Datasheet

Outputvoltage
Vout (PWM)
Vout +1%
PFMComparator
threshold
VoltagePositioning
Lightload
PFMMode
moderatetoheavyload
PWMMode
TPS62065, TPS62067
SLVS833B –MARCH 2010–REVISED NOVEMBER 2013 www.ti.com
Figure 24. Power Save Mode Operation with automatic Mode transition
100% Duty Cycle Low Dropout Operation
The device starts to enter 100% duty cycle mode as the input voltage comes close to the nominal output voltage.
In order to maintain the output voltage, the High-Side MOSFET switch is turned on 100% for one or more cycles.
With further decreasing VIN the High-Side MOSFET switch is turned on completely. In this case the converter
offers a low input-to-output voltage difference. This is particularly useful in battery-powered applications to
achieve longest operation time by taking full advantage of the whole battery voltage range.
The minimum input voltage to maintain regulation depends on the load current and output voltage, and can be
calculated as:
V
IN
min = V
O
max + I
O
max × (R
DS(on)
max + R
L
)
With:
I
O
max = maximum output current
R
DS(on)
max = maximum P-channel switch R
DS(on)
.
R
L
= DC resistance of the inductor
V
O
max = nominal output voltage plus maximum output voltage tolerance
Undervoltage Lockout
The under voltage lockout circuit prevents the device from malfunctioning at low input voltages and from
excessive discharge of the battery. It disables the output stage of the converter once the falling VIN trips the
under-voltage lockout threshold V
UVLO
. The under-voltage lockout threshold V
UVLO
for falling V
IN
is typically
1.78V. The device starts operation once the rising V
IN
trips under-voltage lockout threshold V
UVLO
again at
typically 1.95V.
Output Capacitor Discharge
With EN = GND, the device enters shutdown mode and all internal circuits are disabled. The SW pin is
connected to PGND via an internal resistor to discharge the output capacitor. This feature ensures a startup in a
discharged output capacitor once the converter is enabled again and prevents "floating" charge on the output
capacitor. The output voltage ramps up monotonic starting from 0V.
MODE SELECTION (TPS62065)
The MODE pin allows mode selection between forced PWM mode and Power Save Mode.
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