MIC2198 Micrel, Inc. MIC2198 500kHz 4mm 4mm Synchronous Buck Controller General Description Features The MIC2198 is a high-power 500kHz synchronous buck 4.5V to 32V input range DC-to-DC controller housed in a small 4mm 4mm MLF 4mm 4mm MLF package 12-pin package. The MIC2198 operates from a wide 4.5V 500kHz PWM operation to 32V input and can be programmed for output voltages >90% efciency from 0.8V to 6V. The wide input voltage capability makes Output voltage adjustable down to 0.8V the MIC2198 an ideal solution for point-of-load DC-to-DC 20A output current capability conversion in 5V, 12V and higher systems. Drives all N-Channel MOSFETs Logic controlled micropower shutdown The 500kHz switching frequency allows the use of a small Cycle-by-cycle current limiting inductor and small output capacitors. The current mode PWM Adjustable undervoltage lockout control along with the external COMP pin allows for ease of Frequency foldback overcurrent protection stability compensation and fast transient response across a wide range of applications. Applications An all N-Channel synchronous architecture and powerful Point-of-load DC-to-DC conversion from 5V, 12V output drivers allow up to 20A of output current capability. and higher supplies For higher efciency at higher input voltages, refer to the Telecom equipment 300kHz MIC2199. Wireless modems Servers The MIC2198 is available in a 12-pin 4mm 4mm MLF Base stations package with a junction temperature range from 40C to 125C. Typical Application V IN 5.5V to 24V U1 MIC2198BML Efficiency SD103BWS vs. Load Current VIN VDD 4.7F 22F 100 BST 95 0.1F IRF7821 V OUT EN/UVLO HSD 90 1H 3.3V/7A 0.01 VSW 85 220F IRF7821 LSD 80 CSH 75 1nF 70 COMP VOUT 10k 65 2k FB V = 5.5V 60 IN 6.04k GND V = 3.3V 55 OUT 50 2.2nF 0 2 4 6 8 (A) I LOAD 5.5V24V to 3.3V/7A Converter MLF and MicroLeadFrame are 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 MIC2198 Micrel, Inc. Ordering Information Part Number Voltage Temperature Range Package Standard Pb-Free MIC2198BML MIC2198YML Adj 40C to +125C 12-Pin 4x4 MLF Pin Conguration 1 12 COMP HSD EN/UVLO 2 11 VSW FB 3 10 BST CSH 4 9 GND VOUT 5 8 LSD VIN 6 7 VDD 12-Pin 44 MLF (ML) Pin Description Pin Number Pin Name Pin Function 1 COMP Compensation (Output): Internal error amplier output. Connect to capacitor or series RC network to compensate the regulator control loop. 2 EN/UVLO Enable/Undervoltage Lockout (Input): Low-level signal powers down the controller. Input below the 2.5V threshold disables switching and functions as an accurate undervoltage lockout (UVLO). Input below the threshold forces complete micropower (<0.1A) shutdown. 3 FB Feedback (Input): Regulates FB pin to 0.8V. See Applications Information for resistor divider calculations. 4 CSH Current-Sense High (Input): Current limit comparator non-inverting input. A built-in offset of 75mV between CSH and V pins in conjunction with the OUT current-sense resistor set the current limit threshold level. This is also the non-inverting input to the current sense amplier. 5 VOUT Current-Sense Low (Input): Output voltage feedback input and inverting input for the current limit comparator and the current sense amplier. 6 VIN Unregulated Input (Input): +4.5V to +32V supply input. 7 VDD 5V Internal Linear-Regulator (Output): V is the external MOSFET gate DD drive supply voltage and internal supply bus for the IC. Bypass to GND with 4.7F. 8 LSD Low-Side Drive (Output): High-current driver output for low-side N-Channel MOSFET. Voltage swing is between ground and V . DD 9 GND Ground (Return). 10 BST Boost (Input): Provides drive voltage for the high-side MOSFET driver. The drive voltage is higher than the input voltage by V minus a diode drop. DD 11 VSW Switch (Return): High-side MOSFET driver return. 12 HSD High-Side Drive (Output): High-current driver output for high-side MOSFET. This node voltage swing is between ground and V +5V minus a diode drop. IN MIC2198 2 October 2005