10

TPS54228

SLVSAU1E – MAY 2011 – REVISED AUGUST 2016

www.ti.com

Product Folder Links: TPS54228

Submit Documentation Feedback

Copyright © 2011–2016, Texas Instruments Incorporated

Feature Description (continued)

cycle begins. In subsequent switching cycles, the on-time is set to a fixed value and the current is monitored in

the same manner. If the overcurrent condition exists for 7 consecutive switching cycles, the internal OCL

threshold is set to a lower level, reducing the available output current. When a switching cycle occurs where the

switch current is not above the lower OCL threshold, the counter is reset and the OCL limit is returned to the

higher value.

There are some important considerations for this type of overcurrent protection. The load current one half of the

peak-to-peak inductor current higher than the overcurrent threshold. Also when the current is being limited, the

output voltage tends to fall as the demanded load current may be higher than the current available from the

converter. This may cause the output voltage to fall. When the overcurrent condition is removed, the output

voltage returns to the regulated value. This protection is non-latching.

7.3.6 UVLO Protection

than UVLO threshold voltage, the TPS54228 is shut off. This protection is non-latching.

7.3.7 Thermal Shutdown

TPS54228 monitors the temperature of itself. If the temperature exceeds the threshold value (typically 165°C),

the device is shut off. This is non-latch protection.

7.4 Device Functional Modes

7.4.1 Normal Operation

When the input voltage is above the UVLO threshold and the EN voltage is above the enable threshold, the

TPS54228 can operate in their normal switching modes. Normal continuous conduction mode (CCM) occurs

when the minimum switch current is above 0 A. In CCM, the TPS54228 operates at a quasi-fixed frequency of

700 kHz.

7.4.2 Standby Operation

When the TPS54228 is operating in either normal CCM or forced CCM, it may be placed in standby by asserting

the EN pin low.