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FUSB252 • Rev. 1.5

Operation and Application Description

Out of Spec Surge/Spike Voltage due to Hot

Plug

The FUSB252 protects end systems against 20 V DC

on the CC pin, in cases where the FUSB252 is tested to

mimic a hot plug event, a fully charged cable connected

to a power supply set to 20 V is used to zap the VICC

pins of the device. In these cases, the inductance of the

cable causes voltage spikes that are higher than the

absolute maximum ratings of the of the VICC pins.

These voltages can cause damage to the VOCC pins.

This scenario does not occur in normal usage. The

Type-C specification prevents the plug from having 20V

on VBUS from a PD source prior to a PD contract being

completed. When the 20 V potential is on VBUS and

shorted to the CC pin, it causes a detach and the

voltage spikes are less likely to occur. The following

reference circuit is required when the application calls

for additional protection to protect against such event as

hot plug.

Application Specific Schematic

§ Place a 5 V to 6 V rated Zener TVS diode such as

(CZRF52C5V6 or CD1005-Z5V1) on the VOCC pin,

and a 5 W resistor to device ground to prevent the

FUSB252 from being damaged during these tests.

With this additional protection if is also important to

select the right external VICC IEC TVS for the best

overall performance.

§ Without the additional protection the device by itself

can withstand up to 9 V under the same hot plug

condition

VICC1

VICC2

INTB/FLAGB

VDD

GND

VOCC1

VOCC2

/OE

SEL

HSD+

HSD-

HSD1-

HSD1+

HSD2-

HSD2+

FUSB252

CC1

D1+

D1-

D2+

D2-

CC2

/OE

SEL

FLAGB

VDD

5Ω

5.6VZener

IECTVS

Figure 6.

Reference Schematic

Over-Voltage Protection

When over-voltage event is detected, device will

activate OVP to shutdown the switch within tOVP, as well

as signal the FLAGB to indicate there is OV event to the

system.

Fault Reporting

Upon the detection of an over-voltage event, the

INTB/FLAGB signals the fault by activating LOW.

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