LOW VOLTAGE MULTI-MODE DC-DC CONVERTER January 30, 1998 SC1630 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The SC1630 is a DC-DC converter designed to drive an external power switch for more flexibility, especially in higher voltage and larger power applications. Typically six components are required to set up a step-up configuration easily achieving an efficiency beyond 80%. A few more components are required to set up a step down configuration delivering 4A load current with 83% typical efficiency, 86% at 2A load, and 300µA quiescent current. FEATURES • Default +5V output voltage • Adjustable output voltage with two resistors • Power-saving shutdown mode (7µA typical) • 120kHz switching rate • On-chip low battery detector BLOCK DIAGRAM The output voltage can be internally set to 5V or externally set to an arbitrary value below breakdown voltage of the power switch. Logic-controlled shutdown mode is provided for power-saving. The low battery detector can also be configured as a linear regulator. A 120kHz switching rate reduces the inductor size. Inductors of 25µH to 50µH inductance are recommended for most applications. APPLICATIONS • Palmtop and notebook computers • Battery charger supply • Cellular telephones • LCD contrast supply • Flash memory programmer • Battery backup supplies • Portable instruments PIN CONFIGURATION ORDERING INFORMATION (1) DEVICE SC1630CS SO-8 Note: (1) Add suffix ‘TR’ for tape and reel. ABSOLUTE MAXIMUM RATINGS Parameter © 1997 SEMTECH CORP. PACKAGE Symbol Maximum Units Supply Voltage VIN 7.0 V Operating Temperature Range TA 0 to 70 °C Storage Temperature Range TSTG -65 to 125 °C 652 MITCHELL ROAD NEWBURY PARK CA 91320 LOW VOLTAGE MULTI-MODE DC-DC CONVERTER SC1630 January 30, 1998 ELECTRICAL CHARACTERISTICS Unless otherwise specified, TA = 25°C, VIN = 3.0V Parameter Conditions Min Input Voltage Default Output Voltage Typ Max Units 7.0 V 5.00 5.20 V 105 140 µA 7 15 µA 1.8 IL = 200mA 4.80 Switch Off Current Shutdown Mode Current VIN = 2.5V,IL = 200mA 0.4 ms IL = 300mA (5V Output Step-Up Converter) 85 % Line Regulation VIN = 2.2 - 3.3V VOUT = 5V, IL = 100mA 0.6 %VOUT Load Regulation IL = 10mA - 500mA VOUT = 5V 2.5 %VOUT Recovery Time from Shutdown Efficiency Oscillator Frequency 90 LBI Pin Trip Point EXT Pin Driving Capabilities LBO “ON Resistance” 120 150 kHz 1.22 V Pin 8 = 5V, Pin 3 = 0.85V Sourcing Sinking 80 50 mA mA VIN = 2V 45 Ω Input Pin Bias Current 10 nA/Pin Output Pin Leakage 10 nA/Pin TYPICAL APPLICATIONS © 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 LOW VOLTAGE MULTI-MODE DC-DC CONVERTER SC1630 January 30, 1998 TYPICAL APPLICATIONS (cont.) 5V Output Step-Up Converter 12V Output Step-Up Converter for Flash Memory 36V Output Step-Up Converter for Color LCD © 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 LOW VOLTAGE MULTI-MODE DC-DC CONVERTER SC1630 January 30, 1998 TYPICAL APPLICATIONS (cont.) -24V Output Inverting Converter for LCD 2V Input 20mA Load -24V Output Inverting Converter for LCD ±12V Dual Output Converter for Computer Interfacing © 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 LOW VOLTAGE MULTI-MODE DC-DC CONVERTER SC1630 January 30, 1998 TYPICAL APPLICATIONS (cont.) 5V Output Step-Down Converter - 1 5V Output Step-Down Converter - 2 © 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 LOW VOLTAGE MULTI-MODE DC-DC CONVERTER SC1630 January 30, 1998 TYPICAL APPLICATIONS (cont.) Step-Up Rechargeable Battery Charger • • • Charging current =0.8A, Auto Cut-Off at 0.25% -Delta-V point and fault conditions (RIF sets the charging current). VDD must be lower than VBAT. Short circuit condition is protected with a 2A fuse. Step-Up/Step-Down Rechargeable Battery Charger • • • • Fast charge current =0.8A when VDD<VBAT, = (VDD-VBAT-0.5)/0.82 when VDD>VBAT. Trickle charge current = 30mA (RIF sets fast charge current, RIT sets trickle charge current). Typical efficiency = 75%. With short circuit protection. TYPICAL PERFORMANCE CHARACTERISTICS © 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 LOW VOLTAGE MULTI-MODE DC-DC CONVERTER SC1630 January 30, 1998 TYPICAL PERFORMANCE CHARACTERISTICS (cont.) © 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 LOW VOLTAGE MULTI-MODE DC-DC CONVERTER SC1630 January 30, 1998 DEVICE OUTLINE - SO-8 PIN DESCRIPTIONS PIN 1: SD The SC1630 goes into shutdown mode and consumes less than 10µA when the SD pin is pulled to ground, and it goes into normal operating mode when the SD pin is pulled to a positive voltage above 100mV. PIN 2: VIN Input supply. PIN 3: EXT Push-Pull driver output to drive external power switch. PIN 4: GND Ground. PIN 5: FB The output voltage can either be internally set to 5 volts by grounding the FB pin, or it can be externally set to an arbitrary voltage by applying to the FB pin the divider voltage of two external divider resistors. VOUT voltage is given by the following equation: V OUT Where: R = 0 . 611 1 + 1 R2 PIN 6: LBO Open drain output of the battery low detector, with 45 Ohm “On Resis tance” at VIN=2V. It is pulled low when the voltage on LBI pin is below 1.22 volts. PIN 7: LBI The inverting input of the battery low detector, of which the non-inverting input is internally connected to the 1.22V voltage reference. PIN 8: VOUT The output voltage feeds back to the IC through this pin for internally set 5V operation. If the output voltage is externally set, the VOUT pin can be tied to any low impedance node with voltage between the external power switch threshold and 7 volts. PIN CONFIGURATION R1= Resistor connected beween FB Pin and VOUT pin. R2= Resistor connected between FB Pin and ground. VOUT = Output voltage to be set. © 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320