FUSB3307 datasheet(18/21 Pages) ONSEMI

18 / 21 page

FUSB3307

www.onsemi.com

OVP and UVP are sensed via an internal resistor divider

that divides VCC by 10 to determine the voltage from the

power source. CC1 and CC2 are directly sensed for over

voltage. For E_OTP (QFN package option only), a pin NTC

is available that is connected to an NTC resistor to ground

usually in parallel with another resistor to ground for

linearity. For I_OTP (SOIC and QFN packages), an internal

temperature monitor is used. For all faults except

VCONN_OCP fault, upon detection, the FUSB3307 will

disable the Type C connection with the Sink (no pull−up on

CC), shut off VBUS load switch and keep monitoring the

fault. Once the fault has been removed, the FUSB3307 starts

up at 5 V after t2S_AR_NM seconds and reconnects with the

Sink.

Output Over Voltage Protection (OVP)

FUSB3307 has built−in OVP based on the Trim Table

(Table 6). For the default OVP case, whenever VCC, as

sensed by an internal 1:10 resistor divider, exceeds

KCC−OVP (typically 120%) of the requested VCC from the

power source for a debounce time of tD−OVP, then the OVP

fault would be triggered. Upon detection, the FUSB3307

will disable the Type C connection with the Sink (no pull−up

on CC), shut off VBUS load switch and keep monitoring

VCC to determine if the OVP is still present. When OVP is

removed, a timer is started which when expired in t2S_AR

seconds, causes the FUSB3307 to reestablish the Sink Type

C connection with the initial 5 V VBUS supplied as if it were

initially attached.

During transitions between VCC voltages, the OVP

circuitry is blanked or disabled for tBNK−OVP time to ensure

that false triggering of OVP doesn’t occur. To ensure safe

operation over all voltages of VCC, the maximum VCC

voltage is limited to VCC−OVP−MAX.

Output Under Voltage Protection (UVP)

FUSB3307 has a built−in UVP based on the Trim Table

(Table 6). For the default UVP case, whenever VCC, as

sensed internally, is below KCC−UVP (typically 65%) of the

requested output voltage from the power source for a

debounce time of tD−UVP, then the UVP fault would be

triggered. No PD Alert messages are sent for this fault.

During transitions between VCC voltages, the UVP

circuitry is blanked or disabled for tBNK−UVP time to ensure

that false triggering of UVP doesn’t occur.

For PPS contracts, if current limiting causes the voltage to

decrease, the UVP fault will not trigger at 65% of VCC since

all voltages from the requested voltage to VCC−OFF, the

lowest voltage, are valid.

For compliance with the USB PD specification, the

FUSB3307 will trigger UVP whenever VCC is below

VCC−OFF. This allows protection for a direct short of VBUS

to ground separately or in conjunction with the OCP fault

described below. If VCC < VCC−OFF fault is triggered, then

to resume normal operation, VCC has to go below VLATCH

to reset the FUSB3307 to exit this fault condition.

Over Current Protection (OCP) and Constant Current

Limit (CL)

If VBUS is shorted to ground, either the UVP fault

described above could trigger or the OCP fault, or both.

FUSB3307 senses the current via a small R4 resistor (5 m

typical) as described in the Voltage and Current Sensing

section above. The OCP fault is triggered at 120% of the

maximum current for the requested Power Data Object

(PDO) for fixed supplies only (ICS−3A typically 3.6 A for a

3 A maximum fixed supply current). Once this OCP fault

occurs, the FUSB3307 protects the system as described in

the Protection Operation section above. An Alert message

is sent upon the FUSB3307 establishing an explicit contract

with the Sink and a PD “Status” message from the

FUSB3307 will include the OCP history.

For PPS APDO’s (Augmented Power Data Objects),

Constant Current Limiting (CL) is used as specified in the

USB PD specification where the voltage will drop to a low

value based on keeping the current constant and equal to the

requested PPS current. In this case UVP described above

will trigger if VCC drops below VCC−OFF since any voltage

from the lowest 3.3 V – 5% to the PPS requested voltage

could occur with current limiting. If the PPS current limit is

changed with a new PD Request message, the VCC voltage

may change accordingly to a new value based on the current

limiting function. An Alert message is sent whenever there

is a switch from Constant Current Limit (CL) to Constant

Voltage (CV) mode and vice versa. For PPS_Status

messages, this flag that shows whether the FUSB3307 is in

CL or CV mode, is sent along with the VCC voltage and load

current as sensed by R4 to monitor the FUSB3307 while it

provides PPS voltages and currents.

Over Temperature Protection (I_OTP and E_OTP)

FUSB3307 has two different over temperature faults,

E_OTP and I_OTP. For E_OTP, when the QFN package is

used, there is a NTC pin that is expected to be connected to

an NTC resistor in parallel with a regular resistor for

linearity. The FUSB3307 provides a INTC current source

(typically 60

mA) on the NTC pin to bias this NTC resistor

so that an internal A/D converter measures the external

temperature as shown in Figure 14.

FUSB3307 датащи(PDF) 18 Page - ON Semiconductor

FUSB3307 датащи(HTML) 18 Page - ON Semiconductor

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

датащи скачать

ссылки URL