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MIC4680
Micrel
MIC4680
1A 200kHz SuperSwitcherTM Buck Regulator Final Information
General Description
The MIC4680 SuperSwitcherTM 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). The MIC4680 is available in 3.3V and 5V fixed output versions or adjustable output down to 1.25V. The MIC4680 has an input voltage range of 4V to 34V, with excellent line, load, and transient response. The regulator performs cycle-by-cycle current limiting and thermal shutdown for protection under fault conditions. In shutdown mode, the regulator draws less than 2A of standby current. The MIC4680 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 MIC4680 is available in the 8-lead SOP with a -40C to +125C junction temperature range.
Features
* * * * * * * * * * * 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 2A typical shutdown-mode current Up to 90% efficiency Thermal shutdown Overcurrent protection
Applications
* * * * * * * * 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 Higher output current regulator using external FET
Typical Applications
+6V to +34V C1 15F 35V SHUTDOWN
ENABLE 2
MIC4680-3.3BM IN SW
3
L1 68H
3.3V/1A C2 220F 16V
1
SHDN GND
5-8
FB
4
Power SOP-8
D1 B260A or SS26
Fixed Regulator Circuit
MIC4680BM IN SW
+5V to +34V C1 15F 35V SHUTDOWN
ENABLE
2
3
L1 68H R1 3.01k R2 2.94k
2.5V/1A C2 220F 16V
1
SHDN GND
5-8
FB
4
Power SOP-8
D1 B260A or SS26
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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MIC4680
MIC4680
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Ordering Information
Part Number MIC4680BM MIC4680-3.3BM MIC4680-5.0BM Voltage Adjustable 3.3V 5.0V Junction Temp. Range -40C to +125C -40C to +125C -40C to +125C Package 8-lead SOP 8-lead SOP 8-lead SOP
Pin Configuration
SHDN 1 IN 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 (>1.6V) shuts down regulator. Supply Voltage (Input): Unregulated +4V to +34V supply voltage. Switch (Output): Emitter of NPN output switch. Connect to external storage inductor and Shottky diode. Feedback (Input): Connect to output on fixed output voltage versions, or to 1.23V-tap of voltage-divider network for adjustable version. Ground
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Absolute Maximum Ratings (Note 1)
Supply Voltage (VIN), Note 3 ...................................... +38V Shutdown Voltage (VSHDN) .......................... -0.3V to +38V 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), Note 4 .......................... +4V to +34V Junction Temperature (TJ) ...................................... +125C Package Thermal Resistance (JA), Note 6 ............ 63C/W
Electrical Characteristics
VIN = 12V; ILOAD = 500mA; TJ = 25C, bold values indicate -40C TJ +125C, Note 7; unless noted. Parameter MIC4680 [Adjustable] Feedback Voltage (1%) (2%) 8V VIN 34V, 0.1A ILOAD 1A, VOUT = 5V Maximum Duty Cycle Output Leakage Current VFB = 1.0V VIN = 34V, VSHDN = 5V, VSW = 0V VIN = 34V, VSHDN = 5V, VSW = -1V Quiescent Current MIC4680-3.3 Output Voltage (1%) (3%) 6V VIN 34V, 0.1A ILOAD 1A Maximum Duty Cycle Output Leakage Current VFB = 2.5V VIN = 34V, VSHDN = 5V, VSW = 0V VIN = 34V, VSHDN = 5V, VSW = -1V Quiescent Current MIC4680-5.0 Output Voltage (1%) (3%) 8V VIN 34V, 0.1A ILOAD 1A Maximum Duty Cycle Output Leakage Current VFB = 4.0V VIN = 34V, VSHDN = 5V, VSW = 0V VIN = 34V, VSHDN = 5V, VSW = -1V Quiescent Current VFB = 6.0V 4.950 4.85 4.800 4.750 93 5.0 5.0 97 50 4 7 500 20 12 5.05 5.15 5.200 5.250 V V V V % A mA mA VFB = 4.0V 3.266 3.201 3.168 3.135 93 3.3 3.3 97 50 4 7 500 20 12 3.333 3.399 3.432 3.465 V V V V % A mA mA VFB = 1.5V 1.217 1.205 1.193 1.180 93 1.230 1.230 97 50 4 7 500 20 12 1.243 1.255 1.267 1.280 V V V V % A mA mA Condition Min Typ Max Units
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MIC4680
Parameter MIC4680/-3.3/-5.0 Frequency Fold Back Oscillator Frequency Saturation Voltage Short Circuit Current Limit Standby Quiescent Current IOUT = 1A VFB = 0V, see Test Circuit VSHDN = VIN VSHDN = 5V (regulator off) Shutdown Input Logic Level regulator off regulator on Shutdown Input Current VSHDN = 5V (regulator off) VSHDN = 0V (regulator on) Thermal Shutdown
Note 1. Note 2. Note 3. Note 4. Note 5. Note 6. Note 7. 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.
Micrel
Condition Min Typ Max Units
30 180
50 200 1.4
100 220 1.8 2.5
kHz kHz V V A A A V
1.3
1.8 1.5 30
100
2
1.6 1.0 0.8 10 10
V A A C
-10 -10
-0.5 -1.5 160
Test Circuit
+12V
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 1V 1.6V
2V
GUARANTEED OFF TYPICAL OFF
0V
VIN(max)
Shutodwn Hysteresis
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Typical Characteristics
Shutdown Current vs. Input Voltage
100 VIN = 12V VOUT = 5V 80
CURRENT (A)
Line Regulation
5.06 5.05 OUTPUT VOLTAGE (V) 5.04 5.03 5.02 5.01 5.00 4.99 4.98 4.97 4.96 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 5.04 IOUT = 1.0A
OUTPUT VOLTAGE (V)
Load Regulation
5.02
60 40 20 0
5.00
4.98
4.96
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 INPUT VOLTAGE (V)
35
Shutdown Current vs. Temperature
4.0
OUTPUT VOLTAGE (V)
Current Limit Characteristic
6 202 201
FREQUENCY (kHz)
Frequency vs. Supply Voltage
3.5 CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5
VIN = 12V VSHDN = VIN
5 4 3 2 1 0 VIN = 12V 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 OUTPUT CURRENT (A)
200 199 198 197 196 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 35
0 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
Frequency vs. Temperature
220 1.242
Feedback Voltage vs. Temperature
1.6 SATURATION VOLTAGE (V) 1.4 1.2 1.0 0.8 0.6 0.4 0.2
Saturation Voltage vs. Temperature
FEEDBACK VOLTAGE (V)
1.240 1.238 1.236 1.234 1.232 1.230 VIN = 12V VOUT = 5V IOUT = 1A
FREQUENCY (kHz)
210
200
190
VIN = 12V VOUT = 5V ILOAD = 1A
180 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
1.228 -50 -25 0 25 50 75 100 125 150 TEMPERATURE (C)
0 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
3.3V Output Efficiency
80 70 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 OUTPUT CURRENT (A) 0 0 12V
5V Output Efficiency
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 15V
12V Output Efficiency
EFFICIENCY (%)
60 50 40 30 20 10 0 12V
24V 6V
7V 24V
24V
0.2 0.4 0.6 0.8 1.0 1.2 1.4 OUTPUT CURRENT (A)
10 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 OUTPUT CURRENT (A)
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Safe Operating Area
1.5 1.4 1.3 1.2 1.1 OUTPUT CURRENT (A) 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 5 10 15 20 25 INPUT VOLTAGE (V) 30 35 VOUT = 5V TA = 60C Demonstration board layout Note Minimum Current Limit
Note. For increased output current, see "Applications Information: Increasing the Maximum Output Current" and Figure 3.
Functional Characteristics
Switching Frequency Foldback
VSW (NORMAL) 12V IN, 5V/1A OUT
Load Transient
VIN = 12V VOUT = 5V IOUT = 1.0A to 0.1A
VOUT (100mV/div.)
Normal Operation
5.1V 5V
200kHz
VSW (SHORTED) 12V IN, 0V OUT
Short Circuit Operation
IOUT (500mA/div.)
1A
0A
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.
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Bode Plots
The following bode plots show that the MIC4680 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 = 106 Full-Load Stability Phase Margin = 114
L = 68F COUT = 220F
VIN = 7V VOUT = 5.0V IOUT = 0.0A
L = 68F COUT = 220F
VIN = 7V VOUT = 5.0V IOUT = 1.0A
TIME (100ms/div.)
TIME (100ms/div.)
No-Load Stability Phase Margin = 117
Full-Load Stability Phase Margin = 69
L = 68F COUT = 220F
VIN = 12V VOUT = 5.0V IOUT = 0.0A
L = 68F COUT = 220F
VIN = 12V VOUT = 5.0V IOUT = 1.0A
TIME (100ms/div.)
TIME (100ms/div.)
No-Load Stability Phase Margin = 125
Full-Load Stability Phase Margin = 71
L = 68F COUT = 220F
L = 68F COUT = 220F
VIN = 34V VOUT = 5.0V IOUT = 1.0A TIME (100ms/div.)
VIN = 34V VOUT = 5.0V IOUT = 1.0A
TIME (100ms/div.)
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MIC4680
Micrel
Block Diagrams
VIN IN SHDN Internal Regulator
200kHz Oscillator
Thermal Shutdown
Current Limit
Comparator SW Driver Reset 1A Switch FB
VOUT COUT
Error Amp MIC4680-x.x
1.23V Bandgap Reference GND
Fixed Regulator
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 1A Switch R1 FB Error Amp MIC4680 [adj.] 1.23V Bandgap Reference R2
200kHz Oscillator
Thermal Shutdown
VOUT COUT
Adjustable Regulator
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A higher feedback voltage increases the error amplifier output voltage. A higher error amplifier voltage (comparator inverting input) causes the comparator to detect only the peaks of the sawtooth, reducing the duty cycle of the comparator output. A lower feedback voltage increases the duty cycle. The MIC4680 uses a 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 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. 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 1.5A when VSHDN = VIN = 12V and 30A when VSHDN = 5V. See "Shutdown Input Behavior: Shutdown Hysteresis." Feedback Fixed-voltage versions of the regulator have an internal resistive divider from the feedback (FB) pin. Connect FB directly to the output voltage. Adjustable versions require an external resistive voltage divider from the output voltage to ground, center tapped to the FB pin. See Figure 6b for recommended resistor values. 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.
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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:
SHUTDOWN ENABLE
VIN CIN
MIC4680BM
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 2A 60V Schottky
L1 68H 1.5A
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
15F 35V AVX TPSE156035R0200
Coiltronics UP2B-680 220F 10V B260A Vishay-Diode, Inc.*** or AVX TPSE227010R0060 or Sumida CDRH125-680MC** SS26 General Semiconductor or Sumida CDRH124-680MC**
Figure 1b. Recommended Components for Common Ouput Voltages
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MIC4680
Thermal Considerations 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 standard SOP-8. The MIC4680 SuperSwitcher is the first dc-to-dc converter 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 though 8 and the die-attach paddle are a single piece of metal. The die is attached to the paddle with thermally conductive adhesive. This provides a low thermal resistance path from the junction of the die to the ground pins. This design significantly improves package power dissipation by allowing excellent heat transfer through the ground leads to the printed circuit board. One of the limitation of the maximum output current on any MIC4680 design is the junction-to-ambient thermal resistance (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
Micrel Minimum Copper/Maximum Current Method Using Figure 3, for a given input voltage range, determine the minimum ground-plane heat-sink area required for the application's maximum output current. Figure 3 assumes a constant die temperature of 75C above ambient.
1.5 8V 12V
OUTPUT CURRENT (I)
1.0
24V 34V
0.5
TA = 50C
Minimum Current Limit = 1.3A
0 0 5 10 15 20 25
AREA (cm2)
Figure 3. Output Current vs. Ground Plane Area When designing with the MIC4680, it is a good practice to connect pins 5 through 8 to the largest ground plane that is practical for the specific design.
Checking the Maximum Junction Temperature:
There are two methods of determining the minimum ground plane area required by the MIC4680. Quick Method Make sure that MIC4680 pins 5 though 8 are connected to a ground plane with a minimum area of 6cm2. This ground plane should be as close to the MIC4680 as possible. The area maybe 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.
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
SOP-8
JA JC CA
AM BIE
ground plane heat sink area
NT
printed circuit board
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 MIC4680 (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 = MIC4680 junction temperature PD(IC) = MIC4680 power dissipation JC = junction-to-case thermal resistance. The JC for the MIC4680's power-SOP-8 is approximately 20C/W. (Also see Figure 1.) TC = "pin" temperature measurement taken at the entry point of pins 6 or 7 into the plastic package
Figure 2. Power SOP-8 Cross Section June 2000 11 MIC4680
MIC4680
at the ambient temperature (TA) at which TC is measured. TA = ambient temperature at which TC is measured. 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 less than the allowable maximum operating junction temperature of 125C as listed in "Operating Ratings." Typical thermal shutdown is 160C and is listed in "Electrical Characteristics." Increasing the Maximum Output Current The maximum output current at high input voltages can be increased for a given board layout. The additional three
Micrel
components shown in Figure 4 will reduce the overall loss in the MIC4680 by about 20% at high VIN and high IOUT. Even higher output current can be achieved by using the MIC4680 to switch an external FET. See Figure 9 for a 5A supply with current limiting. Layout Considerations Layout is very important when designing any switching regulator. Rapidly changing switching currents through the printed circuit board traces and stray inductance can generate voltage transients which can cause problems. To minimize stray inductance and ground loops, keep trace lengths, indicated by the heavy lines in Figure 5, as short as possible. For example, keep D1 close to pin 3 and pins 5 through 8, keep L1 away from sensitive node FB, and keep CIN close to pin 2 and pins 5 though 8. See "Applications Information: Thermal Considerations" for ground plane layout. The feedback pin should be kept as far way from the switching elements (usually L1 and D1) as possible. A circuit with sample layouts are provided. See Figure 6a though 6e.
MIC4680BM IN SW
3
1N4148 82 SHDN GND
5678
D1
FB 2.2nF
Figure 4. Increasing Maximum Output Current at High Input Voltages
VIN +4V to +34V CIN
MIC4680BM
2
IN
SW
3
L1 68H COUT
VOUT R1
1
Power SOP-8
GND
5678
D1
R2
GND
Figure 5. Critical Traces for Layout
J1 VIN 4V to +34V C1 15F 35V J3 GND C2 0.1F 50V S1 NKK G12AP
SOP-8
Load
SHDN
FB
4
2
U1 MIC4680BM IN SW
3
L1 68H R1 3.01k R2 6.49k JP1a 1.8V
3
J2 VOUT 1A C3* optional R3 2.94k JP1b 2.5V
5
OFF ON
1
SHDN GND
5-8
FB
4
D1 R6 B260A optional or 1 SS26
2
R4 1.78k JP1c 3.3V
7
R5 976 JP1d 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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Printed Circuit Board Layouts
Figure 6b. Top-Side Silk Screen
Figure 6d. Bottom-Side Silk Screen
Figure 6c. Top-Side Copper
Figure 6e. Bottom-Side Copper
Abbreviated Bill of Material (Critical Components)
Reference C1 C4 D1 L1 Part Number TPSD156M035R0300 ECE-A1HFS470 TPSD227M010R0150 B260A SS26 UP2B-680 CDH115-680MC CDRH124-680MC MIC4680BM
http://www.avxcorp.com
Manufacturer AVX1 Panasonic2 AVX Vishay-Diodes, General Semiconductor Coiltronics4 Sumida5 Sumida5 Micrel Semiconductor6 Inc.3
Description 15F 35V 47F 50V, 8mm x 11.5mm 220F 10V Schottky 68H, 1.5A, nonshielded 68H, 1.5A, nonshielded 68H, 1.5A, shielded 1A 200kHz power-SO-8 buck regulator
Qty 1 1 1 1
U1
1 AVX: 2 3 4 5 6
1
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
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Applications Circuits* For continuously updated circuits using the MIC4680, see Application Hint 37 at www.micrel.com.
Micrel
J1 +34V max. C1 22F 35V J3 GND C2 100nF
OFF ON
D3 1N4148
2
MIC4680BM 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 MIC4680BM 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 MIC4680BM MIC4417BM4 IN SW 3
4
2
SHUTDOWN ENABLE
C1 330F 25V
Si4425DY L1* 50H C2 220F 16V C3 220F 16V
R2 20m C4 1000pF R3 1k 1% R4 1k 1% R7 3.01k 1% D2 1N4148
3.3V/5A
1
SHDN GND
SOP-8 5-8
FB
R1 1k
D1 5A
* ISAT = 8A
R6 16k 1%
C5 0.1F
R5 16k 1%
U3 R8 MIC6211BM5 1.78k 1%
Figure 9. 5V to 3.3V/5A Power Supply
* See Application Hint 37 for bills of material.
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To Cellular Telephone
GND
C3 220F 10V
MIC4680
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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)
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
MIC4680
16
June 2000

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Price & Availability of MIC4680

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