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MIC2605/6
0.5A, 1.2MHz / 2MHz Wide Input Range Boost Regulator with Integrated Switch and Schottky Diode
General Description
The MIC2605/6 is a 1.2MHz/2MHz, PWM DC/DC boost switching regulator available in a 2mm x 2mm MLF(R) package. High power density is achieved with the MIC2605/6's internal 40V/0.5A switch and schottky diode, allowing it to power large loads in a tiny footprint. The MIC2605/6 implements constant frequency 1.2MHz/2MHz PWM current mode control. The MIC2605/6 offers internal compensation that offers excellent transient response and output regulation performance. The high frequency operation saves board space by allowing small, low-profile external components. The fixed frequency PWM scheme also reduces spurious switching noise and ripple to the input power source. The MIC2605/6 is available in an 8-pin 2mm x 2mm MLF(R) leadless package. This package has an output overvoltage protection feature. The MIC2605/6 has an operating junction temperature range of -40C to +125C. Data sheets and support documentation can be found on Micrel's web site at www.micrel.com.
Features
* * * * * * * * * * * * * * Wide input voltage range: 4.5V to 20V Output voltage adjustable to 40V 0.5A switch current and schottky diode MIC2605 operates at 1.2MHz MIC2606 operates at 2MHz Programmable soft start Stable with small size ceramic capacitors High efficiency Low input and output ripple <10A shutdown current UVLO Output over-voltage and over-temperature protection 8-pin 2mm x 2mm MLF(R) package -40C to +125C junction temperature range
Applications
* TV-tuners * Broadband communications * TFT-LCD bias supplies * Bias supply * Positive output regulators * SEPIC converters * DSL applications * Local boost regulators ___________________________________________________________________________________________________________
Typical Application
10H VOUT 32V, 30mA MIC2605/6 VIN VIN = 12V 1F 0.1F EN VDD SS SW OUT FB PGND 0.1F 12.4K
90 80 70 60 50
32VOUT Efficiency
1F 499
40 30 20 10 0 20 VIN = 12V 40 60 80 100 120 LOAD CURRENT (mA)
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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
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MIC2605/6
Ordering Information
Part Number MIC2605YML MIC2606YML
Notes 1. 2. Overbar (
(R)
Marking Code(1) WZ5 WZ6
Frequency 1.2MHz 2MHz
Output Over Voltage Protection 40V 40V
Temperature Range -40 to +125C -40 to +125C
Package
(2)
Lead Finish Pb-Free Pb-Free
8-Pin 2mm x 2mm MLF(R) 8-Pin 2mm x 2mm MLF
(R)
) symbol my not be to scale.
MLF is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
Pin Configuration
VOUT VIN VDD EN
1 2 3 4 8 7 6 5
PGND SW FB SS
8-Pin 2mm x 2mm MLF(R) (ML)
Pin Description
Pin Number 1 2 3 4 5 6 7 8 EP Pin Name VOUT VIN VDD EN SS FB SW PGND EPAD Pin Function Output Pin: Connect to the output capacitor. Supply (Input): 4.5V to 20V input voltage. Internal regulated supply. VDD should be connected to VIN when VIN 7V. Enable (Input): Logic high enables regulator. Logic low shuts down regulator. Soft start Feedback (Input): 1.25V output voltage sense node. VOUT = 1.25V (1 + R1/R2). Switch Node (Input): Internal power BIPOLAR collector. Power ground Exposed backside pad for thermal cooling.
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Absolute Maximum Ratings(1)
Supply Voltage (VIN) .......................................................22V Switch Voltage (VSW)....................................... -0.3V to 40V Enable Voltage (VEN)......................................... -0.3V to VIN FB Voltage (VFB)............................................................. VDD Ambient Storage Temperature (Ts) ...........-65C to +150C ESD Rating(3) (MIC2605)................................................ 2kV ESD Rating(3) (MIC2606)............................................. 1.5kV
Operating Ratings(2)
Supply Voltage (VIN).......................................... 4.5V to 20V Junction Temperature (TJ) ........................ -40C to +125C Junction Thermal Resistance 2mm x 2mm MLF-8 (JC) ...................................90C/W
Electrical Characteristics(4)
TA = 25C, VIN = VEN = 12V; unless otherwise noted. Bold values indicate -40C TJ +125C.
Symbol VIN VDD VULVO IQ ISD VFB IFB Parameter Input Voltage Range Internal Regulated Voltage Under-voltage Lockout Quiescent Current Shutdown Current Feedback Voltage Feedback Input Current Line Regulation Load Regulation DMAX ISW VSW ISW VEN IEN fSW VD IRD VOVP TJ
Notes: 1. Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(Max), the junction-to-ambient thermal resistance, JA, and the ambient temperature, TA. The maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. 2. The device is not guaranteed to function outside its operating rating. 3. IC devices are inherently ESD sensitive. Handling precautions required. Human body model rating: 1.5k in series with 100pF. 4. Specification for packaged product only. 5. Connect VDD pin to VIN pin when VIN 7V. 6. ISD = IVIN. 7. Guaranteed by design.
Condition Note 5 For VDD VFB = 2V (not switching) VEN = 0V, Note 6 (2%) (3%) (over temperature) VFB = 1.25V 8V VIN 14V, VOUT = 18V 5mA IOUT 40mA, VOUT = 18V, Note 7 MIC2605 MIC2606 Note 7 ISW = 0.5A VEN = 0V, VSW = 18V Turn ON Turn OFF VEN = 12V
Min 4.5
Typ 5.8
Max 20
Units V V V mA A V V nA % % % %
1.8
2.1 4.2 0.1
2.4 6 10 1.275 1.288
1.225 1.212
1.25 -550 0.04
1 1.5
Maximum Duty Cycle Switch Current Limit Switch Saturation Voltage Switch Leakage Current Enable Threshold Enable Pin Current Oscillator Frequency (MIC2605) Oscillator Frequency (MIC2606) Schottky Forward Drop Schottky Leakage Current Output Over-voltage Protection Over-temperature Threshold Shutdown
85 80 0.5 0.8 600 0.01 1.5 0.3 20 1.02 1.7 1.2 2 450 850 0.1 10 15 150 10 4 20 40 1.38 2.3 5
A mV A V V A MHz MHz mV mV A % C C
ID = 1mA ID = 150mA VR = 30V 15% Over programmed VOUT Hysteresis
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Typical Characteristics
2.0 1.8 1.6 1.4 1.2 MIC2605 1.0 4 6 8 10 12 14 16 INPUT VOLTAGE (V) 18
Frequency vs. Input Voltage
MIC2606
7 6 5 4 3 2 1 0 1
Quiescent Current vs. Input Voltage
97 96 95 94 93 92 91
Max Duty Cycle vs. Input Voltage
No Switching FB Pin @ 2V
3
5 7 9 11 13 15 17 19 INPUT VOLTAGE (V)
90 4
6
EN = VIN 8 10 12 14 16 18 20 INPUT VOLTAGE (V)
1100 1000 900 800 700 600 500 400 300 200 100 0 4
Switch Saturation Voltage vs. Input Voltage
-50mA -0.25A -0.45A -0.65A -0.85A -0.1A -0.3A -0.5A -0.7A -0.15A -0.35A -0.55A -0.75A -0.2A -0.4A -0.6A -0.8A
6
8 10 12 14 16 18 20 INPUT VOLTAGE (V)
1100 1000 900 800 700 600 500 400 300 200 100 0
Switch Saturation Voltage vs. Switch Current
-4.5V -5V -6V -7V -8V -9V -10V -11V -12V -15V -20
1.00 0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 4
Switch Current Limit vs. Input Voltage
EN = VIN 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V)
SWITCH CURRENT (mA)
Line Regulation
33.4 33.3 33.2 33.1 33.0 32.9 32.8 4 Load = 40mA 6 8 10 12 14 16 18 INPUT VOLTAGE (V) 90 80 70 60 50 40 30 20 10 0 4
32VOUT Efficiency
12VIN
90 80 70 60 50 40 30 20 10 0 20
32VOUT Efficiency
4.5VIN
8 12 16 20 24 28 32 36 40 LOAD CURRENT (mA)
VIN = 12V 40 60 80 100 120 LOAD CURRENT (mA)
1.266 1.264 1.262 1.260 1.258 1.256 1.254
Feedback Voltage vs. Temperature
1.00 0.95 0.90 0.85 0.80 0.75
Switch Current Limit vs. Temperature
1000
VSAT vs. Temperature
ISW=750mA ISW=400mA
100
VIN = 12V Load = 100mA 1.250 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C) 1.252
VIN = 12V 0.70 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
ISW=100mA 10 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
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Typical Characteristics (continued)
1.270 1.265 1.260 1.255 1.250 1.245 VIN = 12V 1.240 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
Enable Threshold ON vs. Temperature
100 98 96 94 92 90 88 86 84 82
Max Duty Cycle vs. Temperature
2.0 1.8 1.6 1.4 1.2
Frequency vs. Temperature
MIC2606
VIN = 12V 80 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
MIC2605 1.0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
25 24 23 22 21 20 19 18 17 16
Enable Current vs. Temperature
0.100 0.095 0.090 0.085 0.080 0.075 0.070
Shutdown Current vs. Temperature
4.30 4.28 4.26 4.24 4.22 4.20 4.18 4.16 4.14
Quiescent Current vs. Temperature
VIN = 12V 15 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
VIN = 12V 0.065 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
4.12 VIN = 12V 4.10 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
Thermal Derating
400 350 300 250 200 150 100 50 VIN = 12V VOUT = 18V 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
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Functional Characteristics
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Functional Diagram
VIN VDD FB
VOUT
Regulator
OVP CMP OVP CL THERMAL UVLO BANDGAP OSC EA S PWM CMP R SW
EN
5.8V
Bandgap
1.25V
SS
+ +
CA
1.2/2MHz Oscillator
OSC
Ramp Generator
PGND
Figure 1. MIC2605/6 Block Diagram
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MIC2605/6 EN The enable pin provides a logic level control of the output. In the off state, supply current of the device is greatly reduced (typically <0.1A). Also, in the off state, the output drive is placed in a "tri-stated" condition, where bipolar output transistor is in an "off" or nonconducting state. Do not drive the enable pin above the supply voltage. SS The SS pin is the soft start pin which allows the monotonic buildup of output when the MIC2605/6 comes up during turn on. The SS pin gives the designer the flexibility to have a desired soft start by placing a capacitor SS to ground. A 0.1F capacitor is used for in the circuit. FB The feedback pin (FB) provides the control path to control the output. For fixed output controller output is directly connected to feedback (FB) pin. SW The switch (SW) pin connects directly to the inductor and provides the switching current necessary to operate in PWM mode. Due to the high speed switching and high voltage associated with this pin, the switch node should be routed away from sensitive nodes. PGND Power ground (PGND) is the ground path for the high current PWM mode. The current loop for the power ground should be as small as possible and separate from the Analog ground (AGND) loop. Refer to the layout considerations for more details. VOUT VOUT pin is the cathode of pin of internal schottky diode. This pin is connected to output cap. At least 1F cap is recommended very close to the VOUT pin and PGND.
Functional Description
The MIC2605/6 is a constant frequency, PWM current mode boost regulator. The block diagram is shown in Figure 1. The MIC2605/6 is composed of an oscillator, slope compensation ramp generator, current amplifier, gm error amplifier, PWM generator, and a 0.5A bipolar output transistor. The oscillator generates a 1.2MHz/ 2MHz clock. The clock's two functions are to trigger the PWM generator that turns on the output transistor and to reset the slope compensation ramp generator. The current amplifier is used to measure the switch current by amplifying the voltage signal from the internal sense resistor. The output of the current amplifier is summed with the output of the slope compensation ramp generator. This summed current-loop signal is fed to one of the inputs of the PWM generator. The gm error amplifier measures the feedback voltage through the external feedback resistors and amplifies the error between the detected signal and the 1.25V reference voltage. The output of the gm error amplifier provides the voltage-loop signal that is fed to the other input of the PWM generator. When the current-loop signal exceeds the voltage-loop signal, the PWM generator turns off the bipolar output transistor. The next clock period initiates the next switching cycle, maintaining the constant frequency current-mode PWM control.
Pin Description
VIN VIN provides power to the MOSFETs for the switch mode regulator section. Due to the high switching speeds, a 1F capacitor is recommended close to VIN and the power ground (PGND) pin for bypassing. Please refer to layout recommendations. VDD The VDD pin supplies the power to the internal power to the control and reference circuitry. The VDD is powered from VIN. A small 0.1F capacitor is recommended for bypassing.
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MIC2605/6 Component Selection Inductor Inductor selection is a balance between efficiency, stability, cost, size, and rated current. For most applications, a 10H is the recommended inductor value; it is usually a good balance between these considerations. Large inductance values reduce the peak-to-peak ripple current, affecting efficiency. This has an effect of reducing both the DC losses and the transition losses. There is also a secondary effect of an inductor's DC resistance (DCR). The DCR of an inductor will be higher for more inductance in the same package size. This is due to the longer windings required for an increase in inductance. Since the majority of input current (minus the MIC2605/6 operating current) is passed through the inductor, higher DCR inductors will reduce efficiency. To maintain stability, increasing inductor size will have to be met with an increase in output capacitance. This is due to the unavoidable "right half plane zero" effect for the continuous current boost converter topology. The frequency at which the right half plane zero occurs can be calculated as follows:
FRHPZ =
Application Information
DC-to-DC PWM Boost Conversion The MIC2605/6 is a constant frequency boost converter. It operates by taking a DC input voltage and regulating a higher DC output voltage. Figure 2 shows a typical circuit. Boost regulation is achieved by turning on an internal switch, which draws current through the inductor (L1). When the switch turns off, the inductor's magnetic field collapses, causing the current to be discharged into the output capacitor through an internal Schottky diode. Voltage regulation is achieved through pulse-width modulation (PWM).
10H VOUT 32V, 30mA MIC2605/6 VIN VIN = 12V 1F 0.1F EN VDD SS SW OUT FB PGND 0.1F 12.4K
1F 499
Figure 2. Typical Application Circuit
(D )2 VO
2 L IO
Duty Cycle Considerations Duty cycle refers to the switch on-to-off time ratio and can be calculated as follows for a boost regulator:
D = 1- VIN VOUT
The duty cycle required for voltage conversion should be less than the maximum duty cycle of 85%. Also, in light load conditions where the input voltage is close to the output voltage, the minimum duty cycle can cause pulse skipping. This is due to the energy stored in the inductor causing the output to overshoot slightly over the regulated output voltage. During the next cycle, the error amplifier detects the output as being high and skips the following pulse. This effect can be reduced by increasing the minimum load or by increasing the inductor value. Increasing the inductor value reduces peak current, which in turn reduces energy transfer in each cycle. Overvoltage Protection For the MIC2605/6 there is an over voltage protection function. If the output voltage overshoots the set voltage by 15% when feedback is high during input higher than output, turn on, load transients, line transients, load disconnection etc. the MIC2605/6 OVP ckt will shut the switch off saving itself and other sensitive circuitry downstream.
The right half plane zero has the undesirable effect of increasing gain, while decreasing phase. This requires that the loop gain is rolled off before this has significant effect on the total loop response. This can be accomplished by either reducing inductance (increasing RHPZ frequency) or increasing the output capacitor value (decreasing loop gain). Output Capacitor Output capacitor selection is also a trade-off between performance, size, and cost. Increasing output capacitance will lead to an improved transient response, but also an increase in size and cost. X5R or X7R dielectric ceramic capacitors are recommended for designs with the MIC2605/6. Y5V values may be used, but to offset their tolerance over temperature, more capacitance is required. Input capacitor A minimum 1F ceramic capacitor is recommended for designing with the MIC2605/6. Increasing input capacitance will improve performance and greater noise immunity on the source. The input capacitor should be as close as possible to the inductor and the MIC2605/6, with short traces for good noise performance.
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Micrel, Inc. Feedback Resistors The MIC2605/6 utilizes a feedback pin to compare the output to an internal reference. The output voltage is adjusted by selecting the appropriate feedback resistor network values. The R2 resistor value must be less than or equal to 1k (R2 1k). The desired output voltage can be calculated as follows:
MIC2605/6
R1 VOUT = VREF + 1 R2 where VREF is equal to 1.25V.
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MIC2605/6
L1 10H
1 2
J1 VIN 4.5V to 12V J2 GND J3 EN R3 10k
U1 MIC2605/6-YML
2
C1 1F/25V
VIN
SW VOUT
7 1
R1 12.4k
6
J4 VOUT 32V
4
EN VDD PGND
FB SS
C4 1F/50V C3 0.1F/50V R2
C5 N.U.
3
5
C2 0.1F/50V
J5 GND
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1608X5R1E105K C1 06033D105MAT 08055D105MAT VJ0603Y104KXAAT C2 06035C104MAT GRM188R71C104KA01D VJ0603Y104KXAAT C3 06035C104MAT GRM188R71C104KA01D C4 C5 L1 R1 R2 R3
U1
Notes:
TDK AVX
(1)
8
Capacitor, 1F, 25V, X5R, Size 0603 Capacitor, 1F, 25V, X5R, Size 0603 Capacitor, 1F, 50V, X5R, Size 0805 Capacitor, 0.1F, 50V, X7R, 0603 Capacitor, 0.1F, 50V, X7R, 0603 Capacitor, 0.1F, 16V, X7R, 0603 Capacitor, 0.1F, 50V, X7R, 0603 Capacitor, 0.1F, 50V, X7R, 0603 Capacitor, 0.1F, 16V, X7R, 0603 Capacitor, 1F, 50V, X5R, Size 0805 ----1 1 1 1 1 1
1
(2) (2) (3)
1
AVX
Vishay
AVX(2) Murata Vishay AVX AVX
(4) (3)
1
(2) (4)
1
Murata
08055D105MAT N.U. LQH43CN100K03 VLCF4020T-100MR85 CRCW06031242FKEA CRCW06034990FKEA CRCW060310K0FKEA
MIC2605/6-YML
(2)
----Murata
(4)
10H, 0.65mA, DCR 240m 10uH, 0.85A-1.22A, DCR 120m Resistor, 12.4k, 1%, 1/16W, Size 0603 Resistor, 499, 1%, 1/16W, Size 0603 Resistor, 10k, 1%, 1/16W, Size 0603
0.5A, 1.2MHz/2MHz Wide Input Range Integrated Switch Boost Regulator
TDK(1) Vishay Dale(3) Vishay Dale(3) Vishay Dale
(3)
Micrel, Inc.(5)
1. TDK: www.tdk.com 2. AVX: www.avx.com 3. Vishay: www.vishay.com 4. Murata: www.murata.com 6. Micrel, Inc.: www.micrel.com
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PCB Layout Recommendations
Top Layer
Bottom Layer
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Package Information
8-Pin 2mm x 2mm MLF(R) (ML)
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. (c) 2008 Micrel, Incorporated.
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