AP63200Q/AP63201Q/AP63203Q/AP63205Q

Document number: DS43698 Rev. 1 - 2

23 of 30

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September 2021

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AP63200Q/AP63201Q/AP63203Q/AP63205Q

Application Information (continued)

5

Adjusting Undervoltage Lockout (UVLO) (continued)

The resistive divider resistor values are calculated by:

������������ =

������. ������������������ ∙ ������������������ − ������������������������

������. ������������������������������

Eq. 2

������������ =

������. ������������ ∙ ������������

������������������������ − ������. ������������������ + ������. ������������������ ∙ ������������

Eq. 3

Where:



VON is the rising edge VIN voltage to enable the regulator and is greater than 3.7V



VOFF is the falling edge VIN voltage to disable the regulator and is greater than 3.26V

6

Output Overvoltage Protection (OVP)

The AP63200Q/AP63201Q/AP63203Q/AP63205Q implements output OVP circuitry to minimize output voltage overshoots during decreasing load

transients. The high-side power MOSFET turns off, and the low-side power MOSFET turns on, when the feedback voltage exceeds 110% of the

0.8V internal reference voltage in order to prevent the output voltage from continuing to increase.

7

Overcurrent Protection (OCP)

The AP63200Q/AP63201Q/AP63203Q/AP63205Q has cycle-by-cycle peak current limit protection by sensing the current through the internal

high-side power MOSFET, Q1. While Q1 is on, the internal sensing circuitry monitors its conduction current. Once the current through Q1 exceeds

the peak current limit, Q1 immediately turns off. If Q1 consistently hits the peak current limit for 512 cycles, the buck converter enters hiccup mode

and shuts down. After 8192 cycles of down time, the buck converter restarts powering up. Hiccup mode reduces the power dissipation in the

overcurrent condition.

8

Thermal Shutdown (TSD)

If the junction temperature of the device reaches the thermal shutdown limit of +160°C, the AP63200Q/AP63201Q/AP63203Q/AP63205Q shuts

down both its high-side and low-side power MOSFETs. When the junction temperature reduces to the required level (+135°C typical), the device

initiates a normal power-up cycle with soft-start.

9

Power Derating Characteristics

To prevent the regulator from exceeding the maximum recommended operating junction temperature, some thermal analysis is required. The

regulator’s temperature rise is given by:

������������������������������ = ������������ ∙ (������������������)

Eq. 4

Where:



PD is the power dissipated by the regulator



θJA is the thermal resistance from the junction of the die to the ambient temperature

The junction temperature, TJ, is given by:

������������ = ������������ + ������������������������������

Eq. 5

Where:



TA is the ambient temperature of the environment