CM2576SCN220 [CHAMP]
3A STEP DOWN VOLTAGE REGULATOR; 3A降压稳压器
| 型号： | CM2576SCN220 |
| 厂家： | 
CHAMPION MICROELECTRONIC CORP. |
| 描述： | 3A STEP DOWN VOLTAGE REGULATOR |
| 文件： | 总12页 (文件大小：314K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
CM2576
3A STEP DOWN VOLTAGE REGULATOR
GENERAL DESCRIPTION
FEATURES
The CM2576 series are step-down switching regulators with ꢀ
all required active functions. It is capable of driving 3A load ꢀ
with excellent line and load regulations. These devices are ꢀ
Guaranteed 3A output current
3.3V, 5V, and adjustable versions
Wide input voltage range, up to 40V
available in fixed output voltages of 3.3V, 5V, and an
adjustable output version.
ꢀ
Internal oscillator of 52KHz fixed frequency
Wide adjustable version output voltage range, from
1.23V to 37V±4% max over line and load conditions
Low standby current, typ. 70µA, at shutdown mode
Requires only 4 external components
ꢀ
The CM2576 series offers a high-efficiency replacement for ꢀ
popular three-terminal linear regulators. Also it requires a
ꢀ
minimum number of external components. It substantially not ꢀ
only reduces the area of board size but also the size of the ꢀ
heat sink, and in some cases no heat sink is required.
Thermal shutdown and current limit protection
P+ product enhancement tested
±4% tolerance on output voltage within specified input
voltages and output load conditions is guaranteed. Also, the
oscillator frequency accuracy is within ±10%. External
shutdown is included, featuring 70µA (typical) standby current.
The output switch includes cycle-by-cycle current limiting, as
well as thermal shutdown for full protection under fault
conditions.
APPLICATIONS
ꢀ
ꢀ
ꢀ
ꢀ
LCD Monitors
ADD-ON Cards Switching Regulators
High Efficiency Step-Down Regulators
Efficient Pre-regulator for Linear Regulators
ORDERING INFORMATION
Package Type
Temperature Range
Output Voltage
TO-220
TO-263
CM2576SCN220
CM2576ZJCN220
CM2576CN220
CM2576SCN263
CM2576ZJCN263
CM2576CN263
-40℃ ~ +125℃
-40℃ ~ +125℃
-40℃ ~ +125℃
3.3V
5.0V
ADJ.
2003/08/07 Preliminary Rev. 1.1
Champion Microelectronic Corporation
Page 1
CM2576
3A STEP DOWN VOLTAGE REGULATOR
PIN CONFIGURATION
TO-220
TO-263
Top View
Top View
ENABLE
5
FB
GND
VOUT
VIN
4
3
2
1
3
4 5
1 2
ABSOLUTE MAXIMUM RATINGS
Input Voltage (VPOWER) …….………………………………………….……. +45V
Pin Input Voltage ….…………………………………. –0.3V ≦V≦VIN
ENABLE
Operating Junction Temperature Range, TJ ……………...… 0℃ to +150℃
Storage Temperature ………………………………….….…... -65℃ to +150℃
Lead Temperature (10 sec.) ……..……………………..….…………….... 260℃
POWER DISSIPATION TABLE
Package
ΘJA (℃/W)
Derating factor (mW/℃)
TA <= 25℃
TA = 70℃
TA = 85℃
Power rating (mW) Power rating (mW) Power rating (mW)
TA >= 25℃
22.2
TO-220
45
45
2775
2775
1776
1776
1443
1443
TO-263
Note:
22.2
1. ΘJA : Thermal Resistance-Junction to Ambient, DF: Derating factor, PO: Power consumption.
Junction Temperature Calculation: TJ = TA + (PD x ΘJA ), PO = DF x (TJ – TA)
The ΘJA numbers are guidelines for the thermal performance of the device/PC-board system.
All of the above assume no ambient airflow.
2. ΘJT : Thermal Resistance-Junction to Ambient, TC: case (Tab) temperature, TJ = TC + (PD x ΘJA
)
RESOMMENDED OPERATING CONDITIONS
Parameter
Symbol
Min.
Typ.
Max
40
125
Units
V
℃
Input Voltage (VIN)
Temperature Range
VIN
TJ
-40
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Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at IOUT = 0mA, and TJ = +25℃; unless otherwise noted
CM2576
Typ.
Parameter
Device
Test Conditions
Unit
Min.
3.234
4.900
3.168
4.800
3.135
Max.
3.366
5.100
3.432
5.200
3.482
Output Voltage
(Note 1)
Output Voltage
(Note 1)
CM2576S
CM2576ZJ
CM2576S
CM2576ZJ
CM2576S
3.300
5.000
3.300
5.000
3.300
V
V
V
V
V
Test circuit of Figure 1
6V<=VIN <=40V
8V<=VIN <=40V
6V<=VIN <=40V
0.5A<=ILOAD <=3A
0.5A<=ILOAD <=3A,
-40℃<=TJ<=125℃
Test circuit of Figure 1
Output Voltage
(Note 1)
CM2576ZJ
CM2576 (Adj)
CM2576 (Adj)
CM2576 (Adj)
8V<=VIN <=40V
4.750
1.217
1.193
1.180
5.000
1.230
1.230
1.230
5.250
1.243
1.267
1.286
V
V
V
V
Feedback Voltage
(Note 1)
Feedback Voltage
(Note 1)
Feedback Voltage
(Note 1)
Test circuit of Figure 2
VOUT =5V
8V<=VIN <=40V, VOUT =5V
Test circuit of Figure 2
8V<=VIN <=40V, VOUT =5V
Test circuit of Figure 2
0.5A<=ILOAD <=3A
0.5A<=ILOAD <=3A,
-40℃<=TJ<=125℃
CM2576S
CM2576ZJ
CM2576(adj)
75
77
77
52
52
5
I
LOAD =3A
ILOAD =3A, VOUT =5V
TJ=25℃
-40℃<=TJ<=125℃
%
%
Efficiency
47
42
58
63
10
200
1.8
2.0
100
500
Oscillator Frequency
Note 2
kHz
Quiescent Current
Standby Current
Note 3
mA
µA
= 5V
70
1.4
ENABLE
TJ=25℃
-40℃<=TJ<=125℃
TJ=25℃
Saturation Voltage
ILOAD =3A (Note 4)
V
VOUT =5V
50
Feedback Bias Current
Duty Cycle (ON)
Current Limit
nA
%
A
(Adj. Version only)
-40℃<=TJ<=125℃
Note 5
93
4.2
3.5
98
7
7.2
0.3
9
TJ=25℃
-40℃<=TJ<=125℃
VOUT =0V
8.8
9.0
2
Note 2,4
Note 3
Output Leakage Current
mA
V
VOUT =-1V
20
TJ=25℃
-40℃<=TJ<=125℃
TJ=25℃
2.2
2.4
1.4
VIH (VOUT =0V)
Threshold Voltage
ENABLE
VIL (VOUT = Normal Output
Voltage)
1.2
1.0
0.8
30
V
-40℃<=TJ<=125℃
= 5V)
I (
IH
12
0
ENABLE
ENABLE
Input Current
µA
ENABLE
I (
IH
= 0V)
10
2003/08/07 Preliminary Rev. 1.1
Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
Note 1: External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system
performance. Refer to Application Information for details.
Note 2: The oscillator frequency reduces to approximately 11KHz in the event of fault conditions, such as output short or
overload. And the regulated output voltage will drop approximately 40% from the nominal output voltage. This self-protection
feature lowers the average power dissipation by lowering the minimum duty cycle from 5% down to approximately 2%.
Note 3: For these parameters, FB is removed from VOUT and connected to +12V to force the output transistor OFF.
Note 4: VOUT pin sourcing current. No diode, inductor or capacitor connect to VOUT
Note 5: FB is removed from VOUT and connected to 0V.
.
BLOCK DIAGRAM
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Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
APPLICATION CIRCUIT
2003/08/07 Preliminary Rev. 1.1
Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
TYPICAL CHARACTERISTICS
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Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
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Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
APPLICATION INFORMATION
It is required that VIN must be bypassed with at least a 100uF electrolytic capacitor for stability. Also, it is strongly recommended
the capacitor’s leads must be dept short, and located near the regulator as possible.
For low operating temperature range, for example, below -25℃, the input capacitor value may need to be larger. This is due to
the reason that the capacitance value of electrolytic capacitors decreases and the ESR increases with lower temperatures and
age. Paralleling a ceramic or solid tantalum capacitor will increase the regulator stability at cold temperatures.
Output Capacitors (COUT
)
An output capacitor is also required to filter the output voltage and is needed for loop stability. The capacitor should be located
near the CM2576 using short PC board traces. Low ESR types capacitors are recommended for low output ripple voltage and
good stability. Generally, low value or low voltage (less than 12V) electrolytic capacitors usually have higher ESR numbers. For
example, the lower capacitor values (220uF – 1000uF) will yield typically 50mV to 150mV of output ripple voltage, while
larger-value capacitors will reduce the ripple to approximately 20mV to 50mV.
The amount of output ripple voltage is primarily a function of the ESR (Equivalent Series Resistance) of the output capacitor and
the amplitude of the inductor ripple current (△IIND).
Output Ripple Voltage = (△IIND) x (ESR of COUT
)
Some capacitors called “high-frequency”, “low-inductance”, or “low-ESR” are recommended to use to further reduce the output
ripple voltage to 10mV or 20mV. However, very low ESR capacitors, such as Tantalum capacitors, should be carefully evaluated.
Catch Diode
This diode is required to provide a return path for the inductor current when the switch is off. It should be located close to the
CM2576 using short leads and short printed circuit traces as possible.
To satisfy the need of fast switching speed and low forward voltage drop, Schottky diodes are widely used to provide the best
efficiency, especially in low output voltage switching regulators (less than 5V). Besides, fast-Recovery, high-efficiency, or
ultra-fast recovery diodes are also suitable. But some types with an abrupt turn-off characteristic may cause instability and EMI
problems. A fast-recovery diode with soft recovery characteristics is better choice.
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Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
Output Voltage Ripple and Transients
The output ripple voltage is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output capacitor. The
output ripple voltage of a switching power supply will contain a sawtooth ripple voltages at the switcher frequency, typically about
1% of the output voltages, and may also contain short voltage spikes of the sawtooth waveform.
Due to the fast switching action, and the parasitic inductance of the output filter capacitor, there is voltage spikes presenting at
the peaks of the sawtooth waveform. Cautions must be taken for stray capacitance, wiring inductance, and even the scope
probes used for transients evaluation. To minimize these voltage spikes, shortening the lead length and PCB traces is always the
first thought. Further more, an additional small LC filter (30uH & 100uF) (as shown in Figure 3) will possibly provide a 10X
reduction in output ripple voltage and transients.
Inductor Selection
The CM2576 can be used for either continuous or discontinuous modes of operation. Each mode has distinctively different
operating characteristics, which can affect the regulator performance and requirements.
With relatively heavy load currents, the circuit operates in the continuous mode (inductor current always flowing), but under light
load conditions, the circuit will be forced to the discontinuous mode (inductor current falls to zero for a period of time). For light
loads (less than approximately 300mA) it may be desirable to operate the regulator in the discontinuous mode, primarily because
of the lower inductor values required for the discontinuous mode.
Inductors are available in different styles such as pot core, toriod, E-frame, bobbin core, et., as well as different core materials,
such as ferrites and powdered iron. The least expensive, the bobbin core type, consists of wire wrapped on a ferrite rod core.
This type of construction makes for an inexpensive inductor, but since the magnetic flux is not completely contained within the
core, it generates more electromagnetic interference (EMI). This EMI can cause problems in sensitive circuits, or can give
incorrect scope readings because of induced voltages in the scope probe.
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Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
An inductor should not be operated beyond its maximum rated current because it may saturate. When an inductor begins to
saturate, the inductance decreases rapidly and the inductor begins to look mainly resistive (the DC resistance of the winding).
This will cause the switch current to rise very rapidly. Different inductor types have different saturation characteristics, and this
should be well considered when selecting as inductor.
Feedback Connection
For fixed output voltage version, the FB (feedback) pin must be connected to VOUT. For the adjustable version, it is important to
place the output voltage ratio resistors near CM2576 as possible in order to minimize the noise introduction.
ENABLE
It is required that the
must not be left open. For normal operation, connect this pin to a “LOW” voltage (typically, below
ENABLE
1.6V). On the other hand, for standby mode, connect this pin with a “HIGH” voltage. This pin can be safely pulled up to +VIN
without a resistor in series with it.
Grounding
To maintain output voltage stability, the power ground connections must be low-impedance. For the 5-lead TO-220 and TO-263
style package, both the tab and pin 3 are ground and either connection may be used.
Heatsink and Thermal Consideration
Although the CM2576 requires only a small heatsink for most cases, the following thermal consideration is important for all
operation. With the package thermal resistances θJA and θJC, total power dissipation can be estimated as follows:
PD = (VIN x IQ) + (VOUT / VIN)(ILOAD x VSAT);
When no heatsink is used, the junction temperature rise can be determined by the following:
∆TJ = PD x θJA;
With the ambient temerpature, the actual junction temperature will be:
TJ = ∆TJ + TA;
If the actual operating junction temperature is out of the safe operating junction temperature (typically 125℃), then a heatsink is
required. When using a heatsink, the junction temperature rise will be reduced by the following:
∆TJ = PD x (θJC + θinterface + θHeatsink);
Also one can see from the above, it is important to choose an heatsink with adequate size and thermal resistance, such that to
maintain the regulator’s junction temperature below the maximum operating temperature.
2003/08/07 Preliminary Rev. 1.1
Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
PACKAGE DIMENSION
TO-220 (N220)
C
B
S
F
A
B
C
D
F
G
J
K
N
R
S
T
1
2 3 4 5
R
D
G
J
N
TO-263 (N263)
D
C
A
G
F
E
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Champion Microelectronic Corporation
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CM2576
3A STEP DOWN VOLTAGE REGULATOR
IMPORTANT NOTICE
Champion Microelectronic Corporation (CMC) reserves the right to make changes to its products or to discontinue any integrated
circuit product or service without notice, and advises its customers to obtain the latest version of relevant information to verify,
before placing orders, that the information being relied on is current.
A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe property or
environmental damage. CMC integrated circuit products are not designed, intended, authorized, or warranted to be suitable for
use in life-support applications, devices or systems or other critical applications. Use of CMC products in such applications is
understood to be fully at the risk of the customer. In order to minimize risks associated with the customer’s applications, the
customer should provide adequate design and operating safeguards.
HsinChu Headquarter
Sales & Marketing
5F, No. 11, Park Avenue II,
Science-Based Industrial Park,
HsinChu City, Taiwan
TEL: +886-3-567 9979
FAX: +886-3-567 9909
11F, No. 306-3, SEC. 1, Ta Tung Road,
Hsichih, Taipei Hsien 221, Taiwan
TEL: +886-2-8692 1591
FAX: +886-2-8692 1596
2003/08/07 Preliminary Rev. 1.1
Champion Microelectronic Corporation
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