FUSB302MPX. datasheet(7/35 Pages) ONSEMI

7 / 35 page

www.fairchildsemi.com

FUSB302

• Rev. 2

www.onsemi.com

The high level software flow diagram for a Type-C

device (SNK) is shown in Figure 7.

Disabled:

FUSB302 in low power

mode looking for an attach

Unattached.SNK:

Host software enables

FUSB302 pull-downs and

measure block to detect

attach

FUSB302 I_TOGDONE

interrupt alerts host

software that something

has attached.

Attached.SNK

Host software uses FUSB302

comparators and DAC to

determine attach orientation and

port type

AudioAccessory

DebugAccessory

FUSB302 I_VBUSOK interrupt alerts

host software that an attach has

occurred

FUSB302 I_VBUSOK interrupt alerts

host software that a detach has

occurred

Host software determines that an

accessory has been attached

FUSB302 I_COMP and I_VBUSOK

interrupts alert host software that a

accessory detach has occurred

Figure 7.

SNK Software Flow

Manual Host Detection and Configuration

When the FUSB302 is configured as a Type-C host, the

software can use the status of the comparators and

DAC to determine when a Type-C device has been

attached or detached and what termination type has

been attached to each CC pin.

The FUSB302 allows the host software to change the

charging current capabilities of the port through the

HOST_CUR control bits. If the HOST_CUR bits are

changed prior to attach, the FUSB302 automatically

indicates the programmed current capability when a

device is attached. If the current capabilities are changed

after a device is attached, the FUSB302 immediately

changes the CC line to the programmed capability.

Figure 8.

HOST_CUR Changed After Attach

Figure 9.

HOST_CUR Changed Prior To Attach

The Type-C specification outlines different attach and

detach thresholds for a Type-C host that are based on

how much current is supplied to each CC pin. Based on

the programmed HOST_CUR setting, the software

adjusts the DAC comparator threshold to match the

Type-C

specification

requirements.

The

BC_LVL

comparators can also be used as part of the Ra

detection flow. This is summarized in Table 3.

Table 3.

Host Interrupt Summary

Termination

HOST_CUR[1:0]

Interrupt Status

Attach/Detach

BC_LVL[1:0]

COMP

COMP Setting

2'b01

2'b00

2'b10

2'b01

6'b00_1001 (0.42 V)

2'b11

2'b10

6'b01_0010 (0.8 V)

2'b01, 2'b10

6'b10_0101 (1.6 V)

Attach

6'b10_0101 (1.6 V)

Detach

2'b11

6'b11_1101 (2.6 V)

Attach

6'b11_1101 (2.6 V)

Detach

HOST_CUR[1:0] = DEFAULT

HIGH CURRENT SETTING

MED CURRENT SETTING

ATTACH

HIGH CURRENT SETTING

MED CURRENT SETTING

ATTACH

DEFAULT CURRENT

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