MIC2601/2 1.2A, 1.2 / 2MHz Wide Input Range Integrated Switch Boost Regulator General Description Features The MIC2601/2 is a 1.2 and 2MHz, PWM DC/DC boost switching regulator available in a 2mm x 2mm MLF® 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 1.2/2MHz 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® leadless package. Both devices have an output overvoltage protection feature. The MIC2601/2 has an operating junction temperature range of –40°C to +125°C. Data sheets and support documentation can be found on Micrel’s web site at: www.micrel.com. • • • • • • • • • • • • • • 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 <10µA shutdown current UVLO Output over-voltage protection Over temperature shutdown 8-pin 2mm x 2mm MLF® package –40°C to +125°C 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 10µH 18VOUT Efficiency VOUT 18V, 500mA MIC2601/2 VIN = 12V 2.2µF 0.1µF VIN SW EN FB VDD SS AGND PGND 100K 70 60 50 10µF 0.1µF 100 90 80 4K 8VIN 12VIN 40 30 20 10 0 0 100 200 300 400 500 600 700 800 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 June 2008 M9999-062508-A Micrel, Inc. MIC2601/2 Ordering Information Part Number Marking Frequency Output Over Voltage Protection Temperature Range Package MIC2601YML SXA 1.2MHz 40V –40° to +125°C 8-Pin 2mm x 2mm MLF® Pb-Free –40° to +125°C ® Pb-Free MIC2602YML SXA 2MHz 40V Lead Finish 8-Pin 2mm x 2mm MLF Pin Configuration VIN 1 8 PGND VDD 2 7 SW EN 3 6 FB AGND 4 5 SS 8-Pin 2mm x 2mm MLF® (ML) Pin Description Pin Number Pin Name 1 VIN Supply (Input): 4.5V to 20V input voltage. 2 VDD Internal regulator June 2008 3 EN 4 AGND 5 SS Pin Function Enable (Input): Logic high enables regulator. Logic low shuts down regulator. Analog Ground Soft Start 6 FB Feedback (Input): 1.24V output voltage sense node. VOUT = 1.24V ( 1 + R1/R2) 7 SW Switch Node (Input): Internal power BIPOLAR collector. 8 PGND Power ground 2 M9999-062508-A Micrel, Inc. MIC2601/2 Absolute Maximum Ratings(1) Operating Ratings(2) 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) ...........–65°C to +150°C ESD Rating..................................................................... 2kV Supply Voltage (VIN).......................................... 4.5V to 20V Enable Voltage (VEN)............................................ 0V to 20V Junction Temperature (TJ) ........................ –40°C to +125°C Junction Thermal Resistance 2mm x 2mm MLF-8 (θJC) ...................................90°C/W Electrical Characteristics(3) TA = 25°C, VIN = VEN = 12V; unless otherwise noted. Bold values indicate –40°C ≤ TJ ≤ +125°C. Symbol Parameter VIN Input Voltage Range Condition Min 4.5 VDD Under-voltage Lockout For VDD IQ Quiescent Current VFB = 2V (not switching) 1.8 ISD Shutdown Current VEN = 0V, Note 4 VFB Feedback Voltage (±2%) 1.225 (±3%) (over temperature) 1.212 Units 20 V V 2.1 2.4 V 4.3 6 mA 0.1 2 µA 1.25 1.275 V 1.288 V Feedback Input Current VFB = 1.24V –550 Line Regulation 8V ≤ VIN ≤ 14V 0.04 Load Regulation 5mA ≤ IOUT ≤ 400mA 0.1 % 15 kΩ SSR Internal Soft Start Resistor DMAX Maximum Duty Cycle ISW Max 6.0 VULVO IFB Typ Switch Current Limit MIC2601 85 MIC2602 80 Note 5 1.2 88 Switch Saturation Voltage ISW = 1.2A 500 Switch Leakage Current VEN = 0V, VSW = 18V 0.01 VEN Enable Threshold Turn ON IEN Enable Pin Current VEN = 12V fSW Oscillator Frequency (MIC2601) TJ Over-temperature Threshold Shutdown A mV 5 1.5 0.3 V 20 40 µA 1.2 1.38 MHz 1.7 2 2.3 MHz 10 15 20 % 1.02 15% Over programmed VOUT (rising) Hysteresis µA V Turn OFF Output Over-voltage Protection % 1.7 ISW Oscillator Frequency (MIC2602) % % VSW VOVP nA 1 150 °C 10 °C 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, θ 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. ISD = IVIN. 5. Guaranteed by design. June 2008 3 M9999-062508-A Micrel, Inc. MIC2601/2 Typical Characteristics Quiescent Current vs. Input Voltage 7 4.00 3.99 6 5 4 90 3.97 3.96 89 3.95 3.94 2 3.93 1 3.92 3.91 No Switching FB Pin @ 2V 8 10 12 14 16 18 INPUT VOLTAGE (V) 20 Max Duty Cycle vs. Temperature 100 98 96 2160 94 92 1890 1620 90 88 1350 1080 86 810 84 82 EN = 20V VIN = 20V 80 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 2.0 Switch Current Limit vs. Input Voltage 87 EN = VIN VIN = 12V Switch Saturation Voltage vs. Input Voltage –0.1A –0.5A –0.9A –1.3A –1.7A 0 4 2.0 1.5 –0.3A –0.7A –1.1A –1.5A –0.4A –0.8A –1.2A –1.6A 86 85 4 2700 2430 2160 1890 6 EN = VIN 8 10 12 14 16 18 20 INPUT VOLTAGE (V) Switch Saturation Voltage vs. Switch Current –4V –5V –6V –7V –8V –9V –10V –12V –15V –20V 1620 1350 1080 810 540 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) VSAT vs. Temperature ISW=Current Limit 270 0 SWITCH CURRENT (A) Line Regulation 18.40 18.35 18.30 18.25 1.4 18.20 1.0 1.2 1.0 0.5 18.15 ISW=850mA ISW=500mA 0.8 0.6 4 –0.2A –0.6A –1.0A –1.4A 540 270 1.8 1.6 88 3.90 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 2700 2430 Max Duty Cycle vs. Input Voltage 91 3.98 3 0 6 Quiescent Current vs. Temperature EN = VIN 6 1.270 8 10 12 14 16 18 20 INPUT VOLTAGE (V) Feedback Voltage vs. Temperature 1.265 18.05 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 1.290 Enable Threshold ON vs. Temperature 1.255 1.250 1.275 VIN = 12V Load = 100mA 1.240 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) June 2008 25 6 Load = 40mA 8 10 12 14 16 18 INPUT VOLTAGE (V) Enable Current vs. Temperature 21 20 1.270 19 18 17 1.265 1.260 1.245 18.00 4 24 23 22 1.285 1.280 1.260 18.10 1.255 VIN = 12V 1.250 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 4 EN = 0V 16 VIN = 12V 15 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) M9999-062508-A Micrel, Inc. MIC2601/2 Typical Characteristics Frequency vs. Input Voltage 2.0 1.9 MIC2602 2.0 1.9 Frequency vs. Temperature MIC2602 18VOUT Efficiency 100 90 80 1.8 1.8 1.7 1.6 1.7 1.6 70 60 1.5 1.4 1.5 1.4 50 40 1.3 1.3 1.2 1.1 1.2 1.1 30 20 1.0 4 MIC2601 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) MIC2601 1.0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 18VOUT Efficiency 100 90 0.075 12VIN 70 60 50 40 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) June 2008 10 0 0 100 200 300 400 500 600 700 800 LOAD CURRENT (mA) Thermal Derating 900 700 0.073 600 500 0.072 8VIN 12VIN 800 0.074 4.5VIN 80 Shutdown Current vs. Temperature 8VIN 400 0.071 300 0.070 EN = 0V VIN = 12V 0.069 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 5 200 100 VIN = 12V VOUT = 19V 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) M9999-062508-A Micrel, Inc. MIC2601/2 Functional Characteristics June 2008 6 M9999-062508-A Micrel, Inc. MIC2601/2 Functional Diagram VIN VDD FB OVP CMP Regulator OVP CL THERMAL UVLO BANDGAP EN Bandgap SW OSC EA 1.25V S PWM CMP R SS + 1.2 / 2MHz Oscillator OSC + Ramp Generator CA PGND AGND Figure 1. MIC2601/2 Block Diagram June 2008 7 M9999-062508-A Micrel, Inc. MIC2601/2 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 0.1µF capacitor is used for in the circuit. 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 1.2/2MHz 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. 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. Pin Description VIN VIN provides power to the MOSFETs for the switch mode regulator section. Due to the high switching speeds, a 2.2µF 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 0.1µF capacitor is recommended for bypassing. 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 <10µA). 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. June 2008 8 M9999-062508-A Micrel, Inc. MIC2601/2 Component Selection Inductor Inductor selection is a balance between efficiency, stability, cost, size, and rated current. For most applications, a 10µH 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: 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). L1 10µH D1 VIN VOUT R1 100K MIC2601/2 C1 2.2µF C3 0.1µF VIN SW EN FB VDD SS AGND PGND C4 0.1µF R2 4K GND C2 10µF FRHPZ = GND Duty Cycle Considerations Duty cycle refers to the switch on-to-off time ratio and can be calculated as follows for a boost regulator: VIN VOUT 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. 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. 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. 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. June 2008 2 ⋅ π ⋅ L ⋅ IO 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). Figure 2. Typical Application Circuit D = 1− (D )2 ⋅ VO Input capacitor A minimum 2.2µF ceramic capacitor is recommended for designing with the MIC2601/2. Increasing input capacitance will improve performance and greater noise 9 M9999-062508-A Micrel, Inc. MIC2601/2 or equal to 1kΩ (R2 ≤ 1kΩ). The desired output voltage can be calculated as follows: immunity on the source. The input capacitor should be as close as possible to the inductor and the MIC2601, with short traces for good noise performance. ⎛ R1 ⎞ VOUT = VREF ⋅ ⎜ + 1⎟ R 2 ⎝ ⎠ Feedback Resistors The MIC2601/2 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 June 2008 where VREF is equal to 1.25V. 10 M9999-062508-A Micrel, Inc. MIC2601/2 D1 B360A L1 10µH 1 2 2 C4 4.7µF/50V U1 MIC2601_YML J2 GND J3 EN 3 R3 10k 2 VIN SW EN FB VDD SS 4 C2 0.1µF/50V PGND C1 2.2µF/16V 7 C5 4.7µF/50V R1 7.15k 6 R2 5 C3 0.1µF/50V 8 1 AGND J1 VIN 12V J4 VO 18V 1 J5 GND Bill of Materials Item C1 Part Number GRM21BR71C225KA12L Murata 0805YC225MAT AVX (2) Vishay(3) 06035C104MAT AVX(2) GRM188R71C104KA01D GRM31CR71H475KA12L SS3P6-E3 D1 B360A Qty. Capacitor, 2.2µF, 16V, X7R, Size 0805 1 Capacitor, 0.1µF, 50V, X7R, Size 0603 2 (1) Capacitor, 0.1µF, 16V, X7R, Size 0603 (1) Capacitor, 4.71µF, 50V, X7R, Size 1206 2 3A, 60V Schottky Diode 1 Murata Murata Vishay(3) Diodes Description (1) VJ0603Y104KXAAT C2, C3 C4, C5 Manufacturer (4) L1 LQH55DN100M03 Murata(1) 10µH, 1700mA 1 R1 CRCW06037K15FKEA Vishay Dale(3) Resistor, 7.15k, 1%, 1/16W, Size 0603 1 CRCW06034990FKEA (3) R2 R3 CRCW060310K0FKEA U1 MIC2601-YML Vishay Dale Resistor, 499Ω, 1%, 1/16W, Size 0603 1 (3) Resistor, 10k, 1%, 1/16W, Size 0603 1 (5) 1.2A, 1.2MHz Wide Range Integrated Switch Boost Regulator 1 Vishay Dale Micrel, Inc. Notes: 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 June 2008 11 M9999-062508-A Micrel, Inc. MIC2601/2 PCB Layout Recommendations Top Layer Bottom Layer June 2008 12 M9999-062508-A Micrel, Inc. MIC2601/2 Package Information 8-Pin 2mm x 2mm MLF® (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. © 2008 Micrel, Incorporated. June 2008 13 M9999-062508-A