CYStech Electronics Corp.
Simple Switcher
3A Step- Down Voltage Regulator
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 1/10
PL2576-XXXF5
Features
3.3V, 5V, 12V, 15V, and adjustable output versions.
Adjustable version output voltage range, 1.23V to 37V±4% 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.
TO-263-5L
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 50µA (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).
PL2576-XXXF5
CYStek Product Specification
CYStech Electronics Corp.
Typical Application
(
Fixed Output Voltage Version
)
7V-40V unregulated
DC input
Feedback
4
Output
2
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 2/10
+VIN
1
PL2576-5.0
L1
100
μ
H
D1
1N5822
+
+5V regulated output
3A load
Cout
1000
μ
F
+
Cin
100
μ
F
3 GND 5 ON/OFF
Figure. 1
Block Diagram
Unregulated
DC Input
Vin
1
Internal
Regulator
ON / OFF
5
ON/OFF
Feedback
Cin
+
4
R2
Fixed Gain
Error Amp
Comparator
Driver
1.0k
R1
3 Amp
Switch
2
Output
GND
L1
Vout
Cout
1.23V
band-gap
reference
52kHz
Oscillator
Reset
Thermal Current
Shutdown Limit
3
+
D1
L
O
A
D
3.3V, R2=1.7k
5V, R2=3.1k
12V, R2=8.84k
15V, R2=11.3k
For Adjustable version, R1=open, R2=0
Ordering Information
Temperature
Range
-40℃≤T
A
≤125℃
Output Voltage
3.3
5.0
12
15
ADJ
Package
Type
PL2576-3.3F5 PL2576-5.0F5 PL2576-12F5 PL2576-15F5 PL2576-ADJF5 TO-263-5L
PL2576-XXXF5
CYStek Product Specification
CYStech Electronics Corp.
Absolute Maximum Ratings
(Note 1)
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 3/10
Maximum supply voltage ………………………………………………………………………………………………45V
ON/OFF pin input voltage …………………………………………………………………………………-0.3V≤V≤+V
IN
Output voltage to ground (steady state)…………………………………………………………………………………-1V
Power dissipation ………………………………………………………………………………………. Internally limited
Storage temperature range…………………………….…………………………………………………..-65°C to +150°C
Maximum junction temperature……. ……………………………………………………………………………….150°C
Minimum ESD rating (C=100pF, R=1.5kΩ)
……………………………………………………………………2kV
Lead temperature (Soldering, 10 seconds)……………………………………………………………….. …………260°C
Operating Ratings
Temperature range…………………………………………………………………………………. .-40°C
≤
T
J
≤
+125°C
Supply voltage…………………………………………………………………………………………………………40V
PL2576-3.3 Electrical Characteristics
Specifications with standard type face are for T
J
=25°C, and those with
boldface type
apply over full
operating temperature range
Symbol
Parameter
Conditions
Typ
3.3
3.3
75
Min
3.234
3.168/3.135
Max
3.336
3.432/3.465
Units
V
V
%
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
V
OUT
η
Output Voltage V
IN
=12V, I
LOAD
=0.5A
Circuit of Figure 2
6V≤
V
IN
≤40V,
0.5A≤I
LOAD
≤3A
Output Voltage Circuit of Figure 2
Efficiency
V
IN
=12V, I
LOAD
=3A
PL2576-5.0 Electrical Characteristics
Specifications with standard type face are for T
J
=25°C, and those with
boldface type
apply over full
operating temperature range
Symbol
Parameter
Conditions
Typ
5.0
3.3
77
Min
4.9
4.800/4.750
Max
5.1
5.200/5.250
Units
V
V
%
CYStek Product Specification
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
V
OUT
η
PL2576-XXXF5
Output Voltage V
IN
=12V, I
LOAD
=0.5A
Circuit of Figure 2
8V≤
V
IN
≤40V,
0.5A≤I
LOAD
≤3A
Output Voltage Circuit of Figure 2
Efficiency
V
IN
=12V, I
LOAD
=3A
CYStech Electronics Corp.
PL2576-12 Electrical Characteristics
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 4/10
Specifications with standard type face are for T
J
=25°C, and those with
boldface type
apply over full
operating temperature range
Symbol
Parameter
Conditions
Typ
12
12
88
Min
11.76
11.52/11.40
Max
12.24
12.48/12.60
Units
V
V
%
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
V
OUT
η
Output Voltage V
IN
=25V, I
LOAD
=0.5A
Circuit of Figure 2
15V≤
V
IN
≤40V,
0.5A≤I
LOAD
≤3A
Output Voltage Circuit of Figure 2
Efficiency
V
IN
=15V, I
LOAD
=3A
PL2576-15 Electrical Characteristics
Specifications with standard type face are for T
J
=25°C, and those with
boldface type
apply over full
operating temperature range
Symbol
Parameter
Conditions
Typ
15
3.3
88
Min
14.7
14.40/14.25
Max
15.3
15.60/15.75
Units
V
V
%
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
V
OUT
η
Output Voltage V
IN
=25V, I
LOAD
=0.5A
Circuit of Figure 2
18V≤
V
IN
≤40V,
0.5A≤I
LOAD
≤3A
Output Voltage Circuit of Figure 2
Efficiency
V
IN
=18V, I
LOAD
=3A
PL2576-ADJ Electrical Characteristics
Specifications with standard type face are for T
J
=25°C, and those with
boldface type
apply over full
operating temperature range
Symbol
Parameter
Feedback
Voltage
Feedback
Voltage
Efficiency
Conditions
V
IN
=12V, I
LOAD
=0.5A,
V
OUT
=5V, Circuit of Figure 2
8V≤
V
IN
≤40V,
0.5A≤I
LOAD
≤3A
V
OUT
=5V, Circuit of Figure 2
V
IN
=12V, I
LOAD
=3A,
V
OUT
=5V
Typ
1.230
1.230
77
Min
1.217
1.193/1.180
Max
1.243
1.267/1.280
Units
V
V
%
System Parameters
(Note 3)
Test Circuit
Figure 2
V
OUT
V
OUT
η
PL2576-XXXF5
CYStek Product Specification
CYStech Electronics Corp.
All Output Voltage Versions Electrical Characteristics
Spec. No. : C543F5
Issued Date : 2004.02.27
Revised Date :
Page No. : 5/10
Specifications with standard type face are for T
J
=25°C, 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
Ib
f
O
V
SAT
DC
I
CL
I
L
I
Q
I
STBY
Parameter
Conditions
Typ
Min
-
47/42
-
93
4.2/3.5
-
-
-
-
Max
100/500
58/63
1.8/2.0
-
6.9/7.5
2
30
10
200
Units
nA
kHz
V
%
A
mA
mA
µA
Feedback bias current V
OUT
=5V (adjustable version only) 50
Oscillator frequency
(Note 8)
52
Saturation voltage
I
OUT
=3A
(Note 4)
1.4
Maximum duty cycle
(Note 5)
98
(ON)
(Notes 4, 8)
Current limit
5.8
(Notes 6, 7) Output = 0V
-
Output leakage current
Output = -1V
7.5
(Note 6)
Quiescent current
5
Standby quiescent
50
ON/OFF pin=5V (OFF)
current
ON/OFF Control
V
IH
V
IL
I
IH
I
IL
ON/OFF pin logic
input level
ON/OFF pin input
current
V
OUT
=0V
V
OUT
=Nominal output voltage
ON/OFF pin=5V (OFF)
ON/OFF pin=0V (ON)
1.4
1.2
12
0
2.2/2.4
-
-
-
-
1.0/0.8
30
10
V
V
µA
µA
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%.
PL2576-XXXF5
CYStek Product Specification
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