MIC4680 DATA SHEET (11/05/2015) DOWNLOAD

MIC4680
1A 200kHz SuperSwitcher™
Buck Regulator
General Description
Features
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 minimum 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.
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•
•
•
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•
•
•
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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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
Power
SOIC-8
MIC4680-3.3BM
2
1
IN
SHDN
SW
3
FB
4
L1
68µH
GND
5–8
D1
B260A or
SS26
Fixed Regulator Circuit
3.3V/1A
C2
220µF
16V
+5V to +34V
C1
15µF
35V
SHUTDOWN
ENABLE
Power
SOIC-8
2
1
MIC4680BM
IN
SW
SHDN
FB
GND
5–8
3
L1
2.5V/1A
68µH
R1
3.01k
4
D1
B260A or
SS26
R2
2.94k
C2
220µF
16V
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
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 Configuration
SHDN 1
8 GND
IN 2
7 GND
SW 3
6 GND
FB 4
5 GND
8-Pin SIOC (M)
Pin Description
Pin Number
Pin Name
1
SHDN
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
March 2008
Pin Function
Shutdown (Input): Logic low enables regulator. Logic high (>1.6V) shuts down
regulator.
Ground
2
M9999-032808
Micrel, Inc.
MIC4680
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN)(3) ..................................................+38V
Shutdown Voltage (VSHDN)............................. –0.3V to +38V
Steady-State Output Switch Voltage (VSW) ....................–1V
Feedback Voltage [Adjustable] (VFB) ...........................+12V
Storage Temperature (Ts) .........................–65°C to +150°C
EDS Rating(5)
Supply voltage (VIN)(4)....................................... +4V to +34V
Junction Temperature (TJ) ....................................... +125°C
Package Thermal Resistance(6)
SIOC (θJA)..........................................................63°C/W
Electrical Characteristics
VIN = 12V; ILOAD = 500mA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C, Note 7; unless noted.
Parameter
Condition
Min
Typ
Max
Units
(±1%)
(±1%)
1.217
1.205
1.230
1.243
1.255
V
V
8V ≤ VIN ≤ 34V, 0.1A ≤ ILOAD ≤ 1A, VOUT = 5V
1.193
1.180
1.230
1.267
1.280
V
V
MIC4680 [Adjustable]
Feedback Voltage
Maximum Duty Cycle
VFB = 1.0V
Output Leakage Current
VIN = 34V, VSHDN = 5V, VSW = 0V
50
500
µA
VIN = 34V, VSHDN = 5V, VSW = –1V
4
20
mA
VFB = 1.5V
7
12
mA
Quiescent Current
93
97
%
MIC4680-3.3
Output Voltage
(±1%)
(±3%)
3.266
3.201
3.3
3.333
3.399
V
V
6V ≤ VIN ≤ 34V, 0.1A ≤ ILOAD ≤ 1A
3.168
3.135
3.3
3.432
3.465
V
V
93
97
Maximum Duty Cycle
VFB = 2.5V
Output Leakage Current
VIN = 34V, VSHDN = 5V, VSW = 0V
50
500
µA
VIN = 34V, VSHDN = 5V, VSW = –1V
4
20
mA
VFB = 4.0V
7
12
mA
Quiescent Current
%
MIC4680-5.0
Output Voltage
(±1%)
(±3%)
4.950
4.85
5.0
5.05
5.15
V
V
8V ≤ VIN ≤ 34V, 0.1A ≤ ILOAD ≤ 1A
4.800
4.750
5.0
5.200
5.250
V
V
93
97
Maximum Duty Cycle
VFB = 4.0V
Output Leakage Current
VIN = 34V, VSHDN = 5V, VSW = 0V
Quiescent Current
%
50
500
µA
VIN = 34V, VSHDN = 5V, VSW = –1V
4
20
mA
VFB = 6.0V
7
12
mA
MIC4680/-3.3/-5.0
Frequency Fold Back
30
50
100
kHz
Oscillator Frequency
180
200
220
kHz
1.4
1.8
V
1.8
2.5
A
Saturation Voltage
IOUT = 1A
Short Circuit
Current Limit
VFB = 0V, see Test Circuit
Standby Quiescent
Current
VSHDN = VIN
1.5
VSHDN = 5V (regulator off)
30
March 2008
1.3
3
µA
100
µA
M9999-032808
Micrel, Inc.
MIC4680
Parameter
Condition
Min
Typ
Shutdown Input Logic
Level
regulator off
2
1.6
1.0
0.8
V
VSHDN = 5V (regulator off)
–10
–0.5
10
µA
VSHDN = 0V (regulator on)
–10
–1.5
10
µA
regulator on
Shutdown Input Current
Thermal Shutdown
160
Max
Units
V
°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. VIN(min) = VOUT + 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 TA = +85°C, guaranteed by design, and characterized to TJ = +125°C.
Test Circuit
+12V
SHUTDOWN
ENABLE
Device Under Test
2
IN
1
SHDN
SW
3
FB
4
68µH
I
GND
SOIC-8
5–8
Current Limit Test Circuit
Shutdown Input Behavior
OFF
ON
0.8V
0V
2V
1V
1.6V
VIN(max)
Shutdown Hysteresis
March 2008
4
M9999-032808
Micrel, Inc.
MIC4680
Typical Characteristics
4.99
4.98
4.97
4.96
3.5
3.0
5
10 15 20 25 30
INPUT VOLTAGE (V)
2.0
1.5
1.0
210
200
190
180
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
80
4
3
2
1
VIN = 12V
1.236
1.234
1.232
VIN = 12V
VOUT = 5V
IOUT = 1A
1.230
1.228
-50 -25 0 25 50 75 100 125 150
TEMPERATURE (°C)
40
30
20
10
70
60
12V
24V
7V
50
40
30
20
10
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
March 2008
0
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
5
EFFICIENCY (%)
50
24V 6V
35
Frequency vs.
Supply Voltage
198
197
0
5 10 15 20 25 30
SUPPLY VOLTAGE (V)
35
Saturation Voltage
vs. Temperature
1.4
1.2
1.0
0.8
0.6
0.4
0.2
VIN = 12V
VOUT = 5V
ILOAD = 1A
0
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
5V Output
Efficiency
90
EFFICIENCY (%)
12V
10 15 20 25 30
INPUT VOLTAGE (V)
199
1.6
80
60
5
200
196
Feedback Voltage
vs. Temperature
1.238
70
0
202
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
OUTPUT CURRENT (A)
1.240
3.3V Output
Efficiency
40
201
1.242
FEEDBACK VOLTAGE (V)
220
60
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
5
0
Frequency vs.
Temperature
0
Current Limit
Characteristic
6
VIN = 12V
VSHDN = VIN
80
20
Shutdown Current
vs. Temperature
0
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
FREQUENCY (kHz)
4.98
35
0.5
EFFICIENCY (%)
5.00
4.96
0
2.5
0
5.02
CURRENT (µA)
5.01
5.00
100
VIN = 12V
VOUT = 5V
FREQUENCY (kHz)
OUTPUT VOLTAGE (V)
5.03
5.02
4.0
CURRENT (µA)
5.04
IOUT = 1.0A
5.05
5.04
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
5.06
Shutdown Current
vs. Input Voltage
Load Regulation
SATURATION VOLTAGE (V)
Line Regulation
100
90
80
70
60
12V Output
Efficiency
15V
24V
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)
M9999-032808
Micrel, Inc.
MIC4680
Safe
Operating Area
1.5
Minimum
Current Limit
1.4
1.3
1.2
Note
OUTPUT CURRENT (A)
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
VOUT = 5V
TA = 60°C
Demonstration
board layout
0.3
0.2
0.1
0
0
5
10
15
20
25
INPUT VOLTAGE (V)
30
35
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.
March 2008
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M9999-032808
Micrel, Inc.
MIC4680
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 (COUT). To assure stability, it is a good practice to maintain a phase margin of greater than 35°.
March 2008
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M9999-032808
Micrel, Inc.
MIC4680
Functional Diagrams
V IN
IN
SHDN
Internal
Regulator
200kHz
Oscillator
Thermal
Shutdown
Current
Limit
Comparator
VOUT
SW
Driver
Reset
1A
Switch
COUT
FB
Error
Amp
1.23V
Bandgap
Reference
MIC4680-x.x
GND
Fixed Regulator
VIN
IN
SHDN
Internal
Regulator
200kHz
Oscillator
Thermal
Shutdown
⎛ R1 ⎞
VOUT = VREF ⎜
+ 1⎟
⎝ R2 ⎠
⎛V
⎞
R1 = R2 ⎜ OUT - 1⎟
⎝ VREF
⎠
Current
Limit
VREF = 1.23V
Comparator
VOUT
SW
Driver
Reset
1A
Switch
COUT
R1
FB
Error
Amp
1.23V
Bandgap
Reference
R2
MIC4680 [adj.]
Adjustable Regulator
March 2008
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M9999-032808
Micrel, Inc.
MIC4680
Functional Description
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 voltagemode control architecture.
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.
Output Switching
When the internal switch is on, an increasing current
flows from the supply VIN, through external storage
inductor L1, to output capacitor COUT 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 COUT.
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 VSHDN = VIN
= 12V and 30µA when VSHDN = 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
Output Capacitor
External output capacitor COUT 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.
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.
March 2008
9
M9999-032808
Micrel, Inc.
MIC4680
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:
V IN
⎛ R1 ⎞
VOUT = VREF ⎜
+ 1⎟
⎝ R2
⎠
2
MIC4680BM
IN
SW
L1
3
R1
CIN
SHUTDOWN
ENABLE
1
SHDN
FB
4
GND
⎛V
⎞
R1
R1 = R2⎜⎜ OUT − 1⎟⎟ , R2 =
V
OUT
⎝ VREF
⎠
−1
VREF
VOUT
D1
R2
COUT
5–8
Figure 1a. Adjustable Regulator Circuit
VREF = 1.23V
VOUT
R1*†
R2*†
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
*
CIN
D1
L1
COUT
68µH 1.5A
2A 60V Schottky
15µF 35V
AVX TPSE156035R0200
B260A Vishay-Diode, Inc***
or
SS26 General Semiconductor
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
March 2008
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M9999-032808
Micrel, Inc.
MIC4680
Thermal Considerations
The MIC4680 SuperSwitcher features the power-SOIC8. 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 (θJA) of the design (package and ground
plane).Examining θJA in more detail:
θJA = (θJC + θCA)
where:
θJC = junction-to-case thermal resistance
θCA = case-to-ambient thermal resistance
θJC is a relatively constant 20°C/W for a power SOIC-8.
θCA 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.
θJA 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 6cm2. 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.
March 2008
SOIC-8
JA
JC
CA
AM
BIE
N
ground plane
heat sink area
T
printed circuit board
Figure 2. Power SOIC-8 Cross Section
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.
1.5
OUTPUT CURRENT (I)
8V
1.0
12V
24V
34V
TA = 50°C
0.5
Minimum Current Limit = 1.3A
0
0
5
10
15
20
25
AREA (cm 2)
Figure 3. Output Current 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 (POUT) of 5W, (5V
output at 1A maximum with VIN = 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 VIN = 12V or perform you own measurement.
η = 79%
The efficiency is used to determine how much of the
output power (POUT) is dissipated in the regulator circuit
(PD).
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M9999-032808
Micrel, Inc.
MIC4680
POUT
− POUT
η
PD =
5W
− 5W
0.79
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 CIN 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.
PD = 1.33W
Calculate the worst-case junction temperature:
TJ = PD(IC)θJC + (TC – TA) + TA(max)
where:
TJ = MIC4680 junction temperature
PD(IC) = MIC4680 power dissipation
θJC = junction-to-case thermal resistance.
The θJC for the MIC4680’s power-SOIC-8
is approximately 20°C/W. (Also see Figure
1.)
TC = “pin” temperature measurement taken at
the entry point of pins 6 or 7 into the
plastic
package
at
the
ambient
temperature (TA) at which TC is measured.
TA = ambient temperature at which TC is
measured.
TA(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 VIN
and high IOUT.
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.
J1
VIN
4V to +34V
C1
15µF
35V
J3
GND
MIC4680BM
IN
SW
SHDN
2
OFF
ON
S1
NKK G12AP
1
IN
SW
SHDN
FB
GND
SOIC-8
5–8
D1
1N4148
FB
2.2nF
GND
5 6 7 8
Figure 4. Increasing Maximum Output Current
at High Input Voltages
V IN
+4V to +34V
MIC4680BM
2
CIN
1
IN
SHDN
SW
3
FB
4
L1
68µH
VOUT
COUT
D1
GND
Power
SOIC-8
R1
R2
5 6 7 8
GND
Figure 5. Critical Traces for Layout
U1 MIC4680BM
C2
0.1µF
50V
3
Load
PD =
J2
VOUT
1A
L1
3
68µH
4
D1
B260A
or
SS26
R6
optional
R2
6.49k
1
2
* C3 can be used to provide additional stability
and improved transient response.
C3*
optional
R1
3.01k
JP1a
1.8V
R3
2.94k
3
4
JP1b
2.5V
R4
1.78k
5
6
JP1c
3.3V
R5
7
8
JP1d
5.0V
C4
220µF
10V
C5
0.1µF
50V
J4
GND
Figure 6a. Evaluation Board Schematic Diagram
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M9999-032808
Micrel, Inc.
MIC4680
Printed Circuit Board Layouts
Figure 6b. Top-Side Silk Screen
Figure 6d. Bottom-Side Silk Screen
Figure 6c. Top-Side Copper
Figure 6e. Bottom-Side Copper
Abbreviated Bill of Materials (Critical Components)
Reference
Part Number
Manufacturer
Description
C1
TPSD156M035R0300
AVX1
15µF 35V
2
Qty.
1
ECE-A1HFS470
Panasonic
C4
TPSD227M010R0150
AVX
220µF 10V
1
D1
B260A
Vishay-Diodes, Inc.3
Schottky
1
SS26
General Semiconductor
UP2B-680
Coiltronics4
68µH, 1.5A, nonshielded
1
L1
U1
5
CDH115-680MC
Sumida
CDRH124-680MC
Sumida
MIC4680BM
Micrel
(6)
47µF 50V, 8mm × 11.5mm
68µH, 1.5A, nonshielded
68µH, 1.5A, shielded
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
March 2008
13
M9999-032808
Micrel, Inc.
MIC4680
Application Circuits
For continuously updated circuits using the MIC4680, see Application Hint 37 at www.micrel.com.
J1
+34V max.
Figure 7. Constant Current and Constant Voltage Battery Charger
Figure 8. +12V to –12V/150mA Buck-Boost Converter
+4.5V to +17V
U1 MIC4680BM MIC4417BM4
2
1
IN
SHDN
SW
3
FB
4
Si4425DY
3.3V/5A
GND
SOIC-8
5–8
* I SAT = 8A
GND
Figure 9. 5V to 3.3V/5A Power Supply
March 2008
14
M9999-032808
Micrel, Inc.
MIC4680
Package Information
8-Pin SOIC (M)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
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indemnify Micrel for any damages resulting from such use or sale.
© 2000 Micrel, Incorporated.
March 2008
15
M9999-032808