CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 1/10
PL2576-XXXF5
CYStek Product Specification
Simple Switcher
3A Step- Down Voltage Regulator
PL2576-XXXF5
Features
3.3V, 5V, 12V, 15V, and adjustable output versions.
Adjustable version output voltage range, 1.23V to 37V4% max over line
and load conditions.
Guaranteed 3A output current.
Wide input voltage range.
Requires only 4 external components
52 kHz fixed frequency oscillator
TTL shutdown capability, low power standby mode.
High efficiency
Uses readily available standard inductors.
Thermal shutdown and current limit protection.
Description
The PL2576-XXXF5 series of regulators are monolithic integrated circuits that provide all the active functions
for a step-down (buck) switching regulator, capable of driving 3A 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 PL2576-XXXF5 series offers a high-efficiency replacement for popular three-terminal linear regulators. It
substantially reduces the size of the heat sink, and in some cases no heat sink is required.
A standard series if inductors optimized for use with the PL2576 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 50A (typical)
standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full
protection under fault conditions.
Applications
Simple high-efficiency step-down (buck) regulator.
Efficient pre-regulator for linear regulators.
On-card switching regulators.
Positive to negative converter (Buck-Boost).
TO-263-5L
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 2/10
PL2576-XXXF5
CYStek Product Specification
Typical Application (
Fixed Output Voltage Version
)
+
+
+
7V-40V unregulated
+VIN
3
5
2
4
+5V regulated output
PL2576-5.0
1
GND
ON/OFF
Feedback
Output
DC input
3A load
Cout
L1
D1
1000
F
1N5822
100
H
Cin
100
F
Block Diagram
1
4
R2
R1
1.23V
reference
52kHz
Oscillator
Reset
Thermal
Current
Shutdown Limit
Internal
Regulator
ON / OFF
5
2
3
+
Vin
Cin
Feedback
ON/OFF
Output
L1
+
L
O
A
D
GND
D1
Cout
Vout
3 Amp
Switch
Driver
Comparator
Fixed Gain
Error Amp
1.0k
Unregulated
DC Input
3.3V, R2=1.7k
5V, R2=3.1k
12V, R2=8.84k
15V, R2=11.3k
For Adjustable version, R1=open, R2=0
band-gap
Ordering Information
Output Voltage
Temperature
Range
3.3 5.0 12 15 ADJ
Package
Type
-40T
A
125
PL2576-3.3F5 PL2576-5.0F5 PL2576-12F5 PL2576-15F5 PL2576-ADJF5 TO-263-5L
Figure. 1
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 3/10
PL2576-XXXF5
CYStek Product Specification
Absolute Maximum Ratings
(Note 1)
Maximum supply voltage ............................................................................................................45V
ON/OFF pin input voltage .............................................................................................-0.3VV+V
IN
Output voltage to ground (steady state).............................................................................................-1V
Power dissipation .................................................................................................... Internally limited
Storage temperature range.............................................................................................-65C to +150C
Maximum junction temperature....... ...........................................................................................150C
Minimum ESD rating (C=100pF, R=1.5k)
..............................................................................2kV
Lead temperature (Soldering, 10 seconds).......................................................................... ............260C
Operating Ratings
Temperature range.............................................................................................. .-40C T
J
+125C
Supply voltage........................................................................................................................40V
PL2576-3.3 Electrical Characteristics
Specifications with standard type face are for T
J
=25C, and those with boldface type apply over full
operating temperature range
Symbol Parameter
Conditions
Typ Min
Max
Units
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
Output Voltage V
IN
=12V, I
LOAD
=0.5A
Circuit of Figure 2
3.3 3.234 3.336 V
V
OUT
Output
Voltage
6V
V
IN
40V, 0.5AI
LOAD
3A
Circuit of Figure 2
3.3 3.168/3.135 3.432/3.465
V
Efficiency
V
IN
=12V, I
LOAD
=3A 75
%
PL2576-5.0 Electrical Characteristics
Specifications with standard type face are for T
J
=25C, and those with boldface type apply over full
operating temperature range
Symbol Parameter
Conditions
Typ Min
Max
Units
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
Output Voltage V
IN
=12V, I
LOAD
=0.5A
Circuit of Figure 2
5.0 4.9
5.1 V
V
OUT
Output
Voltage
8V
V
IN
40V, 0.5AI
LOAD
3A
Circuit of Figure 2
3.3 4.800/4.750 5.200/5.250
V
Efficiency
V
IN
=12V, I
LOAD
=3A 77
%
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 4/10
PL2576-XXXF5
CYStek Product Specification
PL2576-12 Electrical Characteristics
Specifications with standard type face are for T
J
=25C, and those with boldface type apply over full
operating temperature range
Symbol Parameter
Conditions
Typ Min
Max
Units
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
Output Voltage V
IN
=25V, I
LOAD
=0.5A
Circuit of Figure 2
12 11.76 12.24 V
V
OUT
Output
Voltage
15V
V
IN
40V, 0.5AI
LOAD
3A
Circuit of Figure 2
12 11.52/11.40 12.48/12.60
V
Efficiency
V
IN
=15V, I
LOAD
=3A 88
%
PL2576-15 Electrical Characteristics
Specifications with standard type face are for T
J
=25C, and those with boldface type apply over full
operating temperature range
Symbol Parameter
Conditions
Typ Min
Max
Units
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
Output Voltage V
IN
=25V, I
LOAD
=0.5A
Circuit of Figure 2
15 14.7
15.3 V
V
OUT
Output
Voltage
18V
V
IN
40V, 0.5AI
LOAD
3A
Circuit of Figure 2
3.3 14.40/14.25 15.60/15.75
V
Efficiency
V
IN
=18V, I
LOAD
=3A 88
%
PL2576-ADJ Electrical Characteristics
Specifications with standard type face are for T
J
=25C, and those with boldface type apply over full
operating temperature range
Symbol Parameter
Conditions
Typ Min
Max
Units
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
Feedback
Voltage
V
IN
=12V, I
LOAD
=0.5A,
V
OUT
=5V, Circuit of Figure 2
1.230 1.217
1.243 V
V
OUT
Feedback
Voltage
8V
V
IN
40V, 0.5AI
LOAD
3A
V
OUT
=5V, Circuit of Figure 2
1.230 1.193/1.180 1.267/1.280
V
Efficiency
V
IN
=12V, I
LOAD
=3A,
V
OUT
=5V
77
%
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 5/10
PL2576-XXXF5
CYStek Product Specification
All Output Voltage Versions Electrical Characteristics
Specifications with standard type face are for T
J
=25C, and those with boldface type apply over full
operating temperature range. Unless otherwise specified, V
IN
=12V for the 3.3V, 5.0V, and adjustable versions,
V
IN
=25V for the 12V version, and V
IN
=30V for the 15V version. I
LOAD
=500mA.
Symbol Parameter
Conditions
Typ Min
Max
Units
Ib
Feedback bias current V
OUT
=5V (adjustable version only) 50 - 100/500
nA
f
O
Oscillator
frequency
(Note 8)
52 47/42 58/63
kHz
V
SAT
Saturation
voltage I
OUT
=3A
(Note 4)
1.4
-
1.8/2.0
V
DC
Maximum duty cycle
(ON)
(Note 5)
98 93
-
%
I
CL
Current
limit
(Notes 4, 8)
5.8 4.2/3.5
6.9/7.5
A
I
L
Output leakage current
(Notes 6, 7) Output = 0V
Output = -1V
-
7.5
-
-
2
30
mA
I
Q
Quiescent
current
(Note 6)
5 -
10
mA
I
STBY
Standby quiescent
current
ON/OFF pin=5V (OFF)
50 -
200
A
ON/OFF Control
V
IH
V
OUT
=0V
1.4 2.2/2.4
-
V
V
IL
ON/OFF pin logic
input level
V
OUT
=Nominal output voltage
1.2 - 1.0/0.8
V
I
IH
ON/OFF pin=5V (OFF)
12 -
30 A
I
IL
ON/OFF pin input
current
ON/OFF pin=0V (ON)
0 -
10
A
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).
Note 3 : External components such as the catch diode, inductor, input and output capacitors can affect switching regulator
system performance. When the PL2576 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.
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 : V
IN
=40V.
Note 8 : The oscillator frequency reduces to approximately 11 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%.
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 6/10
PL2576-XXXF5
CYStek Product Specification
Typical Performance Characteristics
(circuit of Figure 2)
Norm alized Output Voltage
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
-50
-25
0
25
50
75
100
125
Junction Temperature()
V
IN
= 20V,I
LOAD
= 500mA
Normalized at T
J
= 25
Line Regulation
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0
10
20
30
40
50
Input Voltage(V)
I
LOAD
= 500mA,
T
J
= 25
3.3V, 5V & ADJ
12V & 15V
Dropout Voltage
0
0.25
0.5
0.75
1
1.25
1.5
1.75
-75 -50 -25
0
25
50
75
100 125 150
Junction Temperature()
I
LOAD
=0.2A
I
LOAD
=1A
I
LOAD
=3A
L
1
= 150H
Rind = 0.1
Standby Quiescent Current
0
25
50
75
100
125
150
175
200
-50
-25
0
25
50
75
100
125
Junction Temperature()
V
IN
=40V
V
IN
=12V
V
ON/OFF
= 5V
Quiescent Current
4
6
8
10
12
14
16
18
20
0
10
20
30
40
50
Input Voltage (V)
I
LOAD
=0.2A
I
LOAD
=3A
V
OUT
= 5V, measured
at ground pin, T
J
= 25
Current Lim it
4
4.5
5
5.5
6
6.5
-75 -50 -25
0
25
50
75
100 125 150
Junction Temperature ()
V
IN
=25V
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 7/10
PL2576-XXXF5
CYStek Product Specification
Switch Saturation Voltage
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0
0.5
1
1.5
2
2.5
3
Switch Current (A)
150
25
-55
Efficiency
60
65
70
75
80
85
90
95
0
10
20
30
40
50
Input Voltage (V)
I
LOAD
= 3A
I
LOAD
= 0.2A
I
LOAD
= 0.2A
I
LOAD
= 3A
5V
15V OUT
T
J
= 25
Oscillator Frequency
-8
-6
-4
-2
0
2
4
6
8
-75 -50 -25
0
25
50
75
100 125 150
Junction Temperature ()
Normalized at 25
V
IN
= 40V
V
IN
= 12V
Minim um Operating Voltage
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
-50
-25
0
25
50
75
100
125
Junction Temperature ()
Adjustable version only
V
OUT
1.23V
I
LOAD
= 0.5A
Quiescent Current vs Duty Cycle
0
2.5
5
7.5
10
12.5
15
17.5
20
0
20
40
60
80
100
Duty Cycle (%)
Adjustable version only
V
IN
=7V
V
IN
=40V
I
LOAD
= 0.5A
Feedback Voltage vs Duty Cycle
-20
-15
-10
-5
0
5
10
15
20
0
20
40
60
80
100
Duty Cycle (%)
Adjustable version only
I
LOAD
= 0.5A
V
IN
=40V
V
IN
=7V
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 8/10
PL2576-XXXF5
CYStek Product Specification
Minim um Power Dissipation
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0
10
20
30
40
50
60
70
80
90 100
Ambient Temperature ()
JA
= 32/W
JA
= 37/W
JA
= 50/W
JA
= 73/W
Feedback Pin Current
-100
-75
-50
-25
0
25
50
75
100
-75 -50 -25
0
25
50
75
100 125 150
Junction Temperature ()
Adjustable version only
Switching Waveforms
0
2A
4A
0
2A
4A
0
50V
5
s/ div
Load Transient Response
0
1A
2A
3A
-100mV
0
100mV
Load
Current
Output
Voltage
Change
100
s / div
VOUT=15V
A : Output Pin Voltage, 50 V / div
B : Output Pin Current, 2A / div
C : Inductor Current, 2A / div
D : Output Ripple Voltage, 50mV / div
AC Coupled
Horizontal Time Base : 5s / div
A
B
C
D
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 9/10
PL2576-XXXF5
CYStek Product Specification
Test Circuit and Layout Guidelines
As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring
inductance generate voltage transients which can cause problems. For minimal inductance and ground
loops, the length of the leads indicated by heavy lines should be kept as short as possible. Single-point
grounding (as indicated) or ground plane construction should be used for best results. When using the
Adjustable version, physically locate the programming resistors near the regulator, to keep the sensitive
feedback wiring short.
+
Cin
D1
L1
+
Cout
Vin
Unregulated
DC Input
PL2576
GND 3
+Vin
Feedback
4
2
Output
5
ON / OFF
100
F
MBR360
100
H
1000
F
Fixed Output
L
O
A
D
1
Vout
Cin--100
F, 75V, Aluminum Electrolytic
Cout--1000
F, 25V, Aluminum Electrolytic
L1--100
H, Pulse Eng, PE92108
D1--Schottky, MBR360
R1--2k, 0.1%
R2--6.12k, 0.1%
+
Cin
D1
L1
+
Cout
7V-40V
Unregulated
DC Input
PL2576-ADJ
GND 3
+Vin
Feedback
4
2
Output
5
ON / OFF
100
F
MBR360
100
H
1000
F
L
O
A
D
1
Vout
R2
R1
5.00V
Adjustable Output Voltage Version
Fixed Output Voltage Versions
Vout=VREF(1+
R2=R1(
where VREF=1.23V, R1 between 1k and 5k
Figure 2
R2
R1
)
Vout
VREF
-1)
CYStech Electronics Corp.
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 10/10
PL2576-XXXF5
CYStek Product Specification
TO-263-5L Dimension
*: Typical
Inches Millimeters
Inches Millimeters
DIM
Min. Max. Min. Max.
DIM
Min. Max. Min. Max.
A 0.176 0.184 4.47 4.67 E 0.323 0.339 0.820 0.860
A1 0 0.006 0 0.150 e 0.067(typical) 1.700(typical)
B 0.061 0.069 1.560 1.760 e1 0.264 0.272 0.670 0.690
b 0.028 0.036 0.710 0.910 L 0.596 0.612 15.140
15.540
c 0.012 0.021 0.310 0.530 L1 0.200 0.216 5.080 5.480
c1 0.046 0.054 1.170 1.370 L2 0.092 0.108 2.340 2.740
D 0.389 0.401 9.880 10.180 V
0.220REF
5.600REF
Notes:
1.Controlling dimension: inch
2.Maximum lead thickness includes lead finish thickness, and minimum lead thickness is the minimum thickness of base material.
3.If there is any question with packing specification or packing method, please contact your local CYStek sales office.
Material:
Lead: 42 Alloy ; solder plating
Mold Compound: Epoxy resin family, flammability solid burning class: UL94V-0
Important Notice:
All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of CYStek.
CYStek reserves the right to make changes to its products without notice.
CYStek semiconductor products are not warranted to be suitable for use in Life-Support Applications, or systems.
CYStek assumes no liability for any consequence of customer product design, infringement of patents, or application assistance.
Style: Pin 1.Vin 2.Vout 3.GND
4.Feedback 5.ON/OFF
5-Lead TO-263-5L Plastic Package
CYStek Package Code: F5
Marking:
2576-XXX
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