SLVSCQ9E November 2014 – March 2022 TPS65400
PRODUCTION DATA
When DCM mode is enabled by setting IOUT_MODE (see (D6h) IOUT_MODE), the switchers transition to DCM operation at light loads. During DCM mode, the low-side FET is turned off to prevent negative inductor current. This increases light-load efficiency, but output ripple and transient response during DCM or during transitions between DCM and CCM mode can be degraded.
At light load, the COMP terminal is driven by the error amplifier to the minimum clamp voltage. When the COMP voltage reaches below 0.6 V and the error amplifier is sinking more than 5 μA, both the high-side and low-side FET will be tri-stated to prevent the output voltage from rising above the set value. The FET function is re-enabled when the GM amplifier sinks less than 3 μA. This results in a burst mode operation at light load. The low-side FET has a 200-ns one-shot ON-time to ensure that the bootstrap capacitor is charged before the normal function of the converter is resumed.