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| 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION 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. 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 100m is recommended. When both supplies are simultaneously available, the drive pin (DR) will be pulled High, turning off the external PMOS switch. 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. The SC1537 is available in the popular SO-8 and 5-lead TO-263 surface mount packages. Q1 FEATURES *= *= *= *= *= *= *= 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 APPLICATIONS *= *= *= *= *= Desktop Computers Network Interface Cards (NICs) PCMCIA/PCI Interface Cards CardbusTM Technology Power supplies with multiple input sources ORDERING INFORMATION Part Number (1) Package SO-8 TO-263-5L SC1537CSTR SC1537CMTR Note: (1) Only available in tape and reel packaging. A reel contains 2500 devices for SO-8 and 800 devices for TO-263. APPLICATION CIRCUIT 3.3V OUT U1 SC1537CS 3.3V 5V 1 2 3 4 VAUX VIN VO DR GND GND GND GND 8 7 6 5 C4 10uF C5 0.1uF C1 0.1uF C2 10uF C3 0.1uF Q1 U1 5V 2 VIN TAB SC1537CM 5 DR 3.3V 1 VAUX GND 3 VO 4 3.3V OUT C1 0.1uF C2 10uF C3 0.1uF C4 10uF C5 0.1uF NOTE: (1) External switch (Q1): use a low threshold P-channel MOSFET such as Vishay Si2305DS (RDS(ON) < 71m at VGS = 2.5V) or International Rectifier IRLML6401 (RDS(ON) < 85m at VGS = 2.5V), or equivalent. 1 (c) 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 ABSOLUTE MAXIMUM RATINGS Parameter Input Supply Voltage Auxiliary Supply Voltage LDO Output Current Operating Ambient Temperature Range Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering) 10 Sec Thermal Impedance Junction to Ambient SO-8(1) TO-263 Thermal Impedance Junction to Case SO-8 TO-263 ESD Rating (Human Body Model) Symbol VIN VAUX IO TA TJ TSTG TLEAD JA Maximum -0.5 to +7 -0.5 to +7 10 to 700 0 to +70 0 to +125 -65 to +150 300 65 60 Units V V mA C C C C C/W J C ESD 39 3 2 C/W kV Note: (1) 1 inch square of 1/16" FR-4, double sided, 1 oz. minimum copper weight. ELECTRICAL CHARACTERISTICS Unless specified, TA = 25C, VIN = 5V, VAUX = 3.3V, IO = 700mA, CO = 10F. Values in bold apply over full operating temperature range. Parameter VIN Supply Voltage Quiescent Current Symbol Test Conditions MIN TYP MAX Units VIN IQ VAUX = 0V VIN = 5V, VAUX = 0V, IO = 0mA VIN = 5V, VAUX = 3.3V, IO = 0mA 4.75 5.00 9.0 5.25 14.0 16.0 V mA 13.0 17.0 18.0 mA Reverse Leakage From VAUX IVIN VAUX = 3.6V, VIN = 0V, IO = 0mA -1.5 -3.0 -4.0 mA VAUX Supply Voltage Quiescent Current VAUX IQ(AUX) VAUX = 3.3V, VIN = 0V, IO = 0mA VAUX = 3.3V, VIN = 5V, IO = 0mA 3.0 3.3 8.0 3.6 11.0 13.0 1.5 2.5 3.0 mA V mA 2 (c) 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 700mA SmartLDO TM SC1537 PRELIMINARY - July 25, 2000 ELECTRICAL CHARACTERISTICS Unless specified, TA = 25C, VIN = 5V, VAUX = 3.3V, IO = 700mA, CO = 10F. Values in bold apply over full operating temperature range. Parameter VAUX (Cont.) Reverse Leakage From VIN Symbol Test Conditions MIN TYP MAX Unit IVAUX VIN = 5.5V, VAUX = 0V, IO = 0mA -5.0 -50.0 100.0 A 5V Detect (1)(2)(3) Low Threshold Voltage VTH(LO) VHYST VTH(HI) VO VIN Falling, IO = 20mA 3.92 3.90 4.05 4.18 4.20 V Hysteresis 90 80 170 mV High Threshold Voltage VO LDO Output Voltage VIN Rising, IO = 20mA IO = 20mA 4.75V VIN 5.25V, 0mA IO 700mA 3.267 3.234 3.300 4.35 V 3.333 3.366 400 V Output Current Line Regulation IO REG(LINE) REG(LOAD) VIN = 4.75V to 5.25V 0.20 mA % 0.60 0.80 Load Regulation IO = 10mA to 700mA 0.6 1.0 1.2 % Drive Output Drive Voltage VDR 4.75V VIN 5.25V, IDR = 200A VIN < VTH(LO), IDR = -200A Peak Drive Current (1)(4) 3.4 3.3 VIN - 0.8 V 35 150 250 mV IDR(PK) tDH tDL Sinking: VIN = 3.9V, VDR = 1V; Sourcing: VIN = 4.35V, VIN - VDR = 2.5V CDR = 1.2nF, VIN ramping up, measured from VIN = VTH(HI) to VDR = 2V CDR = 1.2nF, VIN ramping down, measured from VIN = VTH(LO) to VDR = 2V 7 6 0.5 1.0 2.0 0.5 1.0 2.0 mA Drive High Delay s Drive Low Delay (1)(4) s NOTES: (1) Guaranteed by design. (2) See 5V Detect Thresholds on page 5. (3) Recommended source impedance for 5V supply: 0.07. This will ensure that IO x RSOURCE < VHYST, thus avoiding DR toggling during 5V detect threshold transitions. (4) See Timing Diagram on page 5. (c) 2000 SEMTECH CORP. 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 DR GND VAUX VIN VO SO-8 Pin # 4 5,6,7,8 1 2 3 TO-263-5L Pin # 5 3/TAB 1 2 4 Pin Function Driver output for external P-channel MOSFET pass element. Logic and power ground. This is the auxiliary input supply, nominally 3.3V. This is the main input supply for the IC, nominally 5V. LDO 3.3V output. 4 (c) 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 =100s. TIMING DIAGRAM NOTE: (1) VIN rise and fall times (10% to 90%) to be =100ns. 5 (c) 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 (c) 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 (c) 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 |
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