参数资料
型号: LM2574DW-ADJ
厂商: MOTOROLA INC
元件分类: 稳压器
英文描述: 1.8 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PDSO16
封装: PLASTIC, SO-16
文件页数: 13/24页
文件大小: 396K
代理商: LM2574DW-ADJ
LM2574
20
MOTOROLA ANALOG IC DEVICE DATA
R1
47 k
LM2574–XX
5
2
and
4
3
Gnds
Pins
ON/OFF
R2
47 k
+Vin
C1
0.1
F
Cin
22
F
NOTE: This picture does not show the complete circuit.
Figure 32. Delayed Startup Circuitry
Undervoltage Lockout
Some applications require the regulator to remain off until
the input voltage reaches a certain threshold level. Figure 33
shows an undervoltage lockout circuit applied to a buck
regulator. A version of this circuit for buck–boost converter is
shown in Figure 34. Resistor R3 pulls the ON/OFF pin high
and keeps the regulator off until the input voltage reaches a
predetermined threshold level, which is determined by the
following expression:
V
th [
V
Z1 )
1.0
) R2
R1
V
BE
(Q1)
R1
10 k
Z1
1N5242B
R2
10 k
Q1
2N3904
R3
47 k
Cin
22
F
LM2574–XX
5
2
and
4
3
Gnds
Pins
ON/OFF
+Vin
NOTE: This picture does not show the complete circuit.
Figure 33. Undervoltage Lockout Circuit for
Buck Converter
R2
15 k
Z1
1N5242
R1
15 k
Q1
2N3904
R3
68 k
Cin
22
F
LM2574–XX
5
2
and
4
3
Gnds
Pins
ON/OFF
+Vin
–Vout
NOTE: This picture does not show the complete circuit (see Figure 27).
Figure 34. Undervoltage Lockout Circuit for
Buck–Boost Converter
Adjustable Output, Low–Ripple Power Supply
A 0.5 A output current capability power supply that
features an adjustable output voltage is shown in Figure 35.
This regulator delivers 0.5 A into 1.2 to 35 V output. The
input voltage ranges from roughly 3.0 to 40 V. In order to
achieve a 10 or more times reduction of output ripple, an
additional L–C filter is included in this circuit.
相关PDF资料
PDF描述
LM2574N-ADJ 1.8 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PDIP8
LM2574DW-ADJR2 1.8 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PDSO16
LM2574N-15 1.8 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PDIP8
LM2575-05IKTTR 4 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSSO5
LM2575-33IKTTR 4 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSSO5
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