MIC2206 2MHz PWM Synchronous Buck Regulator with LOWQ Mode and Voltage Scaling General Description Features The Micrel MIC2206 is a high efficiency 2MHz PWM synchronous buck (step-down) regulator that features a LOWQ™ LDO standby mode that draws only 18µA of quiescent current. The MIC2206 allows an ultra-low noise, small size, and high efficiency solution for portable power applications. In PWM mode, the MIC2206 operates with a constant frequency 2MHz PWM control. Under light load conditions, such as in system sleep or standby modes, the PWM switching operation can be disabled to reduce switching losses. In this light load LOWQ™ mode, the LDO maintains an output voltage of 1V and draws only 18µA of quiescent current. The LDO mode of operation saves battery life while not introducing spurious noise and high ripple as experienced with pulse skipping or bursting mode regulators. The MIC2206 operates from 2.7V to 5.5V input and features internal power MOSFETs that can supply up to 600mA output current in PWM mode. It can operate with a maximum duty cycle of 100% for use in low-dropout conditions. The MIC2206 is available in the 3mm x 3mm MLF10L package with a junction operating range from –40°C to +125°C. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. • 2.7 to 5.5V supply voltage • Light load LOWQ™ LDO mode 18µA quiescent current Low noise, 75µVrms • 2MHz PWM mode Output current to 600mA >95% efficiency 100% maximum duty cycle • Output Voltage Scaling (1V output in LOWQ Mode) • Ultra-fast transient response • Stable with 1µF ceramic output capacitor • Fully integrated MOSFET switches • Micropower shutdown • Thermal shutdown and current limit protection • Pb-free 3mm x 3mm MLF-10L package • –40°C to +125°C junction temperature range Applications • Cellular phones • PDAs • USB peripherals ____________________________________________________________________________________________________ Typical Application MIC2206 VIN Li Ion Battery CIN 4.7µF VIN LDO AVIN SW EN FB LOWQ PGND 0.1µF BIAS 2.2µH 100pF VOUT 1.8V/600mA COUT 2.2µF Ceramic AGND Fixed Output Buck Regulator with LOWQ™ Mode LOWQ is a trademark of Micrel, 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 October 2005 M9999-102105 [email protected] Micrel, Inc. MIC2206 Ordering Information Output Voltage(1) (PWM/LDO) Junction Temp. Range Package MIC2206-1.8YML 1.8V/1.0V –40° to +125°C 3x3 MLF-10L MIC2206-1.2YML 1.2V/1.0V –40° to +125°C 3x3 MLF-10L Part Number (Pb-Free) Note: 1. Other Voltage options available. Contact Micrel for details. Pin Configuration AGND 1 10 PGND LDO 2 9 SW BIAS 3 8 VIN AVIN 4 FB 5 7 LOWQ EP 6 EN 3mm x 3mm MLF-10L (ML) Pin Description Pin Number Pin Name 1 AGND 2 LDO LDO Output (Output): Connect to VOUT for LDO mode operation. 3 BIAS Internal circuit bias supply. Must be de-coupled to signal ground with a 0.1µF capacitor and should not be loaded. 4 AVIN Analog Supply Voltage (Input): Supply voltage for the analog control circuitry and LDO input power. Requires bypass capacitor to GND. 5 FB Feedback. Input to the error amplifier and internal feedback resistors. Place a 100pF ceramic capacitor from FB to the output. 6 EN Enable (Input). Logic low will shut down the device, reducing the quiescent current to less than 5µA. 7 _____ LOWQ 8 VIN Supply Voltage (Input): Supply voltage for the internal switches and drivers. 9 SW Switch (Output): Internal power MOSFET output switches. 10 PGND EP GND October 2005 Pin Function Analog (signal) Ground. Enable LDO Mode (Input): Logic low enables the internal LDO and disables the PWM operation. Logic high enables the PWM mode and disables the LDO mode. Power Ground. Ground, backside pad. 2 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) ............................................ +6V Output Switch Voltage (VSW) ............................... +6V Output Switch Current (ISW) ................................... 2A Logic Input Voltage (VEN,VLOWQ) .............. -0.3V to VIN Storage Temperature (Ts)................ -60°C to +150°C ESD Rating(3) ....................................................... 3kV Supply Voltage (VIN)............................+2.7V to +5.5V Logic Input Voltage (VEN,VLOWQ) .............. -0.3V to VIN Junction Temperature (TJ) .............. –40°C to +125°C Junction Thermal Resistance 3x3 MLF-10L (θJA) ................................... 60°C/W Electrical Characteristics (4) VIN = VEN = VLOWQ =3.6V; L = 2.2µH; COUT = 2.2µF; TA = 25°C, unless noted. Bold values indicate –40°C< TJ < +125°C Parameter Condition Min 2.7 Supply Voltage Range Under-Voltage Lockout Threshold Typ (turn-on) 2.45 UVLO Hysteresis 2.55 Max Units 5.5 V 2.65 V 100 mV Quiescent Current, PWM mode VFB = 0.9 * VNOM (not switching) 690 900 µA Quiescent Current, LDO mode VLOWQ = 0V;IOUT = 0mA 16 29 µA Shutdown Current VEN = 0V 0.1 5 µA [Fixed Output] Voltages Nominal VOUT tolerance +1 +2 % Current Limit in PWM Mode VFB = 0.9 * VNOM 1.85 A Output Voltage Line Regulation VOUT > 2V; VIN = VOUT+300mV to 5.5V; ILOAD= 100mA VOUT < 2V; VIN = 2.7V to 5.5V; ILOAD= 100mA 0.13 Output Voltage Load Regulation, PWM Mode 20mA < ILOAD < 300mA 0.2 0.5 % Output Voltage Load Regulation, LDO Mode 100µA < ILOAD < 50mA VLOWQ = 0V 0.2 0.5 % Maximum Duty Cycle VFB ≤ 0.4V PWM Switch ONResistance ISW = 50mA VFB = 0.7VFB_NOM (High Side Switch) ISW = -50mA VFB = 1.1VFB_NOM (Low Side Switch) -1 -2 0.75 1 % 100 % 0.4 Ω 0.4 Oscillator Frequency 1.8 2 2.2 MHz LOWQ threshold voltage 0.5 0.85 1.3 V 0.1 2 µA 0.5 0.85 1.3 V 0.1 2 µA LOWQ Input Current Enable Threshold Enable Input Current October 2005 3 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Parameter Condition Min Output Voltage Noise LOWQ = 0V; COUT = 2.2μF, 10Hz to 100kHz LDO Current Limit LOWQ = 0V; VOUT = 0V (LDO Mode) Typ Max Units 75 µVrms 120 mA Over-Temperature Shutdown 160 °C Over-Temperature Hysteresis 20 °C 60 Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. Human body model: 1.5kΩ in series with 100pF. 4. Specification for packaged product only. October 2005 4 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Typical Characteristics – PWM Mode October 2005 5 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Typical Characteristics - LDO Mode October 2005 6 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Functional Diagram VIN AVIN P-Channel Current Limit 6 BIAS HSD SW PWM Control VOUT Anti-Shoot Through COUT LSD N-Channel Current Limit EN Enable and Control Logic LOWQ Bias, UVLO, Thermal Shutdown FB Soft EA Start 1.0V 100pF R1 LDO Block R2 LDO Current Limit EA 1.0V LDO PGND SGND MIC2206 Block Diagram October 2005 7 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Functional Characteristics Load Transient PWM Mode Load Transient LDO Mode LowQ = VIN Output Voltaeg AC Coupled (10mV/div) Output Voltage AC Coupled (50mV/div) Output Current (50mV/div) Output Current (20mA/div) LowQ = 0V VOUT = 1.8V VOUT = 1V Time 20 s/div Time 20 s/div Enable Transient PWM Mode Enable Transient LDO Mode LowQ = 0V Output Voltage (500mV/div) VOUT (500mV/div) ENABLE (1V/div) Enable Voltage (500mV/div) LowQ = 0V Time 40 s/div PWM Waveform PWM Mode to LDO Mode Transition LowQ Voltage (1V/div) Output Ripple Voltage (10mV/div) Output Voltage (50mV/div) Switch Node Voltage (2V/div) Time 40 s/div L = 2.2 H COUT = 2.2 F Time 400µs/div October 2005 Time 100 s/div 8 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Functional Description VIN VIN provides power to the MOSFETs for the switch mode regulator section, along with the current limiting sensing. Due to the high switching speeds, a 1µF capacitor is recommended close to VIN and the power ground (PGND) pin for bypassing. BIAS The BIAS pin supplies the power to the internal power to the control and reference circuitry. The bias is powered from AVIN through an internal 6Ω resistor. A small 0.1µF capacitor is recommended for bypassing. AVIN Analog VIN (AVIN) provides power to the LDO section and the bias through an internal 6 Ohm resistor. AVIN and VIN must be tied together. Careful layout should be considered to ensure high frequency switching noise caused by VIN is reduced before reaching AVIN. FB The feedback pin (FB) provides the connection to the internal FB resistor divider. Place a small 100pF ceramic capacitor between FB and the output voltage. SW The switch (SW) pin connects directly to the inductor and provides the switching current nessasary to operate in PWM mode. Due to the high speed switching on this pin, the switch node should be routed away from sensitive nodes. LDO The LDO pin is the output of the linear regulator and should be connected to the output. In LOWQ mode (LOWQ<1.5V), the LDO provides the output voltage. In PWM mode (LOWQ>1.5V) the LDO pin is high impedance. 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 fro more details. 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 <1µA). Also, in the off state, the output drive is placed in a "tri-stated" condition, where both the high side P-channel Mosfet and the low-side N-channel are in an off or non-conducting state. Do not drive the enable pin above the supply voltage. SGND Signal ground (SGND) 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. LOWQ The LOWQ pin provides a logic level control between the internal PWM mode and the low noise linear regulator mode. With LOWQ pulled low (<0.5V), quiescent current of the device is greatly reduced by switching to a low noise linear regulator mode that has a typical IQ of 18µA. In linear (LDO) mode the output can deliver 60mA of current at 1.0V to the output. By placing LOWQ high (>1.5V) , this transitions the device into a constant frequency PWM buck regulator mode. This allows the device the ability to efficiently deliver up to 600mA of output current at the same output voltage. October 2005 9 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Applications Information Output Capacitor The MIC2206 is a 600mA PWM power supply that utilizes a LOWQ™ light load mode to maximize battery efficiency in light load conditions. This is achieved with a LOWQ control pin that when pulled low, shuts down all the biasing and drive current for the PWM regulator, drawing only 18µA of operating current. This allows the output to be scaled down and regulated to 1.0V through the LDO output, capable of providing 60mA of output current. This method has the advantage of producing a clean, low current, ultra low noise output in LOWQ™ mode. During LOWQ™ mode, the SW node becomes high impedance, blocking current flow. Other methods of reducing quiescent current, such as pulse frequency modulation (PFM) or bursting techniques create large amplitude, low frequency ripple voltages that can be detrimental to system operation. When more than 60mA is required, the LOWQ pin can be forced high, causing the MIC2206 to enter PWM mode. In this case, the LDO output makes a "hand-off" to the PWM regulator. The LDO output then turns off allowing up to 600mA of current to be efficiently supplied through the PWM output to the load. Even though the MIC2206 is optimized for a 2.2µF output capacitor, output capacitance can be varied from 1µF to 4.7µF. The MIC2206 utilizes type III internal compensation and utilizes an internal high frequency zero to compensate for the double pole roll off of the LC filter. For this reason, larger output capacitors can create instabilities. X5R or X7R dielectrics are recommended for the output capacitor. Y5V dielectrics lose most of their capacitance over temperature and are therefore not recommended. In addition to a 2.2µF, a small 10nF is recommended close to the load for high frequency filtering. Smaller case size capacitors are recommended due to there lower ESR and ESL. Inductor Selection The MIC2206 is designed for use with a 2.2µH inductor. Proper selection should ensure the inductor can handle the maximum average and peak currents required by the load. Maximum current ratings of the inductor are generally given in two methods; permissible DC current and saturation current. Permissible DC current can be rated either for a 40°C temperature rise or a 10% to 20% loss in inductance. Ensure the inductor selected can handle the maximum operating current. When saturation current is specified, make sure that there is enough margin that the peak current will not saturate the inductor. Peak inductor current can be calculated as follows: Input Capacitor A minimum 1µF ceramic is recommended on the VIN pin for bypassing. X5R or X7R dielectrics are recommended for the input capacitor. Y5V dielectrics lose most of their capacitance over temperature and are therefore not recommended. A minimum 1µF is recommended close to the VIN and PGND pins for high frequency filtering. Smaller case size capacitors are recommended due to their lower ESR and ESL. October 2005 IPK = IOUT 10 ⎛ V VOUT ⎜⎜1 − OUT VIN ⎝ + 2× f ×L ⎞ ⎟ ⎟ ⎠ M9999-102105 www.micrel.com Micrel, Inc. MIC2206 MIC2206 VIN 2.7V to 5.5V 8 C1 1µF LowQ C2 10nF SW 9 LDO 2 FB 5 VIN 4 AVIN 6 EN 7 LOWQ 3 BIAS 2.2µH VOUT 1.8V/600mA C3 100pF C4 2.2µF PGND AGND 10 GND 1 GND Item Part Number Description Manufacturer C1 06036D105MAT2 GRM185R60J105KE21D 1µF Ceramic Capacitor X5R, 6.3V 0603 1µF Ceramic Capacitor X5R, 6.3V 0603 AVX Murata 1 C4 06036D225MAT2 GRM188R61A225KE34 2.2µF Ceramic Capacitor X5R, 10V 0603 2.2µuF Ceramic Capacitor X5R, 10V 0603 AVX Murata 1 C3 VJ0402A101KXAA 100pF Ceramic Capacitor Vishay 1 C2 0201ZD103MAT2 GRM033R10J103KA01D 10nF Ceramic Capacitor 6.3V 0201 10nF Ceramic Capacitor 6.3V 0201 AVX Murata 1 L1 LQH32CN2R2M53K CDRH2D14-2R2 2.2µH Inductor 97mΩ 3.2mmx2.5mmx1.55mm 2.2µH Inductor 94mΩ 3.2mmx3.2mmx1.55mm Murata Sumida 1 U1 MIC2206BML 2MHz Synchronous Buck Regulator with LOWQ Mode Micrel Semiconductor 1 TM Qty Notes: Sumida Tel: 408-982-9660 Murata Tel: 949-916-4000 Vishay Tel: 402-644-4218 Micrel Semiconductor Tel: 408-944-0800 October 2005 11 M9999-102105 www.micrel.com Micrel, Inc. MIC2206 Package Information 10-Lead 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. © 2005 Micrel, Incorporated. October 2005 12 M9999-102105 www.micrel.com