MIC4684YMTR [MICREL]
SWITCHING REGULATOR, 225kHz SWITCHING FREQ-MAX, PDSO8, LEAD FREE, SOP-8;
| 型号： | MIC4684YMTR |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | SWITCHING REGULATOR, 225kHz SWITCHING FREQ-MAX, PDSO8, LEAD FREE, SOP-8 开关 光电二极管 |
| 文件： | 总16页 (文件大小：482K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC4684
2A High-Efficiency SuperSwitcher™ Buck Regulator
General Description
Features
The MIC4684 is a high-efficiency 200kHz stepdown (buck)
switching regulator. Power conversion efficiency of above
85% is easily obtainable for a wide variety of applications.
The MIC4684 achieves 2Aof continuous current in an 8-lead
SO (small outline) package at 60°C ambient temperature.
• SO-8 package with 2A continuous output current
• Over 85% efficiency
• Fixed 200kHz PWM operation
• Wide 4V to 30V input voltage range
• Output voltage adjustable to 1.235V
• All surface mount solution
• Internally compensated with fast transient response
• Over-current protection
• Frequency foldback short-circuit protection
• Thermal shutdown
Highefficiencyismaintainedoverawideoutputcurrentrange
byutilizingaboostcapacitortoincreasethevoltageavailable
to saturate the internal power switch. As a result of this high
efficiency, no external heat sink is required. The MIC4684,
housed in an SO-8, can replace larger TO-220 and TO-263
packages in many applications.
Applications
The MIC4684 allows for a high degree of safety. It has a wide
input voltage range of 4V to 30V (34V transient), allowing
it to be used in applications where input voltage transients
may be present. Built-in safety features include over-current
protection, frequency-foldback short-circuit protection, and
thermal shutdown.
• Simple high-efficiency step-down regulator
• 5V to 3.3V/1.7A converter (60°C ambient)
• 12V to 1.8V/2A converter (60°C ambient)
• On-card switching regulator
• Dual-output ±5V converter
• Battery charger
The MIC4684 is available in an 8-lead SO package with a
junction temperature range of –40°C to +125°C.
Ordering Information
Part Number
Voltage Junction Temp. Range Package
Standard Pb-Free
MIC4684BM MIC4684YM
Adj
-40°C to +125°C
SOP-8
Typical Application
VIN
Efficiency
MIC4684BM
CBS
6.5V to 25V
vs. Output Current
3
4
1
5
0.33µF/50V
VIN
BS
SW
FB
VOUT
2.5V/1.5A
100
VOUT = 3.3V
8
EN
68µH
R1
80
60
40
20
0
CIN
33µF
35V
3.01k
330µF
6.3V
R2
3.01k
GND
2, 6, 7
VOUT = 1.8V
VOUT = 2.5V
3A
40V
Adjustable Buck Converter
VIN = 5.0V
0
0.5
1
1.5
2
OUTPUT CURRENT (A)
Efficiency vs. Output Current
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
January 2010
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Micrel, Inc.
MIC4684
Pin Configuration
SW
GND
VIN
1
2
3
4
8
7
6
5
EN
GND
GND
FB
BS
8-Pin SOP (M)
Pin Description
Pin Number
Pin Name
Pin Function
1
SW
Switch (Output): Emitter of NPN output switch. Connect to external storage
inductor and Shottky diode.
2, 6, 7
GND
IN
Ground
3
4
Supply (Input): Unregulated +4V to 30V supply voltage (34V transient)
BS
Booststrap Voltage Node (External Component): Connect to external boost
capacitor.
5
8
FB
EN
Feedback (Input): Outback voltage feedback to regulator. Connect to output
of supply for fixed versions. Connect to 1.23V tap of resistive divider for
adjustable versions.
Enable (Input): Logic high = enable; logic low = shutdown
Bootstrap (BS, pin 4)
Detailed Pin Description
Switch (SW, pin 1)
The bootstrap pin in conjunction with the external bootstrap
capacitor provides a bias voltage higher than the input volt-
agetotheMIC4684’smainNPNpasselement.Thebootstrap
capacitor sees the dv/dt of the switching action at the SW
pin as an AC voltage. The bootstrap capacitor then couples
the AC voltage back to the BS pin plus the dc offset of V
where it is rectified and used to provide additional drive to
the main switch, in this case a NPN transistor.
The switch pin is tied to the emitter of the main internal NPN
transistor. This pin is biased up to the input voltage minus the
V
ofthemainNPNpasselement.Theemitterisalsodriven
SAT
negative when the output inductor’s magnetic field collapses
at turn-off. During the OFF time the SW pin is clamped by
the output schottky diode to a –0.5V typically.
IN
Ground (GND, pins 2,6,7)
ThisadditionaldrivereducestheNPN’ssaturationvoltageand
There are two main areas of concern when it comes to the
ground pin, EMI and ground current. In a buck regulator
or any other non-isolated switching regulator the output
capacitor(s) and diode(s) ground is referenced back to the
switchingregulator’sorcontroller’sgroundpin.Anyresistance
between these reference points causes an offset voltage/IR
drop proportional to load current and poor load regulation.
This is why its important to keep the output grounds placed
as close as possible to the switching regulator’s ground pin.
To keep radiated EMI to a minimum its necessary to place
the input capacitor ground lead as close as possible to the
switching regulators ground pin.
increases efficiency, from a V
of 1.8V, and 75% efficiency
SAT
to a V
of 0.5V and 88% efficiency respectively.
SAT
Feedback (FB, pin 5)
The feedback pin is tied to the inverting side of a GM error
amplifier. The noninverting side is tied to a 1.235V bandgap
reference. Fixed voltage versions have an internal voltage
divider from the feedback pin.Adjustable versions require an
external resistor voltage divider from the output to ground,
with the center tied to the feedback pin.
Enable (EN, pin 8)
The enable (EN) input is used to turn on the regulator and is
TTL compatible. Note: connect the enable pin to the input if
unused. A logic-high enables the regulator. A logic-low shuts
down the regulator and reduces the stand-by quiescent
input current to typically 150µA. The enable pin has an up-
per threshold of 2.0V minimum and lower threshold of 0.8V
maximum. The hysterisis provided by the upper and lower
thresholds acts as an UVLO and prevents unwanted turn on
of the regulator due to noise.
Input Voltage (V , pin 3)
IN
The V pin is the collector of the main NPN pass element.
IN
Thispinisalsoconnectedtotheinternalregulator.Theoutput
diode or clamping diode should have its cathode as close as
possible to this point to avoid voltage spikes adding to the
voltage across the collector.
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Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Voltage (V ), Note 3.......................................+34V
Supply Voltage (V ) Note 4............................ +4V to +30V
IN
IN
Enable Voltage (V )......................................–0.3V to +V
Ambient Temperature (T ).......................... –40°C to +85°C
EN
IN
A
Steady-State Output Switch Voltage (V ).........–1V to V
Junction Temperature (T )........................ –40°C to +125°C
SW
IN
J
Feedback Voltage (V ) ..............................................+12V
Package Thermal Resistance
FB
Storage Temperature (T ) ........................ –65°C to +150°C
θ , Note 5 ..........................................................75°C/W
S
JA
ESD Rating............................................................... Note 3
ꢀ θ , Note 5 ..........................................................25°C/W
JC
Electrical Characteristics
VIN = VEN = 12V, VOUT = 5V; IOUT = 500mA; TA = 25°C, unless otherwise noted. Bold values indicate –40°C ≤ TJ ≤ +125°C.
Parameter
Condition
Min
1.210 1.235 1.260
1.198 1.272
1.186 1.235 1.284
Typ
Max
Units
Feedback Voltage
(±2%)
(±3%)
V
V
8V ≤ VIN ≤ 30V, 0.1A ≤ ILOAD ≤ 1A, VOUT = 5V
V
V
1.173
1.297
Feedback Bias Current
Maximum Duty Cycle
Output Leakage Current
50
94
nA
%
VFB = 1.0V
VIN = 30V, VEN = 0V, VSW = 0V
VIN = 30V, VEN = 0V, VSW = –1V
VFB = 1.5V
5
500
20
µA
mA
mA
mA
V
1.4
6
Quiescent Current
12
Bootstrap Drive Current
Bootstrap Voltage
VFB = 1.5V, VSW = 0V
IBS = 10mA, VFB = 1.5V, VSW = 0V
VFB = 0V
250
5.5
30
380
6.2
50
Frequency Fold Back
Oscillator Frequency
Saturation Voltage
120
225
kHz
kHz
V
180
200
0.59
IOUT = 1A
Short Circuit Current Limit
Shutdown Current
VFB = 0V, See Test Circuit
VEN = 0V
2.2
A
150
µA
V
Enable Input Logic Level
regulator on
2
regulator off
0.8
50
V
Enable Pin Input Current
Thermal Shutdown @ TJ
VEN = 0V (regulator off)
VEN = 12V (regulator on)
16
µA
mA
°C
–1
–0.83
160
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. Devices are ESD sensitive. Handling precautions recommended.
Note 4. 2.5V of headroom is required between V and V
. The headroom can be reduced by implementing a feed-forward diode a seen on the 5V
OUT
IN
to 3.3V circuit on page 1.
Note 5. Measured on 1” square of 1 oz. copper FR4 printed circuit board connected to the device ground leads.
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MIC4684
Test Circuit
Device Under Test
68µH
+12V
3
1
4
VIN
SW
8
EN
BS
I
GND
FB
5
SOP-8
2,6,7
Current Limit Test Circuit
Shutdown Input Behavior
ON
OFF
GUARANTEED
GUARANTEED
OFF
ON
0.8V
1.25V
2V
TYPICAL
OFF
TYPICAL
ON
0V
1.4V
VIN(max)
Enable Hysteresis
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Typical Characteristics
(T = 25°C unless otherwise noted)
A
5VOUT Efficiency without Feed
3.3VOUT Efficiency without
Feed Forward Diode
5VIN Efficiency with Feed
Forward Diode
Forward Diode
100
100
95
90
85
80
75
70
65
60
55
50
100
95
90
85
80
75
70
65
60
55
50
95
VIN = 8V
VOUT = 3.3V
90
85
VIN = 8V
VOUT = 2.5V
80
VIN = 12V
75
70
VIN = 12V
VIN = 24V
65
60
55
50
VIN = 24V
VOUT = 1.8V
VIN = 5.0V
VOUT = 5V
1.2 1.4 1.6
VOUT = 3.3V
0
0.2 0.4 0.6 0.8
1
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
0
0.5
1
1.5
2
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Efficiency vs. Output Current
with Feed Forward Diode
Bootstrap Voltage
vs. Input Voltage
Bootstrap Drive Current
vs. Input Voltage
7
6
5
4
3
2
1
0
350
300
250
200
150
100
50
100
90
80
70
60
50
40
30
20
10
0
5VOUT
3.3VOUT
2.5VOUT
1.8VOUT
VIN = 12V
VIN = 12V
VFB = 1.5V
VIN = 12V
2.5
VFB = 1.5V
0
0
10 15 20 25 30
INPUT VOLTAGE (V)
0
2
4
6
8 10 12 14 16 18 20
0
0.5
1
1.5
2
3
5
INPUT VOLTAGE (V)
OUTPUT CURRENT (A)
Minimum Duty Cycle
vs. Input Voltage
Reference Voltage
vs. Input Voltage
Quiescent Current
vs. Input Voltage
10.9
10.8
10.7
10.6
10.5
10.4
10.3
1.255
1.250
1.245
1.240
1.235
1.230
1.225
6.3
6.2
6.1
6
VIN = 12V
VOUT = 5V
VFB = 1.3V
5.9
5.8
5.7
VIN = 12V
VOUT = VREF
IOUT = 500mA
VEN= 5V
0
5
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
0
5
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
0
5
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
Shutdown Current
vs. Input Voltage
Saturation Voltage
vs. Input Voltage
Foldback Frequency
vs. Input Voltage
200
180
160
140
120
100
80
605
600
595
590
585
580
575
570
51.5
51
50.5
50
49.5
49
60
40
IOUT = 1A
VOUT = 5V
VFB = 0V
20
VEN = 0V
0
48.5
0
5
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
0
5
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
0
5
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
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MIC4684
Feedback Voltage
vs. Temperature
Shutdown Hysteresis
vs. Temperature
Load Regulation
5.020
5.018
5.016
5.014
5.012
5.010
5.008
5.006
5.004
5.002
5.000
1.210
1.209
1.208
1.207
1.206
1.205
1.204
6
5
VIN = 12V
ON
4
3
2
1.203 VIN = 12V
1
OFF
VOUT =V FB
IOUT = 100mA
1.202
1.201
1.200
0
-1
0
0.2 0.4 0.6 0.8
1
1.2 1.4
-50
0
50
100 150 200
OUTPUT CURRENT (A)
TEMPERATURE (°C)
TEMPERATURE (°C)
Enable Threshold
vs. Temperature
Line Regulation
5.08
5.07
5.06
5.05
5.04
5.03
5.02
5.01
5
1.2
1.18
1.16
1.14
1.12
1.1
Upper Threshold
Lower Threshold
VIN = 12V
1.08
1.06
1.04
1.02
1
VOUT = 5V
4.99
IOUT = 500mA
IOUT = 100mA
4.98
0
5
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
TEMPERATURE (°C)
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Typical 5VOUT SOA with
Standard Configuration
Typical 3.3VOUT SOA with
Feed Forward Diode
2.5
2
2.5
2
TA = 25°C
1.5
1
1.5
1
VOUT = 5V
TA = 60°C
TJ = 125°C
VOUT = 3.3V
TA = 60°C
TJ = 125°C
0.5
0.5
0
0
0
5
10 15 20 25 30 35
INPUT VOL T AGE (V)
0
10
15
20
5
INPUT VOLTAGE (V)
SOA Measured on the MIC4684 Evaluation Board.
SOA Measured on the MIC4684 Evaluation Board.
Typical 2.5VOUT SOA with
Typical 1.8VOUT SOA with
Feed Forward Diode
Feed Forward Diode
2.5
2.5
2
1.5
1
2
1.5
1
VOUT = 1.8V
VOUT = 2.5V
0.5
0.5
TA = 60°C
T
A = 60°C
TJ = 125°C
10
INPUT VOLTAGE (V)
TJ = 125°C
0
0
0
15
20
0
10
15
20
5
5
INPUT VOLTAGE (V)
SOA measured on the MIC4684 Evaluation Board.
SOA measured on the MIC4684 Evaluation Board.
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MIC4684
Functional Characteristics
Switching Frequency Foldback
Load Transient
VIN = 12V
OUT = 5V
OUT = 1.0A to 0.1A
V
I
Normal
Operation
5.1V
5V
200kHz
1A
0A
Short
Circuit
Operation
70kHz
TIME
TIME (100ms/div.)
Frequency Foldback
The MIC4684 folds the switching frequency back during a hard short
circuit condition to reduce the energy per cycle and protect the device.
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MIC4684
Micrel, Inc.
Block Diagrams
VIN
IN
Bootstrap
Charger
Enable
Internal
Regulator
R1
R2
VOUT = VREF
+1
)
(
VOUT
R1=R2
- 1
)
(
200kHz
Oscillator
Thermal
Shutdown
Current
Limit
VREF
VREF =1.235V
Com-
parator
VOUT
SW
Driver
COUT
Reset
R1
R2
FB
Error
Amp
1.235V
Bandgap
Reference
MIC4684
Adjustable Regulator
waveform to produce a voltage controlled variable duty cycle
output.
Functional Description
The MIC4684 is a variable duty cycle switch-mode regula-
tor with an internal power switch. Refer to the above block
diagram.
Ahigherfeedbackvoltageincreasestheerroramplifieroutput
voltage. A higher error amplifier voltage (comparator invert-
ing 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 MIC4684 uses a voltage-mode control architecture.
Supply Voltage
The MIC4684 operates from a +4V to +30V (34V transient)
unregulatedinput.Highestefficiencyoperationisfromasupply
voltage around +12V. See the efficiency curves on page 5.
Output Switching
Enable/Shutdown
When the internal switch is ON, an increasing current flows
The enable (EN) input is TTL compatible. Tie the input high
if unused. A logic-high enables the regulator. A logic-low
shuts down the internal regulator which reduces the current
from the supply V through external storage inductor L1, to
IN,
output capacitor C
and the load. Energy is stored in the
OUT
inductor as the current increases with time.
to typically 150µA when V = 0V.
EN
When the internal switch is turned OFF, the collapse of the
magneticfieldinL1forcescurrenttoflowthroughfastrecovery
Feedback
Fixed-voltageversionsoftheregulatorhaveaninternalresis-
tive divider from the feedback (fb) pin. Connect fb directly
to the output voltage.
diode D1, charging C
.
OUT
Output Capacitor
External output capacitor C
reduces ripple.
provides stabilization and
OUT
Adjustable versions require an external resistive voltage
divider from the output voltage to ground, center tapped to
the fb pin. See Table 1 and Table 2 for recommended resis-
tor values.
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 1.235V bandgap voltage reference. The resulting error
amplifier output voltage is compared to a 200kHz sawtooth
January 2010
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MIC4684
Examining θ in more detail:
Applications Information
Adjustable Regulators
JA
θ
= (θ + θ
)
JA
JC
CA
where:
Adjustable regulators require a 1.23V feedback signal. Rec-
ommendedvoltage-dividerresistorvaluesforcommonoutput
voltages are included in Table 1.
θ
θ
= junction-to-case thermal resistance
= case-to-ambient thermal resistance
JC
CA
ꢀ
For other voltages, the resistor values can be determined
using the following formulas:
θ
θ
is a relatively constant 25°C/W for a power SOP-8.
JC
is dependent on layout and is primarily governed by the
CA
R1
R2
connection of pins 2, 6, and 7 to the ground plane. The pur-
pose of the ground plane is to function as a heat sink.
VOUT = VREF
+1
θ
is ideally 75°C/W, but will vary depending on the size of
JA
VOUT
R1 = R2
−1
the ground plane to which the power SOP-8 is attached.
V
REF
Determining Ground-Plane Heat-Sink Area
VREF = 1.235V
Minimum Pulse Width
Make sure that MIC4684 pins 2, 6, and 7 are connected to
a ground plane with a minimum area of 6cm . This ground
2
plane should be as close to the MIC4684 as possible. The
area may be distributed in any shape around the package
or on any pcb layer as long as there is good thermal contact
to pins 2, 6, and 7. This ground plane area is more than suf-
ficient for most designs.
The minimum duty cycle of the MIC4684 is approximately
10%. See Minimum Duty Cycle Graph. If this input-to-output
voltage characteristic is exceeded, the MIC4684 will skip
cycles to maintain a regulated V
.
OUT
Max. V for a Given V
for
IN
OUT
Constant-Frequency Switching
40
35
30
25
20
15
10
5
SOP-8
θJA
0
0
1
2
3
4
5
6
ground plane
AMBIENTheat sink area
θJC
θCA
OUTPUT VOLTAGE (V)
Figure 1. Minimum Pulse Width Characteristic
Thermal Considerations
printed circuit board
The MIC4684 SuperSwitcher™ features the power-SOP-8.
This package has a standard 8-lead small-outline package
profile,butwithmuchhigherpowerdissipationthanastandard
SOP-8.Micrel’sMIC4684SuperSwitcher™familyarethefirst
dc-to-dc converters to take full advantage of this package.
Figure 2. Power SOP-8 Cross Section
When designing with the MIC4684, it is a good practice to
connect pins 2, 6, and 7 to the largest ground plane that is
practical for the specific design.
The reason that the power SOP-8 has higher power dissipa-
tion (lower thermal resistance) is that pins 2, 6, and 7 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
ofthedietothegroundpins.Thisdesignsignificantlyimproves
packagepowerdissipationbyallowingexcellentheattransfer
through the ground leads to the printed circuit board.
Checking the Maximum Junction Temperature:
For this example, with an output power (P
) of 5W, (5V
OUT
output at 1A with V = 12V) and 60°C maximum ambient
IN
temperature, what is the junction temperature?
Referringtothe“TypicalCharacteristics:5VOutputEfficiency”
graph, read the efficiency (η) for 1A output current at V
12V or perform you own measurement.
=
IN
η = 84%
OnelimitationofthemaximumoutputcurrentonanyMIC4684
The efficiency is used to determine how much of the output
design is the junction-to-ambient thermal resistance (θ ) of
JA
power (P
) is dissipated in the regulator circuit (P ).
the design (package and ground plane).
OUT
D
P
OUT
P =
−P
OUT
D
η
5W
PD =
− 5W
0.84
P = 0.95W
D
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Aworst-case rule of thumb is to assume that 80% of the total
Thisvalueiswithintheallowablemaximumoperatingjunction
temperatureof125°Caslistedin“OperatingRatings.”Typical
thermal shutdown is 160°C and is listed in Electrical Charac-
teristics. Also see SOA curves on pages 7 through 8.
output power dissipation is in the MIC4684 (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)
Layout Considerations
= 0.8 × 0.95W
Layout is very important when designing any switching regu-
lator. Rapidly changing currents through the printed circuit
board traces and stray inductance can generate voltage
transients which can cause problems.
= 0.76W
Calculate the worst-case junction temperature:
T = P + (T – T ) + T
θ
J
D(IC) JC
C
A
A(max)
where:
T = MIC4684 junction temperature
To minimize stray inductance and ground loops, keep trace
lengths as short as possible. For example, keep D1 close
to pin 1 and pins 2, 6, and 7, keep L1 away from sensitive
J
P
= MIC4684 power dissipation
D(IC)
node FB, and keep C close to pin 3 and pins 2, 6, and 7.
IN
θ
= junction-to-case thermal resistance.
JC
See Applications Information: Thermal Considerations for
ground plane layout.
The θ for the MIC4684’s power-SOP-8 is approximately
25°C/W.
JC
The feedback pin should be kept as far way from the switch-
ing elements (usually L1 and D1) as possible.
T = “pin” temperature measurement taken at the
C
A circuit with sample layouts are provided. See Figure 7.
Gerber files are available upon request.
entry point of pins 2, 6 or 7
T = ambient temperature
A
Feed Forward Diode
T
= maximum ambient operating temperature
A(max)
TheFFdiode(feedforward)providesanexternalbiassource
directly to the main pass element, this reduces V
allowing the MIC4684 to be used in very low head-room ap-
for the specific design.
thus
SAT
Calculating the maximum junction temperature given a
maximum ambient temperature of 60°C:
plications I.E. 5V to 3.3V
IN
OUT.
T = 0.76 × 25°C/W + (41°C – 25°C) + 60°C
J
T = 95°C
J
VIN
+4V to +30V
MIC4684BM
(34V transient)
3
4
1
IN
BS
L1
VOUT
R1
8
EN
SW
CIN
68µH
COUT
5
FB
Power
SOP-8
GND
D1
2
6
7
R2
GND
Figure 5. Critical Traces for Layout
January 2010
11
M9999-012610
Micrel, Inc.
MIC4684
Recommended Components for a Given Output Voltage (Feed-Forward Configuration)
V
= 4V to 16V (in feed-forward configuration)
IN
VOUT IOUT
R1
R2
VIN
CIN
D1
D2
L1
COUT
5.0V 1.6A 3.01k 976kΩ
3.3V 1.7A 3.01k 1.78k
2.5V 1.8A 3.01k 2.94k
6.5V–16V 47µF, 20V
Vishay-Dale
2A, 30V 1A, 20V
Schottky Schottky Sumida
27µH
120µF, 6.3V
Vishay-Dale
594D127X06R3C2T
595D476X0020D2T
SS23
MBRX120 CDH74-270MC
4.85V–16V 47µF, 20V
Vishay-Dale
2A, 30V 1A, 20V
Schottky Schottky Sumida
27µH
220µF, 6.3V
Vishay-Dale
594D227X06R3C2T
595D476X0020D2T
SS23
MBRX120 CDH74-270MC
4.5V–16V 47µF, 20V
Vishay-Dale Schottky
2A, 30V 1A, 20V
Schottky Sumida
27µH
Vishay-Dale
330µF, 6.3V
595D476X0020D2T
SS23
2A, 30V 1A, 20V
Schottky Schottky Sumida
SS23 MBRX120 CDH74-270MC
MBRX120 CDH74-270MC
594D337X06R3D2T
1.8V
2A
3.01k 6.49k
4.2V–16V 47µF, 20V
Vishay-Dale
27µH
330µF, 6.3V
Vishay-Dale
594D337X06R3D2T
595D476X0020D2T
Note 1. This bill of materials assumes the use of feedforward schotty diode from V to the bootstrap pin.
IN
Table 1. Recommended Components for Common Ouput Voltages
(V = 4V to 16V)
IN
D2
MBRX120
1A/20V
J1
VIN
4V to +16V
J2
VOUT
2A
L1
47µH
U1 MIC4684BM
3
1
VIN
SW
C6
0.33µF
50V
4
5
C2
0.1µF
50V
BS
FB
C3*
R1
optional
C1
15µF
35V
J3
GND
3.01k
ON
8
EN
C4
330µF
6.3V
C5
0.1µF
50V
OFF
D1
R2
6.49k
R3
2.94k
R4
1.78k
R5
976Ω
GND
2, 6, 7
B340A
or
SOP-8
1
2
3
5
SS34
JP1a
1.8V
JP1b
2.5V
JP1c7
JP1d
5.0V
3.3V
J4
GND
8
4
6
* C3 can be used to provide additional stability
and improved transient response.
Note: optimized for 5VOUT
Figure 6. 4V - 16V Input Evaluation Board Schematic Diagram
January 2010
12
M9999-012610
MIC4684
Micrel, Inc.
Printed Circuit Board
Evaluation Board Optimized for Low Input Voltage by using Feed-Forward Diode Configuration (V = 4V to 16V)
IN
Figure 7a. Bottom Side Copper
Figure 7b. Top Side Copper
Figure 7c. Bottom Side Silk Screen
Figure 7d. Top Side Silk Screen
Abbreviated Bill of Material (Critical Components)
Reference
C1
Part Number
Manufacturer
Vishay Sprague(1)
Vitramon
Description
Qty
1
594D156X0035D2T
VJ0805Y104KXAAB
GRM426X7R334K50
Optional
15µF 35V
C2, C5
C6
0.1µF 50V
2
Murata
0.33µF, 50V ceramic capacitor
1800pF, 50V ceramic
330µF, 6.3V, tantalum
Schottky 3A, 40V
C3
(1)
1
C4
594D337X06R3D2T
B340A
Vishay Sprague(2)
Diode Inc(3)
D1
1
D2
MBRX120
Micro Com. Components(5)
Sumida(4)
Micrel, Inc.(6)
Schottky 1A, 20V
1
L1
CDRH104R-470MC
MIC4684BM
47µH, 2.1A ISAT
1
U1
1A 200kHz power-SO-8 buck regulator
1
Notes:
1. Vishay Dale, Inc., tel: 1 402-644-4218, http://www.vishay.com
2. Vishay Sprague, Inc., tel: 1 207-490-7256, http://www.vishay.com
3. Diodes Inc, tel: (805) 446-4800, http://www.diodes.com
4. Sumida, tel: (408) 982-9960, http://www.sumida.com
5. Micro Commercial Components, tel: (800) 346-3371
6. Micrel, Inc. tel: (408) 944-0800, http://www.micrel.com
January 2010
13
M9999-012610
Micrel, Inc.
MIC4684
Recommended Components for a Given Output Voltage (Standard Configuration)
V
= 4V to 30V
IN
VOUT IOUT
R1
R2
VIN
CIN
D1
L1
COUT
5.0V
3.3V
2.5V
1.8V
1.7A 3.01k 976kΩ
8V–30V
33µF, 35V
Vishay-Dale
595D336X0035R2T
3A, 40V
Schotty
SS34
68µH
Sumida
CDRH104R-680MC
120µF, 6.3V
Vishay-Dale
594D127X06R3C2T
1.5A 3.01k
1.5A 3.01k
1.5A 3.01k
1.78k
2.94k
6.49k
7V–28V
6.5V–23V
6V–17V
33µF, 35V
Vishay-Dale
595D336X0035R2T
3A, 40V
Schotty
SS34
68µH
Sumida
CDRH104R-680MC
220µF, 6.3V
Vishay-Dale
594D227X06R3C2T
33µF, 35V
Vishay-Dale
595D336X0035R2T
3A, 40V
Schotty
SS334
68µH
Sumida
CDRH104R-680MC
330µF, 6.3V
Vishay-Dale
594D337X06R3D2T
47µF, 25V
Vishay-Dale
595D476X0025D2T
3A, 40V
Schotty
SS334
68µH
Sumida
CDRH104R-680MC
330µF, 6.3V
Vishay-Dale
594D337X06R3D2T
Table 2. Recommended Components for Common Ouput Voltages
(V = 4V to 30V)
IN
J1
VIN
L1
J2
VOUT
2A
4V to +30V
(34V transient)
U1 MIC4684BM
47µH
3
1
VIN
SW
C6
0.33µF
50V
4
5
C2
0.1µF
50V
BS
FB
C3*
R1
optional
C1
15µF
35V
J3
GND
3.01k
ON
8
EN
C4
330µF
6.3V
C5
0.1µF
50V
OFF
D1
R2
6.49k
R3
2.94k
R4
1.78k
R5
976Ω
GND
2, 6, 7
B340A
or
SOP-8
1
2
3
5
SS34
JP1a
1.8V
JP1b
2.5V
JP1c7 JP1d
3.3V 5.0V
J4
GND
8
4
6
* C3 can be used to provide additional stability
and improved transient response.
Note: optimized for 5VOUT
Figure 8. 4V - 30V Input Evaluation Board Schematic Diagram
January 2010
14
M9999-012610
MIC4684
Micrel, Inc.
Printed Circuit Board
General Purpose Evaluation Board (V = 4V to 30V)
IN
Figure 9a. Bottom Side Copper
Figure 9b. Top Side Copper
Figure 9c. Bottom Side Silk Screen
Figure 9d. Top Side Silk Screen
Abbreviated Bill of Material (Critical Components)
Reference
C1
Part Number
Manufacturer
Vishay Sprague(1)
Vitramon
Description
Qty
1
594D156X0035D2T
VJ0805Y104KXAAB
GRM426X7R334K50
Optional
15µF 35V
C2, C5
C6
0.1µF 50V
2
Murata
0.33µF, 50V ceramic capacitor
1800pF, 50V ceramic
330µF, 6.3V, tantalum
Schottky 3A 40V
C3
(1)
1
C4
594D337X06R3D2T
B340A
Vishay Sprague(2)
Diode Inc(3)
D1
1
L1
CDRH104R-470MC
MIC4684BM
Sumida(4)
Micrel, Inc.(5)
47µH, 2.1A ISAT
1
U1
1A 200kHz power-SO-8 buck regulator
1
Notes:
1. Vishay Dale, Inc., tel: 1 402-644-4218, http://www.vishay.com
2. Vishay Sprague, Inc., tel: 1 207-490-7256, http://www.vishay.com
3. Diodes Inc, tel: (805) 446-4800, http://www.diodes.com
4. Sumida, tel: (408) 982-9960, http://www.sumida.com
5. Micrel, Inc. tel: (408) 944-0800, http://www.micrel.com
January 2010
15
M9999-012610
Micrel, Inc.
MIC4684
Package Information
8-Lead SOP (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
This 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 Purchaser's
use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2001 Micrel Incorporated
January 2010
16
M9999-012610
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