LTC1705EGN

LTC1705 Dual 550kHz Synchronous Switching Regulator Controller with 5-Bit VID and 150mA LDO DESCRIPTIO U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ The LTC®1705 is a complete power supply controller for Intel Mobile Pentium processors. It includes two switching regulator controllers, each designed to drive a pair of N-channel MOSFETs in a voltage mode feedback, synchronous buck configuration, to provide the core and I/O supplies. The core controller includes a 5-bit DAC that conforms to the Intel Mobile VID specification. The IC also includes a low dropout linear regulator (LDO) that delivers up to 150mA of output current to provide the CLK supply. The LTC1705 uses a constant-frequency 550kHz PWM architecture, minimizing external component size and cost, as well as optimizing load transient performance. It provides better than 1.25% DC accuracy at its core output, and 2% at I/0 and CLK outputs. The high performance feedback loops allow the circuit to keep total output regulation within ±5% under all transient conditions. An open-drain PGOOD flag indicates that all three outputs are within ±10% of their regulated values. A shutdown circuit disables all three outputs if the RUN/SS pin is pulled to ground. In this mode, the LTC1705 supply current drops to below 100µA. Three Regulated Outputs: Core, I/O and CLK in One Package Integrated Intel Mobile 5-Bit VID DAC No External Current Sense Resistors All N-Channel External MOSFET Architecture 550kHz Switching Frequency Minimizes External Component Size and Cost Integrated 150mA LDO Linear Regulator Excellent DC Accuracy: 1.25% for Core, 2% for I/O and CLK Supplies PGOOD Flag Monitors All Three Outputs High Efficiency Over Wide Load Current Range Low Shutdown Current: < 100µA Switchers Run Out-of-Phase to Minimize CIN Small 28-Pin Narrow SSOP Package U APPLICATIO S ■ ■ Complete Power Supply Controller for Intel Mobile Pentium® Processors Intel Mobile Pentium Core, I/O, Clock Supplies Multiple Logic Supply Generator , LTC and LT are registered trademarks of Linear Technology Corporation. Pentium is a registered trademark of Intel Corporation. U ■ TYPICAL APPLICATIO VIN 5V CIN 330µF 10V ×3 + Intel Mobile Pentium VRM Supply 1µF QTCA QTCB LC 0.68µH VOUTC 0.9V TO 2V 15A 1µF + COUTC 180µF 4V ×6 RPGOOD 5k DCPC MBR 0520LT1 CCPC 1µF QBCB 2 22 PVCC 5 TGC 3 BOOSTC PGOOD 6 19 DCPIO MBR 0520LT1 VCC 26 TGIO 27 BOOSTIO SWC SWIO BGC BGIO QTIO 4 RIMAXC, 27k 8 11 C11 R31 C31 1.8k 1800pF 1800pF C21 330pF 9 R21, 11k 10k 10 CSS 0.1µF 7 12 IMAXC SENSEC FBC COMPC RUN/SS 25 IMAXIO COMPIO FBIO VINCLK 28 RIMAXI0, 16k 1 GND VID4:0 VOUTCLK COUTIO QBIO 100µF 10V ×2 R22, 11k 21 C22 100pF 20 24 + PGND 14–18 5-BIT VID LTC1705 LIO 3µH CCPIO 1µF QBCA 13 SHUTDOWN CIN: KEMET T510X337K010AS COUTC: PANASONIC EEFUE0G181R COUTIO: AVX TPS0107M010R0065 LC: SUMIDA CEP125-4712-T007 LIO: SUMIDA CDRH6D28-3R0 QTCA, QTCB, QBCA, QBCB: FAIRCHILD FDS6670A QTIO, QBIO: 1/2 FAIRCHILD NDS8926 10µF 10Ω + ■ CVINCLK 10µF 10V C12 2200pF + 1µF VOUTIO 1.5V 3A R12 8.87k 1% VINCLK 3.3V 23 CVOUTCLK 10µF 10V RB2 10k 1% + 1µF VOUTCLK 2.5V 150mA 1705 TA01 1 LTC1705 U W W W ABSOLUTE AXI U RATI GS (Note 1) U W U PACKAGE/ORDER I FOR ATIO ORDER PART NUMBER TOP VIEW Supply Voltage VCC, PVCC, VINCLK .................................................. 6V BOOSTC, BOOSTIO ............................................. 12V BOOSTC – SWC, BOOSTIO – SWIO ....................... 6V Input Voltage SWC, SWIO ................................................ –1V to 6V SENSEC, FBC, FBIO, VIDn ....... – 0.3V to (VCC + 0.3V) PGOOD, RUN/SS, IMAXC, IMAXIO .................................. – 0.3V to (VCC + 0.3V) Peak Output Current