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| Final Electrical Specifications LT1611 Inverting 1.4MHz Switching Regulator in 5-Lead SOT-23 October 1998 FEATURES s s s s s s s s s DESCRIPTION The LT(R)1611 is the industry's first inverting 5-lead SOT-23 current mode DC/DC converter. Intended for use in small, low power applications, it operates from an input voltage as low as 1.1V and switches at 1.4MHz, allowing the use of tiny, low cost capacitors and inductors 2mm or less in height. Its small size and high switching frequency enable the complete DC/DC converter function to take up less than 0.25 square inches of PC board area. Capable of generating - 5V at 150mA from a 5V supply or - 5V at 100mA from a 3V supply, the LT1611 replaces nonregulated "charge pump" solutions in many applications. The LT1611 operates in a dual inductor inverting topology which filters the input side as well as the output side of the DC/DC converter. Fixed frequency switching ensures a clean output free from low frequency noise typically present with charge pump solutions. No load quiescent current of the LT1611 is 3mA, while in shutdown quiescent current drops to 0.5A. The 36V switch allows VIN to VOUT differential of up to 33V. The LT1611 is available in the 5-lead SOT-23 package. , LTC and LT are registered trademarks of Linear Technology Corporation. Better Regulation Than a Charge Pump Effective Output Impedance: 0.1 - 5V at 150mA from a 5V Input Uses Tiny Capacitors and Inductor Internally Compensated Fixed Frequency 1.4MHz Operation Low Shutdown Current: <1A Low VCESAT Switch: 300mV at 300mA 5-Lead SOT-23 Package APPLICATIONS s s s s s Digital Camera CCD Bias MR Head Bias LCD Bias Positive-to-Negative Conversion GaAs FET Bias TYPICAL APPLICATION 5V to - 5V, 150mA Inverting DC/DC Converter L1A 22H C3 1F L1B 22H 85 80 D1 VIN SW LT1611 FB GND R2 10k R1 29.4k SHDN C1 22F 75 EFFICIENCY (%) 70 65 60 55 C1, C2: AVX TAJB226M010 C3: X7R CERAMIC D1: MBR0520 L1: SUMIDA CLS62-220 OR 2x MURATA LQH3C220 (UNCOUPLED) 1611 TA01 VIN 5V + VOUT -5V 150mA C2 22F 50 0 25 50 75 100 LOAD CURRENT (mA) 125 150 Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U + U U Efficiency VIN = 5V VIN = 3V 1611 TA02 1 LT1611 ABSOLUTE MAXIMUM RATINGS (Note 1) PACKAGE/ORDER INFORMATION TOP VIEW SW 1 GND 2 NFB 3 4 SHDN 5 VIN VIN Voltage .............................................................. 10V SW Voltage ................................................- 0.4V to 36V NFB Voltage ............................................................. - 3V Current into NFB Pin ............................................. 1mA SHDN Voltage .......................................................... 10V Maximum Junction Temperature .......................... 125C Operating Temperature Range Commercial ............................................. 0C to 70C Extended Commercial (Note 2) ........... - 40C to 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C ORDER PART NUMBER LT1611CS5 S5 PART MARKING LTES S5 PACKAGE 5-LEAD PLASTIC SOT-23 TJMAX = 125C, JA = 256C/W Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS VIN = 1.5V, VSHDN = VIN, TA = 25C, unless otherwise noted. PARAMETER Minimum Operating Voltage Maximum Operating Voltage NFB Pin Bias Current Feedback Voltage Quiescent Current Quiescent Current in Shutdown Reference Line Regulation Switching Frequency Maximum Duty Cycle Switch Current Limit Switch VCESAT Switch Leakage Current SHDN Input Voltage High SHDN Input Voltage Low SHDN Pin Bias Current VSHDN = 3V VSHDN = 0V 25 0 (Note 3) ISW = 300mA VSW = 5V 1 0.3 50 0.1 VSHDN = 1.5V, Not Switching VSHDN = 0V, VIN = 2V VSHDN = 0V, VIN = 5V 1.5V VIN 10V q q CONDITIONS MIN TYP 0.9 MAX 1.1 10 - 6.7 - 1.255 4.5 0.5 1.0 0.2 1.8 UNITS V V A V mA A A %/V MHz % mA VNFB = -1.23V q q - 2.7 - 1.205 - 4.7 - 1.23 3 0 0 0.02 1.0 82 550 1.4 86 800 300 0.01 350 1 The q denotes specifications which apply over the specified temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: C grade device specifications are guaranteed over the 0C to 70C temperature range. In addition, C grade device specifications are assured over the - 40C to 85C temperature range by design or correlation, but are not production tested. Note 3: Current limit guaranteed by design and/or correlation to static test. 2 U W U U WW W mV A V V A A LT1611 PIN FUNCTIONS SW (Pin 1): Switch Pin. Minimize trace area at this pin to keep EMI down. GND (Pin 2): Ground. Tie directly to local ground plane. NFB (Pin 3): Negative Feedback Pin. Minimize trace area. Reference voltage is -1.23V. Connect resistive divider tap here. The suggested value for R2 is 10k. Set R1 and R2 according to: BLOCK DIAGRAM VIN 5 R5 40k gm - Q1 Q2 x10 R3 30k R4 140k 3 NFB CC A=3 1.4MHz OSCILLATOR SHDN 4 SHUTDOWN VOUT R1 (EXTERNAL) NFB R2 (EXTERNAL) PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S5 Package 5-Lead Plastic SOT-23 (LTC DWG # 05-08-1633) 2.60 - 3.00 (0.102 - 0.118) 1.50 - 1.75 (0.059 - 0.069) 0.00 - 0.15 (0.00 - 0.006) 2.80 - 3.00 0.90 - 1.45 (0.110 - 0.118) (NOTE 3) (0.035 - 0.057) 0.10 - 0.60 (0.004 - 0.024) REF 0.09 - 0.20 (0.004 - 0.008) (NOTE 2) 0.35 - 0.50 0.90 - 1.30 (0.014 - 0.020) (0.035 - 0.051) FIVE PLACES (NOTE 2) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DIMENSIONS ARE INCLUSIVE OF PLATING 3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 4. MOLD FLASH SHALL NOT EXCEED 0.254mm 5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ) + RC RAMP GENERATOR - U W U U U 1.23 + 4.5 * 10- 6 R2 SHDN (Pin 4): Shutdown Pin. Tie to 1V or more to enable device. Ground to shut the device down. VIN (Pin 5): Input Supply Pin. Must be locally bypassed. R1 = VOUT - 1.23 VIN R6 40k 1 SW COMPARATOR FF S DRIVER Q Q3 + A2 R + 0.15 - 2 GND 1611 BD 1.90 (0.074) REF 0.95 (0.037) REF S5 SOT-23 0797 3 LT1611 SUGGESTED LAYOUT L1B -VOUT C3 C2 L1A C1 + VIN GND RELATED PARTS PART NUMBER LT1307 LT1316 LT1317 LT1370 LT1371 LT1610 LT1614 DESCRIPTION Single Cell Micropower DC/DC with Low Battery Detector Burst Mode Operation DC/DC with Programmable Current Limit 2-Cell Micropower DC/DC with Low Battery Detector 500kHz High Efficiency DC/DC Converter 500kHz High Efficiency DC/DC Converter Single Cell Micropower DC/DC Inverting Mode Switching Regulator with Low-Battery Detector TM Burst Mode is a trademark of Linear Technology Corporation. 4 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com + R2 1 2 3 5 4 SHUTDOWN R1 1611 LO COMMENTS 3.3V/75mA from 1V; 600kHz Fixed Frequency 1.5V Minimum VIN; Precise Control of Peak Switch Current 3.3V/200mA from Two Cells; 600kHz Fixed Frequency 42V, 6A Internal Switch, Negative Feedback Regulation 42V, 3A Internal Switch, Negative Feedback Regulation 3V/30mA from 1V; 1.7MHz Fixed Frequency - 5V at 200mA from 5V Input in MSOP 1611I LT/TP 1098 4K * PRINTED IN USA (c) LINEAR TECHNOLOGY CORPORATION 1998 |
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