MIC4680
Micrel
MIC4680
1A 200kHz SuperSwitcher™ Buck Regulator
Final Information
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-lead SOP (small outline package).
The MIC4680 is available in 3.3V and 5V fixed output ver-
sions 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 shut-
down 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 re-
sponse and ease of use.
The MIC4680 is available in the 8-lead SOP with a
–40°C to +125°C junction temperature range.
Features
•
•
•
•
•
•
•
•
•
•
•
SO-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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Simple 1A high-efficiency step-down (buck) regulator
Replacement of TO-220 and TO-263 designs
Efficient preregulator (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 Applications
+6V to +34V
C1
15µF
35V
SHUTDOWN
ENABLE
2
MIC4680-3.3BM
IN
SW
3
L1
68µH
3.3V/1A
C2
220µF
16V
1
SHDN
GND
5–8
FB
4
Power
SOP-8
D1
B260A or
SS26
Fixed Regulator Circuit
MIC4680BM
IN
SW
+5V to +34V
C1
15µF
35V
SHUTDOWN
ENABLE
2
3
L1
68µH
R1
3.01k
R2
2.94k
2.5V/1A
C2
220µF
16V
1
SHDN
GND
5–8
FB
4
Power
SOP-8
D1
B260A or
SS26
Adjustable Regulator Circuit
SuperSwitcher is a trademark of Micrel, Inc.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
June 2000
1
MIC4680
MIC4680
Micrel
Ordering Information
Part Number
MIC4680BM
MIC4680-3.3BM
MIC4680-5.0BM
Voltage
Adjustable
3.3V
5.0V
Junction Temp. Range
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
Package
8-lead SOP
8-lead SOP
8-lead SOP
Pin Configuration
SHDN 1
IN 2
SW 3
FB 4
8 GND
7 GND
6 GND
5 GND
SOP-8 (M)
Pin Description
Pin Number
1
2
3
4
5–8
Pin Name
SHDN
VIN
SW
FB
GND
Pin Function
Shutdown (Input): Logic low enables regulator. Logic high (>1.6V) shuts
down regulator.
Supply Voltage (Input): Unregulated +4V to +34V supply voltage.
Switch (Output): Emitter of NPN output switch. Connect to external storage
inductor and Shottky diode.
Feedback (Input): Connect to output on fixed output voltage versions, or to
1.23V-tap of voltage-divider network for adjustable version.
Ground
MIC4680
2
June 2000
MIC4680
Micrel
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V
IN
),
Note 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
ESD,
Note 5
Operating Ratings
(Note 2)
Supply Voltage (V
IN
),
Note 4
.......................... +4V to +34V
Junction Temperature (T
J
) ...................................... +125°C
Package Thermal Resistance (θ
JA
),
Note 6
............ 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%)
(±2%)
8V
≤
V
IN
≤
34V, 0.1A
≤
I
LOAD
≤
1A, V
OUT
= 5V
Maximum Duty Cycle
Output Leakage Current
V
FB
= 1.0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V
Quiescent Current
MIC4680-3.3
Output Voltage
(±1%)
(±3%)
6V
≤
V
IN
≤
34V, 0.1A
≤
I
LOAD
≤
1A
Maximum Duty Cycle
Output Leakage Current
V
FB
= 2.5V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V
Quiescent Current
MIC4680-5.0
Output Voltage
(±1%)
(±3%)
8V
≤
V
IN
≤
34V, 0.1A
≤
I
LOAD
≤
1A
Maximum Duty Cycle
Output Leakage Current
V
FB
= 4.0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V
Quiescent Current
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
= 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
= 1.5V
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
June 2000
3
MIC4680
MIC4680
Parameter
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)
Shutdown Input Logic Level
regulator off
regulator on
Shutdown Input Current
V
SHDN
= 5V (regulator off)
V
SHDN
= 0V (regulator on)
Thermal Shutdown
Note 1.
Note 2.
Note 3.
Note 4.
Note 5.
Note 6.
Note 7.
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Absolute maximum rating is intended for voltage transients only, prolonged dc operation is not recommended.
V
IN(min)
= V
OUT
+ 2.5V or 4V whichever is greater.
Devices are ESD sensitive. Handling precautions recommended.
Measured on 1" square of 1 oz. copper FR4 printed circuit board connected to the device ground leads.
Test at T
A
= +85°C, guaranteed by design, and characterized to T
J
= +125°C.
Micrel
Condition
Min
Typ
Max
Units
30
180
50
200
1.4
100
220
1.8
2.5
kHz
kHz
V
V
A
µA
µA
V
1.3
1.8
1.5
30
100
2
1.6
1.0
0.8
10
10
V
µA
µA
°C
–10
–10
–0.5
–1.5
160
Test Circuit
+12V
2
Device Under Test
3
IN
SW
4
68µH
SHUTDOWN
ENABLE
1
SHDN
GND
SOP-8
5–8
FB
I
Current Limit Test Circuit
Shutdown Input Behavior
OFF
ON
GUARANTEED
ON
TYPICAL
ON
0.8V
1V
1.6V
2V
GUARANTEED
OFF
TYPICAL
OFF
0V
V
IN(max)
Shutodwn Hysteresis
MIC4680
4
June 2000
MIC4680
Micrel
Typical Characteristics
Shutdown Current
vs. Input Voltage
100
V
IN
= 12V
V
OUT
= 5V
80
CURRENT (µA)
Line Regulation
5.06
5.05
OUTPUT VOLTAGE (V)
5.04
5.03
5.02
5.01
5.00
4.99
4.98
4.97
4.96
0
5
10 15 20 25 30
INPUT VOLTAGE (V)
35
5.04
I
OUT
= 1.0A
OUTPUT VOLTAGE (V)
Load Regulation
5.02
60
40
20
0
5.00
4.98
4.96
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
0
5
10 15 20 25 30
INPUT VOLTAGE (V)
35
Shutdown Current
vs. Temperature
4.0
OUTPUT VOLTAGE (V)
Current Limit
Characteristic
6
202
201
FREQUENCY (kHz)
Frequency vs.
Supply Voltage
3.5
CURRENT (µA)
3.0
2.5
2.0
1.5
1.0
0.5
V
IN
= 12V
V
SHDN
= V
IN
5
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)
200
199
198
197
196
0
5 10 15 20 25 30
SUPPLY VOLTAGE (V)
35
0
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
Frequency vs.
Temperature
220
1.242
Feedback Voltage
vs. Temperature
1.6
SATURATION VOLTAGE (V)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
Saturation Voltage
vs. Temperature
FEEDBACK VOLTAGE (V)
1.240
1.238
1.236
1.234
1.232
1.230
V
IN
= 12V
V
OUT
= 5V
I
OUT
= 1A
FREQUENCY (kHz)
210
200
190
V
IN
= 12V
V
OUT
= 5V
I
LOAD
= 1A
180
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
1.228
-50 -25 0 25 50 75 100 125 150
TEMPERATURE (°C)
0
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
3.3V Output
Efficiency
80
70
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
0
0
12V
5V Output
Efficiency
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
15V
12V Output
Efficiency
EFFICIENCY (%)
60
50
40
30
20
10
0
12V
24V 6V
7V
24V
24V
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
10
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
June 2000
5
MIC4680
51mcu
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