MIC4680
1A 200kHz SuperSwitcher™
Buck Regulator
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
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
• 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
SW
L1
68µH
IN
FB
GND
SHDN
C2
220µF
16V
D1
B260A or
SS26
3.3V/1A
MIC4680-3.3BM
C1
15µF
35V
+6V to +34V
SHUTDOWN
ENABLE
5–8
4
32
1
Power
SOIC-8
SW
L1
68µH
IN
FB
GND
SHDN
C2
220µF
16V
R1
3.01k
R2
2.94k
2.5V/1A
MIC4680BM
C1
15µF
35V
+5V to +34V
SHUTDOWN
ENABLE
Power
SOIC-8
5–8
4
32
1
D1
B260A or
SS26
Fixed Regulato r Circu it
Adjustable Regulator Circuit
Micrel, Inc. MIC4680
March 2008 2 M9999-032808
Ordering Information
Part Number
Standard Pb-Free Voltage Junction Temp. Range Package
MIC4680BM MIC4680YM Adj. –40°C to +125°C 8-Pin SOIC
MIC4680-3.3BM MIC4680-3.3YM 3.3V –40°C to +125°C 8-Pin SOIC
MIC4680-5.0BM MIC4680-5.0YM 5.0V –40°C to +125°C 8-Pin SOIC
Pin Configur ation
1SHDN
IN
SW
FB
8 GND
GND
GND
GND
7
6
5
2
3
4
8-Pin SIOC (M)
Pin Description
Pin Number Pin Name Pin Function
1 SHDN
Shutdown (Input): Logic low enables regulator. Logic high (>1.6V) shuts down
regulator.
2 VIN Supply Voltage (Input): Unregulated +4V to +34V supply voltage.
3 SW
Switch (Output): Emitter of NPN output switch. Connect to external storage inductor
and Shottky diode.
4 FB
Feedback (Input): Connect to output on fixed output voltage versions, or to 1.23V-tap
of voltage-divider network for adjustable version.
5 – 8 GND Ground
Micrel, Inc. MIC4680
March 2008 3 M9999-032808
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 Condition Min Typ Max Units
MIC4680 [Adjustable]
(±1%)
(±1%)
1.217
1.205
1.230 1.243
1.255
V
V
Feedback Voltage
8V ≤ V
IN
≤ 34V, 0.1A ≤ I
LOAD
≤ 1A, V
OUT
= 5V 1.193
1.180
1.230 1.267
1.280
V
V
Maximum Duty Cycle V
FB
= 1.0V 93 97 %
Output Leakage Current V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V 50 500 µA
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V 4 20 mA
Quiescent Current V
FB
= 1.5V 7 12 mA
MIC4680-3.3
Output Voltage (±1%)
(±3%)
3.266
3.201
3.3 3.333
3.399
V
V
6V ≤ V
IN
≤ 34V, 0.1A ≤ I
LOAD
≤ 1A 3.168
3.135
3.3 3.432
3.465
V
V
Maximum Duty Cycle V
FB
= 2.5V 93 97 %
Output Leakage Current V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V 50 500 µA
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V 4 20 mA
Quiescent Current V
FB
= 4.0V 7 12 mA
MIC4680-5.0
Output Voltage (±1%)
(±3%)
4.950
4.85
5.0 5.05
5.15
V
V
8V ≤ V
IN
≤ 34V, 0.1A ≤ I
LOAD
≤ 1A 4.800
4.750
5.0 5.200
5.250
V
V
Maximum Duty Cycle V
FB
= 4.0V 93 97 %
Output Leakage Current V
IN
= 34V, V
SHDN
= 5V, V
SW
= 0V 50 500 µA
V
IN
= 34V, V
SHDN
= 5V, V
SW
= –1V 4 20 mA
Quiescent Current V
FB
= 6.0V 7 12 mA
MIC4680/-3.3/-5.0
Frequency Fold Back 30 50 100 kHz
Oscillator Frequency 180 200 220 kHz
Saturation Voltage I
OUT
= 1A 1.4 1.8 V
Short Circuit
Current Limit
V
FB
= 0V, see Test Circuit 1.3 1.8 2.5 A
V
SHDN
= V
IN
1.5 µA
Standby Quiescent
Current V
SHDN
= 5V (regulator off) 30 100 µA
Micrel, Inc. MIC4680
March 2008 4 M9999-032808
Parameter Condition Min Typ Max Units
regulator off 2 1.6 V
Shutdown Input Logic
Level regulator on 1.0 0.8 V
V
SHDN
= 5V (regulator off) –10 –0.5 10 µA Shutdown Input Current
V
SHDN
= 0V (regulator on) –10 –1.5 10 µA
Thermal Shutdown 160 °C
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.
Test Circuit
SW
68µH
IN
FB
GND
SHDN
Device Unde
r
Test
+12V
SHUTDOWN
ENABLE
SOIC-8 5–8
4
32
1
I
Current Limit Test Circuit
Shutdown Input Behavior
OFF
ON
0.8V
1V0V 1.6V V
IN(max)
2V
Shutdown Hysteresis
Micrel, Inc. MIC4680
March 2008 5 M9999-032808
Typical Characteristics
Line Regulation
4.96
4.97
4.98
4.99
5.00
5.01
5.02
5.03
5.04
5.05
5.06
0 5 10 15 20 25 30 35
)V(EGATLOVTUPTUO
INPUT VOLTAGE (V)
I
OUT
= 1.0A
4.96
4.98
5.00
5.02
5.04
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (A)
Load Regulatio
n
V
IN
= 12V
V
OUT
=5V
0
20
40
60
80
100
0 5 10 15 20 25 30 35
CURRENT (µA)
INPUT VOLTAGE (V)
Shutdown Current
vs. Input Voltage
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
-50 -25 0 25 50 75 100 125
CURRENT (µA)
TEMPERATURE (°C)
Shutdown Current
vs. Te m p er at u r e
V
IN
=12V
V
SHDN
=V
IN
0
1
2
3
4
5
6
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (A)
Current Limit
Characteristic
V
IN
= 12V
196
197
198
199
200
201
202
0 5 10 15 20 25 30 35
FREQUENCY (kHz)
SUPPLY VOLTAGE (V)
Frequ ency vs.
Supply Voltage
180
190
200
210
220
-50 -25 0 25 50 75 100 125
FREQUENCY (kHz)
TEMPERATURE (°C)
Frequency vs.
Temperature
1.228
1.230
1.232
1.234
1.236
1.238
1.240
1.242
-50 -25 0 25 50 75 100 125 150
FEEDBACK VOLTAGE (V)
TEMPERATURE (°C)
Feedback Voltag e
vs. Temperature
V
IN
=12V
V
OUT
=5V
I
OUT
=1A
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
-50 -25 0 25 50 75 100 125
SATURATION VOLTAGE (V)
TEMPERATURE (°C)
Saturation Voltage
vs. Temperature
V
IN
=12V
V
OUT
=5V
I
LOAD
=1A
0
10
20
30
40
50
60
70
80
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
EFFICIENCY (%)
OUTPUT CURRENT (A)
3.3V Output
Efficiency
12V
6V
24V
0
10
20
30
40
50
60
70
80
90
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
EFFICIENCY (%)
OUTPUT CURRENT (A)
5V Output
Efficiency
7V
12V 24V
0
10
20
30
40
50
60
70
80
90
100
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
EFFICIENCY (%)
OUTPUT CURRENT (A)
12V Output
Efficiency
15V 24V
Micrel, Inc. MIC4680
March 2008 6 M9999-032808
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
0 5 10 15 20 25 30 35
OUTPUT CURRENT (A)
INPUT VOLTAGE (V)
Saf
e
Operating Area
V
OUT
=5V
T
A
=60°C
Demonstration
board layout
Minimum
Current Limit
Note
Functional Characteristics
Frequency Foldback
The MIC4680 folds the switching frequency back during a
hard short-circuit condition to reduce the energy per cycle
and protect the device.
Micrel, Inc. MIC4680
March 2008 7 M9999-032808
Bode Plots
The following bode plots show that the MIC4680 is stable over all conditions using a 68µF inductor (L) and a 220µF
output capacitor (C
OUT
). To assure stability, it is a good practice to maintain a phase margin of greater than 35°.
Micrel, Inc. MIC4680
March 2008 8 M9999-032808
Functional Diagrams
SW
GND
FB
C
OUT
V
IN
IN
V
OUT
MIC4680-x.x
Internal
Regulator
SHDN
200kHz
Oscillator
Thermal
Shutdown
Reset
Current
Limit
Com-
parator
Error
Amp
1A
Switch
Driver
1.23V
Bandgap
Reference
Fixed Regulator
SW
FB
R1
R2
C
OUT
V
IN
IN
V
OUT
MIC4680 [adj.]
Internal
Regulator
SHDN
200kHz
Oscillator
Thermal
Shutdown
Reset
Current
Limit
Com-
parator
Error
Amp
1A
Switch
Driver
1.23V
Bandgap
Reference
VV
R1
R2 1
R1 R2 V
V1
V 1.23V
OUT REF
OUT
REF
REF
=+
⎛
⎝
⎜⎞
⎠
⎟
=-
⎛
⎝
⎜
⎞
⎠
⎟
=
Adjustable Regulator
Micrel, Inc. MIC4680
March 2008 9 M9999-032808
Functional Description
The MIC4680 is a variable duty cycle switch-mode
regulator with an internal power switch. Refer to the
block diagrams.
Supply Voltage
The MIC4680 operates from a +4V to +34V unregulated
input. Highest efficiency operation is from a supply
voltage around +15V. See the efficiency curves.
Enable/Shutdown
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 1.5µA when V
SHDN
= V
IN
= 12V and 30µA when V
SHDN
= 5V. See “Shutdown Input
Behavior: Shutdown Hysteresis.”
Feedback
Fixed-voltage versions of the regulator have an internal
resistive divider from the feedback (FB) pin. Connect FB
directly to the output voltage.
Adjustable versions require an external resistive voltage
divider from the output voltage to ground, center tapped
to the FB pin. See Figure 6b for recommended resistor
values
Duty Cy cle 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.
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 comparator output. A lower feedback voltage
increases the duty cycle. The MIC4680 uses a voltage-
mode control architecture.
Output Switching
When the internal switch is on, an increasing current
flows from the supply V
IN
, through external storage
inductor L1, to output capacitor C
OUT
and the load.
Energy is stored in the 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
recovery diode D1, charging C
OUT
.
Output Capacitor
External output capacitor C
OUT
provides stabilization and
reduces ripple. See “Bode Plots” for additional
information.
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.
Micrel, Inc. MIC4680
March 2008 10 M9999-032808
Applications Information
Adjustable Regulators
Adjustable regulators require a 1.23V feedback signal.
Recommended voltage-divider resistor values for
common output voltages are included in Figure 1b.
For other voltages, the resistor values can be
determined using the following formulas:
⎟
⎠
⎞
⎜
⎝
⎛+= 1
R2
R1
VV
REFOUT
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−= 1
V
V
R2R1
REF
OUT
,
1
V
V
R1
2R
REF
OUT
−
=
V
REF
= 1.23V
SW
L1
IN
FB
GND
SHDN C
OUT
R1
R2D1
V
OUT
MIC4680BM
C
IN
V
IN
SHUTDOWN
ENABLE
5–8
4
32
1
Figure 1a. Adjustable Regulator Circuit
V
OUT
R1*† R2*† C
IN
D1 L1 C
OUT
1.8V 3.01k 6.495k
2.5V 3.01k 2.915k
3.3V 3.01k 1.788k
5.0V 3.01k 982Ω
6.0V 3.01k 776Ω
15µF 35V
AVX TPSE156035R0200
2A 60V Schottky
B260A Vishay-Diode, Inc***
or
SS26 General Semiconductor
68µH 1.5A
Coiltronics UP2B-680
or
Sumida CDRH125-680MC**
or
Sumida CDRH124-680MC**
220µF 10V
AVX TPSE227010R0060
* All resistors 1%
** Shielded magnetics for low RFI applications
*** Vishay-Diode, Inc. (805) 446-48600
† Nearest available resistor values
Figure 1b. Recommended Components for Common Output Voltages
Micrel, Inc. MIC4680
March 2008 11 M9999-032808
Thermal Considerations
The MIC4680 SuperSwitcher features the power-SOIC-
8. This package has a standard 8-pin small-outline
package profile but with much higher power dissipation
than a standard SOIC-8. The MIC4680 SuperSwitcher is
the first dc-to-dc converter to take full advantage of this
package.
The reason that the power SOIC-8 has higher power
dissipation (lower thermal resistance) is that pins 5
though 8 and the die-attach paddle are a single piece of
metal. The die is attached to the paddle with thermally
conductive adhesive. This provides a low thermal
resistance path from the junction of the die to the ground
pins. This design significantly improves package power
dissipation by allowing excellent heat transfer through
the ground leads to the printed circuit board.
One of the limitation of the maximum output current on
any MIC4680 design is the junction-to-ambient thermal
resistance (θ
JA
) of the design (package and ground
plane).Examining θ
JA
in more detail:
θ
JA
= (θ
JC
+ θ
CA
)
where:
θ
JC
= junction-to-case thermal resistance
θ
CA
= case-to-ambient thermal resistance
θ
JC
is a relatively constant 20°C/W for a power SOIC-8.
θ
CA
is dependent on layout and is primarily governed by
the connection of pins 5 though 8 to the ground plane.
The purpose of the ground plane is to function as a heat
sink.
θ
JA
is ideally 63°C/W but will vary depending on the size
of the ground plane to which the power SOIC-8 is
attached.
Determining Ground-Plane Heat-Sink Area
There are two methods of determining the minimum
ground plane area required by the MIC4680.
Quick Method
Make sure that MIC4680 pins 5 though 8 are connected
to a ground plane with a minimum area of 6cm
2
. This
ground plane should be as close to the MIC4680 as
possible. The area maybe distributed in any shape
around the package or on any pcb layer as long as there
is good thermal contact to pins 5 though 8. This ground
plane area is more than sufficient for most designs.
JA
JC CA
AMBIENT
printed circuit board
ground plane
heat sink area
SOIC-8
Figure 2. Power SOIC-8 Cross Sectio n
Minimum Copper/Maximum Current Method
Using Figure 3, for a given input voltage range,
determine the minimum ground-plane heat-sink area
required for the application’s maximum output current.
Figure 3 assumes a constant die temperature of 75°C
above ambient.
0
0.5
1.0
1.5
0 5 10 15 20 25
OUTPUT CURRENT (I)
AREA (cm
2
)
12V
8V
34V
24V
T
A
=50°C
Minimum Current Limit = 1.3A
Figure 3. Output Curren t vs. Ground Plane Area
When designing with the MIC4680, it is a good practice
to connect pins 5 through 8 to the largest ground plane
that is practical for the specific design.
Checking the Maximum Junction Temperature:
For this example, with an output power (P
OUT
) of 5W, (5V
output at 1A maximum with V
IN
= 12V) and 65°C
maximum ambient temperature, what is the maximum
junction temperature?
Referring to the “Typical Characteristics: 5V Output
Efficiency” graph, read the efficiency (η) for 1A output
current at V
IN
= 12V or perform you own measurement.
η = 79%
The efficiency is used to determine how much of the
output power (P
OUT
) is dissipated in the regulator circuit
(P
D
).
Micrel, Inc. MIC4680
March 2008 12 M9999-032808
OUT
OUT
D
P
η
P
P−=
5W
0.79
5W
P
D
−=
1.33WP
D
=
Calculate the worst-case junction temperature:
T
J
= P
D(IC)
θ
JC
+ (T
C
– T
A
) + T
A(max)
where:
T
J
= MIC4680 junction temperature
P
D(IC)
= MIC4680 power dissipation
θ
JC
= junction-to-case thermal resistance.
The θ
JC
for the MIC4680’s power-SOIC-8
is approximately 20°C/W. (Also see Figure
1.)
T
C
= “pin” temperature measurement taken at
the entry point of pins 6 or 7 into the
plastic package at the ambient
temperature (T
A
) at which T
C
is measured.
T
A
= ambient temperature at which T
C
is
measured.
T
A(max)
= maximum ambient operating temp. for
the specific design.
Calculating the maximum junction temperature given a
maximum ambient temperature of 65°C:
TJ = 1.064 × 20°C/W + (45°C – 25°C) + 65°C
TJ = 106.3°C
This value is less than the allowable maximum operating
junction temperature of 125°C as listed in “Operating
Ratings.” Typical thermal shutdown is 160°C and is
listed in “Electrical Characteristics.”
Increasing the Maximum Output Current
The maximum output current at high input voltages can
be increased for a given board layout. The additional
three components shown in Figure 4 will reduce the
overall loss in the MIC4680 by about 20% at high V
IN
and high I
OUT
.
Even higher output current can be achieved by using the
MIC4680 to switch an external FET. See Figure 9 for a
5A supply with current limiting.
Layout Considerations
Layout is very important when designing any switching
regulator. Rapidly changing switching currents through
the printed circuit board traces and stray inductance can
generate voltage transients which can cause problems.
To minimize stray inductance and ground loops, keep
trace lengths, indicated by the heavy lines in Figure 5, as
short as possible. For example, keep D1 close to pin 3
and pins 5 through 8, keep L1 away from sensitive node
FB, and keep C
IN
close to pin 2 and pins 5 though 8. See
“Applications Information: Thermal Considerations” for
ground plane layout.
The feedback pin should be kept as far way from the
switching elements (usually L1 and D1) as possible.
A circuit with sample layouts is provided. See Figure 6a
through 6e.
SWIN
FB
GND
SHDN
D1
1N4148
2.2nF
MIC4680BM
5678
3
Figure 4. Increasing Maxim um Output Current
at High Input Voltages
Load
SW
L1
68µH
IN
FB
GND
SHDN
C
OUT
R1
R2D1
V
OUT
MIC4680BM
GND
C
IN
V
IN
+4V to +34V
Power
SOIC-8
5678
4
32
1
Figure 5. Critical Traces for L ayout
SW
L1
68µH
IN
FB
GND
SHDN
D1
B260A
or
SS26
J2
V
OUT
1A
J4
GND
U1 MIC4680BM
C2
0.1µF
50V
C1
15µF
35V
J1
V
IN
4V to +34V
J3
GND
SOIC-8 5–8
4
32
1
S1
NKK G12AP
ON
OFF
C4
220µF
10V
C3*
optional
C5
0.1µF
50V
R1
3.01k
R2
6.49k
JP1a
1.8V
R6
optional
R3
2.94k
R4
1.78k
R5
JP1b
2.5V
JP1c
3.3V
JP1d
5.0V
1
2
3
4
5
6
7
8
* C3 can be used to provide additional stability
and improved transient response.
Figure 6a. Evaluation Board Schematic Diagram
Micrel, Inc. MIC4680
March 2008 13 M9999-032808
Printed Circuit Board Layouts
Figure 6b. Top-Sid e Silk Screen Figure 6d. Bottom-Sid e Silk Screen
Figure 6c. Top-Side Copper Figure 6e. Bottom-Side Copper
Abbreviated Bill of Materials
(Critical Components)
Reference Part Number Manufacturer Description Qty.
TPSD156M035R0300 AVX
1
15µF 35V C1
ECE-A1HFS470 Panasonic
2
47µF 50V, 8mm × 11.5mm
1
C4 TPSD227M010R0150 AVX 220µF 10V 1
B260A Vishay-Diodes, Inc.
3
Schottky D1
SS26 General Semiconductor
1
UP2B-680 Coiltronics
4
68µH, 1.5A, nonshielded
CDH115-680MC Sumida
5
68µH, 1.5A, nonshielded
L1
CDRH124-680MC Sumida 68µH, 1.5A, shielded
1
U1 MIC4680BM Micrel
(6)
1A 200kHz power-SO-8 buck regulator 1
Notes:
1. AVX: www.avxcorp.com
2. Panasonic: www.maco.panasonic.co.jp/eccd/index.html
3. Vishay-Diodes, Inc.: www.diodes.com
4. Coiltronics: www.coiltronics.com
5. Sumida: www.sumida.com
6. Micrel, Inc.: www.micrel.com
Micrel, Inc. MIC4680
March 2008 14 M9999-032808
Application Circuits
For continuously updated circuits using the MIC4680, see Application Hint 37 at www.micrel.com.
J1
+34V max.
Figure 7. Constant Curren t and Constant Voltage Battery Cha rg er
Figure 8. +12V to –12V/150mA Buck-Boost Converter
SWIN
FB
GND
3.3V/5A
GND
U1 MIC4680BM MIC4417BM4 Si4425DY
+4.5V to +17V
SOIC-8 5–8
4
32
1
* I
SAT
= 8A
SHDN
Figure 9. 5V to 3.3V/5A Pow er Supply
Micrel, Inc. MIC4680
March 2008 15 M9999-032808
Package Information
8-Pin SOIC (M)
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use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
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