MIC4576 [MICREL]
200kHz Simple 3A Buck Voltage Regulator; 在200kHz简易3A降压稳压器
| 型号： | MIC4576 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 200kHz Simple 3A Buck Voltage Regulator |
| 文件： | 总7页 (文件大小：74K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC4576
200kHz Simple 3A Buck Voltage Regulator
General Description
Features
The MIC4576 is a series of easy to use fixed and adjustable
BiCMOS step-down (buck) switch-mode voltage regulators.
The 200kHz MIC4576 duplicates the pinout and function of
the 52kHz LM2576. The higher switching frequency may
allow up to a 2:1 reduction in output filter inductor size.
• Fixed 200kHz operation
• 3.3V, 5V, and adjustable output versions
• Voltage over specified line and load conditions:
Fixed version: ±3% max. output voltage
Adjustable version: ±2% max. feedback voltage
• Guaranteed 3A switch current
• Wide 4V to 36V input voltage range
• Wide 1.23V to 33V output voltage range
• Requires minimum external components
• < 200µA typical shutdown mode
The MIC4576 is available in 3.3V, and 5V fixed output
versions or a 1.23V to 33V adjustable output version. Both
versions are capable of driving a 3A load with excellent line
and load regulation.
The feedback voltage is guaranteed to ±2% tolerance for
adjustable versions, and the output voltage is guaranteed to
±3% for fixed versions, within specified voltages and load
conditions. The oscillator frequency is guaranteed to ±10%.
• 75% efficiency (adjustable version > 75% typical)
• Standard inductors are 25% of typical LM2576 values
• Thermal shutdown
• Overcurrent protection
In shutdown mode, the regulator draws less than 200µA
standby current. The regulator performs cycle-by-cycle
current limiting and thermal shutdown for protection under
fault conditions.
• 100% electrical thermal limit burn-in
Applications
• Simple high-efficiency step-down (buck) regulator
• Efficient preregulator for linear regulators
• On-card switching regulators
• Positive-to-negative converter (inverting buck-boost)
• Battery Charger
• Negative boost converter
This series of simple switch-mode regulators requires a
minimum number of external components and can operate
using a standard series of inductors. Frequency compensa-
tion is provided internally.
The MIC4576 is available in TO-220 (T) and TO-263 (U)
packages for the industrial temperature range.
• Step-down to 3.3V for Intel Pentium™
and similar microprocessors
Typical Applications
L1
5V/3A
5
1
2
Shutdown
Enable
SHDN
MIC4576-5.0BT
VIN FB
SW
33µH
8V to 36V
4
C2
1000µF
16V
C1
470µF
63V
GND
D1
3
MBR360
Fixed Regulator
L1
68µH
12V/3A
C2
1000µF
16V
5
1
2
4
Shutdown
Enable
SHDN
SW
FB
R2
MIC4576BT
13.0k
1%
16V to 36V
VIN
C1
470µF
63V
GND
3
R1
1.50k
1%
MBR360
Adjustable Regulator
MIC4576
4-128
April 1998•
MIC4576
Micrel
Ordering Information
Part Number
Voltage
3.3V
Temperature Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Package
MIC4576-3.3BT
MIC4576-5.0BT
MIC4576BT
5-lead TO-220
5-lead TO-220
5-lead TO-220
5-lead TO-263
5-lead TO-263
5-lead TO-263
5.0V
Adjustable
3.3V
MIC4576-3.3BU
MIC4576-5.0BU
MIC4576BU
5.0V
Adjustable
Pin Configuration
5
4
3
2
1
SHDN
FB
GND
SW
VIN
5-Lead TO-220 (T)
5
SHDN
FB
GND
SW
4
3
2
1
VIN
5-Lead TO-263 (U)
Pin Description
Pin Number
Pin Name
VIN
Pin Function
Supply Voltage (Input): Unregulated +4V to +36V supply voltage.
1
2
SW
Switch (Output): Emitter of NPN output switch. Connect to external storage
inductor and Shottky diode.
3, TAB
4
GND
FB
Ground
Feedback (Input): Output voltage feedback to regulator. Connect to output
of supply for fixed versions. Connect to 1.23V tap of resistive divider for
adjustable versions.
5
SHDN
Shutdown (Input): Logic low enables regulator. Logic high (> 2.4V) shuts
down regulator.
April 1998•
4-129
MIC4576
MIC4576
Micrel
Absolute Maximum Ratings
Operating Ratings
Supply Voltage (V ) ...................................................+40V
Supply Voltage (V ) ...................................................+36V
IN
IN
Shutdown Voltage (V
) .......................... –0.3V to +36V
Junction Temperature ............................................. +150°C
SHDN
Output Switch (V ), Steady State...............................–1V
Package Thermal Resistance
SW
TO-220, TO-263 (θ ) .........................................65°C/W
Feedback Voltage (V ) [Adjustable] .........................+3.8V
JA
FB
TO-220, TO-263 (θ ) ...........................................2°C/W
JA
Storage Temperature ............................... –65°C to +150°C
Electrical Characteristics
VIN = 12V; ILOAD = 500mA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +85°C; unless noted.
Parameter
Condition
Min
Typ
Max
Units
MIC4576 [Adjustable]
Feedback Voltage
Feedback Voltage
1.217 1.230 1.243
1.193 1.230 1.267
V
8V ≤ VIN ≤ 36V, 0.5A ≤ ILOAD ≤ 3A
V
V
1.180
1.280
Efficiency
ILOAD = 3A, Note 1
77
95
%
%
Maximum Duty Cycle (On)
Output Leakage Current
VFB = 1.0V
90
VIN = 36V, VFB = 1.5V
output = 0V
output = –1V
0
7.5
2
30
mA
mA
Quiescent Current
VFB = 1.5V
5
10
mA
Feedback Bias Current
50
100
500
nA
nA
MIC4576-3.3
Output Voltage
Output Voltage
3.234
3.3
3.3
3.366
V
6V ≤ VIN ≤ 36V, 0.5A ≤ ILOAD ≤ 3A
3.168
3.135
3.432
3.465
V
V
Efficiency
ILOAD = 3A
VFB = 2.5V
72
95
%
%
Maximum Duty Cycle (On)
Output Leakage Current
90
VIN = 36V, VFB = 4.0V
output = 0V
output = –1V
0
7.5
2
30
mA
mA
Quiescent Current
MIC4576-5.0
VFB = 4.0V
5
10
mA
Output Voltage
Output Voltage
4.900
5.0
5.0
5.100
V
8V ≤ VIN ≤ 36V, 0.5A ≤ ILOAD ≤ 3A
4.800
4.750
5.200
5.250
V
V
Efficiency
ILOAD = 3A
VFB = 4.0V
77
95
%
%
Maximum Duty Cycle (On)
Output Leakage Current
90
VIN = 36V, VFB = 6.0V
output = 0V
output = –1V
0
7.5
2
30
mA
mA
Quiescent Current
VFB = 6.0V
5
10
mA
MIC4576
4-130
April 1998•
MIC4576
Micrel
Parameter
Condition
Min
Typ
Max
Units
MIC4576 / -3.3 / -5.0
Oscillator Frequency
Saturation Voltage
180
200
1.7
220
kHz
I
OUT = 3A
2.3
2.5
V
V
Current Limit
peak current, tON ≤ 3µs; VFB = 0V
4.2
3.5
5.2
6.9
7.5
A
A
Standby Quiescent Current
SHDN Input Logic Level
VSHDN = 5V (regulator off), VFB = 0V
VOUT = 0V (regulator off)
50
200
µA
2.2
2.4
1.4
V
V
VOUT = 3.3V or 5V (regulator on)
1.2
1.0
0.8
V
V
SHDN Input Current
V
SHDN = 5V (regulator off)
4
0.01
30
10
µA
µA
VSHDN = 0V (regulator on)
–10
General Note: Devices are ESD protected, however, handling precautions are recommended.
Note 1: = 5V
V
OUT
April 1998•
4-131
MIC4576
MIC4576
Micrel
Block Diagrams
+36V max.
VIN
CIN
Shutdown
Enable
Internal
Regulator
SHDN
Thermal
Shutdown
Current
Limit
200kHz
Oscillator
Driver
Com-
parator
L1
SW
VOUT
COUT
3A
Switch
D1
1.23V
Bandgap
Error
Amp.
R1
R2
GND
FB
MIC4576-x.x
Block Diagram with External Components
Fixed Step-Down Regulator
+36V max.
VIN
CIN
Shutdown
Enable
Internal
Regulator
SHDN
1
2
V
V
+
OUT
RE
Thermal
Shutdown
Current
Limit
200kHz
Oscillator
OUT
R1
R
REF
Driver
Com-
parator
L1
SW
VOUT
COUT
3A
Switch
D1
1.23V
Bandgap
Error
Amp.
R1
R2
FB
[Adjustable]
MIC4576
GND
Block Diagram with External Components
Adjustable Step-Down Regulator
MIC4576
4-132
April 1998•
MIC4576
Micrel
Functional Description
The MIC4576 is a variable duty cycle switch-mode regulator
with an internal power switch. Refer to the block diagrams.
A higher feedback voltage increases the error amplifier
output voltage. A higher error amplifier voltage (comparator
inverting input) causes the comparator to detect only the
peaks of the sawtooth, reducing the duty cycle of the com-
parator output. A lower feedback voltage increases the duty
cycle.
Supply Voltage
The MIC4576 operates from a +4V to +36V unregulated
input. Highest efficiency operation is from a supply voltage
around +15V.
Output Switching
Enable/Shutdown
When the internal switch is on, an increasing current flows
The shutdown (SHDN) input is TTL compatible. Ground the
input if unused. A logic-low enables the regulator. A logic-
high shuts down the internal regulator which reduces the
current to typically 50µA.
from the supply V through external storage inductor L1, to
IN,
output capacitor C
and the load. Energy is stored in the
OUT
inductor as the current increases with time.
When the internal switch is turned off, the collapse of the
magnetic field in L1 forces current to flow through fast
Feedback
Fixed versions of the regulator have an internal resistive
divider from the feedback (FB) pin. Connect FB directly to the
output line.
recovery diode D1, charging C
.
OUT
Output Capacitor
External output capacitor C
provides stabilization and
OUT
Adjustable versions require an external resistive voltage
divider from the output voltage to ground, connected from the
1.23V tap to FB.
reduces ripple.
Return Paths
During the on portion of the cycle, the output capacitor and
load currents return to the supply ground. During the off
portion of the cycle, current is being supplied to the output
capacitor and load by storage inductor L1, which means that
D1 is part of the high-current return path.
Duty Cycle Control
A fixed-gain error amplifier compares the feedback signal
with a 1.23V bandgap voltage reference. The resulting error
amplifier output voltage is compared to a 200kHz sawtooth
waveform to produce a voltage controlled variable duty cycle
output.
Applications Information
The applications circuits that follow have been constructed
and tested. Refer to Application Note 15 for additional
information, including efficiency graphs and manufacturer’s
addresses and telephone numbers for most circuits.
For a mathematical approach to component selection and
circuit design, refer to Application Note 14.
L1
L1
3.3V/3A
3.3V/3A
5
1
2
4
5
1
2
4
SHDN
MIC4576-3.3BT
VIN FB
SW
SHDN
MIC4576-3.3BT
VIN FB
SW
33µH
33µH
6V to 24V
6V to 36V
C2
1000µF
16V
C2
1000µF
16V
C1
470µF
35V
C1
470µF
63V
GND
3
GND
3
D1
1N5822
D1
MBR360
C1 Nichicon UPL1V471MPH, ESR = 0.046Ω
C2 Nichicon UPL1C221MPH, ESR = 0.047Ω
D1 Motorola 1N5822
C1 Nichicon UPL1J471MRH, ESR = 0.039Ω
C2 Nichicon UPL1C102MPH, ESR = 0.047Ω
D1 Motorola MBR360
L1 Coiltronics PL52C-33-1000, DCR = 0.036Ω
L1 Coiltronics PL52C-33-1000 DCR = 0.036
L1 Bi
HM77-30004, DCR = 0.045Ω, Note 2
L1 Bi
HM77-30004, DCR = 0.045Ω, Note 2
Figure 1. 6V–24V to 3.3V/3A Buck Converter
Through Hole
Figure 2. 6V–36V to 3.3V/3A Buck Converter
Through Hole
Note 2: Surface-mount component.
April 1998•
4-133
MIC4576
MIC4576
Micrel
L1
L1
5V/3A
5V/3A
5
1
2
4
5
1
2
4
SHDN
MIC4576-5.0BT
VIN FB
SW
SHDN
MIC4576-5.0BT
VIN FB
SW
33µH
33µH
8V to 24V
8V to 36V
C2
1000µF
16V
C2
1000µF
16V
C1
470µF
35V
C1
470µF
63V
GND
3
GND
3
D1
1N5822
D1
MBR360
C1 Nichicon UPL1J471MRH, ESR = 0.039Ω
C2 Nichicon UPL1C102MPH, ESR = 0.047Ω
D1 Motorola MBR360
C1 Nichicon UPL1J471MPH, ESR = 0.046Ω
C2 Nichicon UPL1C102MPH, ESR = 0.047Ω
D1 Motorola MBR5822
L1 Coiltronics PLS2C-33-1000, DCR = 0.036
L1 Coiltronics PL52C-33-1000, DCR = 0.036
L1 Bi
HM77-30004, DCR = 0.045Ω, Note 2
L1 Bi
HM77-30004, DCR = 0.045Ω, Note 2
Figure 4. 8V–36V to 5V/3A Buck Converter
Through Hole
Figure 3. 8V–24V to 5V/3A Buck Converter
Through Hole
L1
12V/3A
5
2
4
SHDN
SW
FB
68µH
R2
MIC4576BT
13.0k
1%
16V to 36V
1
C2
1000µF
16V
VIN
C1
470µF
63V
GND
3
R1
1.50k
1%
MBR360
C1 Nichicon UPL1J471MPH, ESR = 0.039Ω
C2 Nichicon UPL1C102MPH, ESR = 0.047Ω
D1 Motorola MBR360
L1 Bi
HM77-29006, DCR = 0.08Ω
Figure 5. 16V–36V to 12V/3A Buck Converter
Through Hole
U1
R1
0.1Ω
VOUT
5V/4A
L1
5
1
2
4
SHDN
MIC4576-5.0BT
VIN FB
SW
33µH
VIN
8V to 36V
C2
1000µF
16V
R3
10K
GND
3
D1
MBR360
C1
470µF
63V
C5
0.01µF
VIN
8
2
3
U3
1
LM358
4
U2
4
2
5
1
SHDN
MIC4576-5.0BT
VIN SW
FB
R2
0.1Ω
L2
33µH
GND
C3
470µF
63V
C4
1000µF
16V
D2
3
MBR360
C1, C3 Nichicon UPL1J471MRH, ESR = 0.039Ω
C2, C4 Nichicon UPL1C102MPH, ESR = 0.047Ω
D1, D2 Motorola MBR360
L1, L2 Coiltronics PL52C-33-1000, DCR = 0.036
R1, R2 KRL
U3
SP-1-A1-0R100J
LM358
National
Figure 6. Parallel Switching Regulators
Note 2: Surface-mount component.
MIC4576
4-134
April 1998•
相关型号：
MIC4576-3.3BT
Switching Regulator, Voltage-mode, 8.5A, 220kHz Switching Freq-Max, BICMOS, PSFM5, TO-220, 5 PIN
MICROCHIP
MIC4576-3.3BU
Switching Regulator, Voltage-mode, 8.5A, 220kHz Switching Freq-Max, BICMOS, PSSO5, TO-263, 5 PIN
MICROCHIP
MIC4576-3.3BUT&R
Switching Regulator, Voltage-mode, 8.5A, 220kHz Switching Freq-Max, BICMOS, PSSO5, TO-263, 5 PIN
MICREL
MIC4576-3.3WUTR
8.5A SWITCHING REGULATOR, 220kHz SWITCHING FREQ-MAX, PSSO5, ROHS COMPLIANT, TO-263, 5 PIN
MICROCHIP
MIC4576-5.0BT
Switching Regulator, Voltage-mode, 8.5A, 220kHz Switching Freq-Max, BICMOS, PSFM5, TO-220, 5 PIN
MICROCHIP
©2020 ICPDF网 联系我们和版权申明