L6732

Device description

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rises with a slope of 100 mV/µs, emulating in this way the breaking of the high-side

MOSFET as an over-voltage cause.

The device realizes the over-current-protection (OCP) sensing the current both on the

high-side MOSFET(s) and the low-side MOSFET(s) and so 2 current limit thresholds can be

set (see OCH pin and OCL pin in Table 4. Pins function):

●

Peak current limit

●

Valley current limit

The peak current protection is active when the high-side MOSFET(s) is turned on, after a

masking time of about 100 ns. The valley-current-protection is enabled when the low-side

MOSFET(s) is turned on after a masking time of about 400 ns. If, when the soft-start phase

is completed, an over current event occurs during the on time (peak-current-protection) or

during the off time (valley-current-protection) the device enters in HICCUP mode: the high-

side and low-side MOSFET(s) are turned off, the soft-start capacitor is discharged with a

constant current of 10 µA and when the voltage at the SS pin reaches 0.5 V the soft-start

phase restarts. During the soft-start phase the OCP provides a constant-current-protection.

immediately turned off (after the masking time and the internal delay) and returned on at the

plus propagation delay because during the masking time the peak-current-protection is

escalate. The valley-current-protection is very helpful in this case to limit the current. If

during the off-time the OCL comparator triggers an over current, the high-side MOSFET(s)

is not turned on until the current is over the valley-current-limit. This implies that, if it is

necessary, some pulses of the high-side MOSFET(s) will be skipped, guaranteeing a

maximum current due to the following formula:

Figure 11.

OVP: the low-side MOSFET is turned-on in advance

LGate

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