ADP2300AUJZ-R2 datasheet(15/28 Pages) AD

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Data Sheet

ADP2300/ADP2301

Rev. C | Page 15 of 28

SHORT-CIRCUIT PROTECTION

The ADP2300/ADP2301 include frequency foldback to prevent

output current runaway when there is a hard short on the output.

The switching frequency is reduced when the voltage at the FB pin

drops below a certain value, which allows more time for the

inductor current to decline, but increases the ripple current while

regulating the peak current. This results in a reduction in average

output current and prevents output current runaway. The corre-

lation between the switching frequency and the FB pin voltage

is shown in Table 5.

Table 5. Correlation Between the Switching Frequency

and the FB Pin Voltage

FB Pin Voltage

Switching Frequency

FB ≥ 0.6 V

0.6 V > V

FB > 0.2 V

½ f

FB ≤ 0.2 V

¼ f

When a hard short (VFB ≤ 0.2 V) is removed, a soft start cycle

is initiated to regulate the output back to its level during normal

operation, which helps to limit the inrush current and prevent

possible overshoot on the output voltage.

UNDERVOLTAGE LOCKOUT (UVLO)

The ADP2300/ADP2301 have fixed, internally set undervoltage

lockout circuitry. If the input voltage drops below 2.4 V, the

ADP2300/ADP2301 shut down and the MOSFET switch turns

off. After the voltage rises again above 2.8 V, the soft start

period is initiated, and the part is enabled.

THERMAL SHUTDOWN

If the ADP2300/ADP2301 junction temperature rises above 140°C,

the thermal shutdown circuit disables the chip. Extreme junction

temperature can be the result of high current operation, poor

circuit board design, or high ambient temperature. A 15°C

hysteresis is included so that when thermal shutdown occurs,

the ADP2300/ADP2301 do not return to operation until the on-

chip temperature drops below 125°C. After the devices recover

from thermal shutdown, a soft start is initiated.

CONTROL LOOP

The ADP2300/ADP2301 are internally compensated to minimize

external component count and cost. In addition, the built-in

slope compensation helps to prevent subharmonic oscillations

when the ADP2300/ADP2301 operate at a duty cycle greater

than or close to 50%.

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