DEMO MANUAL DC252 DESIGN-READY SWITCHER LTC1736 5-Bit VID Constant Frequency Synchronous DC/DC Converter DESCRIPTIO Demonstration Circuit DC252 is designed for mobile 5-bit ciently. Output voltages can be configured according to VID-programmed notebook CPU applications using the Intel mobile VID standards of 0.9V to 2.0V. An internal LTC 1736 switching regulator controller. A high perfor- power-good circuit monitors the output voltage for out-of- mance, constant frequency current mode architecture regulation conditions. External frequency synchronization TM generates a precise low voltage CPU core supply. Protec- is provided, as are three modes of operation: Burst Mode tion features include an externally defeatable overcurrent operation to reduce switching losses and maintain high latchoff and internal current foldback for overload condi- operating efficiencies, burst inhibit/forced continuous tions. A soft-latched crowbar monitors the output voltage mode and a low noise pulse-skipping mode that provides TM for overvoltage protection. OPTI-LOOP compensation constant frequency operation down to 1% maximum load allows the transient response to be optimized over a wide currents with low quiescent current. This results in a range of output capacitance and ESR values. The circuit power supply that has very high efficiency, low ripple and was designed for a 5V to 24V input range but allows a 4.5V fast transient response. Gerber files for this circuit board to 28V range (limited by the external MOSFETs). Strong are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. output drivers easily handle large power MOSFETs effi- Burst Mode and OPTI-LOOP are trademarks of Linear Technology Corporation. PERFOR A CE SU ARY PARAMETER CONDITIONS VALUE Input Voltage Range (Maximum Input Voltage Limited By External MOSFET and Input Capacitor) 5V to 24V Output Output Voltage (Programmed with a 5-Bit Mobile VID Code) 0.9V to 2.0V Max Output Current (Continuous) 11.0A Max Output Current (Peak) 12A Typical Output Ripple Measured with 10MHz Bandwidth (Burst Mode Operation) I = 100mA 45mV O P-P Typical Output Ripple Measured with 10MHz Bandwidth (Continuous) I = 5A 20mV O P-P V Line Regulation 5V to 24V 0.002%/V IN TYPICAL PERFOR A CE CHARACTERISTICS A D BOARD PHOTOS Efficiency Component Side Solder Side 100 EXTV = 5V CC 90 V = 5V IN 80 70 V = 15V IN V = 24V IN 60 50 40 10mA 100mA 1A 10A LOAD CURRENT (A) 252 TA01 1 EFFICIENCY (%) UWU WW UW UDEMO MANUAL DC252 DESIGN-READY SWITCHER PERFOR A CE SU ARY PARAMETER CONDITIONS VALUE I Load Regulation: No Load to Full Rated Output 0.3% OUT I Supply Current (Typical), No Load, V = 15V, FCB = INTV 950m A Q IN CC Supply Current in Shutdown (Typical), V = 15V 15m A IN I EXTV Pin Current, V = 5V, V = 10V, FCB = INTV No Load, V = 1.6V 850m A EXTVCC CC EXTVCC IN CC, OUT V Run Pin Threshold (Typical) 1.3V RUN Frequency Operating Frequency (Typical), C = 47pF 270kHz OSC PACKAGE A D SCHE ATIC DIAGRA LTC1736CG24 TOP VIEW 1 24 TG C OSC RUN/SS 2 23 BOOST I 3 22 SW TH FCB/SYNC RUN JP1 E4 E3 4 V FCB 21 IN BURST MODE SGND 5 20 INTV CC R6 RF1 JP2 OFF 680k 4.7 LATCHOFF 6 19 BG ON PGOOD +V IN INTV CC E10 CF1 SENSE 7 18 PGND C + + C 0.1F IN1 IN3 C + OSC1 22F 22F SENSE 8 17 EXTV CC R8 U1 47pF 30V 30V 0 9 VIDV 1 24 V 16 M2 GND FB CC TG C OSC FDS6680A C C E9 SS1 B1 V 10 15 VID4 OSENSE 0.1F 0.22F 11 14 VID3 2 23 VID0 BOOST RUN/SS C C2 VID1 12 13 VID2 R C1 330pF 33k 3 22 G PACKAGE SW I TH C C1 24-LEAD PLASTIC SSOP LTC1736 47pF L1 R CS1 4 21 D1 1.2H 0.004 V V FCB IN OUT CMDSH-3 0.9V TO 2V/11A E7 5 20 R S1 INTV SGND CC 10 + C4 C2 V OSNS 1F 4.7F M1, M3 E11 6 19 PGOOD BG FDS6680A PGOOD E1 2X CO1, CO2, C04, C06 R1 D2 + 180F 100k MBRS340T3 7 18 JP3 4V PGND SENSE PGOOD X4 C S1 1000pF INTV CC 8 17 EXTV CC + GND EXTV SENSE CC E2 C1 E8 47pF 9 16 VIDV V CC FB C3 47pF 10 15 VID4 V OSENSE 11 14 VID3 VID0 12 13 VID2 VID1 LSB MSB JP4 B0 B4 R5, 10 R2, 10 247 F01 Figure 1. Demo Board Schematic 2 W WU WW UW