Datasheet

TPS63060

TPS63061

SLVSA92A –DECEMBER 2011– REVISED FEBRUARY 2012

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Figure 28. Average Current Mode Control

Power-save mode and synchronization

The PS/SYNC pin can be used to select different operation modes. Power Save Mode is used to improve

efficiency at light load. To enable Power-Save, PS/SYNC must be set low. If PS/SYNC is set low then Power

Save Mode is entered when the average inductor current gets lower then about 100mA. At this point the

converter operates with reduced switching frequency and with a minimum quiescent current to maintain high

efficiency.

During the Power Save Mode, the output voltage is monitored with a comparator by the threshold comp low and

comp high. When the device enters Power Save Mode, the converter stops operating and the output voltage

drops. The slope of the output voltage depends on the load and the value of output capacitance. As the output

voltage falls below the comp low threshold set to 2.5% typical above Vout, the device ramps up the output

voltage again, by starting operation using a programmed average inductor current higher than required by the

current load condition. Operation can last for one or several pulses. The converter continues these pulses until

the comp high threshold, set to typically 3.5% above Vout nominal, is reached and the average inductor current

gets lower than about 100mA. When the load increases above the minimum forced inductor current of about

100mA, the device will automatically switch to PWM mode.

The Power Save Mode can be disabled by programming the PS/SYNC high. Connecting a clock signal at

PS/SYNC forces the device to synchronize to the connected clock frequency.

Synchronization is done by a PLL to lower and higher frequencies compared to the internal clock. The PLL can

also tolerate missing clock pulses without the converter malfunctioning. The PS/SYNC input supports standard

logic thresholds.

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