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MIC2601/2
1.2A, 1.2MHz/2MHz Wide Input Range Integrated Switch Boost Regulator
General Description
The MIC2601/2 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 MIC2601/2's internal 40V/1.2A switch, allowing it to power large loads in a tiny footprint. The MIC2601/2 implements constant frequency 1.2MHz/2MHz PWM current mode control. The MIC2601/2 offers internal compensation that provides 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. Soft start reduces in rush current and is programmable via external capacitor. The MIC2601/2 is available in a 2mm x 2mm 8-pin MLF(R) leadless package. Both devices have an output overvoltage protection feature. The MIC2601/2 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 1.2A switch current MIC2601 operates at 1.2MHz MIC2602 operates at 2MHz Stable with small size ceramic capacitors High efficiency Programmable soft start <10A shutdown current UVLO Output over-voltage protection Over temperature shutdown 8-pin 2mm x 2mm MLF(R) package -40C to +125C junction temperature range
Applications
* * * * * * * * Multimedia STB/Antenna Broadband communications TFT-LCD bias supplies Bias supply Positive output regulators SEPIC converters DSL applications Local boost regulators
___________________________________________________________________________________________________________
Typical Application
10H VOUT 18V, 500mA MIC2601/2 VIN VIN = 12V 2.2F 0.1F EN SW FB 0.1F 10F 6.65K
100 90 80 70 60 50 40 30 20 10 0 0 100 200 300 400 500 600 700 800 LOAD CURRENT (mA)
18V OUT Efficiency
8VIN
12VIN
VDD SS AGND PGND
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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MIC2601/2
Ordering Information
Part Number MIC2601YML MIC2602YML
Notes 1. 2. Overbar (
(R)
Marking Code(1) RD1 RE1
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
VIN VDD EN AGND
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 VIN VDD EN AGND SS FB SW PGND GND Pin Function Supply (Input): 4.5V to 20V input voltage. Internal regulator. VDD should be connected to VIN when VIN 7V. Enable (Input): Logic high enables regulator. Logic low shuts down regulator. Analog Ground 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 Ground (Return): Exposed backside pad. Internally fused to AGND and PGND pins.
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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)...............................................................6V Ambient Storage Temperature (Ts) ...........-65C to +150C Lead Temperature (soldering 10sec)......................... 260C ESD Rating..................................................................... 2kV
Operating Ratings(2)
Supply Voltage (VIN).......................................... 4.5V to 20V Enable Voltage (VEN)............................................ 0V to 20V Junction Temperature (TJ) ........................ -40C to +125C Junction Thermal Resistance 2mm x 2mm MLF-8 (JA) ...................................90C/W 2mm x 2mm MLF-8 (JC) ...................................45C/W
Electrical Characteristics(3)
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 SSR DMAX ISW VSW ISW VEN IEN fSW 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. Specification for packaged product only. 4. Connect VDD pin to VIN pin when VIN 7V. 5. ISD = IVIN. 6. Guaranteed by design.
Condition Note 4 For VDD VFB = 2V (not switching) VEN = 0V, Note 5 (2%) (3%) (over temperature) VFB = 1.25V 8V VIN 14V, VOUT = 18V 5mA IOUT 400mA, VOUT = 18V, Note 6 MIC2601 MIC2602 Note 6 ISW = 1.2A VEN = 0V, VSW = 18V Turn ON Turn OFF VEN = 12V
Min 4.5
Typ 6.0
Max 20
Units V V V mA A V V nA % % k % %
1.8
2.1 4.2 0.08
2.4 6 2 1.285 1.298
1.235 1.222
1.26 -550 0.04 0.1 15
1
Internal Soft Start Resistor Maximum Duty Cycle Switch Current Limit Switch Saturation Voltage Switch Leakage Current Enable Threshold Enable Pin Current Oscillator Frequency (MIC2601) Oscillator Frequency (MIC2602) Output Over-voltage Protection Over-temperature Threshold Shutdown 15% Over programmed VOUT (rising) Hysteresis 85 80 1.2
1.7 500 0.01 5 0.3 18.5 40 1.38 2.3 20
A mV A V V A MHz MHz % C C
1.5
1.02 1.7 10
1.12 1.92 15 150 10
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Typical Characteristics
7 6 5 4 3 2 1 0 0
No Switching FB Pin @ 2V
Quiescent Current vs. Input Voltage
4.5 4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6
Quiescent Current vs. Temperature
91 90 89 88 87 86
Max Duty Cycle vs. Input Voltage
246 81 01 21 41 61 8 INPUT VOLTAGE (V)
3.5 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
No Switching FB Pin @ 2V
85 46
EN = VIN 81 01 21 41 61 82 0 INPUT VOLTAGE (V)
100 98 96 94 92 90 88 86 84 82
Max Duty Cycle vs. Temperature
2700 2430 2160 1890 1620 1350 1080 810 540 270
Switch Saturation Voltage vs. Input Voltage
-0.1A -0.5A -0.9A -1.3A -1.7A -0.2A -0.6A -1.0A -1.4A -0.3A -0.7A -1.1A -1.5A -0.4A -0.8A -1.2A -1.6A
2700 2430 2160 1890 1620 1350 1080 810 540 270 0
Switch Saturation Voltage vs. Switch Current
-4V -5V -6V -7V -8V -9V -10V -12V -15V -20V
80 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
EN = 20V VIN = 20V
0 46
81 01 21 41 61 82 0 INPUT VOLTAGE (V)
SWITCH CURRENT (A)
2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 46
Switch Current Limit vs. Input Voltage
2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1
Switch Current Limit vs. Temperature
2.0
VSAT vs. Temperature
1.5
ISW = Current Limit
1.0 I SW = 850mA 0.5
ISW = 1200mA ISW = 500mA
EN = VIN 81 01 21 41 61 82 0 INPUT VOLTAGE (V)
VIN = 12V 1.0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
1.270 1.265 1.260 1.255 1.250 1.245
Feedback Voltage vs. Temperature
1.290 1.285 1.280 1.275 1.270 1.265 1.260
Enable Threshold ON vs. Temperature
25 24 23 22 21 20 19 18 17
Enable Current vs. Temperature
VIN = 12V Load = 100mA 1.240 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
1.255
1.250 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
VIN = 12V
EN = 0V 16 VIN = 12V 15 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
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Typical Characteristics
2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 46
Frequency vs. Input Voltage
MIC2602
2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1
Frequency vs. Temperature
MIC2602
18V OUT Efficiency
100 90 80 70 60 50 40 30 20 10 0 0 100 200 300 400 500 600 700 800 LOAD CURRENT (mA)
8VIN
12VIN
MIC2601 81 01 21 41 61 82 0 INPUT VOLTAGE (V)
MIC2601 1.0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
18V OUT Efficiency
100 90 80 70 60 50 40 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) 8VIN 4.5VIN 12VIN 0.100 0.097 0.094 0.091 0.088 0.085 0.082 0.079 0.076 0.073
Shutdown Current vs. Temperature
Thermal Derating
900 800 700 600 500 400 300 200
0.070 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (C)
EN = 0V VIN = 12V
100 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
Regulator
OVP CMP OVP CL THERMAL UVLO BANDGAP OSC EA S PWM CMP R SW
EN
Bandgap
1.25V
SS
+ +
CA
1.2 / 2MHz Oscillator AGND
OSC
Ramp Generator
PGND
Figure 1. MIC2601/2 Block Diagram
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MIC2601/2 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 MIC2601/2 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. AGND Analog ground (AGND) is the ground path for the biasing and control circuitry. The current loop for the signal ground should be separate from the Power ground (PGND) loop. Refer to the layout considerations for more details.
Functional Description
The MIC2601/2 is a constant frequency, PWM current mode boost regulator. The block diagram is shown in Figure 1. The MIC2601/2 is composed of an oscillator, slope compensation ramp generator, current amplifier, gm error amplifier, PWM generator, and a 1.2A 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 2.2F 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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MIC2601/2 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 MIC2601 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 MIC2601/2 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 external Schottky diode (D1). Voltage regulation is achieved through pulse-width modulation (PWM).
10H VIN MIC2601/2 VIN 2.2F 0.1F GND EN SW FB 10F 0.1F GND 6.65K VOUT
VDD SS AGND PGND
(D )2 VO
2 L IO
Figure 2. Typical Application Circuit
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 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 MIC2601/2. Y5V values may be used, but to offset their tolerance over temperature, more capacitance is required. Diode Selection The MIC2601/2 requires an external diode for operation. A Schottky diode is recommended for most applications due to their lower forward voltage drop and reverse recovery time. Ensure the diode selected can deliver the peak inductor current and the maximum reverse voltage is rated greater than the output voltage. Input capacitor A minimum 2.2F ceramic capacitor is recommended for designing with the MIC2601/2. Increasing input capacitance will improve performance and greater noise
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 MIC2601/2 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 MIC2601/2 OVP ckt will shut the switch off saving itself and other sensitive circuitry downstream.
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MIC2601/2 or equal to 1k (R2 1k). The desired output voltage can be calculated as follows:
R1 VOUT = VREF + 1 R2 where VREF is equal to 1.25V.
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MIC2601/2
L1 10H
1 2 2
D1 B360A
1
J1 VIN 12V J2 GND J3 EN R3 10k
U1 MIC2601/2
1
C1 2.2F/16V
3
VIN
SW
7
C4 4.7F/50V R1 6.65k
C5 4.7F/50V
J4 VO 18V
EN VDD
FB SS
6
2
5
R2 C3 0.1F/50V
AGND
4
C2 0.1F/50V
8
PGND
J5 GND
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1
GRM21BR71C225KA12L 0805YC225MAT VJ0603Y104KXAAT 06035C104MAT GRM188R71C104KA01D GRM31CR71H475KA12L SS3P6-E3 B360A LQH55DN100M03 CRCW06036K65FKEA CRCW06034990FKEA CRCW060310K0FKEA
MIC2601YML MIC2602YML
Murata AVX
(1)
(2)
Capacitor, 2.2F, 16V, X7R, Size 0805 Capacitor, 0.1F, 50V, X7R, Size 0603 Capacitor, 0.1F, 16V, X7R, Size 0603 Capacitor, 4.71F, 50V, X7R, Size 1206 3A, 60V Schottky Diode 10H, 1700mA Resistor, 6.65k, 1%, 1/10W, Size 0603 Resistor, 499, 1%, 1/10W, Size 0603 Resistor, 10k, 1%, 1/10W, Size 0603
1.2A, 1.2MHz Wide Range Integrated Switch Boost Regulator 1.2A, 2MHz Wide Range Integrated Switch Boost Regulator
(3) (3)
1
Vishay(3) AVX(2) Murata
(1) (1)
C2, C3 C4, C5 D1 L1 R1 R2 R3
U1
Notes:
2 2 1 1 1 1 1
1
Murata Diodes
Vishay(3)
(4)
Murata(1) Vishay Dale(3) Vishay Dale Vishay Dale
Micrel, Inc.(5)
1. Murata: www.murata.com 2. AVX: www.avx.com 3. Vishay: www.vishay.com 4. Murata: www.diodes.com 5. 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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