参数资料
型号: LM2576T-ADJLB03/NOPB
厂商: NATIONAL SEMICONDUCTOR CORP
元件分类: 稳压器
英文描述: 3 A SWITCHING REGULATOR, 52 kHz SWITCHING FREQ-MAX, SFM5
封装: ROHS COMPLIANT, TO-220, 5 PIN
文件页数: 11/24页
文件大小: 750K
代理商: LM2576T-ADJLB03/NOPB
Additional Applications (Continued)
DELAYED STARTUP
The ON /OFF pin can be used to provide a delayed startup
feature as shown in Figure 14. With an input voltage of 20V
and for the part values shown, the circuit provides approxi-
mately 10 ms of delay time before the circuit begins switch-
ing. Increasing the RC time constant can provide longer
delay times. But excessively large RC time constants can
cause problems with input voltages that are high in 60 Hz or
120 Hz ripple, by coupling the ripple into the ON /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.
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.
01147617
Note: Complete circuit not shown (see Figure 10).
FIGURE 13. Undervoltage Lockout
for Buck-Boost Circuit
01147618
Note: Complete circuit not shown.
FIGURE 14. Delayed Startup
01147619
FIGURE 15. 1.2V to 55V Adjustable 3A Power Supply with Low Output Ripple
LM2576/LM2576HV
www.national.com
19
相关PDF资料
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LM2576T-12FLOWLB03 3.5 A SWITCHING REGULATOR, 52 kHz SWITCHING FREQ-MAX, PSFM5
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