mic4682 Micrel Semiconductor, mic4682 Datasheet

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mic4682

Manufacturer Part Number
mic4682
Description
Mic4682 Precision Current Limit So-8 Superswitcher? Buck Regulator
Manufacturer
Micrel Semiconductor
Datasheet

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General Description
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.
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
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.
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.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
___________________________________________________________________________________________________________
Typical Application
SuperSwitcher is a trademark of Micrel, Inc
June 2007
+7.5V to +34V
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
10µF
50V
(x2)
C1
protection
R3
10M
5
4
IN
SHDN
ISET
features
MIC4682
3
R4
16.2k
GND
SW
FB
2, 6, 7
Constant Current/Constant Voltage Li-Ion Battery Charger
8
1
include
D1
B240
68µH
L1
cycle-by-cycle
R1
3.01k
R2
976
5V/1A
C2
220µF
10V
Features
• Programmable output current limit
• Wide 4V to 34V operating input voltage range
• Fixed 200kHz PWM operation
• Power SOIC-8 package allows 2A continuous output
• All surface mount solution
• Internally compensated
• Less than 1µA typical shutdown-mode current
• Thermal shutdown protection
Applications
• Battery chargers
• White LED drivers
• Constant voltage constant current step-down
• Simple step-down regulator with precise current limit
• USB power supplies
408
current
converters
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
SuperSwitcher™ Buck Regulator
10% accuracy over temperature
Precision Current Limit SOIC-8
MIC4682
6
5
4
3
2
1
0
0
V
MIC4682 Current Limit
IN
= 12V
CURRENT LIMIT (A)
0.5
Characteristics
1
1.5
2
M9999-061507

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mic4682 Summary of contents

Page 1

... This allows the use of the smallest possible inductors for a given application, saving valuable space and cost. 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. ...

Page 2

... Do not ground or float this pin. Shutdown (Input): Logic low (<0.8V) enables regulator. Logic high (>2V) shuts down regulator. Supply Voltage (Input): Unregulated +4V to +34V supply voltage. Switch (Output): Internal power emitter of NPN output switch. 2 Package 8-Pin SOIC GND GND IN MIC4682 M9999-061507 ...

Page 3

... J Min Typ 4 35 1.217 1.230 1.205 ≤ 0.8A 1.193 1.230 1.180 0.9 180 200 – 1.4 1.25 –10 –0.5 –10 –0.5 160 MIC4682 Max Units 100 µA 1 µA 1.243 V 1.255 V 1.267 V 1.280 V 1 1.1 A 220 kHz % 1 100 µA ...

Page 4

... FB R3 ISET GND 10M ISET Current Limit Test Circuit Shutdown Input Behavior June 2007 L1 V OUT 68µ 3.01k 220µF 10V D1 R2 B240A ON 0.8V 0V 1.25V 1.4V Shutdown Hysteresis 4 5.0 3.6 10% 0 0.90 OUTPUT CURRENT (A) Constant-Current Constant-Voltage Accuracy OFF 2V V IN(max) MIC4682 1.10 M9999-061507 ...

Page 5

... ISET 1 R =30k 0.8 ISET R =40k 0.6 ISET R =50k L = 68µH 0.4 ISET R3 = 10M 0.2 V ~0V (Pulsed Load) OUT INPUT VOLTAGE (V) 5 MIC4682 Efficiency vs. Output Current 12V 30V 2.5V OUT ...

Page 6

... 210 -40 - 100120 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) 6 MIC4682 Quiescent Current vs. Input Voltage 1. INPUT VOLTAGE (V) M9999-061507 ...

Page 7

... T = 25°C A 1.6 1.4 1 60°C A 1.0 0 2.5V OUT 0 125° Max Peak I 0.2 LIMIT INPUT VOLTAGE (V) Note 1. SOA measured on the MIC4682 evaluation board. Functional Characteristics June 2007 ( MIC4682 3.3V Output SOA 2 1 25°C 1.6 A 1.4 1 60° 0 3.3V OUT 0 125° ...

Page 8

... Micrel, Inc. Typical Bode Plots The following bode plots show that the MIC4682 is stable using a 68µH inductor (L) and a 220µF output capacitor (C ).To assure stability good practice to maintain a phase margin of greater than 35°C. OUT June 2007 8 MIC4682 M9999-061507 ...

Page 9

... Amp Bandgap Reference 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. ...

Page 10

... 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 ...

Page 11

... There are two methods of determining the minimum ground plane area required by the MIC4682. Quick Method Make sure that MIC4682 pins 2, 6 and 7 are connected to a ground plane with a minimum area of 6cm 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 ...

Page 12

... OUT OUT η − 0. 1.17W D A worst-case rule of thumb is to assume that 80% of the total output power dissipation is in the MIC4682 (P and 20%is in the diode-inductor-capacitor circuit 0.8 P D(IC 0.8 × 1.17W D(IC 0.936W D(IC) Calculate the worst-case junction temperature: θ – T ...

Page 13

... June 2007 Manufacturer (1) Vishay Sprague (1) Vishay Vitramon (1) Vishay Sprague (2) Diodes, Inc (3) Sumida (4) Micrel, Inc. Precision Circuit Limit Buck Regulator 13 Figure 5d. Bottom Silkscreen Figure 5e. Bottom Layer Description 10µF/50V 0.1µF/50V 220µF/10V Schottky 3A/40V 68µH, 2.1A ISAT M9999-061507 MIC4682 Qty ...

Page 14

... Figure 6.Low-Cost Li Ion Battery Charger with 0.75% Precision Output Voltage June 2007 L1 47H Sumida MIC4682 CDRH6D28-470NC 3.01k ISET FB R4 SHDN GND 4 2,6,7 D1 1A/40V MBRX140 Micro Commercial Components MIC4682 Current Limit Characteristics 4 12V IN 2.5 0 250 500 OUTPUT CURRENT (mA) Typical Charging Characteristics 5 Constant Current 4.5 Constant Voltage 4 3 12V IN 3 Batt = 1 ...

Page 15

... 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 June 2007 8-Pin SOIC (M) indemnify Micrel for any damages resulting from such use or sale. © 2003 Micrel, Incorporated. 15 MIC4682 M9999-061507 ...

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