ltc3528-2 Linear Technology Corporation, ltc3528-2 Datasheet - Page 11

• Manufacturer Part Number: ltc3528-2
• Description: Ltc3528-2 - 1a, 2mhz Synchronous Step-up Dc/dc Converter In 2mm ? 3mm Dfn
• Manufacturer: Linear Technology Corporation

OPERATION
when switching between modes. In Burst Mode opera-
tion, energy is delivered to the output until it reaches the
nominal regulated value, then the LTC3528-2 transitions to
sleep mode where the outputs are off and the LTC3528–2
consumes only 12µA of quiescent current from V
the output voltage has drooped slightly, switching resumes
again. This maximizes efficiency at very light loads by
minimizing switching and quiescent current losses. Burst
Mode output ripple, which is typically 1% peak-to-peak,
can be reduced by using more output capacitance (10µF
or greater).
As the load current increases, the LTC3528-2 automatically
leaves Burst Mode operation. Note that larger output ca-
pacitor values may cause this transition to occur at lighter
loads. The regulator will also leave Burst Mode operation if
a load transient occurs which causes the inductor current
to repeatedly reach current limit. Once the LTC3528-2 has
(Refer to Block Diagram)
OUT
. Once
left Burst Mode operation and returned to normal opera-
tion, it will remain there until the output load is reduced
below the Burst threshold.
Burst Mode operation is inhibited during start-up and
until soft-start is done and V
than V
Single Cell to 5V Step-Up Applications
Due to the high inductor current slew rate in applications
boosting to 5V from a single cell (alkaline, NiCd or NiMH),
the LTC3528-2 may not enter Burst Mode operation at in-
put voltages below 1.5V. For single cell to 5V applications
requiring Burst Mode operation, the 1MHz LTC3528 is
recommended. Refer to the Typical Performance Charac-
teristics for the Burst Mode thresholds for different input
and output voltages.
IN
.
OUT
is at least 0.24V greater
LTC3528-2
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