LT1106

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The LT ®1106 is the industry’s first DC/DC converter designed for use on Type I and Type II PCMCIA cards. The device senses the VPP1 and VPP2 lines at the PCMCIA socket and generates a regulated 12V, 60mA program- ming supply if the socket does not provide it. Internal logic simplifies the interface to PCMCIA card microcontrollers. One input selects a 12V or 5V regulated output, while another input controls micropower shutdown. Two logic outputs indicate when the selected programming voltage is valid and whether the input supply is 3.3V or 5V. The regulator features Burst Mode TM operation with a 0.5A, 300mV switch for efficiency up to 85%. High frequency 500kHz switching permits the use of small value, flat inductors that fit neatly on PCMCIA cards. The device requires just 1µF of output capacitance. Quiescent current is 750µA which drops to 350µA when the card runs off the socket supply. The shutdown pin reduces supply current to only 10µA. The device includes a soft start feature which limits supply current transients when the card is inserted into a hot socket. USA OPPLICATI n PCMCIA Card Flash Memory VPP Generator n Portable Computers n Portable Instruments n DC/DC Converter Module Replacements n 60mA Output Current at 12V from 3V Supply n Shutdown to 10µA n Programmable 12V or 5V Output n Up to 85% Efficiency n Quiescent Current: 750µA n Low VCESAT Switch: 300mV at 0.5A Typical n Uses Low Value, Thin, Surface Mount Inductors n Ultra-Thin 20-Lead TSSOP Package , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. LOAD CURRENT (mA) EFFICIENCY (%) 10 100 LT1106 • TA02 VIN = 5V VIN = 5V VIN = 3.3V VIN = 3.3V D1 = MBR0530 D1 = 4 BAT54Cs IN PARALLEL 12V Output Efficiency12V, 60mA Flash Memory Programming Supply UA OPPLICATITYPICAL VCC VPP1 VPP2 ON/OFF GNDPGND SW D S BSS84 D S BSS84 POWER ON DALE ILS-3825-01 OR COILTRONICS CTX02-11238-3 MOTOROLA MBR0530 LT1106 • TA01 SOFT START AVPP 1M 0.1µF 3/5 DETECT VPP VALID 1µF D1** L1* 10µH 0.1µF 4.7µF TANT ALUM VPP1 VPP2 V CC 3.3V/5V LT1106 VPP VALID 12V/60mA 0.1µF 0.1µF 470pF

A UGWA WU WARBSOLUTEX I T I S V LT1106CF WU UPACKAGE/ORDER I FOR ATIO Consult factory for Industrial and Military grade parts TJMAX = 100°C, θJA = 90°C/W ORDER PART NUMBER ELECTRICAL C CHARA TERISTICS TA = 25°C, VCC = 5V, VON/OFF = 3V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS IQ Quiescent Current V SEL = 0.2V, AVPP = 12V 750 900 µA Quiescent Current, Shutdown V ON/OFF = 0.2V 9 15 µA “Doze” Mode Current V SEL = 0.2V, VPP1 or VPP2 = 12V 320 µA Input Voltage Range 2 6 V Output Sense Voltage V SEL = 3V, VPP1 and VPP2 Floating l 4.75 5 5.25 V VSEL = 0.2V, VPP1 and VPP2 Floating l 11.50 12 12.60 V Output Referred V SEL = 3V 15 mV Comparator Hysteresis V SEL = 0.2V 35 mV fOSC Oscillator Frequency Current Limit Not Asserted 400 500 700 kHz DC Maximum Duty Cycle l 80 85 92 % tON Switch On-Time 1.7 µs Reference Line Regulation 2V < V IN < 6V 0.06 0.15 %/V VCESAT Switch Saturation Voltage I SW = 0.5A 230 350 mV Switch Leakage Current V SW = 12V, Switch Off 0.1 10 µA Switch Current Limit V IN = 5V, Soft Start Floating 450 600 900 mA VIN = 3V, Soft Start Floating 500 650 950 mA Soft Start Pin Current Soft Start Grounded 80 120 µA Select Input Voltage Low 0.8 V Select Input Voltage High 1.6 V ON/OFF Input Voltage Low 0.8 V ON/OFF Input Voltage High 1.6 V ON/OFF Bias Current V ON/OFF = 5V 16.0 24.0 µA VON/OFF = 3V 8.0 14.0 µA VON/OFF = 0V 0.1 1.1 µA TOP VIEW F PACKAGE 20-LEAD PLASTIC TSSOP SELECT 12/5 SOFT START V CC VCC PGND PGND NC V SW VSW ON/OFF AVPP VPP1 VPP2 VPP VALID GND NC V SW

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Select Pin Bias Current 0V < V SEL < 5V 0.1 1 µA VPP1/VPP2 Input Sense Threshold 11.0 11.5 11.9 V AVPP Pin Input Current 50 90 µA VON/OFF = 0.2V 0.1 1 µA VPP1/VPP2 Pin Input Current 50 90 µA VON/OFF = 0.2V 0.1 1 µA VPP VALID Threshold AVPP Rising (High to Low Transition) l 11.4 12 V VPP VALID Output Voltage Low I SINK = 100µA 0.13 0.3 V VPP VALID Output Voltage High I SOURCE = 2.5µA 4 4.5 V 3/5 Comparator Threshold l 3.6 3.75 4.2 V 3/5 Comparator Output High I LOAD = 50µA 3.65 3.8 V 3/5 Comparator Output Low I LOAD = 50µA 0.75 0.9 V Off State Current at G1/G2 VPP1 = 10V, VG1 = 12V or VPP2 = 10V, 0.1 1 µA VG2 = 12V or VON/OFF = 0V TA = 25°C, VCC = 5V, VON/OFF = 3V, unless otherwise noted.ELECTRICAL C CHARA TERISTICS The l denotes specifications which apply over the full operating temperature range. TYPICAL PERFORMANCE CHARACTERISTICS UW Oscillator Frequency Switch Current Limit Switch Saturation Voltage TEMPERATURE (°C) –50

300 OSCILLATOR FREQUENCY (kHz)400

–25 02 5 5 0 LT1106 • TPC01 75 100 TEMPERATURE (°C) –50

400 SWITCH CURRENT (mA)

–25 02 5 5 0 LT1106 • TPC02 75 100 900 VCC = 3V VCC = 5V TEMPERATURE (°C) –50

100 SWITCH SATURATION VOLTAGE (mV)

–25 02 5 5 0 LT1106 • TPC03 75 100 225 ISW = 500mA

TYPICAL PERFORMANCE CHARACTERISTICS UW 3/ 5 Comparator Threshold AVPP Sense Voltage AVPP Sense Voltage TEMPERATURE (°C) –50

3.70 THRESHOLD VOLTAGE (V)

3.75 3.80 3.85 3.90 4.00 –25 02 5 5 0 LT1106 • TPC04 75 100 3.95 TEMPERATURE (°C) –50 AVPP SENSE VOLTAGE (V) 11.95 12.00 12.05 25 75 LT1106 • TPC05 11.90 11.85 11.80 –25 0 50 12.10 12.15 12.20 100 12/5 SELECT = 0 TEMPERATURE (°C) –50

4.80 AVPP SENSE VOLTAGE (V)

4.85 4.90 4.95 5.00 5.10 –25 02 5 5 0 LT1106 • TPC06 75 100 5.05 12/5 SELECT = 1 Supply Current in Shutdown TEMPERATURE (°C) –50 25 75 LT1106 • TPC07 –25 0 50 100 SUPPLY CURRENT (µA) VCC = 5V VCC = 3V Supply Current TEMPERATURE (°C) –50

300 SUPPLY CURRENT (µA)

–25 02 5 5 0 LT1106 • TPC08 75 100 VCC = 5V VCC = 3V TEMPERATURE (°C) –50 MAXIMUM DUTY CYCLE (%)75 –25 02 5 5 0 LT1106 • TPC09 75 100 Load Transient Response, COUT = 1µF LT1106 • TPC12 50µs/DIV 12V OUTPUT 1V/DIV AC COUPLED 60mA 10mAILOAD Start-Up Waveforms, ILOAD = 1mA VAVPP 2V/DIV 12V ON/OFF 10V/DIV VPP VALID 10V/DIV LT1106 • TPC10 50µs/DIV LT1106 • TPC11 50µs/DIV IL 500mA/DIV VON/OFF 10V/DIV VOUT 5V/DIV Start-Up Waveforms with Soft Start, ILOAD = 10mA Maximum Duty Cycle

SELECT 12/5 (Pin 1): Tie to VIN or logic 1 for 5V output; tie to GND or logic 0 for 12V output. SOFT START (Pin 2): A 0.1µF/1MΩ parallel RC from this pin to GND provides a Soft Start function upon device turn-on. Initially about 80µA will flow from the pin into the capacitor. When the voltage at the pin reaches approxi- mately 0.4V, current ceases flowing out of the pin. See Applications Information section. V CC (Pins 3, 4): Input Supply. Both pins should be tied together. At least 1 µF input bypass capacitance is re- quired. More capacitance reduces ringing on the supply line. 3/5 (Pin 5): Supply Comparator Output. This pin provides logic output indicating the value of the input supply. High when VCC = 5V; low when VCC = 3.3V. PGND (Pins 6, 7): Power Ground. Connect to ground plane. VSW (Pins 9, 10, 11): Collector of Power Switch. High dV/ dt present on this pin. To minimize radiated noise keep layout short and direct. GND (Pin 13): Signal Ground. Connect of ground plane. VPP VALID (Pin 14): This pin provides a logic signal indicating that ouput voltage is greater than 11.4V. Active low with internal 200k pull-up resistor. G1, G2 (Pins 16, 15): External MOSFET Gate Drives. When VPP1 or VPP2 is greater than 11.7V, G1 or G2 is driven to about 0.8V. When VPP1 or VPP2 is less than 11.7V, the drives assume a high impedance state pulled up to the AVPP pin through an internal 100k resistor. VPP1, VPP2 (Pins 18, 17): Programming Power Inputs. The LT1106 senses both VPP1 and VPP2 supplies at the PCMCIA card socket. If VPP1 or VPP2 is greater than 11V, the LT1106 operates in “Doze” Mode — the switching regulator turns off and the drive to external P-channel MOSFETs turns on. Supply current in Doze Mode is about 350µA. Input current into VPP1 and VPP2 is about 1 µA when the device is shut down. AVPP (Pin 19): Output Sense Pin. This pin connects to a 1MΩ resistive divider that sets the output voltage. In shutdown, the resistor string is disconnected and current into this pin is reduced to < 1µA. ON/OFF (Pin 20): Shutdown Control. When pulled below 1.5V, this pin disables the LT1106 and reduces supply current to 10µA. All circuitry except the 3/5 comparator is disabled in shutdown. The part is enabled when ON/OFF is greater than 1.5V.

1× Q1 50×100k VREF 1.24V 36mV VCC PGND LT1106 • BD SW 700Ω 3,4 6,7 9,10,11 GND SOFT START BIAS 500kHz OSCILLATOR 5 3/5 VCC 3.7V APPLICATIONS INFORMATIONWU UU Functional Description The LT1106 is a micropower, step-up DC/DC converter specifically configured for PCMCIA flash memory card VPP generation. The device generates a 5V or 12V output selectable via the 12/5 Select pin. If 12V is present on either the VPP1 or VPP2 pins, gate drive outputs G1 and G2 are driven low, turning on external PMOS devices. The switching regulator inside the LT1106 is idled when 12V is present on VPP1 or VPP2. The VPP VALID output goes low when the voltage at AVPP exceeds 11.4V This signal can be used to indicate pres- ence of a valid programming voltage. The 3/5 comparator indicates whether the input voltage is 3.3V or 5V. The Soft Start pin can be used to limit inrush current upon start-up. A 0.1µF capacitor in parallel with a 1M resistor is connected between this pin and ground to limit peak inductor current at start-up. Switching Regulator Operation When 12V is not present on the VPP1 or VPP2 pins and the device is enabled (ON/OFF = 1), the LT1106 generates a regulated voltage at the AVPP pin. This voltage is pro- grammable between 5V or 12V depending on the state of the 12/5 Select pin. Referring to the block diagram, hyster- etic comparator C1 monitors AVPP via the resistor divider. When the negative input of C2 falls below 1.24V, C1’s

output goes high, enabling the oscillator. Switch Q1 alternately turns on causing current build-up in the induc- tor; then turns off allowing the built-up current to flow into the output capacitor via the catch diode. As the output voltage increases, so does the voltage at C1’s negative input. When it exceeds the reference voltage plus C1’s hysteresis, C1 turns the oscillator off. Switch current is limited to approximately 600mA by Q2, R1 and C3. Two percent of Q1’s collector current flows in Q2; this current flows through R1 causing a voltage drop in R1 proportional to Q1’s collector current. When R1’s drop equals 36mV, comparator C3 forces the oscillator off. This action results in varying on-time, fixed off-time operation that keeps peak switch current controlled. By connecting a 0.1 µF capacitor from the Soft Start pin to ground, a current will flow in Q3 upon start-up. The current flows through 700Ω resistor R2, reducing the amount of current needed from Q2 to force the oscillator off. As current flows into the 0.1µF capacitor, the voltage at pin 2 increases and eventually current ceases to flow in Q3. Inductor Selection All components for use in PCMCIA Type I cards must be less than 1.1mm high. This somewhat limits the selection of appropriate inductors. Dale Electronics (605-665-9301) manufactures the ILS-3825-01, a monolithic ferrite induc- tor that meets Type I height requirements. Generally, inductors used with the LT1106 must fulfill several re- quirements. It must be able to carry 0.95A (the maximum switch current) without saturation. DCR should be kept low to maintain efficiency. The switching frequency of the LT1106 is quite high, over 500kHz so magnetic material is important. Ferrite core material works well in this fre- quency range. Avoid low cost iron powder cores which APPLICATIONS INFORMATIONWU UU have substantial AC loss at the LT1106’s switching fre- quency. Inductance value need not be over 10µH. Capacitor Selection The LT1106 will operate with 1µF of output capacitance. Output ripple voltage is approximately 400mV with this value and can be reduced significantly by increasing output capacitance. The ripple voltage, although on the high side, poses no problems for programming flash memory. If operating the device in 5V ouput mode the capacitance should be increased. Ceramic capacitors are suitable for the output. Distributed capacitance, i.e., 0.1µF or 0.2 µF units next to individual flash memory chips, is acceptable. The input capacitor should have at least some tantalum capacitance (low Q) to minimize resonance on the input. Flash memory cards are typically several inches away from a solid low impedance supply due to sockets, connectors, etc. If just ceramic capaci- tors are used at the supply pin of the LT1106, switching currents will resonate the supply line causing ringing that can exceed 500mV P-P. The high Q, low ESR nature of ceramic capacitors causes this. A few microfarad’s worth of tantalum capacitors with moderate ESR and low Q characteristics will reduce or eliminate the problem. Diode Selection As with inductors, most good power Schottky diodes are in packages that exceed the 1.1mm height limit of the Type I PCMCIA card. Motorola manufactures the MBRO530 Schottky diode, ideal for use with the LT1106. This diode’s maximum height however, is 1.35mm, making it difficult to use in Type 1 cards. Philips Components manufactures the BAT54C. Four units in parallel make an adequate diode. 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 l FAX: (408) 434-0507 l TELEX: 499-3977  LINEAR TECHNOLOGY CORPORA TION 1995 LT/GP 0595 10K • PRINTED IN THE USA TYPICAL APPLICATIONU Alternative Scheme Allows 12V from VPP1/VPP2 to Provide Power When LT1106 is in Shutdown VCC ON/OFF SELPGND SW POWER ON DALE ILS-3824-01 MBR0530 OR 4 BAT54s IN PARALLEL LT1106 • TA03 GND SOFT START AVPP VPP2 VPP1 1M 0.1µF VPP VALID 1µF D D D L1* 10µH 4.7µF VCC 3.3V/5V LT1106 VPP VALID 12V/60mA 470pF Dimensions in inches (millimeters) unless otherwise noted. F Package 20-Lead Plastic TSSOP F20 TSSOP 0395 0.004 – 0.071 (0.09 – 0.18) 0° – 8° 0.020 – 0.028 (0.50 – 0.70) 0.169 – 0.176* (4.30 – 4.48) 0.043 (1.10) MAX 0.002 – 0.006 (0.05 – 0.15) 0.0256 (0.65) BSC 0.007 – 0.012 (0.18 – 0.30) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm). 0.246 – 0.256 (6.25 – 6.50) 13 4 5 6 7 89 1 0 111214 13 0.252 – 0.260* (6.40 – 6.60) 20 19 18 17 16 15 PACKAGE DESCRIPTIONU RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1109 5V to 12V/60mA VPP Generator 300 µA IQ, 120kHz Oscillator LT1109A 5V to 12V/120mA VPP Generator 300 µA IQ, 120kHz Oscillator LT1301 5V to 12V/200mA VPP Generator 120 µA IQ, 155kHz Oscillator LT1309 5V to 12V/60mA VPP Generator 650 µA IQ, 650kHz Oscillator