LM2574 查看數據表（PDF） - Motorola => Freescale
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LM2574 Datasheet PDF : 24 Pages
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LM2574
SYSTEM PARAMETERS ([Note 1] Test Circuit Figure 16)
ELECTRICAL CHARACTERISTICS (continued) (Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version,
Vin = 25 V for the 12 V version, Vin = 30 V for the 15 V version. ILoad = 100 mA. For typical values TJ = 25°C, for min/max values TJ is the
operating junction temperature range that applies [Note 2], unless otherwise noted).
Characteristic
Symbol
Min
Typ
Max
Unit
ALL OUTPUT VOLTAGE VERSIONS
Feedback Bias Current Vout = 5.0 V (Adjustable Version Only)
TJ = 25°C
TJ = –40 to +125°C
Oscillator Frequency (Note 3)
TJ = 25°C
TJ = 0 to +125°C
TJ = –40 to +125°C
Saturation Voltage (Iout = 0.5 A, [Note 4])
TJ = 25°C
TJ = –40 to +125°C
Max Duty Cycle (“on”) [Note 5]
Ib
fO
Vsat
DC
nA
–
25
100
–
–
200
kHz
–
52
–
47
52
58
42
–
63
V
–
1.0
1.2
–
–
1.4
93
98
–
%
Current Limit Peak Current (Notes 3 and 4)
TJ = 25°C
TJ = –40 to +125°C
Output Leakage Current (Notes 6 and 7), TJ = 25°C
Output = 0 V
Output = – 1.0 V
ICL
A
0.7
1.0
1.6
0.65
–
1.8
IL
mA
–
0.6
2.0
–
10
30
Quiescent Current (Note 6)
TJ = 25°C
TJ = –40 to +125°C
IQ
mA
–
5.0
9.0
–
–
11
Standby Quiescent Current (ON/OFF Pin = 5.0 V (“off”))
TJ = 25°C
TJ = –40 to +125°C
Istby
µA
–
60
200
–
–
400
ON/OFF Pin Logic Input Level
Vout = 0 V
TJ = 25°C
TJ = –40 to +125°C
Nominal Output Voltage
TJ = 25°C
TJ = –40 to +125°C
V
VIH
2.2
1.4
–
2.4
–
–
VIL
–
1.2
1.0
–
–
0.8
ON/OFF Pin Input Current
ON/OFF Pin = 5.0 V (“off”), TJ = 25°C
ON/OFF Pin = 0 V (“on”), TJ = 25°C
µA
IIH
–
15
30
IIL
–
0
5.0
NOTES: 1. External components such as the catch diode, inductor, input and output capacitors can affect the switching regulator system
performance. When the LM2574 is used as shown in the Figure 16 test circuit, the system performance will be as
shown in the system parameters section of the Electrical Characteristics.
2. Tested junction temperature range for the LM2574: Tlow = –40°C Thigh = +125°C
3. The oscillator frequency reduces to approximately 18 kHz in the event of an output short or an overload which causes the regulated output
voltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average power dissipation of
the IC by lowering the minimum duty cycle from 5% down to approximately 2%.
4. Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to the output pin.
5. Feedback (Pin 4) removed from output and connected to 0 V.
6. Feedback (Pin 4) removed from output and connected to 12 V for the Adjustable, 3.3 V, and 5.0 V versions, and 25 V for the 12 V and 15 V
versions, to force the output transistor OFF.
7. Vin = 40 V.
4
MOTOROLA ANALOG IC DEVICE DATA
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