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PDF LM2574HV Data sheet ( Hoja de datos )

Número de pieza LM2574HV
Descripción SIMPLE SWITCHER 0.5A Step-Down Voltage Regulator
Fabricantes National Semiconductor 
Logotipo National Semiconductor Logotipo



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No Preview Available ! LM2574HV Hoja de datos, Descripción, Manual

June 1999
LM2574/LM2574HV
SIMPLE SWITCHER0.5A Step-Down Voltage Regulator
General Description
The LM2574 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 0.5A load
with excellent line and load regulation. These devices are
available in fixed output voltages of 3.3V, 5V, 12V, 15V, and
an adjustable output version.
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation and a fixed-frequency oscillator.
The LM2574 series offers a high-efficiency replacement for
popular three-terminal linear regulators. Because of its high
efficiency, the copper traces on the printed circuit board are
normally the only heat sinking needed.
A standard series of inductors optimized for use with the
LM2574 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode
power supplies.
Other features include a guaranteed ±4% tolerance on out-
put voltage within specified input voltages and output load
conditions, and ±10% on the oscillator frequency. External
shutdown is included, featuring 50 µA (typical) standby cur-
rent. The output switch includes cycle-by-cycle current limit-
ing, as well as thermal shutdown for full protection under
fault conditions.
Features
n 3.3V, 5V, 12V, 15V, and adjustable output versions
n Adjustable version output voltage range, 1.23V to 37V
(57V for HV version) ±4% max over line and load
conditions
n Guaranteed 0.5A output current
n Wide input voltage range, 40V, up to 60V for HV version
n Requires only 4 external components
n 52 kHz fixed frequency internal oscillator
n TTL shutdown capability, low power standby mode
n High efficiency
n Uses readily available standard inductors
n Thermal shutdown and current limit protection
Applications
n Simple high-efficiency step-down (buck) regulator
n Efficient pre-regulator for linear regulators
n On-card switching regulators
n Positive to negative converter (Buck-Boost)
Typical Application (Fixed Output Voltage Versions)
Note: Pin numbers are for 8-pin DIP package.
DS011394-1
Patent Pending
SIMPLE SWITCHERis a trademark of National Semiconductor Corporation
© 1999 National Semiconductor Corporation DS011394
www.national.com

1 page




LM2574HV pdf
LM2574-ADJ, LM2574HV-ADJ
Electrical Characteristics (Continued)
Specifications with standard type face are for
ture Range. Unless otherwise specified, VIN
=TJ12=V2, 5IL˚OCA, Dan=d1t0h0osme Aw.ith
boldface
type
apply
over
full
Operating
Tempera-
Symbol
Parameter
Conditions
LM2574-ADJ
LM2574HV-ADJ
Units
(Limits)
Typ Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
VFB
Feedback Voltage
7V VIN 40V, 0.1A ILOAD 0.5A
1.230
LM2574
VOUT Programmed for 5V. Circuit of Figure 2
1.193/1.180
1.267/1.280
V
V(Min)
V(Max)
VFB
Feedback Voltage
7V VIN 60V, 0.1A ILOAD 0.5A
1.230
LM2574HV
VOUT Programmed for 5V. Circuit of Figure 2
1.193/1.180
1.273/1.286
V(Min)
V(Max)
η Efficiency
VIN = 12V, VOUT = 5V, ILOAD = 0.5A
77
%
All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture
and
VRINan=ge3.0UVnfloerstsheoth1e5rVwviseerssiopne.ciIfLieOdA,DV=IN1=0012mVA.for
the
3.3V,
5V,
and
Adjustable
version,
VIN
=
25V
for
the
12V
version,
Symbol
Parameter
Conditions
LM2574-XX
LM2574HV-XX
Units
(Limits)
Typ Limit
(Note 2)
DEVICE PARAMETERS
Ib
Feedback Bias
Adjustable Version Only, VOUT = 5V
Current
50 100/500
nA
fO Oscillator Frequency (see Note 10)
52 kHz
47/42
kHz(Min)
58/63
kHz(Max)
VSAT
Saturation Voltage
IOUT = 0.5A (Note 4)
0.9
1.2/1.4
V
V(max)
DC Max Duty Cycle (Note 5)
(ON)
98 %
93 %(Min)
ICL Current Limit
Peak Current, (Notes 4, 10)
1.0
0.7/0.65
A
A(Min)
1.6/1.8
A(Max)
IL
Output Leakage
(Notes 6, 7)
Current
Output = 0V
2 mA(Max)
Output = −1V 7.5
mA
Output = −1V
30 mA(Max)
IQ
Quiescent Current
(Note 6)
5 mA
10 mA(Max)
ISTBY
Standby Quiescent
Current
ON /OFF Pin= 5V (OFF)
50 µA
200 µA(Max)
θJA Thermal Resistance N Package, Junction to Ambient (Note 8)
θJA N Package, Junction to Ambient (Note 9)
θJA M Package, Junction to Ambient (Note 8)
θJA M Package, Junction to Ambient (Note 9)
92
72
102
78
˚C/W
5 www.national.com

5 Page





LM2574HV arduino
Test Circuit and Layout Guidelines
(Continued)
Inductor
Value
68 µH
100 µH
150 µH
220 µH
330 µH
470 µH
680 µH
1000 µH
1500 µH
2200 µH
Pulse Eng.
(Note 1)
*
*
52625
52626
52627
52628
52629
52631
*
*
Renco
(Note 2)
RL-1284-68-43
RL-1284-100-43
RL-1284-150-43
RL-1284-220-43
RL-1284-330-43
RL-1284-470-43
RL-1283-680-43
RL-1283-1000-43
RL-1283-1500-43
RL-1283-2200-43
NPI
(Note 3)
NP5915
NP5916
NP5917
NP5918/5919
NP5920/5921
NP5922
NP5923
*
*
*
FIGURE 3. Inductor Selection by
Manufacturer’s Part Number
U.S. Source
Note 1: Pulse Engineering,
(619) 674-8100
P.O. Box 12236, San Diego, CA 92112
Note 2: Renco Electronics Inc.,
(516) 586-5566
60 Jeffryn Blvd. East, Deer Park, NY 11729
*Contact Manufacturer
European Source
Note 3: NPI/APC
+44 (0) 634 290588
47 Riverside, Medway City Estate
Strood, Rochester, Kent ME2 4DP. UK
*Contact Manufacturer
11 www.national.com

11 Page







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