Data Sheet

ADP2164

Rev. 0 | Page 15 of 20

POWER GOOD

PGOOD is an active high, open-drain output and requires a

resistor to pull it up to the logic supply voltage. PGOOD high

indicates that the voltage on the FB pin (and, therefore, the

output voltage) is within 10% of the desired value. PGOOD low

indicates the opposite. There is a 16-cycle waiting period after

the FB voltage is detected as being out of bounds. If FB returns

to within the ±10% range, it is ignored by the PGOOD circuitry.

CURRENT LIMIT AND SHORT-CIRCUIT PROTECTION

The ADP2164 has a peak current limit protection circuit to

prevent current runaway. The peak current limit is 6.2 A. When

the inductor current reaches the peak current limit, the high-side

MOSFET turns off and the low-side MOSFET turns on until the

next cycle begins.

The overcurrent counter is incremented by 1 at each peak

current limit event. If the overcurrent counter exceeds 10, the

part enters hiccup mode, and the high-side FET and low-side

FET are both turned off. The part remains in this mode for

4096 clock cycles and then attempts to restart using soft start.

If the current limit fault has cleared, the part resumes normal

operation. If the current limit fault has not cleared, the part

reenters hiccup mode after first counting 10 current limit

violations.

OVERVOLTAGE PROTECTION (OVP)

Overvoltage protection (OVP) circuitry is integrated in the

ADP2164. The output voltage is continuously monitored by

a comparator through the FB pin, which is at 0.6 V (typical)

under normal operation. The comparator is activated when the

FB voltage exceeds 0.66 V (typical), thus indicating an output

overvoltage condition. If the voltage remains above the OVP

threshold for 16 clock cycles, the high-side MOSFET turns off

and the low-side MOSFET turns on until the current through it

reaches the −1.3 A current limit. Both MOSFETs remain in the

off state until FB falls below 0.54 V (typical), after which the

part restarts. The behavior of PGOOD under this condition is

described in the Power Good section.

UNDERVOLTAGE LOCKOUT (UVLO)

Undervoltage lockout (UVLO) circuitry is integrated in the

ADP2164. If the input voltage falls below 2.5 V, the ADP2164

shuts down, and both the power switch and the synchronous

rectifier turn off. When the voltage rises above 2.6 V again,

the soft start is initiated, and the part is enabled.

THERMAL SHUTDOWN

If the ADP2164 junction temperature rises above 140°C, the

thermal shutdown circuit turns off the regulator. Extreme junc-

tion temperatures can be the result of high current operation,

poor circuit board design, and/or high ambient temperature.

When thermal shutdown occurs, a 15°C hysteresis ensures that

the ADP2164 does not return to operation until the on-chip

temperature falls below 125°C. Soft start is initiated when the

part comes out of thermal shutdown.