LT1106 Micropower Step-Up DC/DC Converter for PCMCIA Card Flash Memory U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ 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 programming 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 ModeTM 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. 60mA Output Current at 12V from 3V Supply Shutdown to 10µA Programmable 12V or 5V Output Up to 85% Efficiency Quiescent Current: 750µA Low VCESAT Switch: 300mV at 0.5A Typical Uses Low Value, Thin, Surface Mount Inductors Ultra-Thin 20-Lead TSSOP Package UO APPLICATI ■ ■ ■ ■ S PCMCIA Card Flash Memory VPP Generator Portable Computers Portable Instruments DC/DC Converter Module Replacements , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. UO TYPICAL APPLICATI 12V, 60mA Flash Memory Programming Supply 86 L1* 10µH + D1** D1 = MBR0530 D1 = 4 BAT54Cs IN PARALLEL 84 4.7µF TANT ALUM VPP1 0.1µF D BSS84 0.1µF S VPP2 0.1µF D BSS84 S POWER ON *DALE ILS-3825-01 OR COILTRONICS CTX02-11238-3 **MOTOROLA MBR0530 82 VCC VPP1 G1 VPP2 SW AVPP 12V/60mA 1µF LT1106 VPP VALID VPP VALID 470pF G2 3/5 DETECT 3/5 SOFT START ON/OFF PGND GND 12/5 EFFICIENCY (%) VCC 3.3V/5V 12V Output Efficiency VIN = 5V VIN = 5V 80 VIN = 3.3V 78 VIN = 3.3V 76 74 72 1M 0.1µF 70 1 LT1106 • TA01 10 LOAD CURRENT (mA) 100 LT1106 • TA02 1 LT1106 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO VCC Voltage ............................................................... 7V VSW Voltage ............................................................ 20V AVPP Voltage ......................................................... 20V VPP1, VPP2 Voltage ............................................... 20V G1, G2 Voltage ....................................................... 20V VON/OFF Voltage......................................................... 7V VSEL Voltage ............................................................. 7V ILIM Voltage .............................................................. 7V Maximum Power Dissipation ............................ 500mW Operating Temperature Range ..................... 0°C to 70°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C TOP VIEW SELECT 12/5 1 20 ON/OFF SOFT START 2 19 AVPP VCC 3 18 VPP1 VCC 4 17 VPP2 ORDER PART NUMBER LT1106CF 3/5 5 16 G1 PGND 6 15 G2 PGND 7 14 VPP VALID NC 8 13 GND VSW 9 12 NC VSW 10 11 VSW F PACKAGE 20-LEAD PLASTIC TSSOP TJMAX = 100°C, θJA = 90°C/W Consult factory for Industrial and Military grade parts ELECTRICAL CHARACTERISTICS TA = 25°C, VCC = 5V, VON/OFF = 3V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS IQ Quiescent Current VSEL = 0.2V, AVPP = 12V Quiescent Current, Shutdown VON/OFF = 0.2V “Doze” Mode Current VSEL = 0.2V, VPP1 or VPP2 = 12V MIN 750 900 µA 9 15 µA 2 Output Sense Voltage VSEL = 3V, VPP1 and VPP2 Floating VSEL = 0.2V, VPP1 and VPP2 Floating Output Referred Comparator Hysteresis VSEL = 3V VSEL = 0.2V fOSC Oscillator Frequency Current Limit Not Asserted DC Maximum Duty Cycle tON Switch On-Time VCESAT MAX ● ● 4.75 11.50 5 12 V V V ● 80 mV mV 500 700 85 92 kHz % µs 1.7 2V < VIN < 6V 0.06 0.15 %/V Switch Saturation Voltage ISW = 0.5A 230 350 mV Switch Leakage Current VSW = 12V, Switch Off 0.1 10 µA Switch Current Limit VIN = 5V, Soft Start Floating VIN = 3V, Soft Start Floating 600 650 900 950 mA mA Soft Start Pin Current Soft Start Grounded 80 120 µA 0.8 V 450 500 Select Input Voltage Low Select Input Voltage High 1.6 V ON/OFF Input Voltage Low 0.8 ON/OFF Input Voltage High ON/OFF Bias Current 2 6 5.25 12.60 15 35 400 UNITS µA 320 Input Voltage Range Reference Line Regulation TYP 1.6 VON/OFF = 5V VON/OFF = 3V VON/OFF = 0V V V 16.0 8.0 0.1 24.0 14.0 1.1 µA µA µA LT1106 ELECTRICAL CHARACTERISTICS SYMBOL TA = 25°C, VCC = 5V, VON/OFF = 3V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP Select Pin Bias Current 0V < VSEL < 5V 0.1 1 µA 11.0 11.5 11.9 V VON/OFF = 0.2V 50 0.1 90 1 µA µA VON/OFF = 0.2V 50 0.1 90 1 µA µA 12 V 0.13 0.3 V VPP1/VPP2 Input Sense Threshold AVPP Pin Input Current VPP1/VPP2 Pin Input Current VPP VALID Threshold AVPP Rising (High to Low Transition) VPP VALID Output Voltage Low ISINK = 100µA VPP VALID Output Voltage High ISOURCE = 2.5µA 11.4 ● 3/5 Comparator Threshold 4 4.5 3.6 3.75 3.65 3.8 ● MAX UNITS V 4.2 V 3/5 Comparator Output High ILOAD = 50µA V 3/5 Comparator Output Low ILOAD = 50µA 0.75 0.9 V Off State Current at G1/G2 VPP1 = 10V, VG1 = 12V or VPP2 = 10V, VG2 = 12V or VON/OFF = 0V 0.1 1 µA The ● denotes specifications which apply over the full operating temperature range. U W TYPICAL PERFORMANCE CHARACTERISTICS Oscillator Frequency Switch Current Limit SWITCH SATURATION VOLTAGE (mV) SWITCH CURRENT (mA) OSCILLATOR FREQUENCY (kHz) 250 900 700 600 500 400 300 –50 Switch Saturation Voltage 1000 800 800 VCC = 3V 700 VCC = 5V 600 500 –25 0 25 50 TEMPERATURE (°C) 75 100 LT1106 • TPC01 400 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 LT1106 • TPC02 ISW = 500mA 225 200 175 150 125 100 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 LT1106 • TPC03 3 LT1106 U W TYPICAL PERFORMANCE CHARACTERISTICS 3/ 5 Comparator Threshold AVPP Sense Voltage 4.00 AVPP Sense Voltage 5.10 12.20 12/5 SELECT = 0 3.90 3.85 3.80 3.75 5.05 AVPP SENSE VOLTAGE (V) AVPP SENSE VOLTAGE (V) 3.95 THRESHOLD VOLTAGE (V) 12/5 SELECT = 1 12.15 12.10 12.05 12.00 11.95 11.90 –25 75 0 25 50 TEMPERATURE (°C) 100 4.95 4.90 4.85 11.85 3.70 –50 5.00 11.80 –50 –25 0 50 25 TEMPERATURE (°C) LT1106 • TPC04 75 4.80 –50 100 –25 0 25 50 TEMPERATURE (°C) Supply Current in Shutdown 100 LT1106 • TPC06 LT1106 • TPC05 Supply Current Maximum Duty Cycle 800 14 75 95 SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 700 VCC = 5V 10 8 6 VCC = 3V 4 VCC = 5V VCC = 3V 600 500 400 2 0 –50 –25 50 25 0 TEMPERATURE (°C) 75 100 300 –50 –25 0 25 50 TEMPERATURE (°C) 75 –25 0 25 50 TEMPERATURE (°C) 75 100 LT1106 • TPC09 Load Transient Response, COUT = 1µF 12V OUTPUT 1V/DIV AC COUPLED ILOAD IL 500mA/DIV VPP VALID 10V/DIV ON/OFF 10V/DIV 80 70 –50 100 VOUT 5V/DIV VAVPP 2V/DIV 85 Start-Up Waveforms with Soft Start, ILOAD = 10mA Start-Up Waveforms, ILOAD = 1mA 12V 75 90 LT1106 • TPC08 LT1106 • TPC07 60mA 10mA VON/OFF 10V/DIV 50µs/DIV 4 MAXIMUM DUTY CYCLE (%) 12 LT1106 • TPC10 50µs/DIV LT1106 • TPC11 50µs/DIV LT1106 • TPC12 LT1106 U U U PI FU CTIO S 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 approximately 0.4V, current ceases flowing out of the pin. See Applications Information section. VCC (Pins 3, 4): Input Supply. Both pins should be tied together. At least 1µF input bypass capacitance is required. 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 1µA 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. 5 LT1106 W BLOCK DIAGRA 12/5 SELECT AVPP VPP1 VPP2 ON/0FF G1 G2 1 19 18 17 20 16 15 BIAS 565k – + – 299k VCC + + – VCC VREF + R2 700Ω C3 – 200k C2 3,4 36mV + 14 VPP VALID Q3 R1 3Ω BIAS – 4k – 100k + 2 SW SOFT START 9,10,11 OFF Q2 1× 500kHz OSCILLATOR C1 VCC + 5 VREF 1.24V 3.7V Q1 50× – 3/5 13 6,7 GND PGND LT1106 • BD U W U U APPLICATIONS INFORMATION 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 presence of a valid programming voltage. The 3/5 comparator indicates whether the input voltage is 3.3V or 5V. 6 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 programmable between 5V or 12V depending on the state of the 12/5 Select pin. Referring to the block diagram, hysteretic comparator C1 monitors AVPP via the resistor divider. When the negative input of C2 falls below 1.24V, C1’s LT1106 U W U U APPLICATIONS INFORMATION output goes high, enabling the oscillator. Switch Q1 alternately turns on causing current build-up in the inductor; 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 0.1µF 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 inductor that meets Type I height requirements. Generally, inductors used with the LT1106 must fulfill several requirements. 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 frequency range. Avoid low cost iron powder cores which have substantial AC loss at the LT1106’s switching frequency. 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 0.2µF 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 capacitors are used at the supply pin of the LT1106, switching currents will resonate the supply line causing ringing that can exceed 500mVP-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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 7 LT1106 U TYPICAL APPLICATION Alternative Scheme Allows 12V from VPP1/VPP2 to Provide Power When LT1106 is in Shutdown D** VPP1 D** VPP2 VCC 3.3V/5V L1* 10µH D** + 4.7µF SW AVPP VCC 12V/60mA 1µF LT1106 VPP VALID VPP VALID 470pF SOFT START ON/OFF GND PGND SEL POWER ON 1M *DALE ILS-3824-01 **MBR0530 OR 4 BAT54s IN PARALLEL U PACKAGE DESCRIPTION 0.1µF LT1106 • TA03 Dimensions in inches (millimeters) unless otherwise noted. F Package 20-Lead Plastic TSSOP 0.043 (1.10) MAX 0.169 – 0.176* (4.30 – 4.48) 0.252 – 0.260* (6.40 – 6.60) 20 19 18 17 16 15 14 13 12 11 0° – 8° 0.020 – 0.028 (0.50 – 0.70) 0.004 – 0.071 (0.09 – 0.18) 0.0256 (0.65) BSC 0.007 – 0.012 (0.18 – 0.30) 0.246 – 0.256 (6.25 – 6.50) 0.002 – 0.006 (0.05 – 0.15) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm). 1 2 3 4 5 6 7 8 F209TSSOP 100395 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1109 5V to 12V/60mA VPP Generator 300µA IQ, 120kHz Oscillator LT1109A 5V to 12V/120mA VPP Generator 300µA IQ, 120kHz Oscillator LT1301 5V to 12V/200mA VPP Generator 120µA IQ, 155kHz Oscillator LT1309 5V to 12V/60mA VPP Generator 650µA IQ, 650kHz Oscillator 8 Linear Technology Corporation LT/GP 0595 10K • PRINTED IN THE USA 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977 LINEAR TECHNOLOGY CORPORATION 1995