POK RISING THRESHOLD

POK FALLING THRESHOLD

POK

STARTUP

A

C

E

SHUTDOWN

B

D

Figure 1. Typical POK Operation

The POK operation versus the output voltage is shown in the Figure 1 above. Different operating regions are:

A: The device is in regulation.

C: The device is in regulation.

rising threshold.

E: The device is in regulation.

Protection

The MAX38909 is fully protected from an output short-circuit by a current-limiting and thermal overload protection circuit.

If the output is shorted to GND, the output current is limited to 2.8A (typ). Under these conditions, the device quickly

heats up. When the junction temperature reaches +165°C, a thermal limit circuit shuts the output device off. Once the

device cools to 150°C, the output turns back on to reestablish regulation. If the fault persists, the output current cycles

on and off as the junction temperature slews between +150°C and +165°C. Continuously operating in the fault conditions

or above +125°C junction temperature is not recommended since long-term reliability might be reduced. In dropout, the

current limit triggers at 4A (typ). Once the limit is triggered, the device limits the current to 2.8A (typ).

The thermal protection can also be triggered when the device is exposed to excessive heat in the system causing the die

temperature to reach undesired levels.

The MAX38909 provides the reverse-current protection when the output voltage is higher than the input. If extra output

capacitance is used at the output, a power-down transient at the input would normally cause a large reverse-current

through a conventional regulator. The MAX38909 include a reverse-voltage detector that trips when IN drops 6.5mV

below OUT shutting off the regulator and opening the body diode connection preventing any reverse current. The reverse

current is a current that flows through the body diode of the pass element and is undesired due to its impact on power

MAX38909

2A High-Performance

nMOS LDO Linear Regulator

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