LT9A Micropower DC/DC Converter Flash Memory VPP Generator Adjustable and Fixed 5V, 2V FEATRE ses ff-the-helf Inductors Low Cost -Pin DIP or Package Fixed 5V or 2V utput or Adjustable Version nly Four External Components Required 6µA tandby Current Logic-Controlled hutdown Flash Memory VPP Generators 5V to 2V Converters.V to 2V Converters Disk Drives PC Plug-In Cards Peripherals Battery-Powered Equipment DECRIPTI The LT9A is a simple step-up DC/DC converter. The - pin DIP or IC devices require only four external components to construct a complete DC/DC converter. Current drain is just 6µA at no load, making the device ideal for cost-sensitive applications where standby current must be kept to a minimum. The LT9A-2 can deliver 2V at over 5mA from a 5V supply, enough power to program four flash memory chips simultaneously. The LT9A-5 can deliver 5V at up to ma from a 2V input. The devices feature a shutdown pin that turns off the oscillator when taken low. The gatedoscillator design requires no frequency compensation components. High frequency 2kHz operation permits the use of small surface mount inductors and capacitors. TYPICAL All urface Mount Flash Memory VPP Generator utput Current utput Voltage L* µh MBRT. 2V 5V C V ** ENE LT9AC-2 PGND GND 4 5 V T 2V C2 4µF 2V TPT VLTAGE (V) 2.5 2..5. = 4.5V = 5V V T 2V/DIV 5V/DIV 5µs/DIV 9A TA * ** CILTRNIC CTX-2 MIDA CD54-LC = PRGRAM = 9A TA.5. 5 5 2 TPT CRRENT (ma) 25 9A TA2
LT9A ABLTE AXI RATI G W W W (Voltages Referred to GND Pin) upply Voltage ( )....4V to 2V Pin Voltage....4V to 5V Feedback Pin Voltage (LT9A)... 5.5V hutdown Pin Voltage... 5.5V witch Current... 2A Maximum Power Dissipation... mw perating Temperature Range... C to C torage Temperature Range... 65 C to 5 C Lead Temperature (oldering, sec)... C PACKAGE/RDER I FR NC PGND 2 4 TP VIEW 6 5 N PACKAGE -LEAD PLATIC DIP *FIXED VERIN T JMAX = 9 C, θ JA = C/W FB (ENE)* NC GND W RDER PART NMBER ATI LT9ACN LT9ACN-5 LT9ACN-2 NC 2 PGND 4 TP VIEW 6 5 PACKAGE -LEAD PLATIC *FIXED VERIN T JMAX = 9 C, θ JA = 5 C/W FB (ENE)* NC GND RDER PART NMBER LT9AC LT9AC-5 LT9AC-2 PART MARKING 9A 9A5 9A ELECTRICAL CHARACTERITIC T A = 25 C, = V, unless otherwise noted. YMBL PARAMETER CNDITIN MIN TYP MAX NIT I Q Quiescent Current witch ff 6 5 µa Input Voltage 2 9 V Comparator Trip Point Voltage LT9A.2.25. V V T utput ense Voltage LT9A-5; 2V 5V 4.5 5. 5.25 V LT9A-2; 2V 2V.52 2. 2.55 V Comparator Hysteresis LT9A 2.5 mv utput Voltage Ripple LT9A-5 25 5 mv LT9A-2 6 2 mv f C scillator Frequency 5 2 5 khz 95 55 khz t N witch n Time 4. 5.5 6.9 µs..4 µs DC Duty Cycle Full Load 6 6 % V CEAT witch aturation Voltage = V, I = 65mA.5.65 V = 5V, I = A.. V witch Leakage Current V = 2V µa V IH Pin High 2. V V IL Pin Low. V I IH Pin Input Current V 2.V µa I L Pin Input Current V V.V 2 µa The denotes specifications which apply over the full operating temperature range. 2
LT9A TYPICAL PERFR A W CE CHARACTERITIC EFFICIENCY (%) 9 5 5 Efficiency scillator Frequency Duty Cycle = 5V V T = 2V LAD = 2mA L = 29µH FREQENCY (khz) 6 4 2 DTY CYCLE (%) 5 65 6 55 4.2 4.4 4.6 4. 5. 5.2 5.4 5.6 INPT VLTAGE (V) 5. 6 5 25 25 5 TEMPERATRE ( C) 5 5 5 25 25 5 5 TEMPERATRE ( C) 9A G 9A G2 9A G VCEAT (V) witch aturation Voltage.4 = V.2 = 2V.. = 5V.6.4.2 V CEAT (V) witch aturation Voltage. I = 65mA.6.5.4..2. ITCH N TIME (µs) 6 5 4 witch n Time.2.4.6...2.4.6 I ITCH (A) 5 25 25 5 5 TEMPERATRE ( C) 5 25 25 5 5 TEMPERATRE ( C) 9A G4 9A G5 9A G6 QIECENT CRRENT (µa) 5 45 4 5 25 Quiescent Current QIECENT CRRENT (µa) Quiescent Current 5 T A = 25 C 45 4 5 2 5 25 25 5 5 TEMPERATRE ( C) 9A G 25 2 4 6 2 4 6 2 INPT VLTAGE (V) 9A G
LT9A TYPICAL PERFR 2. A W LT9A-2 utput Voltage CE CHARACTERITIC 6 Minimum/Maximum scillator Frequency vs t N TPT VLTAGE (V) 2.2 2. 2..9. CILLATR FREQENCY (khz) 5 4 2 9 C T A C T A = 25 C. 5 25 25 5 5 25 TEMPERATRE ( C)..5 4. 4.5 5. 5.5 6. 6.5..5. t N (µs) 9A G9 9A G BLCK DAGRA I W LT9A-5, LT9A-2 LT9A (Adjustable) ENE FB R2 25k.25V REF CMP A 2kHz C DRIVER Q.25V REF CMP A 2kHz C DRIVER Q R* GND PGND GND PGND *LT9A-5: R = k LT9A-2: R = 29k 9A BD 4
LT9A PERATI The LT9A is a micropower step-up DC/DC converter. It uses Burst Mode TM operation to achieve micropower operation yet still deliver more than 2W of output power from a 5V supply. Circuit operation can be best understood by referring to the LT9A block diagram. With high, comparator A compares the feedback (FB) pin voltage with the.25v reference signal. When FB drops below.25v, A switches on the 2kHz oscillator. The driver amplifier boosts the signal level to drive the output NPN power switch. When the FB voltage is sufficient to trip A, the oscillator is turned off. A low signal on the shutdown pin gates off the oscillator, overriding A. With low, quiescent current remains at 6µA. Burst Mode TM is a trademark of Linear Technology Corporation I FR W ATI Inductor election A DC/DC converter operates by storing energy as magnetic flux in an inductor core, and then switching this energy into the load. To operate as an efficient energy transfer element, the inductor must fulfill three requirements: inductance value, saturation current and DC resistance. A fourth requirement is physical size. The inductors recommended with the LT9A circuits are small, surface-mountable and are designed for switch-mode applications. Avoid using RF chokes or air core units since they have very low peak current ratings. The LT9A works best in situations where the input voltage does not vary much since the device has no internal switch current limit function. For situations where the input voltage varies, such as battery inputs, the LT or LT is suggested instead. Capacitor election The output capacitor should be chosen on the basis of its equivalent series resistance (ER) and capacitance value. Low ER tantalum surface-mountable capacitors such as those made by AVX are well-suited for DC/DC converter applications. Inexpensive aluminum electrolytics may have excessive ER, resulting in high output ripple. These should be avoided. Diode election peed, forward drop, and leakage current are the three main considerations in selecting a diode for LT9A converters. General purpose rectifiers such as the N4 are unsuitable for use in any switching regulator application. Although they are rated at A, the switching time of a N4 is in the µs to 5µs range. At best, efficiency will be severely compromised if this diode is used; at worst, the circuit may not work at all. The N5 is an ideal choice for LT9A circuits. urface-mountable versions, such as the MBRT, are available as well. Table. Inductor Manufacturers MANFACTRER PART NMBER Coiltronics International urface Mount 94.W. th Court CTA-PAC TM eries Pompano Beach, FL 69 5--9 umida Electric Co., Ltd. CD54 6 E. Golf Road, uite 29 CD5 Arlington Heights, IL 65 urface Mount -956-666 CTA-PAC TM is a trademark of Coiltronics International Table 2. Capacitor Manufacturers MANFACTRER AVX Myrtle Beach, C 295-946-69 Philips Components 2 W. Blue Heron Blvd. P.. Box Riviera Beach, FL 44 4--2 anyo Video Components 2 anyo Avenue an Diego, CA 92 69-66-622 PART NMBER TP eries 49MC eries -CN eries 5
LT9A TYPICAL.V Powered Flash Memory VPP Generator.V 2µH* MBRT ENE 2V 6mA * CILTRNIC CTX2- MIDA CD54-22LC LT9A-2 GND PGND 5 4 µf** 25V ** AVX TP ERIE 9A TA4 2V Powered Flash Memory VPP Generator 2V µh* MBRT ENE 2V 5mA LT9A-2 GND PGND 5 4 µf** 25V * CILTRNIC CTX- MIDA CD54-LC ** AVX TP ERIE 9A TA5 6
LT9A TYPICAL 2V to 5V Converter 2V µh* MBRT ENE 5V ma * CILTRNIC CTX- MIDA CD54-LC LT9A-2 GND PGND 5 4 µf** V ** AVX TP ERIE 9A TA6 5V to 2V Converter with hutdown to V at utput 2k 5V µh* MBRT ENE LT9A-2 GND PGND 5 4 2N44 4µF** 2V V T 2V ma µf * CILTRNIC CTX-2 MIDA CD54-LC ** AVX TP ERIE 9A TA 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.
LT9A PACKAGE DECRIPTI Dimensions are in inches (millimeters) unless otherwise noted...2 (.62.2).45.65 (.4.65) N Package -Lead Plastic DIP. ±.5 (.2 ±.2).4 (.6) MAX 6 5.9.5 (.229.).25.25.5.65.255. ( ).65 (.65) TYP.45 ±.5 (.4 ±.). ±. (2.54 ±.254).25 (.5) MIN. ±. (.45 ±.6).2 (.5) MIN 2 4.25 ±. (6.5 ±.254) N 92 Package -Lead Plastic IC.9.9 (4. 5.4) 6 5..2 45 (.254.5).. (.2.254).5.69 (.46.52).4. (..254).22.244 (5.9 6.9).5.5 (..9) TYP.6.5.46.2.4.9 (.55.4).5 (.2) BC 2 4 92 sn9a 9afs LT/GP 49 K REV Linear Technology Corporation 6 McCarthy Blvd., Milpitas, CA 955-4 (4) 42-9 FAX: (4) 44-5 TELEX: 499-9 LINEAR TECHNLGY CRPRATIN 99