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MIC4681
Micrel
MIC4681
2A-Peak SuperSwitcherTM SOP-8 Buck Regulator Final Information
General Description
The MIC4681 SuperSwitcherTM is an easy-to-use step-down (buck) voltage-mode switching regulator. The 200kHz MIC4681 achieves over 1A of continuous output current over a 4V to 30V input range in an 8-lead SOPpackage . The MIC4681 features a high 2.1A minimum current limit, making the device ideal for pulsed current applications such as GSM and TDMA cell phone battery chargers and power supplies. The MIC4681 sustains an output of 4.2V/2A within a typical GSM charging environment. The MIC4681 has an input voltage range of 4V to 30V, 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 6A of standby current. The MIC4681 SuperSwitcherTM 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 MIC4681 is available in the 8-lead SOP with a -40C to +125C junction temperature range.
Features
* * * * * * * * * * * * SO-8 package with over 1A continuous output current Capable of 2A pulse charging for GSM applications All surface mount solution Only 4 external components required Fixed 200kHz operation Output adjustable down to 1.25V Internally compensated with fast transient response Wide 4V to 30V operating input voltage range Less than 6A typical shutdown-mode current Up to 90% efficiency Thermal shutdown Overcurrent protection
Applications
* Cellular phone battery charger * Cellular phone power supply * Simple 1A continuous high-efficiency step-down (buck) regulator * Replacement of a TO-220 and TO-263 designs * Positive-to-negative converter (inverting buck-boost) * Negative boost converter * Higher output current regulator using external FET
Typical Applications
+5V to +30V C1 22F 35V SHUTDOWN
ENABLE
2
MIC4681BM IN SW
3
L1 68H R1 3.01k R2 2.94k
2.5V/1A C2 220F 10V
1
SHDN GND
5-8
FB
4
Power SOP-8
D1 B340A or SS36
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
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MIC4681
MIC4681
Micrel
Ordering Information
Part Number MIC4681BM Voltage Adjustable Junction Temp. Range -40C to +125C Package 8-lead SOP
Pin Configuration
SHDN 1 VIN 2 SW 3 FB 4 8 GND 7 GND 6 GND 5 GND
SOP-8 (M)
Pin Description
Pin Number 1 2 3 4 5-8 Pin Name SHDN VIN SW FB GND Pin Function Shutdown (Input): Logic low enables regulator. Logic high (>2V) shuts down regulator. Supply Voltage (Input): Unregulated +4V to +30V supply voltage. Switch (Output): Emitter of NPN output switch. Connect to external storage inductor and Shottky diode. Feedback (Input): Connect to 1.23V-tap of voltage-divider network Ground
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Absolute Maximum Ratings (Note 1)
Supply Voltage (VIN), Note 3 ...................................... +34V Shutdown Voltage (VSHDN) .......................... -0.3V to +34V Steady-State Output Switch Voltage (VSW) .................. -1V Feedback Voltage [Adjustable] (VFB) .......................... +12V Storage Temperature (TS) ....................... -65C to +150C ESD, Note 5
Operating Ratings (Note 2)
Supply Voltage (VIN) ....................................... +4V to +30V Junction Temperature (TJ) ...................................... +125C Package Thermal Resistance (JA), Note 6 ............ 63C/W (JC), Note 6 ........... 20C/W
Electrical Characteristics
VIN = 12V; ILOAD = 500mA; TJ = 25C, bold values indicate -40C TJ +125C, Note 7; unless noted. Parameter Feedback Voltage Condition (1%) (2%) 8V VIN 30V, 0.1A ILOAD 1A, VOUT = 5V Maximum Duty Cycle Output Leakage Current VFB = 1.0V VIN = 30V, VSHDN = 5V, VSW = 0V VIN = 30V, VSHDN = 5V, VSW = -1V Quiescent Current Frequency Fold Back Oscillator Frequency Saturation Voltage Short Circuit Current Limit Standby Quiescent Current IOUT = 1A VFB = 0V, see Test Circuit VIN = 30V (Note 8) VSHDN = 5V (regulator off) VSHDN = VIN Shutdown Input Logic Level regulator off regulator on Shutdown Input Current VSHDN = 5V (regulator off) VSHDN = 0V (regulator on) Thermal Shutdown @ TJ
Note 1. Note 2. Note 3. Note 4. Note 5. Note 6. Note 7. Note 8. Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Absolute maximum rating is intended for voltage transients only, prolonged dc operation is not recommended. VIN(min) = VOUT + 2.5V or 4V whichever is greater. Devices are ESD sensitive. Handling precautions recommended. Measured on 1" square of 1 oz. copper FR4 printed circuit board connected to the device ground leads. Test at TA = +85C, guaranteed by design, and characterized to TJ = +125C. Short circuit protection is guaranteed to 30V max.
Min 1.217 1.205 1.193 1.180 93
Typ 1.230 1.230 95 50 4 7 50
Max 1.243 1.255 1.267 1.280
Units V V V V % A mA mA kHz kHz V A A A V
500 20 12 110 220 1.8 4.5 100
VFB = 1.5V 180
200 1.4
2.2
3.4 35 6
2
1.4 1.25 0.8 1 1
V A A C
-10 -10
-0.5 -1.5 160
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MIC4681
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Test Circuit
+30V
2
Device Under Test 3 IN SW
4
68H
SHUTDOWN ENABLE
1
SHDN GND
SOP-8 5-8
FB
I
Current Limit Test Circuit
Shutdown Input Behavior
OFF ON
GUARANTEED ON TYPICAL ON
0.8V 1.25V 1.4V
2V
GUARANTEED OFF TYPICAL OFF
0V
VIN(max)
Shutdown Hysteresis
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Typical Characteristics
Line Regulation
5.05 OUTPUT VOLTAGE (V) 5.03 5.01 4.99 4.97 4.95 0 Amb = 25C 5 10 15 20 25 30 INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
Load Regulation
5.05 5.03 5.01 4.99 4.97 4.95 0
SHUTDOWN CURRENT (A)
Shutdown Current vs. Input Voltage
100 90 80 70 60 50 40 30 20 10 0 0 5
Amb = 25C VIN = 12V 0.5 1.0 1.5 OUTPUT CURRENT (A) 2.0
VSHDN = 5V Amb = 25C 10 15 20 25 30 INPUT VOLTAGE (V) 35
Shutdown Current vs. Input Voltage
14 SHUTDOWN CURRENT (A) 12 10 8 6 4 2 0 0 5 VSHDN = VIN Amb = 25C 10 15 20 25 30 INPUT VOLTAGE (V) 35
SHUTDOWN CURRENT (A)
Shutdown Current vs. Temperature
6.6
OUTPUT VOLTAGE (V)
Current Limit Characteristics
6 5 4 3 2 1 V = 12V IN Amb = 25C 0 0 0.5 1 1.5 2 2.5 OUTPUT CURRENT (A)
VIN = 12V VSHDN = VIN
6.4
6.2
6
5.8 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
3
MIC4681BM Frequency vs. Supply Voltage
205 215
FREQUENCY (KHz)
Frequency vs. Temperature
210 205 200 195 190 185 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C) FEEDBACK VOLTAGE (V) VIN = 12V 1.238 1.236 1.234 1.232 1.230 1.228 1.226 1.224
Feedback Voltage vs. Temperature
FREQUENCY (KHz)
203 201 199 197 195 0
IOUT = 100mA Amb = 25C 5 10 15 20 25 30 35 INPUT VOLTAGE (V)
VIN = 12V 1.222 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
MIC4681 3.3V Output Efficiency
80 12Vin 24Vin 6Vin EFFICIENCY (%) 100 80 60 40 20 Amb = 25C 0 0 0.5 1 1.5 2 OUTPUT CURRENT (A) 2.5 0 0
5V Output Efficiency
100
12V Output Efficiency
15Vin 24Vin 60 40 20
12Vin 7Vin 24Vin
EFFICIENCY (%)
EFFICIENCY (%)
60
80
40
20
Amb = 25C 0.5 1.0 1.5 2.0 OUTPUT CURRENT (A)
0 0
Amb = 25C 0.5 1 OUTPUT CURRENT (A) 1.5
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MIC4681
Micrel
ENABLE THRESHOLD VOLTAGE (V)
Shutdown Thresholds vs. Temperature
1.5 Regulator Off 1.0 Regulator On 2
Saturation Voltage vs. Output Current
SATURATION VOLTAGE (V)
1.5
1
0.5
0.5 V 0 0
IN
= 12V
V
0.0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
IN
= 12V
Amb = 25C 0.5 1 1.5 2 OUTPUT CURRENT (A)
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MIC4681
Micrel
4681BM SOA 5Vout 4681BM SOA 5Vout
CONTINUOUS OUTPUT CURRENT (A)
1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 5 VOUT = 5V TA = 60C 10 15 20 25 30 INPUT VOLTAGE (V) 35 TA = 25C
4681BM SOA 3.3Vout 4681BM SOA3.3Vout
CONTINUOUS OUTPUT CURRENT (A)
2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0
TA = 25C
VOUT = 3.3V TA = 60C 5 10 15 20 25 30 INPUT VOLTAGE (V) 35
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Functional Characteristics
Switching Frequency Foldback
VSW (NORMAL) 12V IN, 5V/1A OUT
Load Transient
IOUT (1A/div)
Normal Operation
1.5A 0A 100mV
200kHz
VSW (SHORTED) 12V IN, 0V OUT
Short Circuit Operation
VOUT (100mV/div)
60kHz
VIN = 12V VOUT = 5V
TIME (100s/div)
TIME
Frequency Foldback The MIC4681 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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Bode Plots
The following bode plots show that the MIC4681 is stable over all conditions using a 68F inductor (L) and a 220F output capacitor (COUT). To assure stability, it is a good practice to maintain a phase margin of greater than 35.
No-Load Stability Phase Margin = 94 Full-Load Stability Phase Margin = 74
L = 68F COUT = 220F
L = 68F COUT = 220F
VIN = 7V VOUT = 5.0V IOUT = 0A Amb = 22C
VIN = 7V VOUT = 5.0V IOUT = 1.1A Amb = 22C
No-Load Stability Phase Margin = 102
Full-Load Stability Phase Margin = 53
L = 68F COUT = 220F
L = 68F COUT = 220F
VIN = 12V VOUT = 5.0V IOUT = 0A Amb = 22C
VIN = 12V VOUT = 5.0V IOUT = 1.4A Amb = 22C
No-Load Stability Phase Margin = 118
Full-Load Stability Phase Margin = 59
L = 68F COUT = 220F
L = 68F COUT = 220F
VIN = 30V VOUT = 5.0V IOUT = 0A Amb = 22C
VIN = 30V VOUT = 5.0V IOUT = 1.1A Amb = 22C
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MIC4681
MIC4681
Micrel
Block Diagrams
VIN IN SHDN Internal Regulator R1 VOUT = VREF + 1 R2 Current Limit V R1 = R2 OUT - 1 VREF VREF = 1.23V Comparator SW Driver Reset 3A Switch R1 FB Error Amp MIC4681 [adj.] 1.23V Bandgap Reference R2
200kHz Oscillator
Thermal Shutdown
VOUT COUT
Adjustable Regulator
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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 MIC4681 uses a voltage-mode control architecture. 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. 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.
Functional Description
The MIC4681 is a variable duty cycle switch-mode regulator with an internal power switch. Refer to the block diagrams. Supply Voltage The MIC4681 operates from a +4V to +30V unregulated input. Highest efficiency operation is from a supply voltage around +12V. See the efficiency curves on page 6. Enable/Shutdown The shutdown (SHDN) input is TTL compatible. Ground the input if unused. A logic-low enables the regulator. A logichigh shuts down the internal regulator which reduces the current to typically 35A when VSHDN = VIN = 12V and 6A when VSHDN = 5V. See "Shutdown Input Behavior: Shutdown Hysteresis." Feedback Require an external resistive voltage divider from the output voltage to ground, center tapped to the FB pin. See Figure 1b for recommended resistor values. 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. A higher feedback voltage increases the error amplifier output voltage. A higher error amplifier voltage (comparator
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:
VIN CIN
SHUTDOWN ENABLE
MIC4681BM
2
IN
SW
3
L1 R1
VOUT
1
SHDN GND
5-8
FB
4
COUT D1 R2
R1 VOUT = VREF + 1 R2 V R1 = R2 OUT - 1 VREF VREF = 1.23V
Figure 1a. Adjustable Regulator Circuit
VOUT
R1*
R2*
CIN
D1 3A 40V Schottky
L1 68H 2.0A
COUT
1.8V 3.01k 6.49k 2.5V 3.01k 2.94k 3.3V 3.01k 1.78k 5.0V 3.01k 976 6.0V 3.01k 787
* All resistors 1% ** shielded magnetics for low RFI applications *** Vishay-Diode, Inc. (805) 446-4800
22F 35V Vishay Dale 593D226X035E2T
B340A Vishay-Diode, Inc.*** Coiltronics UP3B-680 or or SS36 General Semiconductor Sumida CDRH127-680MC**
220F 10V Vishay Dale 594D227X0010D2
Figure 1b. Recommended Components for Common Ouput Voltages February 2001 11 MIC4681
MIC4681
Thermal Considerations The MIC4681 SuperSwitcherTM features the power-SOP-8. This package has a standard 8-lead small-outline package profile, but with much higher power dissipation than a standard SOP-8. Micrel's MIC4681 SuperSwitcherTM family are the first dc-to-dc converters to take full advantage of this package. The reason that the power SOP-8 has higher power dissipation (lower thermal resistance) is that pins 5 through 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 limitation of the maximum output current on any MIC4681 design is the junction-to-ambient thermal resistance (JA) of the design (package and ground plane). Examining JA in more detail: JA = (JC + CA) where: JC = junction-to-case thermal resistance CA = case-to-ambient thermal resistance JC is a relatively constant 20C/W for a power SOP-8. CA is dependent on layout and is primarily governed by the connection of pins 5 though 8 to the ground plane. The purpose of the ground plane is to function as a heat sink. JA is ideally 63C/W, but will vary depending on the size of the ground plane to which the power SOP-8 is attached.
Determining Ground-Plane Heat-Sink Area Minimum Copper/Maximum Current Method
Micrel
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 75C above ambient.
CONTINUOUS OUTPUT CURRENT (A)
1.5 8V 1.0 12V
24V VIN = 30V
0.5
TA = 50C 0 0 5 10 15 20 25 AREA (cm2)
Figure 3. Output Current vs. Ground Plane Area When designing with the MIC4681, 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:
There are two methods of determining the minimum ground plane area required by the MIC4681.
Quick Method
For this example, with an output power (POUT) of 5W, (5V output at 1A maximum with VIN = 12V) and 65C maximum ambient temperature, what is the maximum junction temperature? Referring to the "Typical Characteristics: 5V Output Efficiency" graph, read the efficiency () for 1A output current at VIN = 12V or perform you own measurement. = 79% The efficiency is used to determine how much of the output power (POUT) is dissipated in the regulator circuit (PD). PD = PD = POUT - POUT
Make sure that MIC4681 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 MIC4681 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 5 though 8. This ground plane area is more than sufficient for most designs.
SOP-8
JA JC CA
AM BIE
ground plane heat sink area
NT
5W - 5W 0.79 PD = 1.33W A worst-case rule of thumb is to assume that 80% of the total output power dissipation is in the MIC4681 (PD(IC)) and 20% is in the diode-inductor-capacitor circuit. PD(IC) = 0.8 PD PD(IC) = 0.8 x 1.33W PD(IC) = 1.064W Calculate the worst-case junction temperature: TJ = PD(IC) JC + (TC - TA) + TA(max) where: TJ = MIC4681 junction temperature PD(IC) = MIC4681 power dissipation JC = junction-to-case thermal resistance. The JC for the MIC4681's power-SOP-8 is approximately 20C/W. TC = "pin" temperature measurement taken at the entry point of pins 6 or 7 12
printed circuit board
Figure 2. Power SOP-8 Cross Section MIC4681 February 2001
MIC4681
TA = ambient temperature TA(max) = maximum ambient operating temperature for the specific design. Calculating the maximum junction temperature given a maximum ambient temperature of 65C: TJ = 1.064 x 20C/W + (45C - 25C) + 65C TJ = 106.3C This value is within the allowable maximum operating junction temperature of 125C as listed in "Operating Ratings." Typical thermal shutdown is 160C and is listed in "Electrical Characteristics." Layout Considerations 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. 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
VIN +4V to +30V CIN
Micrel
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 are provided. See Figures 6a though 6e. Gerber files are available upon request.
MIC4681BM
2
IN
SW
3
L1 68H COUT
VOUT R1
Power SOP-8
GND
5678
D1
R2
GND
Figure 5. Critical Traces for Layout
J1 VIN 4V to +30V C1 22F 35V J3 GND C2 0.1F 50V JP1
Load
1
SHDN
FB
4
2
U1 MIC4681BM IN SW
3
L1 68H R1 3.01k R2 6.49k JP2a 1.8V
3
J2 VOUT 1A C3* 1800pF / 50V optional R3 2.94k JP2b 2.5V
5
OFF ON
1
SHDN GND
SOP-8 5-8
FB
4
D1 R6 B340A optional or 1 SS36
2
R4 1.78k JP2c 3.3V
7
R5 976 JP2d 5.0V
C4 220F 10V
C5 0.1F 50V J4 GND
* C3 can be used to provide additional stability and improved transient response.
4
6
8
Figure 6a. Evaluation Board Schematic Diagram
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MIC4681
MIC4681
Printed Circuit Board Layouts
Micrel
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 Material (Critical Components)
Reference C1 C4 C2,C5 D1 L1 U1
1 2 3 4
Part Number 593D226X035E2T 594D227X0010D2 VJ0805Y104KXXMB 340A CDRH127-680MC MIC4681BM
Manufacturer Vishay Vishay Vishay Dale1 Dale1 Dale1
Description 22F / 35V 220F / 10V 0.1 / 50V Schottky Diode 3A, 40V 68H, ISAT 2.1A, shielded 200kHz Super SwitcherTMSOIC 8 pin
Qty 1 1 1 1 1 1
Diodes Inc.2 Sumida3 Micrel Semiconductor4
Vishay Dale, Inc., tel: 1 877-847-4291, http://www.vishay.com Diodes Inc, tel: (805) 446-4800, http://www.diodes.com Sumida, tel: (408) 982-9960, http://www.sumida.com Micrel, tel: (408) 944-0800, http://www.micrel.com
MIC4681
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MIC4681
Applications Circuits* For continuously updated circuits using the MIC4681, see Application Hint 37 at www.micrel.com.
Micrel
J1 +30V max. C1 22F 35V J3 GND C2 100nF
OFF ON
D3 1N4148
2
U1 MIC4681 IN SW
3
L1 100H
C5 220nF R1 0.100 R7 4.99k
4
J2 5V 2% 800mA 5% C4 10nF D2 1N4148 U3 MIC6211BM5
1
SHDN GND
SOP-8 5-8
FB
4
S1 NKK G12AP
D1 MMBR140LT3
5
U2 LM4041DIM3-1.2 R6 10k
R4 16.2k R5 221k
R2 3.01k R3 976
3 2
J4 GND
Figure 7. Constant Current and Constant Voltage Battery Charger
J1 +12V
2
U1 MIC4681 IN SW
3
L1 33H C3 0.022F 50V R1 8.87k R2 1k
J3 GND
C4 68F 20V J2 GND
C5 33F 35V
1
SHDN GND
SOP-8 5-8
FB
4
D1 ES1B 1A 100V
C1 68F 20V
C2 0.1F J4 -12V/150mA
Figure 8. +12V to -12V/150mA Buck-Boost Converter
+4.5V to +17V U2 U1 MIC4681 MIC4417BM4 IN SW 3
4
Q1 Si4425DY L1*
* ISAT = 7.5A R2 20m C3 470F 6.3V C4 1000pF R3 1k 1% R4 1k 1% R7 3.01k 1% D2 1N4148 3.3V/5A
2
C1 100F 20V
SHUTDOWN ENABLE
C6 0.1F 50V
1
SHDN GND
SOP-8 5-8
FB
R1 1k 1%
D1 5A
50H C2 470F 6.3V
R6 16k 1%
R5 16k 1%
U3 R8 MIC6211BM5 1.78k 1%
Figure 9. 5V to 3.3V/5A Power Supply
* See Application Hint 37 at www.micrel.com for bills of material.
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MIC4681
To Cellular Telephone
C5 0.1F GND
C3 220F 10V
MIC4681
Micrel
Package Information
0.026 (0.65) MAX)
PIN 1
0.157 (3.99) 0.150 (3.81)
DIMENSIONS: INCHES (MM)
0.050 (1.27) TYP
0.020 (0.51) 0.013 (0.33) 0.0098 (0.249) 0.0040 (0.102) 0-8 SEATING PLANE 45 0.010 (0.25) 0.007 (0.18)
0.064 (1.63) 0.045 (1.14)
0.197 (5.0) 0.189 (4.8)
0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79)
8-Lead SOP (M)
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MIC4681
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MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
USA
+ 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. (c) 2000 Micrel Incorporated
February 2001
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MIC4681

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