700mA SmartLDO PRELIMINARY - July 25, 2000 TM SC1537 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION FEATURES •= •= •= •= •= •= •= The SC1537 is designed to maintain a glitch-free 3.3V output when at least one of two inputs, 5V (VIN) and 3.3V (VAUX), is present. Whenever VIN exceeds a predetermined threshold value, the internal 3.3V linear regulator is enabled, and DR is pulled high. Glitch-free transition between input sources Internal logic selects input source Gate drive for external PMOS bypass switch 5V detector with hysteresis 1% regulated output voltage accuracy 700mA load current capability SO-8 and TO-263 packages When VIN falls below a lower threshold value, DR is pulled low and the internal linear regulator is turned off. DR has been designed to drive the gate of an external low threshold P-channel MOSFET, which can be used to connect the 3.3V supply directly to the regulator output. This ensures an uninterrupted 3.3V output even if VIN falls out of specification. A maximum RDS(ON) of 100mΩ is recommended. APPLICATIONS When both supplies are simultaneously available, the drive pin (DR) will be pulled High, turning off the external PMOS switch. ORDERING INFORMATION •= •= •= •= •= Desktop Computers Network Interface Cards (NICs) PCMCIA/PCI Interface Cards CardbusTM Technology Power supplies with multiple input sources (1) The internal 5V detector has its upper threshold (for VIN rising) set to 4.22V (typical) while the lower threshold (for VIN falling) is at 4.05V (typical) giving a hysteresis of approximately 170mV. Part Number Package SC1537CSTR SO-8 SC1537CMTR TO-263-5L Note: (1) Only available in tape and reel packaging. A reel contains 2500 devices for SO-8 and 800 devices for TO-263. The SC1537 is available in the popular SO-8 and 5-lead TO-263 surface mount packages. APPLICATION CIRCUIT Q1 3.3V OUT U1 SC1537CS 1 2 3 4 3.3V 5V C1 0.1uF C2 10uF VAUX VIN VO DR GND GND GND GND 8 7 6 5 C4 10uF C3 0.1uF C5 0.1uF Q1 U1 2 5V 1 3.3V C1 0.1uF C2 10uF C3 0.1uF VIN TAB SC1537CM 5 DR VAUX GND 3 VO 4 3.3V OUT C4 10uF C5 0.1uF NOTE: (1) External switch (Q1): use a low threshold P-channel MOSFET such as Vishay Si2305DS (RDS(ON) < 71mΩ at VGS = 2.5V) or International Rectifier IRLML6401 (RDS(ON) < 85mΩ at VGS = 2.5V), or equivalent. 1 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 ABSOLUTE MAXIMUM RATINGS Parameter Symbol Maximum Units VIN -0.5 to +7 V VAUX -0.5 to +7 V LDO Output Current IO 10 to 700 mA Operating Ambient Temperature Range TA 0 to +70 °C Operating Junction Temperature Range TJ 0 to +125 °C Storage Temperature Range TSTG -65 to +150 °C Lead Temperature (Soldering) 10 Sec TLEAD 300 °C θJA 65 60 °C/W θJ C 39 3 °C/W ESD 2 kV Input Supply Voltage Auxiliary Supply Voltage Thermal Impedance Junction to Ambient SO-8(1) TO-263 Thermal Impedance Junction to Case SO-8 TO-263 ESD Rating (Human Body Model) Note: (1) 1 inch square of 1/16” FR-4, double sided, 1 oz. minimum copper weight. ELECTRICAL CHARACTERISTICS Unless specified, TA = 25°C, VIN = 5V, VAUX = 3.3V, IO = 700mA, CO = 10µF. Values in bold apply over full operating temperature range. Parameter Symbol Test Conditions MIN TYP MAX Units VIN VAUX = 0V 4.75 5.00 5.25 V IQ VIN = 5V, VAUX = 0V, IO = 0mA 9.0 14.0 mA VIN Supply Voltage Quiescent Current 16.0 VIN = 5V, VAUX = 3.3V, IO = 0mA 13.0 17.0 mA 18.0 Reverse Leakage From VAUX IVIN VAUX = 3.6V, VIN = 0V, IO = 0mA -1.5 -3.0 mA -4.0 VAUX Supply Voltage VAUX Quiescent Current IQ(AUX) 3.0 VAUX = 3.3V, VIN = 0V, IO = 0mA 3.3 3.6 V 8.0 11.0 mA 13.0 VAUX = 3.3V, VIN = 5V, IO = 0mA 1.5 2.5 mA 3.0 2 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 ELECTRICAL CHARACTERISTICS Unless specified, TA = 25°C, VIN = 5V, VAUX = 3.3V, IO = 700mA, CO = 10µF. Values in bold apply over full operating temperature range. Parameter Symbol Test Conditions IVAUX VIN = 5.5V, VAUX = 0V, IO = 0mA MIN TYP MAX Unit -5.0 -50.0 µA VAUX (Cont.) Reverse Leakage From VIN 100.0 5V Detect (1)(2)(3) Low Threshold Voltage VTH(LO) VIN Falling, IO = 20mA 3.92 4.05 3.90 Hysteresis VHYST 90 4.18 V 4.20 170 mV 80 High Threshold Voltage VTH(HI) VIN Rising, IO = 20mA VO IO = 20mA 3.267 4.75V ≤ VIN ≤ 5.25V, 0mA ≤ IO ≤ 700mA 3.234 4.35 V 3.333 V VO LDO Output Voltage Output Current IO Line Regulation REG(LINE) VIN = 4.75V to 5.25V 3.300 3.366 0.20 400 mA 0.60 % 0.80 Load Regulation REG(LOAD) IO = 10mA to 700mA 0.6 1.0 % 1.2 Drive Output Drive Voltage VDR 4.75V ≤ VIN ≤ 5.25V, IDR = 200µA 3.4 VIN - 0.8 V 3.3 VIN < VTH(LO), IDR = -200µA 35 150 mV 250 Peak Drive Current (1)(4) Drive High Delay IDR(PK) tDH Sinking: VIN = 3.9V, VDR = 1V; 7 Sourcing: VIN = 4.35V, VIN - VDR = 2.5V 6 CDR = 1.2nF, VIN ramping up, measured mA 0.5 from VIN = VTH(HI) to VDR = 2V (1)(4) Drive Low Delay tDL CDR = 1.2nF, VIN ramping down, measured from VIN = VTH(LO) to VDR = 2V 1.0 2.0 0.5 1.0 µs 2.0 NOTES: (1) Guaranteed by design. (2) See 5V Detect Thresholds on page 5. (3) Recommended source impedance for 5V supply: ≤ 0.07Ω. This will ensure that IO x RSOURCE < VHYST, thus avoiding DR toggling during 5V detect threshold transitions. (4) See Timing Diagram on page 5. © 2000 SEMTECH CORP. µs 3 652 MITCHELL ROAD NEWBURY PARK CA 91320 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 BLOCK DIAGRAM PIN CONFIGURATION Top View SO-8 TO-263-5L PIN DESCRIPTION Pin Name SO-8 Pin # TO-263-5L Pin # Pin Function DR 4 5 GND 5,6,7,8 3/TAB VAUX 1 1 This is the auxiliary input supply, nominally 3.3V. VIN 2 2 This is the main input supply for the IC, nominally 5V. VO 3 4 LDO 3.3V output. Driver output for external P-channel MOSFET pass element. Logic and power ground. 4 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 5V DETECT THRESHOLDS NOTE: (1) VIN rise and fall times (10% to 90%) to be ≥=100µs. TIMING DIAGRAM NOTE: (1) VIN rise and fall times (10% to 90%) to be ≤=100ns. 5 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 OUTLINE DRAWING - SO-8 JEDEC REF: MS-012AA MINIMUM LAND PATTERN - SO-8 6 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 DEVICE OUTLINE - TO-263, 5 PIN MINIMUM LAND PATTERN - TO-263, 5 PIN ECN00-1177 7 © 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320