DUAL LINEAR CONTROLLER PRELIMINARY - October 5, 1999 SC1538 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION FEATURES The SC1538 is a dual power supply controller designed to simplify power management on motherboards. It is part of Semtech’s Smart LDO™ family of products. The SC1538CS15/18 can provide a 1.818V power supply for the I/O plane and a 1.515V power supply for the GTL+ and AGP planes. The SC1538CS25/25 can provide two 2.525V supplies for clock and memory. • • SC1538 features include Enable controls for each linear FET controller and over current protection. Over current protection is provided by feedback to the sense pins. If any output drops below 1V (typical) for greater than 4ms (typical), that output will shut down. The SC1538 is available in a SO-8 surface mount package. • • • Dual power supplies 1.515V Supply for GTL+ and AGP planes/1.818V Supply for chipset I/O and memory termination Dual 2.525V supplies for clock and memory Individual Enable control of each supply Over current protection APPLICATIONS • • Motherboards Simple dual power supplies ORDERING INFORMATION (1) Part Number Output Voltages Package SC1538CS15/18 1.515V and 1.818V SO-8 SC1538CS25/25 2.525V and 2.525V SO-8 Note: (1) Add suffix ‘TR’ for tape and reel packaging. BLOCK DIAGRAM ABSOLUTE MAXIMUM RATINGS Parameter Input Supply Voltage Symbol Maximum Units VIN -0.5 to +15 V -0.5 to +7 V Input Pins PIN CONFIGURATION Top View Operating Temperature Range TA 0 to +70 °C Operating Junction Temperature TJ 0 to +125 °C Storage Temperature Range TSTG -65 to +150 °C Lead Temperature (Soldering) 10 Sec TLEAD 300 °C Thermal Temperature Junction to Ambient θJA 130 °C/W Thermal Impedance Junction to Case θJC 47 °C/W ESD 2 kV ESD Rating (SO-8) 1 © 1999 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 DUAL LINEAR CONTROLLER SC1538 PRELIMINARY - October 5, 1999 PIN DESCRIPTION Pin Pin Name Pin Function 1 DRV1 Output of regulator #1. Drives the gate of an N-channel MOSFET to maintain 1.818V/ 2.525V. 2 SNS1 Regulator #1 Sense input. Use as a remote sense to the source of the N-channel MOSFET (Output 1). 3 EN1 Active high enable control with internal pullup. Output of regulator #1 turns off when EN1 is taken low. 4 GND Ground 5 EN2 Active high enable control with internal pullup. Output of regulator #2 turns off when EN2 is taken low. 6 SNS2 Regulator #2 Sense input. Use as a remote sense to the source of the N-channel MOSFET (Output 2). 7 DRV2 Output of regulator #2. Drives the gate of an N-channel MOSFET to maintain 1.515V/ 2.525V. 8 VIN +12V Supply. APPLICATION CIRCUIT 3.3V IN 12V IN Q1 PHB11N06LT 1.818V / 2.525V OUT C1 100uF C2 100uF Q2 PHB11N06LT C3 100uF C4 100uF R1 10k 1.515V / 2.525V OUT C5 100uF C6 100uF R2 10k U1 1 2 3 1.818V / 2.525V ENABLE 4 DRV1 VIN SNS1 DRV2 EN1 SNS2 GND EN2 8 7 6 5 1.818V / 2.525V ENABLE SC1538 C7 0.1uF 2 © 1999 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 DUAL LINEAR CONTROLLER SC1538 PRELIMINARY - October 5, 1999 ELECTRICAL CHARACTERISTICS Unless specified, TA = 25°C. Values in bold apply over full operating temperature range. Parameter Symbol Test Conditions MIN TYP MAX Units 11.28 12.00 12.72 V 2 3 mA VIN Supply Voltage VIN Quiescent Current IQ Both EN High 4 One or both EN Low 1.5 2.0 mA 2.5 Undervoltage Lockout Start Threshold UVLO 7 8 9 V 50 100 µA Enable Enable Pin Current IEN Input = Low 150 Threshold Voltage VTH Hysteresis VEN rising VHYST (1) Enable Delay Time (1) Disable Delay Time 1.6 100 180 2.3 V 300 mV tD(ON) EN = Low to High, measured from EN = VTH to 10% DRV 500 ns tD(OFF) EN = High to Low, measured from EN = VTH to 90% DRV 150 ns 5 10 mA 9.0 10.5 V 1.6 ms 550 ns DRV Output Current IDRV Output Voltage VDRV Full On tr EN = Low to High, measured from EN = VTH to 90% DRV (1) Rise Time (1) Fall Time tf Output Voltage Regulation (1) Output Voltage VO 3.0V ≤ VFET (2) ≤ 3.6V, 1mA ≤ IO ≤ 1A -1.5% VO -2.5% +1.5% V +2.5% Overcurrent Protection Trip Threshold VOC Power-up Output Short Circuit Immunity Output Short Circuit Glitch Immunity -20% 1.00 +15% V 1 5 60 ms 0.5 4 6 ms Control Section Bandwidth NOTES: (1) See Application Circuit (2) Connected to FET drains. © 1999 SEMTECH CORP. DRV = 9V, THD = 5%, CL = 600pF 5 MHz 3 652 MITCHELL ROAD NEWBURY PARK CA 91320 DUAL LINEAR CONTROLLER SC1538 PRELIMINARY - October 5, 1999 OUTLINE DRAWING - SO-8 JEDEC REF: MS-012AA LAND PATTERN - SO-8 ECN99-633 - 10-5-99 4 © 1999 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320