LT1612ES8 Ver la hoja de datos (PDF) - Linear Technology
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LT1612ES8 Datasheet PDF : 12 Pages
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OPERATIO
Burst Mode Operation Defeat
To maintain high efficiency at light loads, the LT1612 will
automatically shift into Burst Mode operation (MODE = 0V
or floating). In this mode of operation the oscillator and
switch drive circuitry is alternately turned on and off,
reducing quiescent current to 160µA. This reduces power
LT1612
consumption but also adds low frequency voltage ripple to
the output. Figure 3 shows switching waveforms for a 5V
to 3.3V converter running in Burst Mode operation. Output
voltage ripple is approximately 20mVP-P. If the MODE pin
is pulled high, Burst Mode operation will be inhibited and
the oscillator runs continuously with no low frequency
ripple at the output. See Figures 4 and 5.
VOUT
20mV/DIV
AC COUPLED
IL
200mA/DIV
5µs/DIV
1612 F03
Figure 3. Output Voltage Ripple is 20mVP-P for
the Circuit of Figure 1
VOUT
200mV/DIV
AC COUPLED
IL
200mA/DIV
ILOAD
10mA TO 310mA
0.1ms/DIV
1612 F04
Figure 4. Transient Response for the Circuit of Figure 1
with the MODE Pin Tied to Ground or Floating
VOUT
200mV/DIV
AC COUPLED
IL
200mA/DIV
ILOAD
10mA TO 300mA
0.1ms/DIV
1612 F05
Figure 5. With the MODE Pin Tied High, Low
Frequency Output Voltage Ripple Is No Longer Present
sn1612 1612fs
7
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