LT8410/LT Ultralow Power Boost Converter with Output Disconnect DESCRIPTION FEATURES APPLICATIONS TYPICAL APPLICATION

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1 FEATURES n Ultralow Quiescent Current.5μA in Active Mode μa in Shutdown Mode n Comparator Built into Pin n Low Noise Control Scheme n Adjustable FB Reference Voltage n Wide Input Range:.5V to 6V n Wide Output Range: Up to 4V n Integrated Power NPN Switch 5 Current Limit (LT4) Current Limit (LT4-) n Integrated Schottky Diode n Integrated Output Disconnect n High Value (.4M/.4M) Feedback Resistors Integrated n Built in Soft-Start (Optional Capacitor from V REF to ) n Overvoltage Protection for CAP and V OUT Pins n Tiny -Pin mm mm DFN Package LT4/LT4- Ultralow Power Boost Converter with Output Disconnect DESCRIPTION The LT 4/LT4- are ultralow power boost converters with integrated power switch, Schottky diode and output disconnect circuitry. The parts control power delivery by varying both the peak inductor current and switch offtime. This control scheme results in low output voltage ripple as well as high efficiency over a wide load range. The quiescent current is a low.5μa, which is further reduced to μa in shutdown. The internal disconnect circuitry allows the output voltage to be blocked from the input during shutdown. High value (.4M/.4M) resistors are integrated on chip for output voltage detection, significantly reducing input referred quiescent current. The LT4/ LT4- also features a comparator built into the pin, overvoltage protection for the CAP and V OUT pins, built in soft-start and comes in a tiny -pin mm mm DFN package. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 547, 655, 63466, 675, , 663. APPLICATIONS n Sensor Power n RF Mems Relay Power n General Purpose Bias TYPICAL APPLICATION General Purpose Bias with Wide Input Voltage V IN.5V to 6V.µF CHIP ENABLE µh SW CAP V CC V OUT LT4 V REF *HIGHER VALUE CAPACITOR IS REQUIRED WHEN THE V IN IS HIGHER THAN 5V 64k 4k.µF 4- TAa.µF.µF* VOUT PEAK-TO-PEAK RIPPLE (mv) 6 4 Output Voltage Ripple vs Load Current. V IN = 3.6V. LOAD CURRENT () 4- TA EFFICIENCY (%) Efficiency vs Load Current V IN = V V IN = 3.6V V IN = 5V. LOAD CURRENT () 4- TA3 4fb

2 LT4/LT4- ABSOLUTE MAXIMUM RATINGS (Note ) V CC Voltage....3V to 6V SW Voltage....3V to 4V CAP Voltage....3V to 4V V OUT Voltage....3V to 4V Voltage....3V to 6V V REF Voltage....3V to.5v Voltage....3V to.5v Maximum Junction Temperature... 5 C Operating Temperature Range (Note ).. 4 C to 5 C Storage Temperature Range C to 5 C PIN CONFIGURATION V CC SW TOP VIEW V REF CAP V OUT DC PACKAGE -LEAD (mm mm) PLASTIC DFN T JMAX = 5 C, θ JA = C/W EXPOSED PAD (PIN #9) IS, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT4EDC#PBF LT4EDC#TRPBF LDQR -Lead (mm mm) Plastic DFN 4 C to 5 C LT4IDC#PBF LT4IDC#TRPBF LDQR -Lead (mm mm) Plastic DFN 4 C to 5 C LT4EDC-#PBF LT4EDC-#TRPBF LFCC -Lead (mm mm) Plastic DFN 4 C to 5 C LT4IDC-#PBF LT4IDC-#TRPBF LFCC -Lead (mm mm) Plastic DFN 4 C to 5 C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: For more information on tape and reel specifications, go to: ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = 5 C. V CC = 3V, V = V CC unless otherwise noted. (Note ) PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage..5 V Maximum Operating Voltage 6 V Reference Voltage l V V REF Current Limit (Note 3) µa V REF Discharge Time 7 µs V REF Line Regulation. %/V Quiescent Current Not Switching l.5 µa Quiescent Current in Shutdown V = V l µa Quiescent Current from V OUT and CAP 3 µa Minimum Switch Off Time After Start-Up (Note 4) During Start-Up (Note 4) Switch Current Limit LT4 LT4- l l ns ns 4fb

3 LT4/LT4- ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = 5 C. V CC = 3V, V = V CC unless otherwise noted. (Note ) PARAMETER CONDITIONS MIN TYP MAX UNITS Switch V CESAT LT4, I SW = LT4-, I SW = 4 5 mv mv Switch Leakage Current V SW = 5V µa Schottky Forward Voltage I DIODE = 65 5 mv Schottky Reverse Leakage V CAP V SW = 5 V CAP V SW = 4 PMOS Disconnect Current Limit LT4 LT4- PMOS Disconnect V CAP V OUT I OUT = 5 mv V OUT Resistor Divider Ratio l Pin Bias Current V =.5V, Current Flows Out of Pin l.3 3 na Minimum Input Voltage High Rising l V Input Voltage High Hysteresis 6 mv Hysteresis Current (Note 3)...4 µa Input Voltage Low.3 V Pin Bias Current V = 3V V = 6V 3 µa µa Note : Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note : The LT4E/LT4E- are guaranteed to meet performance specifications from C to 5 C junction temperature. Specifications over the 4 C to 5 C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT4I/LT4I- are guaranteed over the full 4 C to 5 C operating junction temperature range Note 3: See the Applications Information section for more information. Note 4: Start-up mode occurs when V OUT is less than V 64/3. µa µa TYPICAL PERFORMANCE CHARACTERISTICS T A = 5 C, unless otherwise noted. SWITCHING FREQUENCY (khz) 6 4 Switching Frequency vs Load Current Load Regulation V OUT vs Voltage FIGURE 4 CIRCUIT OUTPUT VOLTAGE CHANGE (%) FIGURE 4 CIRCUIT OUTPUT VOLTAGE (V) LOAD CURRENT () 3 4- G.6 LOAD CURRENT () 3 4- G.5.5 VOLTAGE (V) 4- G3 4fb 3

4 LT4/LT4- TYPICAL PERFORMANCE CHARACTERISTICS OUTPUT VOLTAGE CHANGE (%) Output Voltage vs Temperature Quiescent Current Not Switching Quiescent Current vs Temperature, LOAD =.5 FIGURE 4 CIRCUIT 4 TEMPERATURE ( C) 4- G4 QUIESCENT CURRENT (µa) V CC VOLTAGE (V) 6 4- G5 QUIESCENT CURRENT (µa) TEMPERATURE ( C) 4- G6 Quiescent Current vs Voltage Quiescent Current in Regulation with No Load Current vs Voltage.5 QUIESCENT CURRENT (µa) 6 4 QUIESCENT CURRENT (µa) PIN BIAS CURRENT (µa) VOLTAGE (V) 5 4- G7 3 OUTPUT VOLTAGE (V) 4 4- G.5 4 VOLTAGE (V) 6 4- G9 PEAK INDUCTOR CURRENT () Peak Inductor Current vs Temperature (LT4) FIGURE 4 CIRCUIT PEAK INDUCTOR CURRENT () Peak Inductor Current vs Temperature (LT4-) FIGURE 5 CIRCUIT V REF VOLTAGE (V) V REF Voltage vs Temperature TEMPERATURE ( C) 4- G TEMPERATURE ( C) 4- G TEMPERATURE ( C) 4- G 4 4fb

5 TYPICAL PERFORMANCE CHARACTERISTICS LT4 Switching Waveform at No Load LT4/LT4- LT4 Switching Waveform at.5 Load V OUT VOLTAGE mv/div AC COUPLED V OUT VOLTAGE mv/div AC COUPLED SW VOLTAGE V/DIV SW VOLTAGE V/DIV INDUCTOR CURRENT /DIV INDUCTOR CURRENT /DIV 5µs/DIV 4- G3 µs/div 4- G4 LT4 Switching Waveform at 3 Load.6 UVLO vs Temperature V OUT VOLTAGE mv/div AC COUPLED SW VOLTAGE V/DIV INDUCTOR CURRENT /DIV 5ns/DIV 4- G5 UVLO VOLTAGE (V).4 V CC RISING. V CC FALLING TEMPERATURE ( C) 4- G6 OUTPUT VOLTAGE CHANGE (%) Line Regulation MINIMUM INPUT VOLTAGE HIGH (V) Minimum Input Voltage High vs Temperature RISING FALLING 4 V CC VOLTAGE (V) 6 4- G TEMPERATURE ( C) 4- G 4fb 5

6 LT4/LT4- TYPICAL PERFORMANCE CHARACTERISTICS PMOS CURRENT () Output Disconnect PMOS Current vs CAP to V OUT Voltage Difference V CAP = 6V LT4 LT4-4 6 CAP TO V OUT VOLTAGE DIFFERENCE (V) 4- G9 VOLTAGE 5V/DIV INDUCTOR CURRENT /DIV CAP VOLTAGE 5V/DIV V OUT VOLTAGE 5V/DIV LT4 Start-Up Waveforms without Capacitor at V REF Pin µs/div 4- G VOLTAGE 5V/DIV INDUCTOR CURRENT /DIV CAP VOLTAGE 5V/DIV V OUT VOLTAGE 5V/DIV LT4 Start-Up Waveforms with.μf Capacitor at V REF Pin V OUT VOLTAGE mv/div AC COUPLED INDUCTOR CURRENT /DIV LOAD CURRENT.5/DIV LT4 Transient Response Load Pulse ms/div 4- G ms/div 4- G 3 SW Saturation Voltage vs Switch Current (LT4) 5 SWITCH V CESAT (mv) SWITCH CURRENT () 5 4- G4 6 4fb

7 + + + PIN FUNCTIONS (Pin ): Shutdown Pin. This pin is used to enable/ disable the chip. Drive below.3v to disable the chip. Drive above.45v to activate the chip. Do not float this pin. V CC (Pin ): Input Supply Pin. Must be locally bypassed to. See the Typical Applications section. (Pin 3): Ground. Tie directly to local ground plane. SW (Pin 4): Switch Pin. This is the collector of the internal NPN power switch. Minimize the metal trace area connected to this pin to minimize EMI. V OUT (Pin 5): Drain of Output Disconnect PMOS. Place a bypass capacitor from this pin to. CAP (Pin 6): Cathode of the Internal Schottky Diode. Place a bypass capacitor from this pin to. LT4/LT4- V REF (Pin 7): Reference Pin. Soft-start can be achieved by placing a capacitor from this pin to. This cap will be discharged for 7µs (typical) at the beginning of start-up and then be charged to.35v with a μa current source. (Pin ): Positive Feedback Pin. This pin is the error amplifier s positive input terminal. To achieve the desired output voltage, choose the pin voltage (V ) according to the following formula: V = V OUT 3.5 For protection purposes, the output voltage can not exceed 4V even if V is driven higher than V REF. Exposed Pad (Pin 9): Pin 9 is floating but must be grounded for proper shielding. BLOCK DIAGRAM V CC MAX µa.35v ENABLE CHIP.4M V OUT CAP SW V REF 7.35V 4k OUTPUT DISCONNECT CONTROL DISCHARGE CONTROL TIMING AND PEAK CURRENT CONTROL SWITCH CONTROL FB +.35V + VC EXPOSED PAD () 9 3 4fb 7

8 LT4/LT4- OPERATION The LT4 series utilizes a variable peak current, variable off-time control scheme to provide high efficiency over a wide output current range. The operation of the part can be better understood by referring to the Block Diagram. The part senses the output voltage by monitoring the internal FB node, and servoing the FB node voltage to be equal to the pin voltage. The chip integrates an accurate high value resistor divider (.4M/.4M) from the V OUT pin. The output voltage is set by the pin voltage, which in turn is set by an external resistor divider from the V REF pin. The pin voltage can also be directly biased with an external reference, allowing full control of the output voltage during operation. The switch control block senses the output of the amplifier and adjusts the switching frequency as well as other parameters to achieve regulation. During the start-up of the circuit, special precautions are taken to ensure that the inductor current remains under control The LT4 series also has a PMOS output disconnect switch. The PMOS switch is turned on when the part is enabled via the pin. When the part is in shutdown, the PMOS switch turns off, allowing the V OUT node to go to ground. This type of disconnect function is often required in power supplies. The differences between the LT4 and LT4- are the SW current limit and the output disconnect PMOS current limit. For the LT4, the SW current limit and PMOS current limit are approximately 5 and 9, respectively, while those of the LT4- are approximately and 4, respectively. APPLICATIONS INFORMATION Inductor Selection Several inductors that work well with the LT4 and LT4- are listed in Table. The tables are not complete, and there are many other manufacturers and devices that can be used. Consult each manufacturer for more detailed information and for their entire selection of related parts, as many different sizes and shapes are available. Inductors with a value of 47μH or higher are recommended for most LT4 series designs. Inductors with low core losses and small DCR (copper wire resistance) are good choices for LT4 series applications. For full output power, the inductor should have a saturation current rating higher than the peak inductor current. The peak inductor current can be calculated as: I PK = I LIMIT + V IN 5 6 L where the worst case I LIMIT is 3 and for LT4 and LT4-, respectively. L is the inductance value in henrys and V IN is the input voltage to the boost circuit. Table. Recommended Inductors for LT4/ LT4- PART LQHMCN6K LQH3CNK53 DO-63ML LPS35-4ML LPS35-54ML LPS334-54ML L (µh) Capacitor Selection DCR (Ω) SIZE (mm) VENDOR Murata Coilcraft The small size and low ESR of ceramic capacitors make them suitable for most LT4 applications. X5R and X7R types are recommended because they retain their capacitance over wider voltage and temperature ranges than other types such as Y5V or Z5U. A.μF or higher input capacitor, and a.μf to μf output capacitor, are sufficient for most applications. Always use a capacitor with a sufficient voltage rating. Many ceramic capacitors rated at.μf to μf have greatly reduced capacitance when bias voltages are applied. Be sure to check actual capacitance at the desired output voltage. Generally, a 63 4fb

9 APPLICATIONS INFORMATION or 5 size capacitor will be adequate. A.μF to μf capacitor placed on the CAP node is recommended to filter the inductor current, while a.μf to μf capacitor placed on the V OUT node will give excellent transient response and stability. To make the V REF pin less sensitive to noise, putting a capacitor on the V REF pin is recommended, but not required. A 47nF to nf 4 capacitor will be sufficient. Table shows a list of several capacitor manufacturers. Consult the manufacturers for more detailed information and for their entire selection of related parts. Table. Recommended Ceramic Capacitor Manufacturers MANUFACTURER PHONE WEB SITE Taiyo Yuden (4) Murata (4) AVX (43) Kemet (4) TDK (47) Setting Output Voltage The output voltage is set by the pin voltage. V OUT is equal to 3.5 V when the output is regulated, as shown in Figure. Since the V REF pin provides a good reference (.35V), the voltage can be easily set by a resistor divider from the V REF pin to ground. The series resistance of this resistor divider should be kept larger than KΩ to prevent loading down the V REF pin. The pin can also be biased directly by an external reference. For overvoltage protection, the output voltage is limited to 4V. Therefore, if V is higher than.35v, the output voltage will stay at 4V. OUTPUT VOLTAGE (V) VOLTAGE (V) 4- F Figure. to V OUT Transfer Curve LT4/LT4- Connecting the Load to the CAP Node The efficiency of the converter can be improved by connecting the load to the CAP pin instead of the V OUT pin. The power loss in the PMOS disconnect circuit is then made negligible. No quiescent current will be consumed in the internal feedback resistor divider string during shutdown since the PMOS transistor will be open and the internal feedback resistor divider is connected at the V OUT pin. The disadvantage of this method is that the CAP node cannot go to ground during shutdown, but will be limited to around a diode drop below V CC. Loads connected to the part should only sink current. Never force external power supplies onto the CAP or V OUT pins. Maximum Output Load Current The maximum output current of a particular LT4 series circuit is a function of several circuit variables. The following method can be helpful in predicting the maximum load current for a given circuit: Step. Calculate the peak inductor current: I PK = I LIMIT + V IN 5 6 L where I LIMIT is 5 and for LT4 and LT4- respectively. L is the inductance value in henrys and V IN is the input voltage to the boost circuit. Step. Calculate the inductor ripple current: ( ) 6 I RIPPLE = V OUT + V IN L where V OUT is the desired output voltage. If the inductor ripple current is less than the peak current, then the circuit will only operate in discontinuous conduction mode. The inductor value should be increased so that I RIPPLE < I PK. An application circuit can be designed to operate only in discontinuous mode, but the output current capability will be reduced. Step 3. Calculate the average input current: I IN(AVG) = I PK I RIPPLE 4fb 9

10 LT4/LT4- APPLICATIONS INFORMATION Step 4. Calculate the nominal output current: I OUT(NOM) = I IN(AVG) V IN.7 V OUT Step 5. Derate output current: I OUT = I OUT(NOM). For low output voltages the output current capability will be increased. When using output disconnect (load current taken from V OUT ), these higher currents will cause the drop in the PMOS switch to be higher resulting in lower output current capability than predicted by the preceding equations. Inrush Current When V CC is stepped from ground to the operating voltage while the output capacitor is discharged, a high level of inrush current may flow through the inductor and Schottky diode into the output capacitor. Conditions that increase inrush current include a larger more abrupt voltage step at V CC, a larger output capacitor tied to the CAP pin and an inductor with a low saturation current. While the chip is designed to handle such events, the inrush current should not be allowed to exceed.3a. For circuits that use output capacitor values within the recommended range and have input voltages of less than 6V, inrush current remains low, posing no hazard to the device. In cases where there are large steps at V CC (more than 6V) and/or a large capacitor is used at the CAP pin, inrush current should be measured to ensure safe operation. Soft-Start The LT4 series contains a soft-start circuit to limit peak switch currents during start-up. High start-up current is inherent in switching regulators, in general, since the feedback loop is saturated due to V OUT being far from its final value. The regulator tries to charge the output capacitor as quickly as possible, which results in large peak current. When the pin voltage is generated by a resistor divider from the V REF pin, the start-up current can be limited by connecting an external capacitor (typically 47nF to nf) to the V REF pin. When the part is brought out of shutdown, this capacitor is first discharged for about 7μs (providing protection against pin glitches and slow ramping), then an internal μa current source pulls the V REF pin slowly to.35v. Since the V OUT voltage is set by the pin voltage, the V OUT voltage will also slowly increase to the regulated voltage, which results in lower peak inductor current. The voltage ramp rate on the pin can be set by the value of the V REF pin capacitor. Output Disconnect The LT4 series has an output disconnect PMOS that blocks the load from the input during shutdown. The maximum current through the PMOS is limited by circuitry inside the chip, helping the chip survive output shorts. Pin Comparator and Hysteresis Current An internal comparator compares the pin voltage with an internal voltage reference (.3V) which gives a precise turn-on voltage level. The internal hysteresis of this turn-on voltage is about 6mV. When the chip is turned on, and the pin voltage is close to this turn-on voltage,.μa current flows out of the pin. This current is called pin hysteresis current, and will go away when the chip is off. By connecting the external resistors as in Figure, a user-programmable enable voltage function can be realized. The turn-on voltage for the configuration is:.3 + R R and the turn-off voltage is: (.4 R3 7 ) + R R (R 7 ) where R, R and R3 are resistance value in Ω. ENABLE VOLTAGE R R R3 CONNECT TO PIN 4 F Figure. Programming Enable Voltage by Using External Resistors 4fb

11 LT4/LT4- APPLICATIONS INFORMATION Board Layout Considerations V IN As with all switching regulators, careful attention must be paid to the PCB layout and component placement. To maximize efficiency, switch rise and fall times are made as short as possible. To prevent electromagnetic interference (EMI) problems, proper layout of the high frequency switching path is essential. The voltage signal of the SW pin has sharp rising and falling edges. Minimize the length and area of all traces connected to the SW pin and always use a ground plane under the switching regulator to minimize interplane coupling. In addition, the pin and V REF pin are sensitive to noise. Minimize the length and area of all traces to these two pins is recommended. Recommended component placement is shown in Figure 3. V CC SW V REF CAP V OUT CAPACITOR GROUNDS MUST BE RETURNED DIRECTLY TO IC GROUND 4- F3 Figure 3. Recommended Board Layout 4fb

12 LT4/LT4- TYPICAL APPLICATIONS V IN.5V to 6V 6V Output Converter with mm mm Inductor V IN.5V to 6V C.µF TURN ON/OFF C.µF TURN ON/OFF L µh L 6µH SW CAP V CC V OUT LT4 V REF SW CAP V CC V OUT LT4 V REF 64k 4k C:.μF, 6V, X5R, 63 C:.μF, 5V, X5R, 63 C3:.μF, 5V, X5R, 63 * C4:.μF, 6V, X7R, 4 L: MURATA LQH3CNK53 * HIGHER CAPACITANCE VALUE IS REQUIRED FOR C3 WHEN THE V IN IS HIGHER THAN 5V R 3k 4- TA5 R k C:.μF, 6V, X5R, 63 C:.μF, 5V, X5R, 63 C3:.μF, 5V, X5R, 63 * C4:.μF, 6V, X7R, 4 L: COILCRAFT DO-63ML * HIGHER CAPACITANCE VALUE IS REQUIRED FOR C3 WHEN THE V IN IS HIGHER THAN 5V C.µF C.µF 4 TA6 C4.µF C4.µF C3.µF Figure 4. 6V Output Converter with Wide Input Voltage C3.µF EFFICIENCY (%) EFFICIENCY (%) Efficiency vs Load Current V IN = V V IN = 5V V IN = 3.6V. LOAD CURRENT () V IN (V) I OUT () Efficiency vs Load Current 9 V IN = V V IN = 5V V IN = 3.6V LOAD CURRENT () 4- TA7 4- TA V OUT (V) RESISTOR DIVIDER FROM V REF R (kω) / R ( kω) LT4 Maximum Output Current vs Output Voltage MAXIMUM OUTPUT CURRENT () V IN =.V V IN = 3.6V V IN = 5V V IN = V 4 NA / / / / / / NA 5 66/7 7 NA 4fb

13 LT4/LT4- TYPICAL APPLICATIONS V IN.5V to 6V 34V Output Converter with Wide Input Voltage L 5µH 9 Efficiency vs Load Current V IN = V C.µF TURN ON/OFF SW CAP V CC V OUT LT4 V REF 33k 66k C.µF V OUT = 34V C4.µF C3.µF EFFICIENCY (%) V IN = 5V V IN = 3.6V C:.μF, 6V, X5R, 63 C:.μF, V, X5R, 63 C3:.μF, V, X5R, 63 * C4:.μF, 6V, X7R, 4 L: COILCRAFT LPS334-54ML * HIGHER CAPACITANCE VALUE IS REQUIRED FOR C3 WHEN THE V IN IS HIGHER THAN V V IN.5V to 6V C.µF TURN ON/OFF L µh SW CAP V CC V OUT LT4- V REF R 64k 4- TA9 R 4k C:.μF, 6V, X5R, 63 C:.μF, 5V, X5R, 63 * C3: μf, ELECTROLYTIC CAPACITOR C4:.μF, 6V, X7R, 4 L: COILCRAFT LPS3-4ML * HIGHER CAPACITANCE VALUE IS REQUIRED FOR C WHEN THE V IN IS HIGHER THAN V C.µF 4- TAa C4.µF C3 µf 4. VOLTAGE V/DIV V OUT VOLTAGE V/DIV V IN (V). LOAD CURRENT () I OUT () TA INPUT CURRENT 5/DIV INDUCTOR CURRENT /DIV 4- Gb V IN = 3.6V s/div Figure 5. Capacitor Charger with the LT4- V OUT (V) FEEDBACK RESISTOR DIVIDER R (kω) / R ( kω) LT4- Maximum Output Current vs Output Voltage MAXIMUM OUTPUT CURRENT () V IN =.V V IN = 3.6V V IN = 5V V IN = V 4 NA / / / / / / NA 5 66/ NA 4fb 3

14 LT4/LT4- PACKAGE DESCRIPTION DC Package -Lead Plastic DFN (mm mm) (Reference LTC DWG # Rev A).7 ±.5.55 ±.5.5 ±.5.64 ±.5 ( SIDES) PACKAGE OUTLINE.5 ±.5.45 BSC.37 ±.5 ( SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED R =.5 TYP R =.5 TYP 5.4 ±. PIN BAR TOP MARK (SEE NOTE 6). REF. ±. (4 SIDES).75 ± ±. ( SIDES) PIN NOTCH R =. OR.5 45 CHAMFER (DC) DFN 49 REVA 4.3 ±.5.45 BSC.37 ±. ( SIDES) BOTTOM VIEW EXPOSED PAD NOTE:. DRAWING IS NOT A JEDEC PACKAGE OUTLINE. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED.5mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN LOCATION ON THE TOP AND BOTTOM OF PACKAGE 4 4fb

15 LT4/LT4- REVISION HISTORY (Revision history begins at Rev B) REV DATE DESCRIPTION PAGE NUMBER B / Corrected Pin Configuration Revised Note in Electrical Characteristics 3 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. 4fb 5

16 LT4/LT4- TYPICAL APPLICATION High Voltage Power Supply Does Not Need a Transformer DANGER HIGH VOLTAGE! OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY C3,.µF C5,.µF V IN.5V to 6V C.µF L µh SW CAP C.µF D D D3 D4 C4.µF C6.µF TURN ON/OFF C:.μF, 6V, X5R, 63 C C7:.μF, V, X5R, 63 C:.μF, 6V, X7R, 4 D D4: ON SEMI RB75S4TG L: MURATA LQH3CNK53 V CC V OUT LT4 V REF 43k 77k C7.µF C.µF OUTPUT = V.4 (V IN = 5V).4 (V IN = V) 4- TA OUTPUT VOLTAGE (V) Output Voltage vs Voltage 4 V IN = 5V 6 4 EFFICIENCY (%) Efficiency vs Load Current 9 V OUT = V V IN = V 7 V IN = 5V VOLTAGE (V) 4- TA 4.. LOAD CURRENT () 4- TA3 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT946/LT946A LT3464 LT347 LT3473/LT3473A LT3494/LT3494A LT3495/LT3495B/ LT3495-/LT3495B-.5A (I SW ),.MHz/.7MHz, High Efficiency Step-Up DC/DC Converters 5 (I SW ), High Efficiency Step-Up DC/DC Converter with Integrated Schottky and PNP Disconnect Dual Output, Boost/Inverter,.3A (I SW ), High Efficiency Boost-Inverting DC/DC Converter A (I SW ),.MHz, High Efficiency Step-Up DC/DC Converter with Integrated Schottky Diode and Output Disconnect /35 (I SW ), High Efficiency, Low Noise Step-Up DC/DC Converter with Output Disconnect 65/35 (I SW ), High Efficiency, Low Noise Step-Up DC/DC Converter with Output Disconnect V IN :.45V to 6V, V OUT(MAX) = 34V, I Q = 3., I SD < µa, -Lead MS Package V IN :.3V to V, V OUT(MAX) = 34V, I Q = 5µA, I SD < µa, ThinSOT Package V IN :.4V to 6V, V OUT(MAX) = ±4V, I Q =.5, I SD < µa, DFN Package V IN :.V to 6V, V OUT(MAX) = 36V, I Q = µa, I SD < µa, DFN Package V IN :.V to 6V, V OUT(MAX) = 4V, I Q = 65µA, I SD < µa, DFN Package V IN :.3 V to 6V, V OUT(MAX) = 4V, I Q = 6µA, I SD < µa, DFN Package 6 LT REV B PRINTED IN USA Linear Technology Corporation 63 McCarthy Blvd., Milpitas, CA (4) 43-9 FAX: (4) LINEAR TECHNOLOGY CORPORATION 4fb