MIC4680 [MICREL]
1A 200kHz SuperSwitcher⑩ Buck Regulator Final Information; 1A 200kHz的SuperSwitcher⑩降压稳压器最终信息
| 型号： | MIC4680 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 1A 200kHz SuperSwitcher⑩ Buck Regulator Final Information |
| 文件： | 总16页 (文件大小：278K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC4680
1A 200kHz SuperSwitcher™ Buck Regulator
Final Information
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-lead SOP (small outline package).
• 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
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.
• Thermal shutdown
• Overcurrent protection
Applications
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.
• 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
The MIC4680 is available in the 8-lead SOP with a
–40°C to +125°C junction temperature range.
• Higher output current regulator using external FET
Typical Applications
MIC4680-3.3BM
L1
+6V to +34V
3.3V/1A
2
3
4
IN
SW
C1
15µF
68µH
C2
220µF
16V
35V
SHUTDOWN
ENABLE
1
SHDN
GND
FB
D1
B260A or
SS26
Power
SOP-8
5–8
Fixed Regulator Circuit
MIC4680BM
L1
+5V to +34V
2.5V/1A
2
1
3
4
IN
SW
C1
15µF
35V
68µH
R1
C2
220µF
16V
3.01k
SHUTDOWN
ENABLE
SHDN
FB
D1
R2
2.94k
GND
5–8
B260A or
SS26
Power
SOP-8
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
Voltage
Adjustable
3.3V
Junction Temp. Range
–40°C to +125°C
Package
8-lead SOP
8-lead SOP
8-lead SOP
MIC4680BM
MIC4680-3.3BM
MIC4680-5.0BM
–40°C to +125°C
5.0V
–40°C to +125°C
Pin Configuration
SHDN
1
2
3
4
8
7
6
5
GND
GND
GND
GND
IN
SW
FB
SOP-8 (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
3
VIN
SW
Supply Voltage (Input): Unregulated +4V to +34V supply voltage.
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
MIC4680
2
June 2000
MIC4680
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Voltage (V ), Note 3 ......................................+38V
Supply Voltage (V ), Note 4 .......................... +4V to +34V
IN
IN
Shutdown Voltage (V
) .......................... –0.3V to +38V
Junction Temperature (T ) ...................................... +125°C
SHDN
J
Steady-State Output Switch Voltage (V ) ..................–1V
Package Thermal Resistance (θ ), Note 6............63°C/W
SW
JA
Feedback Voltage [Adjustable] (V ) ..........................+12V
FB
Storage Temperature (T ) ....................... –65°C to +150°C
S
ESD, Note 5
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
MIC4680 [Adjustable]
Feedback Voltage
(±1%)
(±2%)
1.217 1.230 1.243
1.205 1.255
V
V
8V ≤ VIN ≤ 34V, 0.1A ≤ ILOAD ≤ 1A, VOUT = 5V
1.193 1.230 1.267
V
V
1.180
1.280
Maximum Duty Cycle
VFB = 1.0V
93
97
50
4
%
Output Leakage Current
VIN = 34V, VSHDN = 5V, VSW = 0V
VIN = 34V, VSHDN = 5V, VSW = –1V
VFB = 1.5V
500
20
µA
mA
mA
Quiescent Current
MIC4680-3.3
7
12
Output Voltage
(±1%)
(±3%)
3.266
3.201
3.3
3.3
3.333
3.399
V
V
6V ≤ VIN ≤ 34V, 0.1A ≤ ILOAD ≤ 1A
3.168
3.135
3.432
3.465
V
V
Maximum Duty Cycle
VFB = 2.5V
93
97
50
4
%
Output Leakage Current
VIN = 34V, VSHDN = 5V, VSW = 0V
VIN = 34V, VSHDN = 5V, VSW = –1V
VFB = 4.0V
500
20
µA
mA
mA
Quiescent Current
MIC4680-5.0
7
12
Output Voltage
(±1%)
(±3%)
4.950
4.85
5.0
5.0
5.05
5.15
V
V
8V ≤ VIN ≤ 34V, 0.1A ≤ ILOAD ≤ 1A
4.800
4.750
5.200
5.250
V
V
Maximum Duty Cycle
VFB = 4.0V
93
97
50
4
%
Output Leakage Current
VIN = 34V, VSHDN = 5V, VSW = 0V
VIN = 34V, VSHDN = 5V, VSW = –1V
VFB = 6.0V
500
20
µA
mA
mA
Quiescent Current
7
12
June 2000
3
MIC4680
MIC4680
Micrel
Parameter
Condition
Min
Typ
Max
Units
MIC4680/-3.3/-5.0
Frequency Fold Back
Oscillator Frequency
Saturation Voltage
30
50
200
1.4
100
220
1.8
kHz
kHz
180
I
OUT = 1A
V
V
Short Circuit Current Limit
Standby Quiescent Current
VFB = 0V, see Test Circuit
VSHDN = VIN
1.3
2
1.8
1.5
2.5
A
µA
µA
V
VSHDN = 5V (regulator off)
regulator off
30
100
Shutdown Input Logic Level
Shutdown Input Current
Thermal Shutdown
1.6
regulator on
1.0
0.8
10
10
V
VSHDN = 5V (regulator off)
VSHDN = 0V (regulator on)
–10
–10
–0.5
–1.5
160
µA
µA
°C
Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Absolute maximum rating is intended for voltage transients only, prolonged dc operation is not recommended.
Note 4. = V + 2.5V or 4V whichever is greater.
V
IN(min)
OUT
Note 5. Devices are ESD sensitive. Handling precautions recommended.
Note 6. Measured on 1" square of 1 oz. copper FR4 printed circuit board connected to the device ground leads.
Note 7. Test at T = +85°C, guaranteed by design, and characterized to T = +125°C.
A
J
Test Circuit
Device Under Test
68µH
+12V
2
1
3
4
IN
SW
SHUTDOWN
ENABLE
SHDN
FB
I
GND
5–8
SOP-8
Current Limit Test Circuit
Shutdown Input Behavior
OFF
ON
GUARANTEED
GUARANTEED
ON
OFF
0.8V
1V
2V
TYPICAL
ON
TYPICAL
OFF
0V
1.6V
VIN(max)
Shutodwn Hysteresis
MIC4680
4
June 2000
MIC4680
Micrel
Typical Characteristics
Shutdown Current
vs. Input Voltage
Line Regulation
Load Regulation
5.06
5.04
5.02
5.00
4.98
4.96
100
80
60
40
20
0
IOUT = 1.0A
5.05
5.04
5.03
5.02
5.01
5.00
4.99
4.98
4.97
4.96
VIN = 12V
VOUT = 5V
0
5
10 15 20 25 30 35
INPUT VOLTAGE (V)
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 35
INPUT VOLTAGE (V)
Shutdown Current
vs. Temperature
Current Limit
Characteristic
Frequency vs.
Supply Voltage
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
6
5
4
3
2
1
0
202
201
200
199
198
197
196
VIN = 12V
SHDN = VIN
V
VIN = 12V
-50 -25
0
25 50 75 100 125
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
OUTPUT CURRENT (A)
0
5
10 15 20 25 30 35
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
Frequency vs.
Temperature
Feedback Voltage
vs. Temperature
Saturation Voltage
vs. Temperature
220
1.242
1.240
1.238
1.236
1.234
1.232
1.230
1.228
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
210
200
190
180
VIN = 12V
VOUT = 5V
ILOAD = 1A
VIN = 12V
VOUT = 5V
IOUT = 1A
-50 -25
0
25 50 75 100 125
-50 -25
0
25 50 75 100 125 150
-50 -25
0
25 50 75 100 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
3.3V Output
Efficiency
5V Output
Efficiency
12V Output
Efficiency
80
70
60
50
40
30
20
10
0
90
100
90
80
70
60
50
40
30
20
10
0
80
70
60
50
40
30
20
10
0
7V
6V
24V
15V
24V
24V
12V
12V
0
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)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
OUTPUT CURRENT (A)
June 2000
5
MIC4680
MIC4680
Micrel
Safe
Operating Area
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Minimum
Current Limit
Note
VOUT = 5V
A = 60°C
Demonstration
board layout
T
0
5
10
15
20
25
30
35
INPUT VOLTAGE (V)
Note. For increased output current, see “Applications Information:
Increasing the Maximum Output Current” and Figure 3.
Functional Characteristics
Switching Frequency Foldback
Load Transient
VIN = 12V
VOUT = 5V
IOUT = 1.0A to 0.1A
Normal
5.1V
Operation
5V
1A
0A
200kHz
Short
Circuit
Operation
60kHz
TIME
TIME (100ms/div.)
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.
MIC4680
6
June 2000
MIC4680
Micrel
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 ). To assure stability, it is a good practice to maintain a phase margin of greater than 35°.
OUT
No-Load Stability
Full-Load Stability
Phase Margin = 106°
Phase Margin = 114°
L = 68µF
COUT = 220µF
L = 68µF
COUT = 220µF
VIN = 7V
VOUT = 5.0V
IOUT = 1.0A
VIN = 7V
VOUT = 5.0V
IOUT = 0.0A
TIME (100ms/div.)
TIME (100ms/div.)
No-Load Stability
Full-Load Stability
Phase Margin = 117°
Phase Margin = 69°
L = 68µF
COUT = 220µF
L = 68µF
COUT = 220µF
VIN = 12V
VIN = 12V
VOUT = 5.0V
IOUT = 0.0A
VOUT = 5.0V
IOUT = 1.0A
TIME (100ms/div.)
TIME (100ms/div.)
No-Load Stability
Full-Load Stability
Phase Margin = 125°
Phase Margin = 71°
L = 68µF
COUT = 220µF
L = 68µF
COUT = 220µF
VIN = 34V
VOUT = 5.0V
IOUT = 1.0A
VIN = 34V
VOUT = 5.0V
IOUT = 1.0A
TIME (100ms/div.)
TIME (100ms/div.)
June 2000
7
MIC4680
MIC4680
Micrel
Block Diagrams
VIN
IN
SHDN
Internal
Regulator
200kHz
Oscillator
Thermal
Shutdown
Current
Limit
Com-
parator
VOUT
COUT
SW
FB
Driver
1A
Switch
Reset
Error
Amp
1.23V
Bandgap
Reference
MIC4680-x.x
GND
Fixed Regulator
VIN
IN
SHDN
Internal
Regulator
R1
R2
V
= V
REF
+1
OUT
V
OUT
R1= R2
−1
200kHz
Oscillator
Thermal
Shutdown
Current
Limit
V
REF
V
= 1.23V
REF
Com-
parator
VOUT
COUT
SW
Driver
1A
Switch
Reset
R1
R2
FB
Error
Amp
1.23V
Bandgap
Reference
MIC4680 [adj.]
Adjustable Regulator
MIC4680
8
June 2000
MIC4680
Micrel
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. The MIC4680 uses a voltage-mode control architec-
ture.
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.
Output Switching
Enable/Shutdown
When the internal switch is on, an increasing current flows
from the supply V through external storage inductor L1, to
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
IN,
output capacitor C
and the load. Energy is stored in the
OUT
inductor as the current increases with time.
current to typically 1.5µA when V
= V = 12V and 30µA
When the internal switch is turned off, the collapse of the
magnetic field in L1 forces current to flow through fast
SHDN
IN
whenV
=5V. See“ShutdownInputBehavior:Shutdown
SHDN
Hysteresis.”
recovery diode D1, charging C
.
OUT
Feedback
Output Capacitor
Fixed-voltage versions of the regulator have an internal
resistive divider from the feedback (FB) pin. Connect FB
directly to the output voltage.
External output capacitor C
reduces ripple. See “Bode Plots” for additional information.
provides stabilization and
OUT
Return Paths
Adjustable versions require an external resistive voltage
dividerfromtheoutputvoltagetoground,centertappedtothe
FB pin. See Figure 6b for recommended resistor values.
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.
June 2000
9
MIC4680
MIC4680
Micrel
Applications Information
Adjustable Regulators
Adjustable regulators require a 1.23V feedback signal. Rec-
ommended voltage-divider resistor values for common out-
put voltages are included in Figure 1b.
MIC4680BM
VIN
CIN
L1
VOUT
2
1
3
4
For other voltages, the resistor values can be determined
using the following formulas:
IN
SW
R1
R2
SHUTDOWN
ENABLE
SHDN
GND
FB
COUT
D1
R1
V
= V
+1
5–8
OUT
REF
R2
V
OUT
R1= R2
−1
Figure 1a. Adjustable Regulator Circuit
V
REF
V
= 1.23V
REF
VOUT R1*
R2*
CIN
D1
L1
COUT
68µH 1.5A
1.8V 3.01k 6.49k
2.5V 3.01k 2.94k
3.3V 3.01k 1.78k
5.0V 3.01k 976Ω
6.0V 3.01k 787Ω
2A 60V Schottky
Coiltronics UP2B-680
15µF 35V
AVX TPSE156035R0200
220µF 10V
AVX TPSE227010R0060
B260A Vishay-Diode, Inc.***
or
SS26 General Semiconductor
or
Sumida CDRH125-680MC**
or
Sumida CDRH124-680MC**
*
All resistors 1%
** shielded magnetics for low RFI applications
*** Vishay-Diode, Inc. (805) 446-4800
Figure 1b. Recommended Components for Common Ouput Voltages
MIC4680
10
June 2000
MIC4680
Micrel
Thermal Considerations
Minimum Copper/Maximum Current Method
The MIC4680 SuperSwitcher features the power-SOP-8.
This package has a standard 8-lead small-outline package
profile but with much higher power dissipation than a stan-
dardSOP-8.TheMIC4680SuperSwitcheristhefirstdc-to-dc
converter to take full advantage of this package.
UsingFigure3, foragiveninputvoltagerange, determinethe
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
12V
8V
The reason that the power SOP-8 has higher power dissipa-
tion (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 im-
proves package power dissipation by allowing excellent heat
transfer through the ground leads to the printed circuit board.
1.0
0.5
0
24V
34V
TA = 50°C
Minimum Current Limit = 1.3A
0
5
10
15
20
25
2
One of the limitation of the maximum output current on any
MIC4680 design is the junction-to-ambient thermal resis-
AREA (cm )
Figure 3. Output Current vs. Ground Plane Area
tance (θ ) of the design (package and ground plane).
JA
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.
Examining θ in more detail:
JA
θ
= (θ + θ
)
CA
JA
JC
where:
Checking the Maximum Junction Temperature:
θ
θ
= junction-to-case thermal resistance
= case-to-ambient thermal resistance
JC
For this example, with an output power (P
) of 5W, (5V
OUT
output at 1A maximum with V = 12V) and 65°C maximum
CA
IN
ambient temperature, what is the maximum junction tem-
perature?
θ
θ
is a relatively constant 20°C/W for a power SOP-8.
JC
is dependent on layout and is primarily governed by the
CA
Referring to the “Typical Characteristics: 5V Output Effi-
ciency” graph, read the efficiency (η) for 1A output current at
connection of pins 5 though 8 to the ground plane. The
purpose of the ground plane is to function as a heat sink.
V
= 12V or perform you own measurement.
IN
θ
isideally63°C/Wbutwillvarydependingonthesizeofthe
JA
η = 79%
ground plane to which the power SOP-8 is attached.
The efficiency is used to determine how much of the output
Determining Ground-Plane Heat-Sink Area
power (P
) is dissipated in the regulator circuit (P ).
OUT
D
There are two methods of determining the minimum ground
plane area required by the MIC4680.
P
OUT
P =
−P
OUT
D
Quick Method
η
Make sure that MIC4680 pins 5 though 8 are connected to a
ground plane with a minimum area of 6cm . This ground
5W
2
PD =
− 5W
0.79
plane should be as close to the MIC4680 as possible. The
area maybe disributed 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.
P = 1.33W
D
A worst-case rule of thumb is to assume that 80% of the total
output power dissipation is in the MIC4680 (P
is in the diode-inductor-capacitor circuit.
) and 20%
D(IC)
P
P
P
= 0.8 P
D
D(IC)
D(IC)
D(IC)
= 0.8 × 1.33W
= 1.064W
SOP-8
Calculate the worst-case junction temperature:
T = P + (T – T ) + T
θ
J
D(IC) JC
C
A
A(max)
where:
T = MIC4680 junction temperature
J
P
= MIC4680 power dissipation
D(IC)
θJA
θ
= junction-to-case thermal resistance.
ground plane
heat sink area
JC
θJC
θCA
AM
BIENT
The θ for the MIC4680’s power-SOP-8 is
JC
approximately 20°C/W. (Also see Figure 1.)
T = “pin” temperature measurement taken at the
C
entry point of pins 6 or 7 into the plastic package
MIC4680
printed circuit board
Figure 2. Power SOP-8 Cross Section
June 2000
11
MIC4680
at the ambient temperature (T ) at which T is
Micrel
components shown in Figure 4 will reduce the overall loss in
A
C
measured.
the MIC4680 by about 20% at high V and high I
.
IN
OUT
T = ambient temperature at which T is measured.
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.
A
C
T
= maximum ambient operating temperature
A(max)
for the specific design.
Layout Considerations
Calculating the maximum junction temperature given a
maximum ambient temperature of 65°C:
Layout is very important when designing any switching regu-
lator.Rapidlychangingswitchingcurrentsthroughtheprinted
circuit board traces and stray inductance can generate volt-
age transients which can cause problems.
T = 1.064 × 20°C/W + (45°C – 25°C) + 65°C
J
T = 106.3°C
J
This value is less than the allowable maximum operating
junction temperature of 125°C as listed in “Operating Rat-
ings.” Typical thermal shutdown is 160°C and is listed in
“Electrical Characteristics.”
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
Increasing the Maximum Output Current
C
close to pin 2 and pins 5 though 8. See “Applications
IN
The maximum output current at high input voltages can be
increased for a given board layout. The additional three
Information: Thermal Considerations” for ground plane lay-
out.
Thefeedbackpinshouldbekeptasfarwayfromtheswitching
elements (usually L1 and D1) as possible.
A circuit with sample layouts are provided. See Figure 6a
though 6e.
MIC4680BM
3
IN
SW
D1
1N4148 82Ω
SHDN
FB
2.2nF
GND
5
6 7 8
Figure 4. Increasing Maximum Output Current at High Input Voltages
VIN
MIC4680BM
L1
VOUT
COUT R1
+4V to +34V
2
1
3
4
IN
SW
68µH
CIN
SHDN
GND
FB
D1
R2
Power
SOP-8
5
6 7 8
GND
Figure 5. Critical Traces for Layout
J1
VIN
J2
VOUT
1A
U1 MIC4680BM
L1
4V to +34V
2
1
3
4
IN
SW
C2
0.1µF
50V
68µH
C3*
optional
R1
C1
15µF
35V
J3
GND
3.01k
OFF
ON
SHDN
FB
C4
220µF
10V
C5
0.1µF
50V
S1
NKK G12AP
D1
R6
R2
R3
2.94k
R4
1.78k
R5
GND
5–8
B260A optional 6.49k
or
976Ω
SOP-8
1
3
5
SS26
JP1a
1.8V
JP1b
JP1c7 JP1d
3.3V 5.0V
2.5V
J4
GND
8
2
4
6
* C3 can be used to provide additional stability
and improved transient response.
Figure 6a. Evaluation Board Schematic Diagram
MIC4680
12
June 2000
MIC4680
Micrel
Printed Circuit Board Layouts
Figure 6d. Bottom-Side Silk Screen
Figure 6b. Top-Side Silk Screen
Figure 6c. Top-Side Copper
Figure 6e. Bottom-Side Copper
Abbreviated Bill of Material (Critical Components)
Reference
Part Number
Manufacturer
Description
Qty
C1
TPSD156M035R0300
ECE-A1HFS470
AVX1
Panasonic2
15µF 35V
47µF 50V, 8mm × 11.5mm
1
C4
D1
TPSD227M010R0150
AVX
220µF 10V
1
1
B260A
SS26
Vishay-Diodes, Inc.3
General Semiconductor
Schottky
L1
UP2B-680
CDH115-680MC
CDRH124-680MC
Coiltronics4
Sumida5
68µH, 1.5A, nonshielded
68µH, 1.5A, nonshielded
68µH, 1.5A, shielded
1
1
Sumida5
U1
MIC4680BM
Micrel Semiconductor6
1A 200kHz power-SO-8 buck regulator
1
2
3
4
5
6
AVX: http://www.avxcorp.com
Panasonic: http://www.maco.panasonic.co.jp/eccd/index.html
Vishay-Diodes, Inc., tel: (805) 446-4800, http://www.diodes.com
Coiltronics, tel: (561) 241-7876, http://www.coiltronics.com
Sumida, tel: (408) 982-9960, http://www.sumida.com
Micrel, tel: (408) 944-0800, http://www.micrel.com
June 2000
13
MIC4680
MIC4680
Micrel
Applications Circuits*
For continuously updated circuits using the MIC4680, see Application Hint 37 at www.micrel.com.
C5
D3
1N4148
220nF
J2
J1
R1
5V ±2%
MIC4680BM
L1
+34V max.
0.100Ω
800mA ±5%
2
1
3
4
IN
SW
C4
10nF
100µH
R7
4.99k
C2
100nF
C1
22µF
35V
J3
GND
C3
220µF
OFF
ON
D1
SHDN
GND
FB
MMBR140LT3
10V
S1
NKK G12AP
D2
4
5
2
R2
1N4148
lphone
3.01k
e
T
SOP-8
5–8
R4
U2
16.2k
3
R3
976Ω
U3
MIC6211BM5
R5
221k
LM4041DIM3-1.2
Ceular
o
T
R6
10k
J4
GND
Figure 7. Constant Current and Constant Voltage Battery Charger
J1
J3
U1 MIC4680BM
L1
+12V
GND
2
1
3
4
IN
SW
33µH
C3
0.022µF
50V
R1
8.87k
C4
68µF
20V
C5
33µF
35V
C1
68µF
20V
C2
0.1µF
SHDN
FB
D1
R2
1k
GND
5–8
ES1B
1A 100V
J4
SOP-8
–12V/150mA
J2
GND
Figure 8. +12V to –12V/150mA Buck-Boost Converter
+4.5V to +17V
U2
U1 MIC4680BM MIC4417BM4
Si4425DY
L1*
2
3
R2
IN
SW
C1
330µF
25V
20mΩ
3.3V/5A
50µH
C4
SHUTDOWN
ENABLE
1
4
SHDN
FB
C2
C3
220µF
16V
1000pF
D1
5A
220µF
R3
1k
1%
R4
1k
1%
R7
3.01k
1%
R1
1k
GND
16V
SOP-8
5–8
C5
0.1µF
R6
16k 1%
D2
* ISAT = 8A
1N4148
U3
R8
R5
16k
1%
MIC6211BM5 1.78k
1%
GND
Figure 9. 5V to 3.3V/5A Power Supply
* See Application Hint 37 for bills of material.
MIC4680
14
June 2000
MIC4680
Micrel
June 2000
15
MIC4680
MIC4680
Micrel
Package Information
0.026 (0.65)
MAX)
PIN 1
0.157 (3.99)
0.150 (3.81)
DIMENSIONS:
INCHES (MM)
0.020 (0.51)
0.013 (0.33)
0.050 (1.27)
TYP
45°
0.0098 (0.249)
0.0040 (0.102)
0.010 (0.25)
0.007 (0.18)
0°–8°
0.197 (5.0)
0.189 (4.8)
0.050 (1.27)
0.016 (0.40)
SEATING
PLANE
0.064 (1.63)
0.045 (1.14)
0.244 (6.20)
0.228 (5.79)
8-Lead SOP (M)
MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
© 2000 Micrel Incorporated
MIC4680
16
June 2000
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