Datasheet
Data Sheet ADP2302/ADP2303
Rev. A | Page 15 of 28
Table 5. Correlation Between f
SW
and V
FB
FB Pin Voltage Switching Frequency
V
FB
≥ 0.6 V f
SW
0.4 V < V
FB
< 0.6 V 1/2 f
SW
0.2 V < V
FB
≤ 0.4 V 1/4 f
SW
V
FB
≤ 0.2 V 1/8 f
SW
When a hard short (V
FB
≤ 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 ADP2302/ADP2303 have fixed, internally set undervoltage
lockout circuitry (UVLO). If the input voltage drops below
2.4 V, the ADP2302/ADP2303 shut down and the MOSFET
switch turns off. After the voltage rises above 2.7 V, the soft
start period is initiated, and the part is enabled.
THERMAL SHUTDOWN (TSD)
If the ADP2302/ADP2303 junction temperature rises above 150C,
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 15C
hysteresis is included so that when thermal shutdown occurs,
the ADP2302/ADP2303 do not return to operation until the on-
chip temperature drops below 135C. When the devices recover
from thermal shutdown, a soft start is initiated.
OVERVOLTAGE PROTECTION (OVP)
The ADP2302/ADP2303 provide an overvoltage protection
feature to protect the system against an output short to a higher
voltage supply. If the feedback voltage is above 0.880 V, the
internal high-side MOSFET is turned off, until the voltage at FB
decreases to 0.850 V. At that time, the ADP2302/ADP2303
resume normal operation.
POWER GOOD
The PGOOD pin is an active high, open-drain output and
requires a resistor to pull it up to a voltage (<20.0 V). A high
indicates that the voltage on the FB pin (and therefore the
output voltage) is above 87.5% of the reference voltage. A low
indicates that the voltage on the FB pin is below 85% of the
reference voltage. There is a 32-cycle waiting period after FB is
detected as being in or out of bounds.
CONTROL LOOP
The ADP2302/ADP2303 are internally compensated to minimize
external component count and cost. In addition, the built-in
slope compensation helps to prevent subharmonic oscillations
when the ADP2302/ADP2303 operate at a duty cycle greater
than or close to 50%.