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FAN7093 • Rev. 1.0.4

8

Protection Functions

The device provides several integrated protection

functions designed to prevent IC damage in fault

conditions. Fault conditions are considered as “outside”

the normal operating range. Protection functions are not

for continuous or repetitive operation, with the exception

of current-limit protection. In a fault condition, the

FAN7093 applies the highest slew rate possible,

Over-voltage,

over-temperature,

and

over-current

the IS pin. The following describes the protection

functions in order of priority. Over-voltage protection

overrides all other protections.

Over-Voltage Protection (OVP)

To ensure a high immunity against over-voltage

conditions like load dump, the device turns off the low-

side MOSFET and turns on the high-side MOSFET

when the supply voltage exceeds the over-voltage

voltage decreases below the over-voltage lockout level,

freewheeling in the high side during over-voltage

lockout, the IC turns off the high-side driver and latches

this state. See Table 1, which shows the condition of the

IS pin flag. This state can be reset (if the conditions no

longer exist) when /INH goes from HIGH to LOW to

HIGH again.

Under-Voltage Protection (UVP)

To avoid uncontrolled motion; for example, a driven

motor at low voltages; the control IC turns off all

MOSFETS when the supply voltage drops below the

normal operation when the supply voltage rises above

NOT flag this fault condition.

Over-Temperature Protection (OTP)

The FAN7093 is protected against over-temperature by

an integrated temperature sensor in the control IC.

Over-temperature protection turns off both output

stages. This state is latched until the device is reset by a

/INH pin, assuming the control IC temperature

decreased by at least the thermal hysteresis. Repetitive

use of the over-temperature protection decreases

product life.

Current Limitation

The current is measured in both MOSFETS. As soon as

side MOSFET is deactivated and the other MOSFET

are ignored. The /INH pin can still be used to turn off

initial setting. The error signal at the IS pin is reset after

circuitry through short current spikes (e.g. inflicted by

EMI coming from a motor) is suppressed by an internal

filter. Reaction delay of the filter circuitry affects the

current dI/dt.

Figure 5.

Current Limitation Timing Diagram

(Inductive Load)

In combination with a typical inductive load, such as a

motor, this results in a switched-mode current limitation.

This method of limiting current has the advantage of

greatly reduced power dissipation compared to driving

the MOSFET in linear mode. Therefore, it is possible to

use the current limitation for a short time without

exceeding the maximum allowed junction temperature

(e.g. for limiting the inrush current during motor startup).

However, regular use of the current limitation is only

allowed as long as the specified maximum junction

temperature

is

not

exceeded.

Exceeding

this

temperature reduces the life of the device.

Short-Circuit Protection (SCP)

The device is short-circuit protected against:

The short-circuit protection is a combination of current

limit and over-temperature shutdown of the device.