the host to turn off the 5 V SMPS (high power

lowest possible level. In the attach detect mode, the consumption of the STCC50x1 is 12

A

only. After the PD attach is detected, the STCC50x1 asserts the CHARGING/ATTACH

output which allows enabling the 5 V SMPS.

Typically the attach detector is useful in S4/S5 states only. In the S0 to S3, the 5 V SMPS is

typically always turned on.

The truth table for the 5 V SMPS supply typically looks as Table 10:

combination of the STCC50x1 CHARGING/ATTACH output and a GPIO or a chipset signal.

For Intel chipset, a good candidate is the SLP_S4 signal described in Section 2.2 on page 5.

Table 9. Attach detector truth table

EN

ATTACH_EN

Attach detector

0

0

Disabled

01

Enabled

1

0

Disabled

1

1

Disabled

Table 10. Truth table for 5 V SMPS

Power state

EN

ATTACH_EN

S0

1

0 (X)

Always enabled

S3

1

0 (X)

Always enabled

S4/S5

1

0 (X)

Always enabled, attach detector disabled

S4/S5

0

1

Enabled after attach detect (CHARGING/ ATTACH = 0)

otherwise disabled

S4/S5

0

0

Always disabled