NSC LM2574N-ADJ, LM2574N-5.0, LM2574N-15, LM2574N-12, LM2574MX-ADJ Datasheet
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June 1999
LM2574/LM2574HV
SIMPLE SWITCHER™ 0.5A 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 output voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency. External shutdown is included, featuring 50 µA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under fault conditions.
Features
n3.3V, 5V, 12V, 15V, and adjustable output versions
nAdjustable version output voltage range, 1.23V to 37V (57V for HV version) ±4% max over line and load conditions
nGuaranteed 0.5A output current
nWide input voltage range, 40V, up to 60V for HV version
nRequires only 4 external components
n52 kHz fixed frequency internal oscillator
nTTL shutdown capability, low power standby mode
nHigh efficiency
nUses readily available standard inductors
nThermal shutdown and current limit protection
Applications
nSimple high-efficiency step-down (buck) regulator
nEfficient pre-regulator for linear regulators
nOn-card switching regulators
nPositive to negative converter (Buck-Boost)
Typical Application (Fixed Output Voltage Versions)
DS011394-1
Note: Pin numbers are for 8-pin DIP package.
Patent Pending
SIMPLE SWITCHER™ is a trademark of National Semiconductor Corporation
Regulator Voltage Down-Step 5A.0 SWITCHER SIMPLE LM2574/LM2574HV
© 1999 National Semiconductor Corporation |
DS011394 |
www.national.com |
Connection Diagrams
8-Lead DIP |
14-Lead Wide |
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Surface Mount (WM) |
DS011394-2
* No internal connection, but should be soldered to PC board for best heat transfer.
Top View
Order Number LM2574-3.3HVN, LM2574HVN-5.0,
LM2574HVN-12, LM2574HVN-15, LM2574HVN-ADJ,
LM2574N-3.3, LM2574N-5.0, LM2574N-12,
LM2574N-15 or LM2574N-ADJ
See NS Package Number N08A
DS011394-3
Top View
Order Number LM2574HVM-3.3, LM2574HVM-5.0,
LM2574HVM-12, LM2574HVM-15, LM2574HVM-ADJ,
LM2574M-3.3 LM2574M-5.0, LM2574M-12,
LM2574M-15 or LM2574M-ADJ
See NS Package Number M14B
www.national.com |
2 |
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
Maximum Supply Voltage |
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LM2574 |
45V |
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LM2574HV |
63V |
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−0.3V ≤ V ≤ +VIN |
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ON |
/OFF Pin Input Voltage |
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Output Voltage to Ground |
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(Steady State) |
−1V |
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Minimum ESD Rating |
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(C = 100 pF, R = 1.5 kΩ) |
2 kV |
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Storage Temperature Range |
−65ÊC to +150ÊC |
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Lead Temperature |
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(Soldering, 10 seconds) |
260ÊC |
Maximum Junction Temperature |
150ÊC |
Power Dissipation |
Internally Limited |
Operating Ratings
Temperature Range |
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LM2574/LM2574HV |
−40ÊC ≤ TJ ≤ +125ÊC |
Supply Voltage |
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LM2574 |
40V |
LM2574HV |
60V |
LM2574-3.3, LM2574HV-3.3
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range.
Symbol |
Parameter |
Conditions |
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LM2574-3.3 |
Units |
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LM2574HV-3.3 |
(Limits) |
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Typ |
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Limit |
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(Note 2) |
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SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2 |
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VOUT |
Output Voltage |
VIN = 12V, ILOAD = 100 mA |
3.3 |
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V |
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3.234 |
V(Min) |
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3.366 |
V(Max) |
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VOUT |
Output Voltage |
4.75V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A |
3.3 |
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V |
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LM2574 |
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3.168/3.135 |
V(Min) |
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3.432/3.465 |
V(Max) |
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VOUT |
Output Voltage |
4.75V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A |
3.3 |
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LM2574HV |
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3.168/3.135 |
V(Min) |
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3.450/3.482 |
V(Max) |
η |
Efficiency |
VIN = 12V, ILOAD = 0.5A |
72 |
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% |
LM2574-5.0, LM2574HV-5.0
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range.
Symbol |
Parameter |
Conditions |
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LM2574-5.0 |
Units |
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LM2574HV-5.0 |
(Limits) |
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Typ |
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Limit |
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(Note 2) |
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SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2 |
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VOUT |
Output Voltage |
VIN = 12V, ILOAD = 100 mA |
5 |
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V |
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4.900 |
V(Min) |
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5.100 |
V(Max) |
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VOUT |
Output Voltage |
7V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A |
5 |
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V |
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LM2574 |
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4.800/4.750 |
V(Min) |
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5.200/5.250 |
V(Max) |
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VOUT |
Output Voltage |
7V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A |
5 |
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LM2574HV |
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4.800/4.750 |
V(Min) |
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5.225/5.275 |
V(Max) |
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η |
Efficiency |
VIN = 12V, ILOAD = 0.5A |
77 |
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% |
3 |
www.national.com |
LM2574-12, LM2574HV-12
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range.
Symbol |
Parameter |
Conditions |
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LM2574-12 |
Units |
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LM2574HV-12 |
(Limits) |
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Typ |
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Limit |
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(Note 2) |
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SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2 |
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VOUT |
Output Voltage |
VIN = 25V, ILOAD = 100 mA |
12 |
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V |
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11.76 |
V(Min) |
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12.24 |
V(Max) |
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VOUT |
Output Voltage |
15V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A |
12 |
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V |
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LM2574 |
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11.52/11.40 |
V(Min) |
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12.48/12.60 |
V(Max) |
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VOUT |
Output Voltage |
15V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A |
12 |
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LM2574HV |
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11.52/11.40 |
V(Min) |
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12.54/12.66 |
V(Max) |
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η |
Efficiency |
VIN = 15V, ILOAD = 0.5A |
88 |
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% |
LM2574-15, LM2574HV-15
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range.
Symbol |
Parameter |
Conditions |
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LM2574-15 |
Units |
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LM2574HV-15 |
(Limits) |
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Typ |
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Limit |
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(Note 2) |
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SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2 |
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VOUT |
Output Voltage |
VIN = 30V, ILOAD = 100 mA |
15 |
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V |
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14.70 |
V(Min) |
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15.30 |
V(Max) |
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VOUT |
Output Voltage |
18V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A |
15 |
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V |
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LM2574 |
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14.40/14.25 |
V(Min) |
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15.60/15.75 |
V(Max) |
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VOUT |
Output Voltage |
18V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A |
15 |
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LM2574HV |
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14.40/14.25 |
V(Min) |
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15.68/15.83 |
V(Max) |
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η |
Efficiency |
VIN = 18V, ILOAD = 0.5A |
88 |
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% |
LM2574-ADJ, LM2574HV-ADJ Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V, ILOAD = 100 mA.
Symbol |
Parameter |
Conditions |
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LM2574-ADJ |
Units |
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LM2574HV-ADJ |
(Limits) |
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Typ |
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Limit |
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(Note 2) |
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SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2 |
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VFB |
Feedback Voltage |
VIN = 12V, ILOAD = 100 mA |
1.230 |
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V |
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1.217 |
V(Min) |
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1.243 |
V(Max) |
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www.national.com |
4 |
LM2574-ADJ, LM2574HV-ADJ
Electrical Characteristics (Continued)
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V, ILOAD = 100 mA.
Symbol |
Parameter |
Conditions |
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LM2574-ADJ |
Units |
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LM2574HV-ADJ |
(Limits) |
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Typ |
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Limit |
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(Note 2) |
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SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2 |
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VFB |
Feedback Voltage |
7V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.5A |
1.230 |
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V |
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LM2574 |
VOUT Programmed for 5V. Circuit of Figure 2 |
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1.193/1.180 |
V(Min) |
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1.267/1.280 |
V(Max) |
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VFB |
Feedback Voltage |
7V ≤ VIN ≤ 60V, 0.1A ≤ ILOAD ≤ 0.5A |
1.230 |
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LM2574HV |
VOUT Programmed for 5V. Circuit of Figure 2 |
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1.193/1.180 |
V(Min) |
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1.273/1.286 |
V(Max) |
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η |
Efficiency |
VIN = 12V, VOUT = 5V, ILOAD = 0.5A |
77 |
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% |
All Output Voltage Versions Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version, VIN = 25V for the 12V version, and VIN = 30V for the 15V version. ILOAD = 100 mA.
Symbol |
Parameter |
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Conditions |
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LM2574-XX |
Units |
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LM2574HV-XX |
(Limits) |
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Typ |
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Limit |
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(Note 2) |
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DEVICE PARAMETERS |
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Ib |
Feedback Bias |
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Adjustable Version Only, VOUT = 5V |
50 |
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100/500 |
nA |
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Current |
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fO |
Oscillator Frequency |
(see Note 10) |
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52 |
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kHz |
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47/42 |
kHz(Min) |
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58/63 |
kHz(Max) |
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VSAT |
Saturation Voltage |
IOUT = 0.5A (Note 4) |
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0.9 |
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V |
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1.2/1.4 |
V(max) |
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DC |
Max Duty Cycle |
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(Note 5) |
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98 |
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% |
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(ON) |
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93 |
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ICL |
Current Limit |
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Peak Current, (Notes 4, 10) |
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1.0 |
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A |
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0.7/0.65 |
A(Min) |
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1.6/1.8 |
A(Max) |
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IL |
Output Leakage |
(Notes 6, 7) |
Output = 0V |
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2 |
mA(Max) |
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Current |
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Output = −1V |
7.5 |
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mA |
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Output = −1V |
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30 |
mA(Max) |
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IQ |
Quiescent Current |
(Note 6) |
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5 |
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mA |
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10 |
mA(Max) |
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ISTBY |
Standby Quiescent |
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/OFF Pin= 5V (OFF) |
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50 |
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µA |
ON |
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Current |
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200 |
µA(Max) |
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θJA |
Thermal Resistance |
N Package, Junction to Ambient (Note 8) |
92 |
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θJA |
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N Package, Junction to Ambient (Note 9) |
72 |
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ÊC/W |
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θJA |
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M Package, Junction to Ambient (Note 8) |
102 |
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θJA |
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M Package, Junction to Ambient (Note 9) |
78 |
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5 |
www.national.com |
All Output Voltage Versions
Electrical Characteristics (Continued)
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version, VIN = 25V for the 12V version, and VIN = 30V for the 15V version. ILOAD = 100 mA.
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Symbol |
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Parameter |
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Conditions |
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LM2574-XX |
Units |
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LM2574HV-XX |
(Limits) |
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Typ |
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Limit |
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(Note 2) |
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/OFF CONTROL Test Circuit Figure 2 |
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ON |
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VIH |
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ON |
/OFF Pin Logic |
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VOUT = 0V |
1.4 |
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2.2/2.4 |
V(Min) |
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VIL |
Input Level |
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VOUT = Nominal Output Voltage |
1.2 |
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1.0/0.8 |
V(Max) |
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IH |
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/OFF Pin = 5V (OFF) |
12 |
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µA |
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ON |
/OFF Pin Input |
ON |
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Current |
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30 |
µA(Max) |
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IIL |
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/OFF Pin = 0V (ON) |
0 |
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µA |
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ON |
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10 |
µA(Max) |
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Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: All limits guaranteed at room temperature (Standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level.
Note 3: External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2574 is used as shown in the Figure 2 test circuit, system performance will be as shown in system parameters section of Electrical Characteristics.
Note 4: Output pin sourcing current. No diode, inductor or capacitor connected to output pin.
Note 5: Feedback pin removed from output and connected to 0V.
Note 6: Feedback pin removed from output and connected to +12V for the Adjustable, 3.3V, and 5V versions, and +25V for the 12V and 15V versions, to force the output transistor OFF.
Note 7: VIN = 40V (60V for high voltage version).
Note 8: Junction to ambient thermal resistance with approximately 1 square inch of printed circuit board copper surrounding the leads. Additional copper area will lower thermal resistance further. See application hints in this data sheet and the thermal model in Switchers Made Simple software.
Note 9: Junction to ambient thermal resistance with approximately 4 square inches of 1 oz. (0.0014 in. thick) printed circuit board copper surrounding the leads. Additional copper area will lower thermal resistance further. (See Note 8.)
Note 10: 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%.
Typical Performance Characteristics (Circuit of Figure 2)
Normalized Output Voltage |
Line Regulation |
Dropout Voltage |
DS011394-27 |
DS011394-28 |
DS011394-29 |
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6 |
Typical Performance Characteristics (Circuit of Figure 2) (Continued)
Current Limit |
Supply Current |
Standby |
|
|
Quiescent Current |
DS011394-30 |
DS011394-31 |
|
DS011394-32 |
Oscillator Frequency |
Switch Saturation |
Efficiency |
|
Voltage |
|
DS011394-33 |
DS011394-35 |
|
DS011394-34 |
Minimum Operating Voltage |
Supply Current |
Feedback Voltage |
|
vs Duty Cycle |
vs Duty Cycle |
DS011394-36
DS011394-37 |
DS011394-38 |
7 |
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Typical Performance Characteristics (Circuit of Figure 2) (Continued)
Feedback |
Junction to Ambient |
Pin Current |
Thermal Resistance |
DS011394-39 |
DS011394-40 |
Continuous Mode Switching Waveforms |
Discontinuous Mode Switching Waveforms |
VOUT = 5V, 500 mA Load Current, L = 330 µH |
VOUT = 5V, 100 mA Load Current, L = 100 µH |
Notes:
A:Output Pin Voltage, 10V/div
B:Inductor Current, 0.2 A/div
C:Output Ripple Voltage, 20 mV/div, AC-Coupled
Horizontal Time Base: 5 µs/div
DS011394-6 |
DS011394-7 |
Notes:
A:Output Pin Voltage, 10V/div
B:Inductor Current, 0.2 A/div
C:Output Ripple Voltage, 20 mV/div, AC-Coupled
Horizontal Time Base: 5 µs/div
500 mA Load Transient Response for Continuous Mode Operation. L = 330 µH, C OUT = 300 µF
250 mA Load Transient Response for Discontinuous Mode Operation. L = 68 µH, C OUT = 470 µF
DS011394-8 |
DS011394-9 |
Notes: |
Notes: |
A: Output Voltage, 50 mV/div. |
A: Output Voltage, 50 mV/div. |
AC Coupled |
AC Coupled |
B: 100 mA to 500 mA Load Pulse |
B: 50 mA to 250 mA Load Pulse |
Horizontal Time Base: 200 µs/div |
Horizontal Time Base: 200 µs/div |
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8 |
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