PFM Mode at Light Load

Comparator High

Comparator Low

Comparator Low 2

PWM Mode at Medium to Full Load

1.6%

0.8%

VO

TPS62200, TPS62201, TPS62202, TPS62203

TPS62204, TPS62205, TPS62207, TPS62208

SLVS417F – MARCH 2002 – REVISED JUNE 2015

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Device Functional Modes (continued)

The N-channel rectifier is turned on and the inductor current ramps down. As the inductor current approaches

zero, the N-channel rectifier is turned off and the P-channel switch is turned on again, starting the next pulse.

The converter continues these pulses until the comparator high threshold (set to typically 1.6% above Vout

nominal) is reached. The converter enters a sleep mode, reducing the quiescent current to a minimum. The

converter wakes up again as the output voltage falls below the comparator low threshold again. This control

method reduces the quiescent current typically to 15 µA and reduces the switching frequency to a minimum,

thereby achieving the high converter efficiency. Setting the skip current thresholds to typically 0.8% and 1.6%

above the nominal output voltage at light load current results in a dynamic output voltage achieving lower

absolute voltage drops during heavy load transient changes. This allows the converter to operate with a small

output capacitor of just 10 µF and still have a low absolute voltage drop during heavy load transient changes.

See Figure 4 for detailed operation of the power save mode.

Figure 4. Power Save Mode Thresholds and Dynamic Voltage Positioning

The converter enters the fixed frequency PWM mode again as soon as the output voltage falls below the

comparator low 2 threshold.

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