IN

OUT

OUT

OUT _ MAX

LS _ LIMIT

SW

IN

V

V

V

I

I

2 f

L

V

u

u

u

18

LMR23630

SNVSAH2C – DECEMBER 2015 – REVISED JUNE 2017

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The current going through LS MOSFET is also sensed and monitored. When the LS switch turns on, the inductor

current begins to ramp down. The LS switch is not turned OFF at the end of a switching cycle if its current is

switch is turned on after a dead time. This is somewhat different than the more typical peak current limit and

results in Equation 10 for the maximum load current.

(10)

If the current of the LS switch is higher than the LS current limit for 64 consecutive cycles, hiccup current

protection mode is activated. In hiccup mode, the regulator is shut down and kept off for 5 ms typically before the

LMR23630 tries to start again. If overcurrent or short-circuit fault condition still exist, hiccup will repeat until the

fault condition is removed. Hiccup mode reduces power dissipation under severe overcurrent conditions,

prevents over-heating and potential damage to the device.

turned off until the next clock cycle. This is used to protect the LS switch from excessive negative current.

8.3.11 Thermal Shutdown

The LMR23630 provides an internal thermal shutdown to protect the device when the junction temperature

exceeds 170°C (typical). The device is turned off when thermal shutdown activates. Once the die temperature

falls below 155°C (typical), the device reinitiates the power-up sequence controlled by the internal soft-start

circuitry.