CBM2576-XX
OPERATION INSTRUCTION
The CBM2576 series of regulators are
FEATURES
monolithic integrated circuits ideally suited
for
3.3 V, 5.0 V, 12 V, 15 V, and Adjustable
step–down
Output Versions
easy
and
convenient
switching
design
regulator
of
a
(buck
converter). All circuits of this series are
Adjustable Version Output Voltage
capable of driving a 3.0 A load with excellent
Range,1.23 to 37 V ±4%
line and load regulation. These devices are
Maximum Over Line and Load Conditions
Guaranteed 3.0 A Output Current
V, 12 V, 15 V, and an adjustable output
Wide Input Voltage Range
version.
Requires Only 4 External Components
52 kHz Fixed Frequency Internal Oscillator
TTL Shutdown Capability, Low Power
available in fixed output voltages of 3.3 V, 5.0
These
regulators
were
designed
to
minimize the number of external components
to simplify the power supply design. Standard
series of inductors optimized for use with the
Standby Mode
CBM2576 are offered by several different
High Efficiency
Uses Readily Available Standard Inductors
Thermal Shutdown and Current Limit
efficiency is significantly higher in comparison
Protection
with popular three–terminal linear regulators,
inductor manufacturers. Since the CBM2576
converter is a switch–mode power supply, its
especially with higher input voltages. In many
cases, the power dissipated is so low that no
heatsink is required or its size could be
APPLICATIONS
reduced dramatically.
A standard series of inductors optimized
Simple High–Efficiency Step–Down (Buck)
for use with the CBM2576 are available from
Regulator
Efficient
Pre–Regulator
for
several different manufacturers. This feature
Linear
greatly simplifies the design of switch–mode
Regulators
power
On–Card Switching Regulators
include a guaranteed ±4% tolerance on
Positive
to
Negative
Power Supply for Battery Chargers
CBM2576
features
and output load conditions, and ±10% on the
(Buck–Boost)
Negative Step–Up Converters
The
output voltage within specified input voltages
Converter
supplies.
oscillator frequency (±2% over 0℃ to 125℃).
External shutdown is included, featuring 80 ㎂
(typical) standby current. The output switch
includes cycle–by–cycle current limiting, as
well as thermal shutdown for full protection
GENERAL DESCRIPTION
under fault conditions.
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CBM2576-XX
OPERATION INSTRUCTION
Typical Application (Fixed Output Voltage Versions)
Figure 1.
Representative Block Diagram and Typical Application
This device contains 162 active transistors.
Figure 2.
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CBM2576-XX
OPERATION INSTRUCTION
ABSOLUTE MAXIMUM RATINGS
(Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.)
Rating
Symbol
Value
Unit
Maximum Supply Voltage
Vin
45
V
ON/OFF Pin Input Voltage
-
-0.3V≤V≤+Vin
V
Output Voltage to Ground (Steady–State)
-
-1.0
V
TO–220, 5–Lead
PD
Internally Limited
W
Thermal Resistance, Junction–to–Ambient
RθJA
65
℃/W
Thermal Resistance, Junction–to–Case
RθJC
5.0
℃/W
TO–263, 5–Lead (D2PAK)
PD
Internally Limited
Thermal Resistance, Junction–to–Ambient
RθJA
70
℃/W
Thermal Resistance, Junction–to–Case
RθJC
5.0
℃/W
Storage Temperature Range
Tstg
–65℃ to +150℃
℃
Minimum ESD Rating (Human Body Model:C=100pF, R=1.5kΩ)
-
2.0
kV
Lead Temperature (Soldering, 10 seconds)
-
260
℃
Maximum Junction Temperature
TJ
150
℃
Power Dissipation
W
* Stresses beyond those listed under “absolute maximum ratings” may cause permanent
damage to the device. These are stress ratings only and functional operation of the device at
these or any other conditions beyond those indicated under “recommended operating
conditions” is not implied.
Exposure to absolute-maximum-rated conditions for extended periods may affect device
reliability.
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CBM2576-XX
OPERATION INSTRUCTION
OPERATING RATINGS
(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.)
Rating
Symbol
Value
Unit
TJ
–40℃ to +125℃
℃
Vin
40
V
Operating Junction Temperature Range
Supply Voltage
SYSTEM PARAMETERS [Note 1]
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin=25V
for the 12V version, and Vin=30V for the 15V version. ILoad=500mA, TJ=25℃, for min/max values
TJ is the operating junction temperature range that applies [Note 2], unless otherwise noted.)
Characteristics
Symbol
Min
Max
Unit
CBM2576–3.3 ([Note 1] Test Circuit Figure 3)
Output Voltage
Vout
Output Voltage (6.0V≤Vin≤40V, 0.5A≤ILoad≤3.0A)
Vout
3.234
3.366
V
V
TJ = 25℃
3.168
3.432
TJ = –40 to +125℃
3.135
3.465
η
65
-
%
Output Voltage
Vout
4.9
5.1
V
Output Voltage (8.0V≤Vin≤40V, 0.5A≤ILoad≤3.0A)
Vout
Efficiency (Vin=12V, ILoad = 3.0A)
CBM2576–5 [Note 1]
V
TJ = 25℃
4.8
5.2
TJ = –40℃ to +125℃
4.75
5.25
η
67
-
%
Output Voltage
Vout
11.76
12.24
V
Output Voltage (15.0V≤Vin≤40V, 0.5A≤ILoad≤3.0 A)
Vout
Efficiency (Vin = 12V, ILoad = 3.0A)
CBM2576–12 [Note 1]
V
TJ = 25℃
11.52
12.48
TJ = –40℃ to +125℃
11.4
12.6
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CBM2576-XX
OPERATION INSTRUCTION
η
78
-
%
Output Voltage
Vout
14.7
15.3
V
Output Voltage (18V≤Vin≤40V, 0.5A≤ILoad≤3.0A)
Vout
Efficiency (Vin = 12V, ILoad = 3.0A)
CBM2576–15 [Note 1]
V
TJ = 25℃
14.4
15.6
TJ = –40℃ to +125℃
14.25
15.75
η
75
-
%
Feedback Voltage (Vin=12V, ILoad=0.5A, VOUT=5.0V, TJ=25℃)
Vout
1.217
1.243
V
Feedback Voltage (8.0V≤Vin≤40V, 0.5A≤ILoad≤3.0A,VOUT=5.0 V)
Vout
Efficiency (Vin = 12V, ILoad = 3.0A)
CBM2576 ADJUSTABLE VERSION [Note 1]
V
TJ= 25℃
1.193
1.267
TJ = –40℃ to +125℃
1.18
1.28
67
-
η
Efficiency (Vin = 12V, ILoad=3.0A, VOUT=5.0V)
%
1. External components such as the catch diode, inductor, input and output capacitors can affect
switching regulator system performance.
When the CBM2576 is used as shown in the test circuit, system performance will be as shown in
system parameters section .
2. Tested junction temperature range for the CBM2576: Tlow = –40℃ Thigh = +125℃
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CBM2576-XX
OPERATION INSTRUCTION
DEVICE PARAMETERS
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, Vin = 12V for the 3.3V, 5.0V, and Adjustable version, Vin = 25V
for the 12V version, and Vin = 30V for the 15V version. ILoad = 500mA, TJ = 25℃, for min/max
values TJ is the operating junction temperature range that applies [Note 2], unless otherwise
noted.)
Characteristics
Symbol
Min
Max
Unit
ALL OUTPUT VOLTAGE VERSIONS
Feedback Bias Current (Vout = 5.0V [Adjustable Version Only])
Ib
nA
TJ = 25℃
-
100
TJ = –40℃ to +125℃
-
500
Oscillator Frequency [Note 3]
fosc
kHz
TJ = 25℃
-
-
TJ = –40℃ to +125℃
42
63
Saturation Voltage (Iout = 3.0 A [Note 4])
Vsat
V
TJ = 25℃
-
1.8
TJ = –40℃ to +125℃
-
2.0
93
-
Max Duty Cycle (“on”) [Note 5]
DC
Current Limit (Peak Current [Notes 3 and 4])
ICL
A
TJ = 25℃
4.2
6.9
TJ = –40℃ to +125℃
3.5
7.5
Output Leakage Current [Notes 6 and 7], TJ = 25℃
IL
mA
Output = 0V
-
2.0
Output = –1.0V
-
30
Quiescent Current [Note 6]
IQ
mA
TJ = 25℃
-
10
TJ = –40℃ to +125℃
-
11
Standby Quiescent Current (ON/OFF Pin = 5.0 V (“off”))
Istby
TJ = 25℃
%
uA
-
200
ON/OFF Pin Logic Input Level
V
Vout = 0V
VIH
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CBM2576-XX
OPERATION INSTRUCTION
TJ = 25℃
2.2
-
TJ = –40℃ to +125℃
2.4
-
TJ = 25℃
-
1.0
TJ = –40℃ to +125℃
-
0.8
Vout = Nominal Output Voltage
VIL
ON/OFF Pin Input Current
uA
ON/OFF Pin = 5.0 V (“off”), TJ = 25℃
IIH
-
30
ON/OFF Pin = 0 V (“on”), TJ = 25℃
IIL
-
10
3.
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 dissipation of the IC
by lowering the minimum duty cycle from 5% down to approximately 2%.
4.
Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to output pin.
5.
Feedback (Pin 4) removed from output and connected to 0 V.
6.
Feedback (Pin 4) removed from output and connected to +12 V for the Adjustable, 3.3 V,
and 5.0 V versions, and +25 V for the 12 V and 15 V versions, to force the output transistor
“off”.
7.
Vin = 40 V.
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CBM2576-XX
OPERATION INSTRUCTION
Fixed Output Voltage Versions
Figure 3.
Cin – 100 mF, 75 V, Aluminium Electrolytic
Cout – 1000 mF, 25 V, Aluminium Electrolytic
D1 – Schottky, MBR360
L1 – 100 mH, Pulse Eng. PE–92108
R1 – 2.0 k, 0.1%
R2 – 6.12 k, 0.1%
Adjustable Output Voltage Versions
Figure 4.
VOUT = VREF 1.0 +
R2
,
R1
Where Vref = 1.23 V, R1 between 1.0 k and 5.0 k
C1 = 10 nF
R2 = R1
VOUT
− 1.0
VREF
C2 = 1 nF
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CBM2576-XX
OPERATION INSTRUCTION
Application Information
INVERTING REGULATOR
Figure 5 shows a CBM2576-12 in a buck-boost configuration to generate a negative 12V
output from a positive input voltage. This circuit bootstraps the regulator’s ground pin to the
negative output voltage, then by grounding the feedback pin, the regulator senses the inverted
output voltage and regulates it to −12V.
For an input voltage of 12V or more, the maximum available output current in this
configuration is approximately 700 mA. At lighter loads, the minimum input voltage required
drops to approximately 4.7V.
The switch currents in this buck-boost configuration are higher than in the standard
buck-mode design, thus lowering the available output current. Also, the start-up input current of
the buck-boost converter is higher than the standard buck-mode regulator, and this may
overload an input power source with a current limit less than 5A. Using a delayed turn-on or an
undervoltage lockout circuit (described in the next section) would allow the input voltage to rise
to a high enough level before the switcher would be allowed to turn on.
Because of the structural differences between the buck and the buck-boost regulator
topologies, the buck regulator design procedure section can not be used to to select the
inductor or the output capacitor. The recommended range of inductor values for the buck-boost
design is between 68 µ H and 220 µ H, and the output capacitor values must be larger than what
is normally required for buck designs. Low input voltages or high output currents require a large
value output capacitor (in the thousands of micro Farads).
The peak inductor current, which is the same as the peak switch current, can be calculated
from the following formula:
IP ≈
ILOAD(VIN+|VO |)
VIN
V |V |
+ V IN+|VO | × 2L
IN
O
1
1 fOSC
Where fosc = 52 kHz. Under normal continuous inductor current operating conditions, the
minimum VIN represents the worst case. Select an inductor that is rated for the peak current
anticipated.
FIGURE 5. Inverting Buck-Boost Develops −12V
Also, the maximum voltage appearing across the regulator is the absolute sum of the input and output
voltage. For a −12V output, the maximum input voltage for the CBM2576 is +28V.
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CBM2576-XX
OPERATION INSTRUCTION
NEGATIVE BOOST REGULATOR
Another variation on the buck-boost topology is the negative boost configuration. The
circuit in Figure 6 accepts an input voltage ranging from −5V to −12V and provides a regulated
−12V output. Input voltages greater than −12V will cause the output to rise above −12V, but will
not damage the regulator.
Typical Load Current
400 mA for VIN = −5.2V
750 mA for VIN = −7V
Note: Heat sink may be required.
FIGURE 6. Negative Boost
Because of the boosting function of this type of regulator, the switch current is relatively
high, especially at low input voltages.
Output load current limitations are a result of the maximum current rating of the switch. Also,
boost regulators can not provide current limiting load protection in the event of a shorted load,
so some other means (such as a fuse) may be necessary.
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CBM2576-XX
OPERATION INSTRUCTION
UNDERVOLTAGE LOCKOUT
In some applications it is desirable to keep the regulator off until the input voltage reaches a
certain threshold. An undervoltage lockout circuit which accomplishes this task is shown in
Figure 7 while Figure 8 shows the same circuit applied to a buck-boost configuration. These
circuits keep the regulator off until the input voltage reaches a predetermined level.
VTH =VZ1 + 2VBE(Q1)
Note: Complete circuit not shown.
FIGURE 7. Undervoltage Lockout for Buck Circuit
Note: Complete circuit not shown (see Figure 10).
FIGURE 8. Undervoltage Lockout for Buck-Boost Circuit
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CBM2576-XX
OPERATION INSTRUCTION
DELAYED STARTUP
The ON /OFF pin can be used to provide a delayed startup feature as shown in Figure 9. With
an input voltage of 20V and for the part values shown, the circuit provides approximately 10 ms
of delay time before the circuit begins switching.
Increasing the RC time constant can provide longer delay times. But excessively large RC
time constants can cause problems with input voltages that are high in 60 Hz or 120 Hz ripple, by
coupling the ripple into the ON /OFF pin.
Note: Complete circuit not shown.
FIGURE 9. Delayed Startup
ADJUSTABLE OUTPUT, LOW-RIPPLE POWER SUPPLY
A 3A power supply that features an adjustable output voltage is shown in Figure 10. An
additional L-C filter that reduces the output ripple by a factor of 10 or more is included in this
circuit.
FIGURE 10. Adjustable 3A Power Supply with Low Output Ripple
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CBM2576-XX
OPERATION INSTRUCTION
Definition of Terms
BUCK REGULATOR
A switching regulator topology in which a higher voltage is converted to a lower voltage.
Also known as a step-down switching regulator.
BUCK-BOOST REGULATOR
A switching regulator topology in which a positive voltage is converted to a negative voltage
without a transformer.
DUTY CYCLE (D)
Ratio of the output switch’s on-time to the oscillator period.
for buck regulator
for buck-boost regulator
D=
D=
tON
T
tON
T
=
=
CATCH DIODE OR CURRENT STEERING DIODE
VOUT
VIN
|VO |
|VO |+VIN
The diode which provides a return path for the load current when the CBM2576 switch is
OFF.
EFFICIENCY (η)
The proportion of input power actually delivered to the load.
η=
POUT
POUT
=
PIN
POUT + PLOSS
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CBM2576-XX
OPERATION INSTRUCTION
PACKAGE
TO-220-5L
Symbol
Dimensions In Millimeters
Dimensions Inches
Min
Nom
Max
Min
Nom
Max
A
4.07
4.45
4.82
0.160
0.175
0.190
b
0.76
0.89
1.02
0.030
0.035
0.040
C
0.36
0.50
0.64
0.014
0.020
0.025
D
14.22
14.86
15.50
0.560
0.585
0.610
E
9.78
10.16
10.54
0.385
0.400
0.415
e
1.57
1.71
1.85
0.062
0.067
0.073
e1
6.68
6.81
6.93
0.263
0.268
0.273
F
1.14
1.27
1.40
0.045
0.050
0.055
H1
5.46
6.16
6.86
0.215
0.243
0.270
J1
2.29
2.74
3.18
0.090
0.108
0.125
L
13.21
13.97
14.73
0.520
0.550
0.580
Øp
3.68
3.81
3.94
0.145
0.150
0.155
Q
2.54
2.73
2.92
0.100
0.107
0.115
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CBM2576-XX
OPERATION INSTRUCTION
TO-263-5L
Symbol
Dimensions In Millimeters
Dimensions Inches
Min
Nom
Max
Min
Nom
Max
A
4.07
4.46
4.85
0.160
0.176
0.191
B
0.66
0.84
1.02
0.026
0.033
0.040
C
0.36
0.50
0.64
0.014
0.020
0.025
C2
1.14
1.27
1.40
0.045
0.050
0.055
D
8.65
9.15
9.65
0.341
0.360
0.380
E
9.78
10.16
10.54
0.385
0.400
0.415
e
1.57
1.71
1.85
0.062
0.068
0.073
F
6.60
6.86
7.11
0.260
0.270
0.280
L
14.61
15.24
15.88
0.575
0.600
0.625
L1
2.29
2.54
2.79
0.090
0.100
0.110
L2
-
-
2.92
-
-
0.115
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CBM2576-XX
OPERATION INSTRUCTION
PACKAGE/ORDERING INFORMATION
PRODUCT
ORDERING
NUMBER
CBM2576T-ADJ
PAKEAGE
TRANSPOT
MARKING
MEDIA,QUANTILY
TO-220
2576T-ADJ
Tape and Reel,46
TO-263-5
2576DT-ADJ
Tape and Reel,800
TEMPRANGE
PACKAGE
-40℃~125℃
CBM2576
CBM2576DT-ADJ -40℃~125℃
CBM72576T-3.3
-40℃~125℃
TO-220
2576T-3.3
Tape and Reel,46
CBM2576DT-3.3
-40℃~125℃
TO-263-5
2576DT-3.3
Tape and Reel,500
CBM2576T-5.0
-40℃~125℃
TO-220
2576T-5.0
Tape and Reel,46
CBM2576DT-5.0
-40℃~125℃
TO-263-5
2576DT-5.0
Tape and Reel,500
CBM2576T-12
-40℃~125℃
TO-220
2576T-12
Tape and Reel,46
CBM2576DT-12
-40℃~125℃
TO-263-5
2576DT-12
Tape and Reel,500
CBM2576T-15
-40℃~125℃
TO-220
2576T-15
Tape and Reel,46
CBM2576DT-15
-40℃~125℃
TO-263-5
2576DT-15
Tape and Reel,500
CBM2576-3.3
CBM2576-5
CBM2576-12
CBM2576-15
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