LTC3499B

LTC3499/LTC3499B 750mA Synchronous Step-Up DC/DC Converters with Reverse-Battery Protection FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Reverse-Battery Protection for DC/DC Converter and Load High Efficiency: Up to 94% Generates 5V at 175mA from a 1.8V Input Operates from 1.8V to 5.5V Input Supply 2V to 6V Adjustable Output Voltage Inrush Current Controlled During Start-Up Output Disconnnect in Shutdown Low Noise 1.2MHz PWM Operation Tiny External Components Automatic Burst Mode® Operation (LTC3499) Continuous Switching at Light Loads (LTC3499B) Overvoltage Protection 8-Lead (3mm × 3mm × 0.75mm) DFN and MSOP Packages The LTC®3499/LTC3499B are synchronous, fixed frequency step-up DC/DC power converters with integrated reverse battery protection that protect and disconnect the devices and load when the battery polarity is reversed while delivering high efficiency in a small (3mm × 3mm) DFN package. True output disconnect eliminates inrush current and allows zero load current in shutdown. The devices feature an input voltage range of 1.8V to 5.5V enabling operation from two alkaline or NiMH batteries. The switching frequency is internally set at 1.2MHz allowing the use of tiny surface mount inductors and capacitors. A minimal number of external components are required to generate output voltages ranging from 2V to 6V. The LTC3499 features automatic Burst Mode operation to increase efficiency at light loads, while the LTC3499B features continuous switching at light loads. The soft-start time is externally programmable through a small capacitor. Anti-ring circuitry reduces EMI emissions by damping the inductor in discontinuous mode. The devices feature VOUT 700 VIN > VOUT INPUT CURRENT (µA) Burst Mode QUIESCENT CURRENT (µA) OUTPUT CURRENT (mA) 600 500 400 300 VOUT = 5V 200 100 0 1.5 2.5 3.5 VIN (V) 3499 G06 VOUT = 3.3V 4.5 4 UW 1 3499 G01 TA = 25°C unless noted. 2-Cell to 5V Efficiency vs Load Current (LTC3499B Only) 100000 10000 Li-Ion to 5V Efficiency vs Load Current (LTC3499 Only) 100000 10000 POWER LOSS (mW) 100 90 EFFICIENCY 80 70 POWER LOSS 60 50 40 30 0.1 VIN = 4.2V VIN = 3.6V VIN = 3V 1 100 LOAD CURRENT (mA) 10 10 1 100 100 90 80 70 60 50 40 30 20 10 0 0.1 1 VIN = 3.2V VIN = 2.4V VIN = 1.8V 10 100 LOAD CURRENT (mA) 1000 3499 G17 POWER LOSS (mW) 1000 100 10 1000 0.1 1000 0.1 1000 3499 G03 2-Cell to 3.3V Efficiency vs Load Current (LTC3499 Only) 100000 10000 EFFICIENCY POWER LOSS (mW) Burst Mode Output Current Threshold vs Input Voltage (LTC3499 Only) 60 VOUT = 5V 50 40 30 20 10 0 80 70 60 POWER LOSS 50 40 0.1 1 VIN = 3V VIN = 2.4V VIN = 1.8V 10 100 LOAD CURRENT (mA) 1000 100 10 1 0.1 1000 1.8 2.3 2.8 3.3 3.8 INPUT VOLTAGE (V) 4.3 4.8 3499 G05 3499 G02 No Load Input Current vs VIN (LTC3499 Only) 200 180 160 140 120 100 80 60 40 20 0 VOUT = 3.3V VOUT = 5V Burst Mode Quiescent Current vs Temperature (LTC3499 Only) 30 25 20 15 10 5 0 –50 5.5 1.5 2.5 3.5 VIN (V) 4.5 5.5 3499 G07 –25 0 25 50 TEMPERATURE (°C) 75 100 3499 G08 3499f LTC3499/LTC3499B TYPICAL PERFOR A CE CHARACTERISTICS FB Voltage vs Temperature 1.2225 OSCILLATOR FREQUENCY (MHz) REVERSE-BATTERY CURRENT (µA) 1.2220 1.2215 FB VOLTAGE (V) 1.2210 1.2205 1.2200 1.2195 1.2190 1.2185 –50 –25 50 25 TEMPERATURE (°C) 0 75 100 3499 G09 Burst Mode Operation (LTC3499 Only) VOUT 50mV/DIV IL 50mA/DIV 20µs/DIV VIN = 2.4V VOUT = 5V L = 4.7µH COUT = 10µF CFF = 10pF (FEEDFORWARD CAPACITOR FROM VOUT TO FB) 3499 G12 Soft-Start into 25Ω Load VIN 2V/DIV SS 2V/DIV VOUT 2V/DIV IL 200mA/DIV VIN = 2.4V VOUT = 5V L = 4.7µH CSS = 0.01µF COUT = 10µF 1ms/DIV 34991G15 UW TA = 25°C unless noted. VIN and SW Reverse-Battery Current vs VIN and SW Voltage 1.0 SHDN = 0V VOUT = 0V 0.5 Oscillator Frequency vs Temperature 1.4 1.3 1.2 0 1.1 –0.5 1.0 –50 –1.0 –25 0 25 50 TEMPERATURE (°C) 75 100 3499 G08 –6 –4 –2 0 2 4 VIN AND SW VOLTAGE (V) 6 3499 G11 Load Transient 50mA to 200mA Fixed Frequency Discontinous Mode Operation VOUT 200mV/DIV 200mA 50mA VIN = 2.4V 200µs/DIV VOUT = 5V ILOAD = 50mA to 200mA RZ = 100k CF = 680pF COUT = 10µF L = 4.7µH 3499 G13 SW 2V/DIV ILOAD 100mA/DIV IL 100mA/DIV VIN = 2.4V VOUT = 5V L = 4.7µH 200ns/DIV 3499 G14 Fixed Frequency Operation SW 2V/DIV IL 100mA/DIV VIN = 2.4V VOUT = 5V L = 4.7µH 200ns/DIV 3499 G16 3499f 5 LTC3499/LTC3499B PI FU CTIO S SHDN (Pin 1): Shutdown Input for IC. Connect to a voltage greater than 1.2V to enable and a voltage less than 0.2V to disable the LTC3499/LTC3499B. VIN (Pin 2): Input Supply Voltage. The valid operating voltage is between 1.8V to 5.5V. VIN has reverse battery protection. Since the LTC3499/LTC3499B use VIN as the main bias source, bypass with a low ESR ceramic capacitor of at least 2.2µF. SW (Pin 3): Switch Pin. Connect an inductor from VIN to this pin with a value between 2.2µH and 10µH. Keep PCB trace lengths as short and wide as possible to minimize EMI and voltage overshoot. If the inductor current falls to zero or SHDN is low an internal 250Ω antiringing switch is connected from VIN to SW to minimize EMI. GND (Pin 4): Signal and Power Ground for the IC. SS (Pin 5): Soft-Start Input. Connect a capacitor from SS to ground to control the inrush current at start-up. An internal 3µA current source charges this pin. SS will be discharged if SHDN is pulled low, thermal shutdown occurs or VIN is below the minimum operating voltage. VOUT (Pin 6): Power Supply Output. Connect a low ESR output filter capacitor from this pin to the ground plane. FB (Pin 7): FB Input to Error Amplifier. Connect a resistor divider tap from VOUT to this pin to set the output voltage. The output voltage can be adjusted between 2V and 6V. Referring to the Functional Block Diagram, the output voltage is given by: ⎡ ⎛ R1 ⎞ ⎤ VOUT = 1.22 • ⎢1+ ⎜ ⎟ ⎥ ⎣ ⎝ R2 ⎠ ⎦ 6 U U U VC (Pin 8): Error Amplifier Output. A frequency compensation network is connected from this pin to GND to compensate the boost converter loop. See Closing the Feedthrough Loop section for guidelines. Exposed Pad—DD Only (Pin 9): Ground. Must be soldered to the PCB power ground plane for electrical connection and rated thermal performance. 3499f LTC3499/LTC3499B FU CTIO AL BLOCK DIAGRA VIN 1.8V TO 5.5V + CIN L 2 3 REVERSE-BATTERY COMPARATOR ANTI-RING 250Ω 1 = CLOSED VIN + 1 = CLOSED 0.7V – VSELECT OV COMPARATOR VOUT + + VOUT 6 CFF (OPTIONAL) 7 R2 R1 + 1 = OFF ERROR AMPLIFIER 6.8V – ENABLE PWM LOGIC AND DRIVERS THERMAL SD SLEEP IZERO 1.2MHz OSCILLATOR SLOPE COMPENSATION Σ + PWM COMPARATOR – ENABLE TSD + SLEEP CURRENT LIMIT COMPARATOR 1 Burst Mode CONTROL (LTC3499 ONLY) – 0.8V + – SHDN 1A TYP REFERENCE BIAS UVLO SD ENABLE GND 4 Figure 1. Functional Block Diagram – W SW U U – + – 1.22V FB COUT – + VC 8 CC1 RZ CC2 3µA SS 5k 5 CSS 34991 F01 3499f 7 LTC3499/LTC3499B OPERATIO U In the event of a commanded shutdown or thermal shutdown (TSD), CSS is discharged through a nominal 5kΩ impedance to GND. Once the condition is removed and SS is discharged near ground, a soft-start will automatically be re-initiated. Error Amplifier A transconductance amplifier generates an error voltage from the difference between the positive input internally connected to the 1.22V reference and the negative input connected to FB. A simple compensation network is placed from VC to ground. Internal clamps limit the minimum and maximum error amplifier output voltage for improved large signal transient response. A voltage divider from VOUT to GND programs the output voltage via FB from 2V to 6V and is defined by the following equation: ⎡ ⎛ R1 ⎞ ⎤ VOUT = 1.22 • ⎢1+ ⎜ ⎟ ⎥ ⎣ ⎝ R2 ⎠ ⎦ The LTC3499/LTC3499B provide high efficiency, low noise power for boost applications with output voltages up to 6V. Operation can be best understood by referring to the Functional Block Diagram in Figure 1. The synchronous boost converters are housed in either an 8-lead (3mm × 3mm) DFN or MSOP package and operates at a fixed 1.2MHz. With a 1.6V typical minimum VIN voltage these devices are well suited for applications using two or three alkaline or nickel-metal hydride (NiMH) cells or one Lithium-Ion (Li+) cell. The LTC3499/LTC3499B have integrated circuitry which protects the battery, IC, and circuitry powered by the device in the event that the input batteries are connected backwards (reverse battery protection). The true output disconnect feature eliminates inrush current and allows VOUT to be zero volts during shutdown. The current mode architecture simplifies loop compensation with excellent load transient response. The low RDS(ON), low gate charge synchronous switches eliminate the need for an external Schottky diode rectifier, and provide efficient high frequency pulse width modulation (PWM). Burst Mode quiescent current to the LTC3499 is only 20µA from VIN, maximizing battery life. The LTC3499B does not have Burst Mode operation and the device continues switching at constant frequency. This results in the absence of low frequency output ripple at the expense of light load efficiency. LOW NOISE FIXED FREQUENCY OPERATION Shutdown The LTC3499/LTC3499B are shut down by pulling SHDN below 0.2V, and activated by pulling the pin above 1.2V. SHDN can be driven above VIN or VOUT as long as it is limited to less than the absolute maximum rating. Soft-Start The soft-start time is programmed with an external capacitor to ground on SS. An internal current source charges the capacitor, CSS, with a nominal 3µA. The voltage on SS is used to clamp the voltage on VC. The soft-start time is given by t(msec) = CSS (µF) • 200 Current Sensing Lossless current sensing converts the peak current signal into a voltage which is summed with the internal slope compensation. This summed signal is compared to the error amplifier output to provide a peak current control command for the PWM. Peak switch current is limited to 750mA minimum. Antiringing Control The antiringing control connects a resistor across the inductor to damp the ringing on SW in discontinuous conduction mode. The LC resonant ringing (L = inductor, CSW = capacitance on SW) is low energy, but can cause EMI radiation if antiringing control is not present. Zero Current Comparator The zero current comparator monitors the inductor current to the output and shuts off the synchronous rectifier once this current reduces to approximately 40mA, preventing negative inductor current. 3499f 8 LTC3499/LTC3499B OPERATIO U sleep if the output load remains less than the sleep threshold. The frequency of this intermittent PWM (or burst) operation is proportional to load current. Therefore, as the load current drops further below the burst threshold, the LTC3499 operates in PWM mode less frequently. When the load current increases above the burst threshold, the LC3499 will resume continuous PWM operation seamlessly. Referring to the Functional Block Diagram, an optional capacitor, CFF, between VOUT and FB in some circumstances can reduce peak-to-peak VOUT ripple and input quiescent current during Burst Mode operation. Typical values for CFF range from 10pF to 220pF. Output Disconnect and Inrush Current Limiting The LTC3499/LTC3499B are designed to allow true output disconnect by eliminating body diode conduction of the internal P-channel MOSFET transistor. This allows VOUT to go to zero volts during shutdown without drawing any current from the input source. It also provides for inrush current limiting at turn-on, minimizing surge current seen by the input supply. VIN > VOUT Operation The LTC3499/LTC3499B will maintain voltage regulation when the input voltage is above the output voltage. This is achieved by terminating the switching on the synchronous P-channel MOSFET and applying VIN statically on the gate. This will ensure the volts • seconds of the inductor will reverse during the time current is flowing to the output. Since this mode will dissipate more power in the IC, the maximum output current is limited in order to maintain an acceptable junction temperature: Reverse-Battery Protection Plugging the battery in backwards poses a severe problem to most power converters. At a minimum the battery will be quickly discharged. Almost all ICs have an inherent diode from VIN (cathode) to ground (anode) which conducts appreciable current when VIN drops more than 0.7V below ground. Under this condition the integrated circuit will most likely be damaged due to the excessive current draw. There exists the possibility for the battery and circuitry powered by the device to also be damaged. The LTC3499/LTC3499B have integrated circuitry which allows negligible current flow under a reverse-battery condition, protecting the battery, device and circuitry attached to the output. A graph of the reverse-battery current drawn is shown in the Typical Performance Characteristics. Discrete methods of reverse battery protection put additional dissipative elements in the high current path reducing efficiency while increasing component count to implement protection. The LTC3499/LTC3499B do not suffer from either of these drawbacks. Burst Mode Operation (LTC3499 only) Portable devices frequently spend extended time in low power or stand-by mode, only drawing high power when specific functions are enabled. In order to improve battery life in these types of products, high power converter efficiency needs to be maintained over a wide output power range. In addition to its high efficiency at moderate and heavy loads, the LTC3499 includes automatic Burst Mode operation that improves efficiency of the power converter at light loads. Burst Mode operation is initiated if the output load current falls below an internally programmed threshold (see Typical Performance graph, Output Load Burst Mode Threshold vs VIN). Once initiated the Burst Mode operation circuitry shuts down most of the circuitry in the LTC3499, only keeping alive the circuitry required to monitor the output voltage. This state is referred to as sleep. In sleep, the LTC3499 only draws 20µA from the input supply, greatly enhancing efficiency. When the output has drooped approximately 1% from its nominal regulation point, the LTC3499 wakes up and commences normal PWM operation. The output capacitor will recharge causing the LTC3499 to re-enter IOUT(MAX ) ≅ θJA 125 – TA • (( VIN + 1.5) – VOUT ) where TA = ambient temperature and θJA is the package thermal resistance (45°C/W for the DD8 and 160°C/W for the MS8). For example at VIN = 4.5V, VOUT = 3.3V and TA = 85°C in the DD8 package, the maximum output current is 330mA. 3499f 9 LTC3499/LTC3499B APPLICATIO S I FOR ATIO PCB LAYOUT GUIDELINES The high speed operation of the LTC3499/LTC3499B demand careful attention to board layout. Advertised performance will not be achieved with careless layout. Figure 2 shows the recommended component placement. A large copper area will help to lower the chip temperature. Traces carrying high current (SW, VOUT, GND) are kept short. The lead length to the battery should be kept as short as possible. The VIN and VOUT ceramic capacitors should be placed as close to the IC pins as possible. CC2 EXPOSED PAD FOR DD8 CC1 SHDN 1 8 VC RZ VIN 2 9 3 7 FB R1 + VBATT CIN L SW 6 VOUT GND 4 5 SS CSS Figure 2: Recommended Component Placement COMPONENT SELECTION Inductor Selection The LTC3499/LTC3499B allow the use of small surface mount inductors and chip inductors due to the fast 1.2MHz switching frequency. A minimum inductance value of 2.2µH is required. Larger values of inductance will allow greater output current capability by reducing the inductor ripple current. Increasing the inductance above 10µH will increase total solution area while providing minimal improvement in output current capability. The inductor current ripple is typically set to 20% to 40% of the maximum inductor current. For high efficiency, choose an inductor with high frequency core material, 10 U such as ferrite, to reduce core losses. The inductor should have low ESR (equivalent series resistance) to reduce the I2R power losses, and must be able to handle the peak inductor current without saturating. To minimize radiated noise, use a toroidal or shielded inductor. See Table 1 for some suggested inductor suppliers. Table 1. Inductor Vendor Information PART NUMBER MSS5131 and MOS6020 Series SLF7028 and SLF7045 Series LQH55D Series CDRH4D28 and CDRH4D28 Series D53LC and D62CB Series DT0703 Series MJPF2520 Series SUPPLIER Coilcraft TDK Murata Sumida Toko CoEV FDK WEB SITE www.coilcraft.com www.component.tdk.com www.murata.com www.sumida.com www.tokoam.com www.coev.net www.fdk.com R2 COUT W U U Output Capacitor Selection The output voltage ripple has three components to it. The bulk value of the capacitor is set to reduce the ripple due to charge into the capacitor each cycle. The maximum ripple voltage due to charge is given by: 34991 F02 VRBULK = IP • (COUT • VOUT • f) VIN where IP = peak inductor current and f = switching frequency. The ESR (equivalent series resistance) is usually the most dominant factor for ripple in most power converters. The ripple due to capacitor ESR is simply given by: VRCESR = IP • CESR where CESR = capacitor equivalent series resistance The ESL (equivalent series inductance) is also an important factor for high frequency converters. Using small surface mount ceramic capacitors, placed as close as possible to VOUT, will minimize ESL. 3499f LTC3499/LTC3499B APPLICATIO S I FOR ATIO U Closing the Feedback Loop The LTC3499/LTC3499B utilize current mode control, with internal slope compensation. Current mode control eliminates the 2nd order filter due to the inductor and output capacitor exhibited in voltage mode controllers, thus simplifying it to a single pole filter response. The product of the modulator control to output DC gain and the error amp open loop gain gives the DC gain of the system: Low ESR capacitors should be used to minimize output voltage ripple. A 4.7µF to 10µF output capacitor is sufficient for most applications and should be placed as close to VOUT as possible. Larger values may be used to obtain even lower output ripple and improve transient response. X5R and X7R dielectric materials are preferred for their ability to maintain capacitance over wide voltage and temperature ranges. Input Capacitor Selection The input filter capacitor reduces peak currents drawn from the input source and reduces input switching noise. Ceramic capacitors are a good choice for input decoupling due to their low ESR and ability to withstand reverse voltage (i.e. non-polar nature). The capacitor should be located as close as possible to the device. In most applications a 2.2µF input capacitor is sufficient. Larger values may be used without limitations. Table 2 shows a list of several ceramic capacitor manufacturers. Table 2. Capacitor Vendor Information SUPPLIER AVX Murata TDK Taiyo Yuden WEB SITE www.avxcorp.com www.murata.com www.component.tdk.com www.t-yuden.com Thermal Considerations For the LTC3499/LTC3499B to deliver full output power, it is imperative that a good thermal path be provided to dissipate the heat generated within the package. For the DFN package, this can be accomplished by taking advantage of the large thermal pad on the underside of the device. It is recommended that multiple vias in the printed circuit board be used to conduct heat away from the part and into a copper plane with as much area as possible. If the junction temperature continues to rise, the part will go into thermal shutdown where switching will stop until the temperature drops. W U U GDC = GCONTROL • GEA • GCONTROL = 2 • VIN IOUT , VREF VOUT • GCURRENT _ SENSE GEA ~ 1000, GCURRENT _ SENSE = 1 RDS(ON) The output filter pole is given by: fFILTER _ POLE = (π • VOUT • COUT ) 1 IOUT where COUT is the output filter capacitor. The output filter zero is given by: fFILTER _ ZERO = (2 • π • RESR • COUT ) where RESR is the capacitor equivalent series resistance. A troublesome feature of the boost regulator topology is the right half plane (RHP) zero, given by: fRPHZ = VIN2 (2 • π • IOUT • VOUT • L ) 3499f 11 LTC3499/LTC3499B APPLICATIO S I FOR ATIO There is a resultant gain increase with a phase lag which makes it difficult to compensate the loop. At heavy loads the right half plane zero can occur at a relatively low frequency. The loop gain is typically rolled off before the RHP zero frequency. The typical error amp compensation is shown in Figure 3, following the equations for the loop dynamics: fPOLE1 ~ ( 1 2 • π • 10e6 • CC1 ) which is extremely close to DC. fZERO1 = fPOLE2 = (2 • π • RZ • CC1) (2 • π • RZ • CC2 ) 1 1 12 U VOUT 6 ERROR AMPLIFIER W U U + – 1.22V FB 7 R1 R2 VC 8 RZ CC1 3499 F03 CC2 Figure 3: Typical Error Amplifier Compensation 3499f LTC3499/LTC3499B TYPICAL APPLICATIO S Lithium-Ion to 5V, 350mA L 4.7µH VIN Li-Ion 3.1V TO 4.2V 100 90 + LTC3499 SHDN VC VOUT 1M FB SS 0.01µF GND 324k VOUT 5V 350mA COUT 10µF X5R EFFICIENCY (%) CIN 2.2µF X5R VIN ON OFF 100k 330pF CIN: TAIYO YUDEN X5R JMK212BJ225MD COUT: TAIYO YUDEN X5R JMK212BJ106MD L: COILCRAFT MSS5131-472MLB Two Cells to 5V, 175mA L 4.7µH VIN 2 AA CELLS 1.8V TO 3.2V + LTC3499 SHDN VC VOUT 1M FB SS 0.01µF GND 324k VOUT 5V 175mA COUT 10µF X5R EFFICIENCY (%) CIN 2.2µF X5R VIN ON OFF 100k 330pF CIN: TAIYO YUDEN X5R JMK212BJ225MD COUT: TAIYO YUDEN X5R JMK212BJ106MD L: COILCRAFT MSS5131-472MLB U Lithium-Ion to 5V Efficiency 100000 10000 EFFICIENCY 80 70 POWER LOSS 60 50 40 30 0.1 3499 F04a SW POWER LOSS (mW) 1000 100 10 VIN = 4.2V VIN = 3.6V VIN = 3V 1 100 LOAD CURRENT (mA) 10 1 0.1 1000 3499 G03 Two Cells to 5V Efficiency 100 90 100000 10000 EFFICIENCY 80 70 60 50 40 0.1 3499 F05a SW POWER LOSS (mW) 1000 100 POWER LOSS 10 1 VIN = 3.2V VIN = 2.4V VIN = 1.8V 1 10 100 LOAD CURRENT (mA) 0.1 1000 3499 G01 3499f 13 LTC3499/LTC3499B PACKAGE DESCRIPTIO U DD Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.675 ± 0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ± 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 5 0.38 ± 0.10 8 3.00 ± 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) (DD8) DFN 1203 3.5 ± 0.05 1.65 ± 0.05 2.15 ± 0.05 (2 SIDES) 1.65 ± 0.10 (2 SIDES) 0.200 REF 0.75 ± 0.05 4 0.25 ± 0.05 2.38 ± 0.10 (2 SIDES) 1 0.50 BSC 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1) 2. 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 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON TOP AND BOTTOM OF PACKAGE 3499f 14 LTC3499/LTC3499B PACKAGE DESCRIPTIO 5.23 (.206) MIN 0.42 ± 0.038 (.0165 ± .0015) TYP RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 0° – 6° TYP 4.90 ± 0.152 (.193 ± .006) 0.254 (.010) GAUGE PLANE 0.18 (.007) SEATING PLANE 0.22 – 0.38 (.009 – .015) TYP 0.127 ± 0.076 (.005 ± .003) MSOP (MS8) 0204 0.65 (.0256) NOTE: BSC 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 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 MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660) 0.889 ± 0.127 (.035 ± .005) 3.20 – 3.45 (.126 – .136) 0.65 (.0256) BSC 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 8 7 65 0.52 (.0205) REF 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 1 23 4 1.10 (.043) MAX 0.86 (.034) REF 3499f 15 LTC3499/LTC3499B TYPICAL APPLICATIO Two Cells to 3.3V, 250mA L 4.7µH VIN 2 AA CELLS 1.8V TO 3.2V 100 90 VIN LTC3499 SHDN VC 100k 330pF FB SS 0.01µF CIN: TAIYO YUDEN X5R JMK212BJ225MD COUT: TAIYO YUDEN X5R JMK212BJ106MD L: COILCRAFT MSS5131-472MB GND 332k VOUT 1M VOUT 3.3V 250mA COUT 10µF X5R SW EFFICIENCY (%) + CIN 2.2µF X5R ON OFF RELATED PARTS PART NUMBER LT1930/LT1930A LT1961 LTC3400/LTC3400B LTC3401 LTC3402 LTC3421 LTC3422 LTC3425 LTC3427 LTC3429/LTC3429B LTC3458/LTC3458L LTC3525 DESCRIPTION 1A (ISW), 1.2MHz/2.2MHz, High Efficiency Step-Up DC/DC Converter 1.5A (ISW), 1.25MHz, High Efficiency Step-Up DC/DC Converter 600mA (ISW), 1.2MHz, Synchronous Step-Up DC/DC Converter 1A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter 2A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter 3A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter with Output Disconnect 1.5A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter with Output Disconnect 5A (ISW), 8MHz, 4-Phase Synchronous Step-Up DC/DC Converter with Output Disconnect 500mA (ISW), 1.25MHz, Synchronous Step-Up DC/DC Converter with Soft-Start/Output Disconnect 600mA (ISW), 550kHz, Synchronous Step-Up DC/DC Converters with Soft-Start/Output Disconnect 1.4A/1.7A (ISW), 1.5MHz, Synchronous Step-Up DC/DC Converter with Soft-Start/Output Disconnect 400mA (ISW), Synchronous Step-Up DC/DC Converter in SC70 COMMENTS High Efficiency, VIN: 2.6V to 16V, VOUT(MAX) = 34V, IQ = 4.2mA/5.5mA, ISD < 1µA, ThinSOT Package 90% Efficiency, VIN: 3V to 25V, VOUT(MAX) = 35V, IQ = 0.9mA, ISD < 6µA, MS8E Package 92% Efficiency, VIN: 0.5V to 5V, VOUT(MAX) = 5V, IQ = 19µA/300µA, ISD < 1µA, ThinSOT Package 97% Efficiency, VIN: 0.5V to 5V, VOUT(MAX) = 5.5V, IQ = 38µA, ISD < 1µA, 10-Lead MS Package 97% Efficiency, VIN: 0.5V to 5V, VOUT(MAX) = 5.5V, IQ = 38µA, ISD < 1µA, 10-Lead MS Package 95% Efficiency, VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 12µA, ISD < 1µA, 24-Lead QFN Package 95% Efficiency, VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 25µA, ISD < 1µA 95% Efficiency, VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 12µA, ISD < 1µA, 32-Lead QFN Package 94% Efficiency, VIN: 1.8V to 5V, VOUT(MAX) = 5.25V, ISD < 1µA, DFN Package 92% Efficiency, VIN: 0.5V to 4.3V, VOUT(MAX) = 5V, IQ = 20µA, ISD < 1µA, ThinSOT Package 93% Efficiency, VIN: 1.5V to 6V, VOUT(MAX) = 7.5V/6V, IQ = 15µA, ISD < 1µA, DFN Package 94% Efficiency, VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 7µA, ISD < 1µA, Output Disconnect 16 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● U Two Cells to 3.3V Efficiency 100000 10000 EFFICIENCY POWER LOSS (mW) 80 70 60 POWER LOSS 50 40 0.1 1 VIN = 3V VIN = 2.4V VIN = 1.8V 10 100 LOAD CURRENT (mA) 1000 100 10 1 0.1 1000 3499 F06a 3499 G02 3499f LT 0106 • PRINTED IN USA www.linear.com © LINEAR TECHNOLOGY CORPORATION 2006