MIC22205 2A, Integrated, Switch, High-Efficiency, Synchronous Buck Regulator with Frequency Programmable up to 4MHz General Description Features The Micrel MIC22205 is a high-efficiency, 2A, integrated Input voltage range: 2.9V to 5.5V switch, synchronous buck (step-down) regulator. The Output voltage adjustable down to 0.7V MIC22205 is optimized for highest efficiency, achieving Output load current up to 2A more than 95% efficiency while still switching at 1MHz. Safe start-up into a pre-biased output The ultra-high speed control loop keeps the output voltage within regulation even under the extreme transient load Full sequencing and tracking capability swings commonly found in FPGAs and low-voltage ASICs. Power Good (PG) output The output voltage is pre-bias safe and can be adjusted Efficiency > 95% across a broad load range down to 0.7V to address all low-voltage power needs. Programmable frequency 300kHz to 4MHz The MIC22205 offers a full range of sequencing and Ultra-fast transient response tracking options. The Enable/Delay (EN/DLY) pin, Easy RC compensation combined with the Power Good (PG) pin, allows multiple outputs to be sequenced in any way during turn-on and 100% maximum duty cycle turn-off. The Ramp Control (RC) pin allows the device to Fully-integrated MOSFET switches be connected to another product in the MIC22xxx and/or Thermal-shutdown and current-limit protection MIC68xxx family, to keep the output voltages within a 12-pin 3mm x 3mm MLF certain V on start-up. 40 C to +125 C junction temperature range The MIC22205 is available in a 12-pin 3mm x 3mm MLF with a junction operating range from 40 C to +125C. Data sheets and support documentation can be found on Applications Micrels web site at: www.micrel.com. High power density point-of-load conversion Servers, routers, and base stations DVD recorders / Blu-ray players Computing peripherals FPGAs, DSP, and low-voltage ASIC power Typical Application Efficiency (V = 5V) IN vs. Output Current 100 3.3V 95 90 85 1.8V 80 75 70 65 V = 5V IN 60 55 50 00.5 11.5 2 OUTPUT CURRENT (A) MIC22205 2A 1MHz Synchronous Output Converter Ramp Control is a trademark of Micrel, Inc. 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 Micrel, Inc. MIC22205 Ordering Information (1) Part Number Voltage Junction Temperature Range Package Lead Finish MIC22205YML Adjustable 40 to +125C 12-Pin 3mm x 3mm MLF Pb-Free Note: 1. MLF is a GREEN ROHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free. Pin Configuration 12-Pin 3mm x 3mm MLF (ML) Pin Description Pin Number Pin Name Description PG (output): This is an open drain output that indicates when the output voltage is below 90% of 1 PG its nominal voltage. The PG flag is asserted without delay when the enable is set low or when the output goes below the 90% threshold. Ramp Control: A capacitor from the RC pin-to-ground determines slew rate of output voltage during start-up. The RC pin is internally fed with a 1A current source. The output voltage tracks 2 RC the RC pin voltage. The slew rate is proportional by the internal 1A source and the RC pin capacitor. This feature can be used for tracking capability as well as soft start. 3 CF Adjustable frequency with external capacitor. Refer to Table 2. 4 SGND Signal Ground: Internal signal ground for all low power circuits. Compensation Pin (Input): The MIC22205 uses an internal compensation network containing a fixed-frequency zero (phase lead response) and pole (phase lag response) which allows the 5 COMP external compensation network to be much simplified for stability. The addition of a single capacitor and resistor to the COMP pin will add the necessary pole and zero for voltage mode loop stability using low-value, low-ESR ceramic capacitors. Feedback: Input to the error amplifier. The FB pin is regulated to 0.7V. A resistor divider 6 FB connecting the feedback to the output is used to adjust the desired output voltage. Signal Power Supply Voltage (Input): This pin is connected externally to the PVIN pin. A 2.2F 7 SVIN ceramic capacitor from the SVIN pin to SGND must be placed next to the IC. Power Supply Voltage (Input): The PVIN pins are the input supply to the internal P-Channel 8 PVIN Power MOSFET. A 10F ceramic is recommended for bypassing at each PVIN pin. The SVIN pin must be connected to a PVIN pin. Switch (Output): This is the connection to the drain of the internal P-Channel MOSFET and drain 9 SW of the N-Channel MOSFET. This is a high-frequency, high-power connection therefore traces should be kept as short and as wide as practical. M9999-082511-A August 2011 2