MIC4680
1A 200kHz SuperSwitcher™
Buck Regulator
General Description
The MIC4680 SuperSwitcher™ is an easy-to-use fixed or
adjustable output voltage step-down (buck) switch-mode
voltage regulator. The 200kHz MIC4680 achieves up to
1.3A of continuous output current over a wide input range
in a 8-pin SOIC.
The MIC4680 is available in 3.3V and 5V fixed output
versions or adjustable output down to 1.25V.
The MIC4680 has an input voltage range of 4V to 34V,
with excellent line, load, and transient response. The
regulator performs cycle-by-cycle current limiting and
thermal shutdown for protection under fault conditions. In
shutdown mode, the regulator draws less than 2µA of
standby current.
The MIC4680 SuperSwitcher™ regulator requires a mini-
mum number of external components and can operate
using a standard series of inductors and capacitors.
Frequency compensation is provided internally for fast
transient response and ease of use.
The MIC4680 is available in the 8-pin SOIC with a
–40°C to +125°C junction temperature range.
Features
•
•
•
•
•
•
•
•
•
•
•
SOIC-8 package with up to 1.3A output current
All surface mount solution
Only 4 external components required
Fixed 200kHz operation
3.3V, 5V, and adjustable output versions
Internally compensated with fast transient response
Wide 4V to 34V operating input voltage range
Less than 2µA typical shutdown-mode current
Up to 90% efficiency
Thermal shutdown
Overcurrent protection
Applications
•
•
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•
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Simple 1A high-efficiency step-down (buck) regulator
Replacement of TO-220 and TO-263 designs
Efficient pre-regulator (5V to 2.5V, 12V to 3.3V, etc.)
On-card switching regulators
Positive-to-negative converter (inverting buck-boost)
Simple battery charger
Negative boost converter
Higher output current regulator using external FET
Typical Application
+6V to +34V
C1
15µF
35V
SHUTDOWN
ENABLE
MIC4680-3.3BM
2
IN
SHDN
GND
5–8
SW
FB
3
L1
68µH
3.3V/1A
C2
220µF
16V
1
4
+5V to +34V
C1
15µF
35V
SHUTDOWN
ENABLE
2
MIC4680BM
IN
SW
SHDN
GND
5–8
3
L1
68µH
R1
3.01k
R2
2.94k
2.5V/1A
C2
220µF
16V
1
Power
SOIC-8
D1
B260A or
SS26
FB
4
Power
SOIC-8
D1
B260A or
SS26
Fixed Regulator Circuit
Adjustable Regulator Circuit
SuperSwitcher is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
March 2008
M9999-032808
Micrel, Inc.
MIC4680
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
)
(3)
..................................................+38V
Shutdown Voltage (V
SHDN
)............................. –0.3V to +38V
Steady-State Output Switch Voltage (V
SW
) ....................–1V
Feedback Voltage [Adjustable] (V
FB
) ...........................+12V
Storage Temperature (T
s
) .........................–65°C to +150°C
EDS Rating
(5)
Operating Ratings
(2)
Supply voltage (V
IN
)
(4)
....................................... +4V to +34V
Junction Temperature (T
J
) ....................................... +125°C
Package Thermal Resistance
(6)
SIOC (θ
JA
)..........................................................63°C/W
Electrical Characteristics
V
IN
= 12V; I
LOAD
= 500mA; T
J
= 25°C,
bold
values indicate –40°C
≤
T
J
≤
+125°C,
Note 7;
unless noted.
Parameter
MIC4680 [Adjustable]
Feedback Voltage
(±1%)
(±1%)
8V
≤
V
IN
≤
34V, 0.1A
≤
I
LOAD
≤
1A, V
OUT
= 5V
Maximum Duty Cycle
Output Leakage Current
Quiescent Current
MIC4680-3.3
Output Voltage
(±1%)
(±3%)
6V
≤
V
IN
≤
34V, 0.1A
≤
I
LOAD
≤
1A
Maximum Duty Cycle
Output Leakage Current
Quiescent Current
MIC4680-5.0
Output Voltage
(±1%)
(±3%)
8V
≤
V
IN
≤
34V, 0.1A
≤
I
LOAD
≤
1A
Maximum Duty Cycle
Output Leakage Current
Quiescent Current
MIC4680/-3.3/-5.0
Frequency Fold Back
Oscillator Frequency
Saturation Voltage
Short Circuit
Current Limit
Standby Quiescent
Current
I
OUT
= 1A
V
FB
= 0V, see Test Circuit
V
SHDN
= V
IN
V
SHDN
= 5V (regulator off)
1.3
30
180
50
200
1.4
1.8
1.5
30
100
100
220
1.8
2.5
kHz
kHz
V
A
µA
µA
V
FB
= 4.0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V
V
FB
= 6.0V
4.950
4.85
4.800
4.750
93
5.0
5.0
97
50
4
7
500
20
12
5.05
5.15
5.200
5.250
V
V
V
V
%
µA
mA
mA
V
FB
= 2.5V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V
V
FB
= 4.0V
3.266
3.201
3.168
3.135
93
3.3
3.3
97
50
4
7
500
20
12
3.333
3.399
3.432
3.465
V
V
V
V
%
µA
mA
mA
V
FB
= 1.0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V
V
FB
= 1.5V
1.217
1.205
1.193
1.180
93
1.230
1.230
97
50
4
7
500
20
12
1.243
1.255
1.267
1.280
V
V
V
V
%
µA
mA
mA
Condition
Min
Typ
Max
Units
March 2008
3
M9999-032808
Micrel, Inc.
Parameter
Shutdown Input Logic
Level
Shutdown Input Current
Thermal Shutdown
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Absolute maximum rating is intended for voltage transients only, prolonged dc operation is not recommended.
4. V
IN(min)
= V
OUT
+ 2.5V or 4V whichever is greater.
5. Devices are ESD sensitive. Handling precautions recommended.
6. Measured on 1" square of 1 oz. copper FR4 printed circuit board connected to the device ground leads.
7. Test at T
A
= +85°C, guaranteed by design, and characterized to T
J
= +125°C.
MIC4680
Condition
regulator off
regulator on
V
SHDN
= 5V (regulator off)
V
SHDN
= 0V (regulator on)
–10
–10
Min
2
Typ
1.6
1.0
–0.5
–1.5
160
0.8
10
10
Max
Units
V
V
µA
µA
°C
Test Circuit
+12V
Device Under Test
2
IN
SHDN
GND
SOIC-8
5–8
SW
FB
3
68µH
SHUTDOWN
ENABLE
1
4
I
Current Limit Test Circuit
Shutdown Input Behavior
OFF
ON
0.8V
0V
1V
1.6V
2V
V
IN(max)
Shutdown Hysteresis
March 2008
4
M9999-032808
Micrel, Inc.
MIC4680
Typical Characteristics
5.06
OUTPUT VOLTAGE (V)
5.05
5.04
5.03
5.02
5.01
5.00
4.99
4.98
4.97
4.96
Line Regulation
OUTPUT VOLTAGE (V)
5.04
Load Regulation
100
V
IN
= 12V
V
OUT
= 5V
Shutdown Current
vs. Input Voltage
I
OUT
= 1.0A
5.02
80
CURRENT (µA)
60
40
20
5.00
4.98
4.96
0
5
10 15 20 25 30
INPUT VOLTAGE (V)
35
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
0
0
5
10 15 20 25 30
INPUT VOLTAGE (V)
35
4.0
3.5
CURRENT (µA)
3.0
2.5
2.0
1.5
1.0
0.5
Shutdown Current
vs. Temperature
OUTPUT VOLTAGE (V)
V
IN
= 12V
V
SHDN
= V
IN
6
5
Current Limit
Characteristic
202
201
FREQUENCY (kHz)
200
199
198
197
196
0
Frequency vs.
Supply Voltage
4
3
2
1
0
V
IN
= 12V
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
OUTPUT CURRENT (A)
0
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
5 10 15 20 25 30
SUPPLY VOLTAGE (V)
35
220
Frequency vs.
Temperature
FEEDBACK VOLTAGE (V)
1.242
1.240
1.238
1.236
1.234
1.232
1.230
Feedback Voltage
vs. Temperature
SATURATION VOLTAGE (V)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
Saturation Voltage
vs. Temperature
FREQUENCY (kHz)
210
200
190
180
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
V
IN
= 12V
V
OUT
= 5V
I
OUT
= 1A
V
IN
= 12V
V
OUT
= 5V
I
LOAD
= 1A
1.228
-50 -25 0 25 50 75 100 125 150
TEMPERATURE (°C)
0
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
80
70
EFFICIENCY (%)
3.3V Output
Efficiency
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
12V
5V Output
Efficiency
EFFICIENCY (%)
60
50
40
30
20
10
0
0
12V
24V 6V
24V
7V
100
90
80
70
60
12V Output
Efficiency
15V
24V
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
50
40
30
20
10
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
March 2008
5
M9999-032808
RF/Wirelessly
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