MIC2290 Micrel MIC2290 2mm × 2mm PWM Boost Regulator with Internal Schotty Diode General Description Features The MIC2290 is a 1.2MHz , PWM, boost-switching regulator housed in the small size 2mm × 2mm MLF™-8 package. The MIC2290 features an internal Schottky diode that reduces circuit board area and total solution cost. High power density is achieved with the MIC2290’s internal 34V/0.5A switch, allowing it to power large loads in a tiny footprint. The MIC2290 implements a constant frequency 1.2MHz PWM control scheme. The high frequency operation saves board space by reducing external component sizes. The fixed frequency PWM topology also reduces switching noise and ripple to the input power source. The MIC2290’s wide 2.5V to 10V input voltage allows direct operation from 3- to 4-cell NiCad/NiMH/Alkaline batteries, 1and 2-cell Li Ion batteries, as well as fixed 3.3V and 5V systems. The MIC2290 is available in a low-profile 2mm × 2mm 8-pin MLF™ leadless package and operates from a junction temperature range of –40°C to +125°C. All support documentation can be found on Micrel’s web site at www.micrel.com. • • • • • • • • • • • • • • Internal Schottky diode 2.5V to 10V input voltage Output voltage adjustable to 34V Over 500mA switch current 1.2MHz PWM operation Stable with ceramic capacitors <1% line and load regulation Low input and output ripple <1µA shutdown current UVLO Output overvoltage protection Over temperature protection 2mm × 2mm 8-pin MLF™ package –40°C to +125°C junction temperature range Applications • • • • • Organic EL power supply TFT LCD bias supply 12V DSL power supply CCD bias supply SEPIC converters Typical Application VOUT 12V L1 10µH VIN 85 C1 1µF EN SW OUT FB 7 R1 1 C2 10µF 6 GND 4, 8 EFFICIENCY (%) Li Ion Battery 3 VIN VIN = 4.2V 80 MIC2290BML 2 12VOUT Efficiency 75 70 VIN = 3.2V VIN = 3.6V 65 R2 60 0 0.02 0.04 0.06 0.08 LOAD CURRENT (A) 0.1 Simple 12V Boost Regulator MicroLeadFrame and MLF are trademarks of Amkor Technology, Inc. Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com August 2004 1 M9999-081104 MIC2290 Micrel Ordering Information Part Number Marking Code Output Voltage Overvoltage Protection Junction Temp. Range Package Lead Finish MIC2290BML SRC Adjustable 34V –40°C to 125°C 2×2 8-pin MLF™ Standard MIC2290YML SRC Adjustable 34V –40°C to 125°C 2×2 8-pin MLF™ Lead Free Pin Configuration OUT 1 8 PGND VIN 2 7 SW EN 3 6 FB AGND 4 5 NC 8-Pin MLF™ (ML) (Top View) Fused Lead Frame Pin Description Pin Number Pin Name Pin Function 1 OUT Output pin (Output): Output voltage. Connect to FB resistor divider. This pin has an internal 34V output overvoltage clamp. See “Block Diagram” and “Applications” section for more information. 2 VIN Supply (Input): 2.5V to 10V input voltage. 3 EN Enable (Input): Logic high enables regulator. Logic low shuts down regulator. 4 AGND 5 NC No connect (no internal connection to die). 6 FB Feedback (Input): Output voltage sense node. Connect feedback resistor Analog ground. network to this pin. VOUT = 1.24V 1+ 7 SW 8 PGND EP GND M9999-081104 R1 R2 Switch node (Input): Internal power Bipolar collector. Power ground. Ground (Return): Exposed backside pad. 2 August 2004 MIC2290 Micrel Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) ..................................................... 12V Switch Voltage (VSW) ..................................... –0.3V to 34V Enable Pin Voltage (VEN) ................................... –0.3 to VIN FB Voltage (VFB) ............................................................. 6V Switch Current (ISW) ....................................................... 2A Storage Temperature (TS) ....................... –65°C to +150°C ESD Rating(3) ................................................................ 2kV Supply Voltage (VIN) ........................................ 2.5V to 10V Junction Temperature Range (TJ) ........... –40°C to +125°C Package Thermal Impedance 2mm × 2mm MLF™ (θJA) .................................... 93°C/W Electrical Characteristics(4) TA = 25°C, VIN = VEN = 3.6V, VOUT = 10V, IOUT = 20mA, unless otherwise noted. Bold values indicate –40°C ≤ TJ ≤ ±125°C. Symbol Parameter Condition Min VIN Supply Voltage Range 2.5 VUVLO Undervoltage Lockout 1.8 IVIN Quiescent Current VFB = 2V, (not switching) 0V(5) Typ Max Units 10 V 2.1 2.4 V 2.5 5 mA 0.2 1 µA 1.24 1.252 1.265 V V ISD Shutdown Current VEN = VFB Feedback Voltage (±1%) (±2%) (Over Temp) IFB Feedback Input Current VFB = 1.24V Line Regulation 3V ≤ VIN ≤ 5V 0.1 1 % Load Regulation 5mA ≤ IOUT ≤ 20mA 0.2 1 % DMAX Maximum Duty Cycle ISW Switch Current Limit VSW Switch Saturation Voltage ISW VEN 1.227 1.215 –450 85 nA 90 % 0.75 A ISW = 0.5A 450 mV Switch Leakage Current VEN = 0V, VSW = 10V 0.01 Enable Threshold Turn on Turn off 5 µA 0.4 V V 20 40 µA 1.2 1.35 MHz 0.8 1 V 4 µA 34 V 1.5 IEN Enable Pin Current VEN = 10V fSW Oscillator Frequency VD Schottky Forward Drop ID = 150mA IRD Schottky Leakage Current VR = 30V VOVP Overvoltage Protection (nominal voltage) TJ Overtemperature Threshold Shutdown Hysteresis 1.05 30 32 150 10 °C °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, θJA, 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. This device is not guaranteed to operate beyond its specified 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. ISD = IVIN. August 2004 3 M9999-081104 MIC2290 Micrel Typical Characteristics 70 VIN = 3.6V 65 60 VIN = 3.3V 55 50 0 0.9 25 50 75 100 OUTPUT CURRENT (mA) FEEDBACK VOLTAGE (V) 75 12.08 12.06 12.04 12.02 12 11.98 11.96 11.94 11.92 11.9 0 Current Limit vs. Supply Voltage 1.0 VIN = 3.6V 20 40 60 LOAD (mA) CURRENT LIMIT (A) CURRENT LIMIT (A) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.8 0.6 0.4 0.2 0.1 700 600 500 400 300 200 VIN = 3.6V 100 0 0 100 200 300 400 500 SWITCH CURRENT (mA) 90 88 86 84 4 5.5 7 8.5 SUPPLY VOLTAGE (V) 10 1.25 1.24 1.24 1.23 1.23 Switch Saturation Voltage vs. Temperature 540 Switch Saturation vs. Supply Voltage 530 520 510 500 490 480 470 460 450 2.5 1.4 ISW = 500mA 4 5.5 7 8.5 SUPPLY VOLTAGE (V) 10 Frequency vs. Temperature 1.35 600 500 400 300 200 VIN = 3.6V I = 500mA 100 SW 1.3 1.25 1.2 1.15 1.1 1.05 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 99 94 92 M9999-081104 700 Maximum Duty Cycle vs. Supply Voltage 98 96 82 80 2.5 SWITCH SATURATION VOLTAGE (mV) 10 Switch Saturation vs. Current 100 MAXIMUM DUTY CYCLE (%) 4 5.5 7 8.5 SUPPLY VOLTAGE (V) 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) MAXIMUM DUTY CYCLE (%) SWITCH SATURATION VOLTAGE (mV) 0 2.5 1.25 1.22 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 80 Current Limit vs. Temperature Feedback Voltage vs. Temperature 1.26 SWITCH SATURATION VOLTAGE (mV) VIN = 4.2V 80 1.26 FREQUENCY (MHz) EFFICIENCY (%) 85 Load Regulation 12.1 1 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) Maximum Duty Cycle vs. Temperature 97 95 93 91 89 VIN = 3.6V 87 85 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 4 700 FEEDBACK CURRENT (nA) Efficiency at VOUT = 12V OUTPUT VOLTAGE (V) 90 FB Pin Current vs. Temperature 600 500 400 300 200 100 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) August 2004 MIC2290 700 1.28 1.26 1.24 1.22 1.2 1.18 1.16 1.14 1.12 1.1 2.5 August 2004 4 5.5 7 8.5 SUPPLY VOLTAGE (V) 10 Schottky Diode Leakage vs. Temperature 600 500 400 300 200 100 VR = 15V 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) 5 100 REVERSE CURRENT (nA) Enable Threshold vs. Supply Voltage FEEDBACK CURRENT (nA) ENABLE THRESHOLD (V) 1.3 Micrel Schottky Reverse Leakage vs. Reverse Voltage 90 80 70 60 50 40 30 20 10 0 0 5 10 15 20 25 30 REVERSE VOLTAGE (V) 35 M9999-081104 MIC2290 Micrel Function Characteristics Enable Characteristics 3.6VIN 12VOUT 150mA Load Load Transient Response Switching Waveforms 6 SWITCH SATURATION (5V/div) 3.6VIN 12VOUT COUT = 10µF OUTPUT VOLTAGE (50mV/div) Time (400µs/div) Time (400µs/div) M9999-081104 12VOUT 150mA Load Time (400µs/div) INDUCTOR CURRENT (500mA/div) LOAD CURRENT OUTPUT VOLTAGE (50mA/div) (100mV/div) AC-Coupled ENABLE VOLTAGE (2V/div) OUTPUT VOLTAGE (5V/div) INPUT VOLTAGE OUTPUT VOLTAGE (2V/div) (100mV/div) AC-Coupled Line Transient Response Output Voltage Inductor Current (10µH) 3.6VIN 12VOUT 60mA VSW Time (400ns/div) August 2004 MIC2290 Micrel Functional Diagram VIN FB OUT EN OVP SW PWM Generator gm VREF 1.24V Σ 1.2MHz Oscillator CA Ramp Generator GND Figure 1. MIC2290 Block Diagram The gm error amplifier measures the feedback voltage through the external feedback resistors and amplifies the error between the detected signal and the 1.24V 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. Functional Description The MIC2290 is a constant frequency, PWM current mode boost regulator. The block diagram is shown in Figure 1. The MIC2290 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 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. August 2004 7 M9999-081104 MIC2290 Micrel Applications Information Component Selection DC-to-DC PWM Boost Conversion The MIC2290 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 (D1). Voltage regulation is achieved through pulse-width modulation (PWM). 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 MIC2290 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: L1 10µH VIN VOUT MIC2290BML VIN C1 2.2µF SW OUT EN C2 10µF FB GND GND R1 R2 GND 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− Frhpz = 2 VOUT × L × IOUT × 2π 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 MIC2290. Y5V values may be used, but to offset their tolerance over temperature, more capacitance is required. The following table shows the recommended ceramic (X5R) output capacitor value vs. output voltage. 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 MLF™ package option, there is an overvoltage protection function. If the feedback resistors are disconnected from the circuit or the feedback pin is shorted to ground, the feedback pin will fall to ground potential. This will cause the MIC2290 to switch at full duty cycle in an attempt to maintain the feedback voltage. As a result, the output voltage will climb out of control. This may cause the switch node voltage to exceed its maximum voltage rating, possibly damaging the IC and the external components. To ensure the highest level of protection, the MIC2290 OVP pin will shut the switch off when an overvoltage condition is detected, saving itself and other sensitive circuitry downstream. M9999-081104 VIN Output Voltage Recomended Output Capacitance <6V 22µF <16V 10µF <34V 4.7µF Table 1. Output Capacitor Selection Input capacitor A minimum 1µF ceramic capacitor is recommended for designing with the MIC2290. 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 MIC2290, with short traces for good noise performance. 8 August 2004 MIC2290 Micrel Feedback Resistors The MIC2290 utilizes a feedback pin to compare the output to an internal reference. The output voltage is adjusted by selecting the appropriate feedback resistor values. The desired output voltage can be calculated as follows: R1 VOUT = VREF × + 1 R2 where VREF is equal to 1.24V. August 2004 9 M9999-081104 MIC2290 Micrel Application Circuits L1 4.7µH VIN 3.3V L1 10µH VIN 3V to 4.2V VOUT 5V @ 180mA MIC2290BML MIC2290BML C1 2.2µF 6.3V SW VIN R1 5.62k FB GND EN FB GND GND R1 54.9k OUT GND R2 100k GND SW VIN C1 2.2µF 6.3V C2 10µF 6.3V OUT EN VOUT 15V @ 45mA R2 5k C2 10µF 16V GND C1 2.2µF, 6.3V, 0805 X5R Ceramic Capacitor 08056D475MAT AVX C1 2.2µF, 6.3V, 0603 X5R Ceramic Capacitor 06036D225MAT AVX C2 10µF, 6.3V, 0805 X5R Ceramic Capacitor 08056D106MAT AVX C2 10µF, 16V, 1206 X5R Ceramic Capacitor 1206YD106MAT AVX L1 4.7µH, 450mA Inductor LQH32CN4R7N11 Murata L1 10µH, 450mA Inductor LQH32CN100K11 Murata Figure 6. 3.3VIN – 4.2VIN to 15VOUT @ 45mA Figure 3. 3.3VIN to 5VOUT @ 180mA L1 10µH VIN 3V to 4.2V L1 10µH VIN 5V VOUT 9V @ 80mA MIC2290BML MIC2290BML C1 2.2µF 6.3V SW VIN R1 31.6k OUT EN FB GND SW VIN C1 2.2µF 6.3V C2 10µF 16V EN FB R2 5k GND GND R1 31.6k OUT GND R2 5k GND VOUT 9V @ 160mA C2 10µF 16V GND C1 2.2µF, 6.3V, 0603 X5R Ceramic Capacitor 06036D225MAT AVX C1 2.2µF, 6.3V, 0603 X5R Ceramic Capacitor 06036D225MAT AVX C2 10µF, 16V, 1206 X5R Ceramic Capacitor 1206YD106MAT AVX C2 10µF, 16V, 1206 X5R Ceramic Capacitor 1206YD106MAT AVX L1 10µH, 450mA Inductor LQH32CN100K11 Murata L1 10µH, 450mA Inductor LQH32CN100K11 Murata Figure 7. 5VIN to 9VOUT @ 160mA Figure 4. 3.3VIN – 4.2VIN to 9VOUT @ 80mA L1 10µH VIN 3V to 4.2V L1 10µH VIN 5V VOUT 12V @ 50mA MIC2290BML MIC2290BML C1 2.2µF 6.3V VIN SW R1 43.2k OUT EN FB GND GND VOUT 12V @ 110mA R2 5k C1 2.2µF 6.3V C2 10µF 16V VIN SW OUT EN FB GND GND GND R1 43.2k R2 5k C2 10µF 16V GND C1 2.2µF, 6.3V, 0603 X5R Ceramic Capacitor 06036D225MAT AVX C1 2.2µF, 6.3V, 0603 X5R Ceramic Capacitor 06036D225MAT AVX C2 10µF, 16V, 1206 X5R Ceramic Capacitor 1206YD106MAT AVX C2 10µF, 16V, 1206 X5R Ceramic Capacitor 1206YD106MAT AVX L1 10µH, 450mA Inductor LQH32CN100K11 Murata L1 10µH, 450mA Inductor LQH32CN100K11 Murata Figure 8. 5VIN to 12VOUT @ 110mA Figure 5. 3.3VIN – 4.2VIN to 12VOUT @ 50mA M9999-081104 10 August 2004 MIC2290 Micrel L1 10µH VIN 5V VOUT 24V @ 40mA MIC2290BML C1 2.2µF 6.3V VIN SW R1 18.2k OUT EN FB GND GND R2 1k C2 4.7µF 25V GND C1 2.2µF, 6.3V, 0603 X5R Ceramic Capacitor 06036D225MAT AVX C2 4.7µF, 25V, 1206 X5R Ceramic Capacitor 12063D475MAT AVX L1 10µH, 450mA Inductor LQH32CN100K11 Murata Figure 9. 5VIN to 24VOUT @ 40mA August 2004 11 M9999-081104 MIC2290 Micrel Package Information 8-Pin MLF™ (ML) MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 TEL + 1 (408) 944-0800 FAX USA + 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2004 Micrel, Incorporated. M9999-081104 12 August 2004