MIC27600 36V, 7A Hyper Speed Control Synchronous DC-DC Buck Regulator SuperSwitcher II General Description Features Hyper Speed Control architecture enables The Micrel MIC27600 is a constant-frequency, synchronous buck regulator featuring a unique digitally-modified adaptive - High Delta V operation (V = 36V and V = 0.8V) IN OUT on-time control architecture. The MIC27600 operates over an - Small output capacitance input supply range of 4.5V to 36V and provides a regulated 4.5V to 36V voltage input output of up to 7A of output current. The output voltage is Adjustable output from 0.8V to 5.5V (V 28V) HSD adjustable down to 0.8V with a guaranteed accuracy of 1%, Adjustable output from 0.8V to 3.6V (V 36V) HSD and the device operates at a switching frequency of 300kHz. 1% FB accuracy Micrels Hyper Speed Control architecture allows for ultra- Any Capacitor Stable - Zero-ESR to high-ESR fast transient response while reducing the output capacitance and also makes (High V )/(Low V ) operation possible. 7A output current capability, up to 95% efficiency IN OUT This digitally modified adaptive t ripple control architecture ON 300kHz switching frequency combines the advantages of fixed-frequency operation and Internal compensation, 6ms Internal soft-start fast transient response in a single device. Foldback current-limit and hiccup mode short-circuit The MIC27600 offers a full suite of protection features to protection ensure protection of the IC during fault conditions. These Thermal shutdown include undervoltage lockout to ensure proper operation Supports safe startup into a pre-biased load under power-sag conditions, internal soft-start to reduce 40 C to +125 C junction temperature range inrush current, foldback current limit, hiccup mode short- circuit protection and thermal shutdown. 28-pin 5mm 6mm MLF package All support documentation can be found on Micrels web site at: www.micrel.com. Applications Distributed power systems Communications/networking infrastructure Set-top box, gateways and routers Printers, scanners, graphic cards and video cards Typical Application Efficiency (V = 28V) IN vs. Output Current 95 5.0V 3.3V 90 2.5V 85 1.8V 1.5V 80 1.2V 1.0V 75 0.9V 0.8V 70 65 60 01 234 567 89 OUTPUT CURRENT (A) 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. MIC27600 Ordering Information Part Number Voltage Switching Frequency Junction Temperature Range Package Lead Finish MIC27600YJL Adjustable 300kHz 40C to +125C 28-pin 5mm 6mm MLF Pb-Free Pin Configuration 28-Pin 5mm 6mm MLF (YJL) Pin Description Pin Pin Name Pin Function Number 13, 14, 15, High-Side N-internal MOSFET Drain Connection (Input): The PV operating voltage range is from IN 16, 17, 18, PVIN 4.5V to 36V. Input capacitors between the PVIN pins and the power ground (PGND) are required and 19 keep the connection short. Enable (Input): A logic level control of the output. The EN pin is CMOS-compatible. Logic high or 24 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 pull the EN pin above the V supply. DD Feedback (Input): Input to the transconductance amplifier of the control loop. The FB pin is regulated 25 FB to 0.8V. A resistor divider connecting the feedback to the output is used to adjust the desired output voltage. Signal ground. SGND must be connected directly to the ground planes. Do not route the SGND pin to 26 SGND the PGND Pad on the top layer, see PCB layout guidelines for details. V Bias (Input): Power to the internal reference and control sections of the MIC27600. The V DD DD operating voltage range is from 4.5V to 5.5V. A 2.2F ceramic capacitor from the VDD pin to the 27 VDD PGND pin must be placed next to the IC. V must be powered up at the same time or after V to DD IN make the soft-start function correctly. Power Ground. PGND is the ground path for the MIC27600 buck converter power stage. The PGND 2, 5, 6, 7, pin connects to the sources of low-side N-Channel internal MOSFETs, the negative terminals of input PGND 8, 21 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 (SGND) loop. Current Sense (Input): High current output driver return. The CS pin connects directly to the switch node. Due to the high-speed switching on this pin, the CS pin should be routed away from sensitive 22 CS nodes. CS pin also senses the current by monitoring the voltage across the low-side internal MOSFET during OFF-time. 2 July 2011 M9999-070811