MIC4682YM-TR [MICREL]
1.1A SWITCHING REGULATOR, 220kHz SWITCHING FREQ-MAX, PDSO8;
| 型号： | MIC4682YM-TR |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 1.1A SWITCHING REGULATOR, 220kHz SWITCHING FREQ-MAX, PDSO8 开关 光电二极管 |
| 文件： | 总15页 (文件大小：907K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC4682
Precision Current Limit SOIC-8
SuperSwitcher™ Buck Regulator
General Description
Features
The MIC4682 is an easy-to-use step-down (buck) switch-
mode voltage regulator. It features a programmable
current limit that allows 10% current limit accuracy over its
full operating temperature range. The precision current
limit makes the MIC4682 ideal for constant-voltage
constant-current applications, such as simple battery
chargers. The precision current limit also gives designers
the ability to set the maximum output current below the
saturation current rating of the inductor. This allows the
use of the smallest possible inductors for a given
application, saving valuable space and cost.
• Programmable output current limit
10% accuracy over temperature
–
• Wide 4V to 34V operating input voltage range
• Fixed 200kHz PWM operation
• Power SOIC-8 package allows 2A continuous output
current
• All surface mount solution
• Internally compensated
• Less than 1µA typical shutdown-mode current
• Thermal shutdown protection
The MIC4682 is a very robust device. Its 4V to 34V input
voltage range allows the MIC4682 to safely be used in
applications where voltage transients may be present.
Additional protection features include cycle-by-cycle
current limiting and over-temperature shutdown. The
MIC4682 is available in a thermally optimized power
SOIC-8 package that allows it to achieve 2A of continuous
output current.
Applications
• Battery chargers
• White LED drivers
• Constant voltage constant current step-down
converters
The MIC4682 requires a minimum number of external
components and can operate using a standard series of
inductors. Compensation is provided internally for fast
transient response and ease of use. The MIC4682 is
available in the 8-pin power SOIC with a –40°C to +125°C
junction temperature range.
• Simple step-down regulator with precise current limit
• USB power supplies
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
___________________________________________________________________________________________________________
Typical Application
MIC4682 Current Limit
Characteristics
MIC4682
L1
+7.5V to +34V
5V/1A
5
8
1
IN
SW
6
5
4
3
2
1
0
C1
10µF
50V
68µH
R1
C2
220µF
10V
3.01k
4
SHDN
FB
(x2)
D1
B240
R2
976
R3
10M
ISET
GND
3
2, 6, 7
R4
16.2k
VIN = 12V
0
0.5
1
1.5
2
CURRENT LIMIT (A)
Constant Current/Constant Voltage Li-Ion Battery Charger
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
M9999-061507
June 2007
Micrel, Inc.
MIC4682
Ordering Information
Part Number
Voltage
Junction Temp. Range
Package
Standard
Pb-Free
MIC4682YM
MIC4682BM
Adj.
–40° to +125°C
8-Pin SOIC
Note: Other Voltage available. Contact Micrel for details.
Pin Configuration
FB
GND
1
2
3
4
8
7
6
5
SW
GND
GND
IN
ISET
SHDN
8-Pin Power SOIC (M)
Pin Description
Pin Number
Pin Name
Pin Function
1
FB
Feedback (Input): Output voltage sense node. Connect to 1.23V-tap of the
output voltage-divider network.
2, 6, 7
3
GND
ISET
Ground (Return): Ground.
Current Limit Set (Input): Connect an external resistor to ground to set the
current limit. Do not ground or float this pin.
4
SHDN
Shutdown (Input): Logic low (<0.8V) enables regulator. Logic high (>2V) shuts
down regulator.
5
8
IN
Supply Voltage (Input): Unregulated +4V to +34V supply voltage.
Switch (Output): Internal power emitter of NPN output switch.
SW
M9999-061507
June 2007
2
Micrel, Inc.
MIC4682
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 (VFB) .................................................12V
Current Limit Set Voltage (VISET)....................... 1.23V to 7V
Ambient Storage Temperature (Ts)...........–65°C to +150°C
ESD Rating(5)..................................................................2kV
Supply Voltage (VIN)(4, 7) ....................................... 4V to 34V
Junction Temperature Range (TJ).............–40°C to +125°C
Thermal Resistance Impedance
SOIC (θJA)(6) .......................................................63°C/W
SOIC (θJC)(6) .......................................................20°C/W
Electrical Characteristics
VIN = 12V; IOUT = 500mA; RISET = 16.2k (1A current limit); TJ = 25°C, bold values indicate –40°C< TJ < +125°C, unless noted.
Symbol
VIN
Parameter
Condition
Min
Typ
Max
34
Units
V
Supply Voltage Range
Quiescent Current
Standby Quiescent Current
Note 4
4
IIN
VFB = 1.5V
7
35
12
mA
µA
VSHDN = 5V (Regulator off)
VSHDN = VIN
100
1
µA
VFB
Feedback Voltage
(±1%)
(±2%)
1.217
1.205
1.230
1.243
1.255
V
V
8V ≤ VIN ≤ 34V, 0.1A ≤ ILOAD ≤ 0.8A
1.193
1.180
1.230
1.267
1.280
V
V
ILIM
Current Limit Accuracy, Note 7
Oscillator Frequency
See Test Circuit, VOUT = 3.6V
0.9
180
93
1
1.1
A
kHz
%
fSW
200
95
220
DMAX
VSW
ISW
Maximum Duty Cycle
VFB = 1.0V
Switch Saturation Voltage
Switch Leakage Current
IOUT = 1A
1.4
2
1.8
100
10
V
VIN = 34V, VSHDN = 5V, VSW = 0V
VIN = 34V, VSHDN = 5V, VSW = –1V
Regulator Off
µA
mA
V
2
VSHDN
Shutdown Input Logic Level
Shutdown Input Current
Thermal Shutdown
2
1.4
1.25
–0.5
–0.5
160
Regulator On
0.8
1
V
ISHDN
VSHDN = 5V (Regulator Off)
VSHDN = 0V (Regulator On)
–10
–10
µA
µA
°C
1
TJ
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. Human body model, 1.5kΩ in series with 100pF.
6. Measured on 1.5” square of 1oz. copper FR4 printed circuit board connected to the device ground leads.
7. Short circuit protection is guaranteed to VIN = 30V max.
M9999-061507
June 2007
3
Micrel, Inc.
MIC4682
Test Circuit
MIC4682
VIN
L1
VOUT
5
4
8
1
IN
SW
5.0
3.6
68µH
C1 (x2)
10µF
50V
R1
C2
220µF
10V
3.01k
SHDN
FB
D1
B240A
R3
10M
R2
ISET
GND
3
2, 6, 7
10%
RISET
0
0.90
OUTPUT CURRENT (A)
1.10
Current Limit Test Circuit
Constant-Current Constant-Voltage Accuracy
Shutdown Input Behavior
OFF
ON
0.8V
1.25V
2V
0V
1.4V
VIN(max)
Shutdown Hysteresis
M9999-061507
June 2007
4
Micrel, Inc.
MIC4682
Typical Characteristics
TA = 25°C unless otherwise noted.
Efficiency
vs. Output Current
80
70
60
50
40
30
20
10
0
VIN = 6V
VIN = 5V
VIN = 12V
VIN = 30V
VOUT = 2.5V
0.8 1.2 1.6 2
0
0.4
OUTPUT CURRENT (A)
Short Circuit Current Limit
Short Circuit Current Limit
Current Limit
vs. R
at T = 125°C
vs. Input Voltageat T = –40°C
vs. Input Voltageat T = 25°C
ISET
J
J
J
2
2
2
1.8
1.6
1.4
1.2
1
RISET=10k
RISET=10k
VIN = 4V
VIN = 5V
VIN = 12V
1.8
1.6
1.4
1.2
1
1.8
RISET=15.8k
1.6
1.4
1.2
1
VIN = 24V
IN = 30V
VIN = 34V
RISET=15.8k
V
RISET=20k
RISET=25k
RISET=20k
ISET=25k
R
RISET=30k
RISET=40k
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
RISET=30k
RISET=40k
R
ISET=50k
L = 68µH
R3 = 10M
OUT~0V (Pulsed Load)
L = 68µH
R3 = 10M
VOUT~0V (Pulsed Load)
L = 68µH
R3 = 10M
VOUT = 1.0V (Pulsed Load)
RISET=50k
V
4
7 10 13 16 19 22 25 28 31 34
INPUT VOLTAGE (V)
4
8
12 16 20 24 28 32
INPUT VOLTAGE (V)
10 15 20 25 30 35 40 45 50
RISET (kΩ)
M9999-061507
June 2007
5
Micrel, Inc.
MIC4682
Typical Characteristics (continued)
Short Circuit Current Limit
Short Circuit Current Limit
Quiescent Current
vs. Input Voltage
vs. Input Voltageat T = 85°C
vs. Input Voltageat T = 125°C
J
J
2
2.0
12
10
8
RISET=10k
15.8k
RISET=10k
1.8
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
1.6
RISET=15.8k
1.4
RISET=20k
1.2
RISET=20k
ISET=25k
RISET=30k
ISET=40k
RISET=50k
R
ISET=25k
RISET=30k
ISET=40k
RISET=50k
1
0.8
0.6
0.4
0.2
0
6
R
4
R
R
L = 68µH
L = 68µH
R3 = 10M
VFB = 1.5V
EN = 0V
2
R3 = 10M
V
VOUT~0V (Pulsed Load)
VOUT~0V (Pulsed Load)
0
0
5
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
4
8
12 16 20 24 28 32
INPUT VOLTAGE (V)
4
8
12 16 20 24 28 32
INPUT VOLTAGE (V)
Quiescent Current
vs. Temperature
Shutdown Current
vs. Input Voltage
12
10
8
140
120
100
80
= 24V
6
= 12V
60
4
40
VFB = 1.5V
VEN = VIN
VFB = 1.5V
EN = 0V
2
20
V
0
0
-40 -20
0
20 40 60 80 100120
0
5 10 15 20 25 30 35 40
INPUT VOLTAGE (V)
TEMPERATURE°(C)
Frequency
vs. Temperature
250
245
240
235
230
225
220
215
210
VIN = 24V
VIN = 12V
VFB = 0V
0 20 40 60 80 100120
-40 -20
TEMPERATURE°(C)
Load Regulation
5.016
5.014
5.012
5.01
5.008
5.006
5.004
5.002
0
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
OUTPUT CURRENT (A)
M9999-061507
June 2007
6
Micrel, Inc.
MIC4682
Typical Safe Operating Area (SOA)(1)
5V Output SOA
3.3V Output SOA
2
2
1.8
1.6
1.4
1.2
1
1.8
TA = 25°C
1.6
TA = 25°C
1.4
1.2
TA = 60°C
TA = 60°C
1
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
VOUT = 5V
TJ = 125°C
D = Max
VOUT = 3.3V
TJ = 125°C
D = Max
Peak ILIMIT= 2A
Peak ILIMIT= 2A
05
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
05
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
2.5V Output SOA
1.8V Output SOA
2
1.8
1.6
1.4
1.2
1
2
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
TA = 25°C
TA = 25°C
TA = 60°C
TA = 60°C
0.8
0.6
0.4
0.2
0
VOUT = 1.8V
TJ = 125°C
D = Max
VOUT = 2.5V
TJ = 125°C
D = Max
Peak ILIMIT= 2A
Peak ILIMIT= 2A
05
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
05
10 15 20 25 30 35 40
INPUT VOLTAGE (V)
Note 1. SOA measured on the MIC4682 evaluation board.
Functional Characteristics
M9999-061507
June 2007
7
Micrel, Inc.
MIC4682
Typical Bode Plots
The following bode plots show that the MIC4682 is stable using a 68µH 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°C.
M9999-061507
June 2007
8
Micrel, Inc.
MIC4682
Functional Diagram
VIN
IN
R1
R2
⎛
⎜
⎝
⎞
⎠
VOUT = VFB
VFB = 1.23V
+ 1
⎟
SHDN
Internal
Regulator
ISET
⎛
⎞
VOUT
VFB
R1= R2
− 1
⎟
⎜
⎝
⎠
200kHz
Oscillator
Thermal
Shutdown
Current
Limit
R1
R2 =
⎛
⎞
VOUT
VFB
–1
⎜
⎟
⎝
⎠
Com-
parator
VOUT
COUT
SW
FB
Driver
2A
Switch
Reset
R1
R2
Error
Amp
1.23V
Bandgap
Reference
MIC4682
GND
Figure 1. MIC4682 Block Diagram
the maximum duty cycle which turns the switch off. The
external resistor at the ISET pin sets the peak current
limit. The maximum duty cycle is controlled by the Reset
circuitry. At this time, energy is stored in the inductor.
The current charges the output capacitor and supplies to
the load. The Schottky diode is reversed bias.
Functional Description
The MIC4862 is a constant frequency, voltage mode-
switching regulator. Referring to the block diagram,
regulation is achieved when the feedback voltage is
equal to the band gap reference. The FB pin senses the
output voltage and feeds into the input of the Error Amp.
The output of the Error Amp produces a positive voltage
to compare with the 200kHz saw-tooth waveform. These
two signals are fed into the comparator to generate the
Pulse Width Modulation (PWM) signal to turn on and off
the internal switch. The duty cycle is defined as the time
the switch turns on divided by the period of the saw-
tooth oscillator. Initially, when power is applied to the IN
pin, the duty cycle is high because the feedback is close
to ground. As the output and feedback voltage start to
rise, the duty cycle decreases.
When the internal switch is off, the stored energy in the
inductor starts to collapse. The voltage across the
inductor reverses polarity and the inductor current starts
to decrease. The Schottky diode clamps the switch
voltage from going too negative and provides the path
for the inductor current. During the off time, the inductor
and the output capacitor provide current to the load.
An internal regulator provides power to the control
circuitry and the thermal protection circuitry turns off the
internal switch when the junction temperature exceeds
about 160°C.
During the on time, current flows through the switch and
into the inductor until it reaches the peak current limit or
M9999-061507
June 2007
9
Micrel, Inc.
MIC4682
Inductor and Output Capacitor
Application Information
A 68µH inductor and a 220µF tantalum output capacitor
are chosen because of their stability over the input
voltage range with maximum output current listed in the
SOA typical tables. The Sumida CDRH127-680 and
Vishay Sprague 593D106X9050D2T are recommended.
See “Bode Plots” for additional information. With the
same conditions, a lower value inductor and a higher
output capacitor can be used. The disadvantages for this
combination are that the output ripple voltage will be
higher and the output capacitor’s package size will be
bigger. For example, a 47µH inductor and 330µF output
capacitor are good combination. Another option is to use
a higher value inductor and a lower output capacitor.
The advantages of this combination are that the switch
peak current and the output ripple voltage will be lower.
The disadvantage is that the inductor’s package size will
be bigger. Applications that have lower output current
requirement can use lower inductor value and output
capacitor. See “Typical Application Circuits” for an
example. A 0.1µF ceramic capacitor is recommended in
parallel with the tantalum output capacitor to reduce the
high frequency ripple.
Output Voltage
The output voltage of the MIC4682 is determined by
using the following formulas:
R1
R2
⎛
⎜
⎞
VOUT = VFB
+ 1
⎟
⎝
⎠
R1
R2 =
⎛
⎞
VOUT
⎜
⎜
⎟
⎟
− 1
VFB
⎝
⎠
VFB = 1.23V
For most applications, a 3.01k resistor is recommended
for R1 and R2 can be calculated.
Input Capacitor
Low ESR (Equivalent Series Resistance) capacitor
should be used for the input capacitor of the MIC4862 to
minimize the input ripple voltage. Selection of the
capacitor value will depend on the input voltage range,
inductor value, and the load. Two Vishay Sprague
593D106X9050D2T (10µF/50V), tantalum capacitors are
good values to use for the conditions listed in the SOA
typical tables. A 0.1µF ceramic capacitor is recomm-
ended in parallel with the tantalum capacitors to filter the
high frequency ripple. The ceramic capacitor should be
placed close to the IN pin of the MIC4682 for optimum
result. For applications that are cost sensitive,
electrolytic capacitors can be used but the input ripple
voltage will be higher.
Current Limit Set Resistor
An external resistor connects between the ISET pin and
ground to control the current limit of the MIC4682
ranging from 400mA to 2A. For resistor value selections,
see the “Typical Characteristics: Current Limit vs. RISET."
In addition to the RISET, a resistor, ranging from 10MΩ to
15MΩ, between the ISET and IN pin is recommended for
current limit accuracy over the input voltage range.
When the MIC4682 is in current limit, the regulator is
incurrent mode. If the duty cycle is equal or greater than
50%, the regulator is in the sub-harmonic region. This
lowers the average current limit. The below simplified
equation determines at which input and output voltage
the MIC4682 exhibits this condition.
Diode
A Schottky diode is recommended for the output diode.
Most of the application circuits on this data sheet specify
the Diode Inc. B340A or Micro Commercial SS34A
surface mount Schottky diode. Both diodes have forward
current of 3A and low forward voltage drop. These
diodes are chosen to operate at wide input voltage range
and at maximum output current. For lower output current
and lower input voltage applications, a smaller Schottky
diode such as B240A or equivalence can be used.
VOUT + 1.4
)
> 50%
VIN
Do not short or float the ISET pin. Shorting the ISET pin
will set a peak current limit greater than 2.1A. Floating
the ISET pin will exhibit unstable conditions. To disable
the current limit circuitry, the voltage at the ISET pin has
to be between 2V and 7V.
M9999-061507
June 2007
10
Micrel, Inc.
MIC4682
Thermal Considerations
The MIC4682 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. Micrel’s MIC4682 Super-
Switcher™ family are the first DC-to-DC converters to
take full advantage of this package.
SOIC-8
JA
The reason that the power SOIC-8 has higher power
dissipation (lower thermal resistance) is that pins 2, 6, 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 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.
ground plane
heat sink area
JC
CA
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 continuous output current. Figure
3 assumes a constant die temperature of 75°C above
ambient.
One limitation of the maximum output current on any
MIC4682 design is the junction-to-ambient thermal
resistance (θJA) of the design (package and ground
plane).
Examining θJA in more detail:
1.5
12V
8V
θ
JA = (θJC + θCA)
where:
θ
θ
JC = junction-to-case thermal resistance
CA = case-to-ambient thermal resistance
1.0
0.5
0
24V
VIN = 30V
θ
JC 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 2, 6 and 7 to the ground plane.
The purpose of the ground plane is to function as a heat
sink.
TA = 50°C
20 25
0
5
10
15
θ
JA is ideally 63°C/W, but will vary depending on the size
AREA (cm2)
of the ground plane to which the power SOIC-8 is
attached.
Figure 3. Output Current vs. Ground Plane Area
When designing with the MIC4682, it is a good practice
to connect pins 2, 6 and 7 to the largest ground plane
that is practical for the specific design.
Determining Ground-Plane Heat-Sink Area
There are two methods of determining the minimum
ground plane area required by the MIC4682.
Checking the Maximum Junction Temperature
Quick Method
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?
Make sure that MIC4682 pins 2, 6 and 7 are connected
to a ground plane with a minimum area of 6cm2. This
ground plane should be as close to the MIC4682 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 sufficient for most
designs.
Referring to the “Typical Characteristics: Efficiency vs.
Output Current” graph, read the efficiency (η) for 1A
output current at VIN = 12V or perform you own
measurement.
η = 81%
The efficiency is used to determine how much of the
output power (POUT) is dissipated in the regulator circuit
(PD).
M9999-061507
June 2007
11
Micrel, Inc.
MIC4682
Calculating the maximum junction temperature given a
maximum ambient temperature of 65°C:
POUT
PD
PD
=
− POUT
− 5W
η
TJ = 0.936 × 20°C/W + (45°C – 25°C) + 65°C
TJ = 103.7°C
5W
=
0.81
This value is within 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.”
PD = 1.17W
A worst-case rule of thumb is to assume that 80% of the
total output power dissipation is in the MIC4682 (PD(IC)
and 20%is in the diode-inductor-capacitor circuit.
)
Layout Considerations
P
P
P
D(IC) = 0.8 PD
Layout is very important when designing any switching
regulator. Rapidly changing currents through the printed
circuit board traces and stray inductance can generate
voltage transients which can cause problems.
D(IC) = 0.8 × 1.17W
D(IC) = 0.936W
Calculate the worst-case junction temperature:
TJ = P D(IC) θJC + (TC – TA) + TA(max)
where:
To minimize stray inductance and ground loops, keep
trace lengths, indicated by the heavy lines in Figure 4, as
short as possible. For example, D1 should be close to
pin 7 and pin 8. CIN should be close to pin 5 and pin 6.
See “Applications Information: Thermal Considerations”
for ground plane layout.
TJ = MIC4682 junction temperature
P
D(IC) = MIC4682 power dissipation
θ
JC = junction-to-case thermal resistance.
The feedback pin should be kept as far way from the
switching elements (usually L1 and D1) as possible.
The θJC for the MIC4682’s power-SOIC-8 is
approximately 20°C/W.
A circuit with sample layouts are provided. See Figures
5a though 5e. Gerber files are available upon request.
TC = “pin” temperature measurement taken at
the entry point of pins 6 or 7.
TA = ambient temperature
TA(max)
=
maximum
ambient
operating
temperature for the specific design.
VIN
MIC4682BM
L1
VOUT
COUT R1
+4V to +34V
5
4
8
1
IN
SW
68µH
CIN
SHDN
FB
Power
SOIC-8
GND ISET
D1
R2
2
6
7
3
GND
Figure 4. Critical Traces for Layout
L1
U1 MIC4682BM
68µH
J1
VIN
J3
VOUT
5
8
1
2
IN
SW
1
1
4V to 34V
JP1 1-2=OFF
JP1 2-3-ON
D1
C4
B340A
C1
C2
10µF
50V
C3
0.1µF
50V
OFF
ON
R1
Option
2
4
3
7
1
10µF
50V
SHDN
ISET
GND
FB
3.01k
C5
220µF
10V
C6
Option
C7
0.1µF
50V
2
R9
10M
JP1
3
J2
GND
R5
R4
2.94k
R3
1.78k
R2
976
R8
option
R7
16.2k
R6
25k
6.49k
GND
2
GND
6
2
1
2
1
8
7
JP3c4
2.0A
3
JP3b6
1.0A
5
JP3a
0.6A
JP2a4
1.8V
3
JP2b 6
2.5V
5
JP2c
3.3V
JP2d
5.0V
J4
GND
Figure 5a. Evaluation Board Schematic Diagram
M9999-061507
June 2007
12
Micrel, Inc.
MIC4682
Layout Example
Figure 5b. Top Silkscreen
Figure 5d. Bottom Silkscreen
Figure 5c. Top Layer
Figure 5e. Bottom Layer
Bill of Materials
Item
C1, C2
C3, C7
C5
Part Number
Manufacturer
Vishay Sprague(1)
Vishay Vitramon(1)
Vishay Sprague(1)
Diodes, Inc(2)
Description
10µF/50V
Qty.
2
593D106X005D2T
VJ0805Y104KXAMT
593D227X0010D2T
B340A
0.1µF/50V
2
220µF/10V
1
D1
Schottky 3A/40V
1
L1
CDRH127-680MC
MIC4682BM
Sumida(3)
Micrel, Inc.(4)
68µH, 2.1A ISAT
1
U1
Precision Circuit Limit Buck Regulator
1
Notes:
1. Vishay: www.vishay.com
2. Diodes, Inc.: www.diodes.com
3. Sumida: www.sumida.com
4. Micrel, Inc.: www.website.com
M9999-061507
June 2007
13
Micrel, Inc.
MIC4682
Typical Application Circuits
L1
47H
Sumida
CDRH6D28-470NC
MIC4682
MIC79050
BAT
VIN
5
3
8
1
2
1
3
4
VOUT
IN
SW
FB
IN
11V to 24V
4.2V 0.75%
R1
R3
10M
3.01k
C1
C2
C3
ISET
EN
FB
10µF/25V
Taiyo Yuden
TMK432BJ106MM
100µF
10V(x2)
AVX
4.7µF/20V
AVX
TPSA475M020R1800
GND
5-8
R2
28k
R4
SHDN
GND
2,6,7
4
TPSC107M010R0200
GND
GND
D1
1A/40V
MBRX140
Micro Commercial Components
MIC4682 Current Limit
Characteristics
4.5
4
3.5
3
VIN = 12V
2.5
0
250
500
750
1000
OUTPUT CURRENT (mA)
Typical
Charging Characteristics
Constant Current
5
4.5
4
0.6
0.5
0.4
0.3
0.2
0.1
0
Constant Voltage
3.5
3
VIN = 12V
Batt = 1.25Ah
Cutoff Voltage = 3.0V
2.5
2
1.5
1
0.5
0
0
1
2
3
4
5
6
7
TIME (hrs)
Figure 6.Low-Cost Li Ion Battery Charger with 0.75% Precision Output Voltage
M9999-061507
June 2007
14
Micrel, Inc.
MIC4682
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
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.
© 2003 Micrel, Incorporated.
M9999-061507
June 2007
15
相关型号：
MIC4685-3.3BR
Switching Regulator, Voltage-mode, 1A, 225kHz Switching Freq-Max, PSSO7, SPAK-7
MICROCHIP
MIC4685-3.3BR
Switching Regulator, Voltage-mode, 1A, 225kHz Switching Freq-Max, PSSO7, SPAK-7
MICREL
©2020 ICPDF网 联系我们和版权申明