LM2576SX-5.0 View Datasheet(PDF) - Unspecified
Part Name
Description
Manufacturer
LM2576SX-5.0 Datasheet PDF : 23 Pages
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Additional Applications (Continued)
LM2576/LM2576HV
cause problems with input voltages that are high in 60Hz
or 120Hz ripple, by coupling the ripple into the /OFF
pin.
ADJUSTABLE OUTPUT, LOW-RIPPLE POWER SUPPLY
A 3A power supply that features an adjustable output voltage is
shown in figure 15. An additional L-C filter that reduces the
output ripple by a factor of 10 or more is included in this circuit.
Note: Complete circuit not shown (see Figure 10)
FIGURE 13. Undervoltage Lockout for Buck-Boost Circuit
DELAYED STARTUP
The /OFF pin can be used to provide a delayed start up
feature as shown in Figure 14. With an input voltage of 20V and
for the part values shown, the circuit provides approximately
10ms of delay time before the circuit beigns switching.
Increasing the RC time constant can provide longer delay
times. But excessively large RC time constants can
01147618
Note: Complete circuit not shown.
FIGURE 14. Delayed Startup
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FIGURE 15. 1.2V to 55V Adjustable 3A Power Supply with Low Output Ripple
Definition of Terms
BUCK REGULATOR
A switching regulator topology in which a higher voltage
is converted to a lower voltage. Also known as a
step-down switching regulator.
BUCK-BOOST REGULATOR
A switching regulator topology in which a positive voltage is
converted to a negative voltage without a transformer.
DUTY CYCLE(D)
Ratio of the output switch’s on-time to the oscillator period.
CATCH DIODE OR CURRENT STEERING DIODE
The diode which provides a return path for the load current
when the LM2576 switch is OFF.
EFFICIENCY(η)
The proportion of input power actually delivered to the load.
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