MIC2176-1/-2/-3 Wide Input Voltage, Synchronous Buck Controllers Featuring Adaptive On-Time Control Hyper Speed Control Family General Description Features TM Hyper Speed Control architecture enables The Micrel MIC2176-1/-2/-3 is a family of constant-frequency, synchronous buck controllers featuring a unique digitally - High delta V operation (V = 75V and V = 1.2V) IN OUT modified adaptive ON-time control architecture. The MIC2176 - Small output capacitance family operates over an input supply range of 4.5V to 75V 4.5V to 75V input voltage and can be used to supply up to 15A of output current. The Output down to 0.8V with 1% accuracy output voltage is adjustable down to 0.8V with a guaranteed TM Any Capacitor Stable accuracy of 1%, and the device operates at a constant - Zero-ESR to high-ESR output capacitance switching frequency of 100kHz, 200kHz, and 300kHz. TM 100kHz/200kHz/300kHz switching frequency Micrels Hyper Speed Control architecture allows for ultra- Internal compensation fast transient response while reducing the output capacitance and also makes (High V )/(Low V ) operation possible. 6ms Internal soft-start IN OUT This digitally modified adaptive t ripple control architecture ON Foldback current limit and hiccup mode short-circuit combines the advantages of fixed-frequency operation and protection fast transient response in a single device. Thermal shutdown The MIC2176 offers a full suite of protection features to Supports safe start-up into a pre-biased output ensure protection of the IC during fault conditions. These 40 C to +125 C junction temperature range include undervoltage lockout to ensure proper operation Available in 10-pin MSOP package under power-sag conditions, internal soft-start to reduce inrush current, fold-back current limit, hiccup mode short- circuit protection and thermal shutdown. Applications All support documentation can be found on Micrels web Distributed power systems site at: www.micrel.com. Networking/Telecom Infrastructure Printers, scanners, graphic cards and video cards Typical Application Efficiency vs. Output Current 95 90 85 28V IN 80 48V IN 75 60V 70 IN 65 60 MIC2176-2 55 V = 3.3V OUT 50 V = 5V LINEAR DD 45 40 0 12 345 OUTPUT CURRENT (A) MIC2176-2 Adjustable Output 200KHz Buck Converter Hyper Speed Control, SuperSwitcher II and Any Capacitor are trademarks 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. MIC2176 Ordering Information Output Part Number Switching Frequency Junction Temperature Range Package Lead Finish Voltage MIC2176-1YMM Adjustable 100kHz 40C to +125C 10-pin MSOP Pb-Free MIC2176-2YMM Adjustable 200kHz 40C to +125C 10-pin MSOP Pb-Free MIC2176-3YMM Adjustable 300kHz 40C to +125C 10-pin MSOP Pb-Free Pin Configuration 10-Pin MSOP (MM) Pin Description Pin Pin Name Pin Function Number High-Side MOSFET Drain Connection (Input): The HSD pin in the input of the adaptive On-time 1 HSD control circuitry. A 0.1uF ceramic capacitor between the HSD pin and the power ground (PGND) is required and must be place as close as possible to the IC. Enable (Input): A logic level control of the output. The EN pin is CMOS compatible. Logic high or 2 EN floating = enable, logic low = shutdown. In the off state, the V supply current of the device is DD reduced (typically 0.7mA). Do not connect the EN pin to the HSD pin. Feedback (Input): Input to the transconductance amplifier of the control loop. The FB pin is regulated 3 FB to 0.8V. A resistor divider connecting the feedback to the output is used to adjust the desired output voltage. Signal ground. GND is the ground path for the device bias voltage V and the control circuitry. The DD 4 GND loop for the signal ground should be separate from the power ground (PGND) loop. V Bias (Input): Power to the internal reference and control sections of the MIC2176. The V DD DD operating voltage range is from 4.5V to 5.5V. A 1F ceramic capacitor from the VDD pin to the PGND 5 VDD pin must be placed next to the IC. Low-Side Drive (output): High-current driver output for external low-side MOSFET. The DL driving 6 DL voltage swings from ground to V . DD Power Ground. PGND is the ground path for the buck converter power stage. The PGND pin connects to the sources of low-side N-Channel external MOSFETs, the negative terminals of input 7 PGND capacitors, and the negative terminals of output capacitors. The loop for the power ground should be as small as possible and separate from the Signal ground (GND) loop. High-Side Drive (output): High-current driver output for external high-side MOSFET. The DH driving voltage is floating on the switch node voltage (V ). Adding a small resistor between DH pin and the SW 8 DH gate of the high-side N-channel MOSFETs can slow down the turn-on and turn-off time of the MOSFETs. 2 November 2010 M9999-111710-A