LT1308B

Final Electrical Specifications LT1308A/LT1308B High Current, Micropower Single Cell, 600kHz DC/DC Converters FEATURES s s s s s s DESCRIPTION August 1999 s s s s s 5V at 1A from a Single Li-Ion Cell 5V at 800mA in SEPIC Mode from Four NiCd Cells Fixed Frequency Operation: 600kHz Boost Converter Outputs up to 34V Starts into Heavy Loads Automatic Burst ModeTM Operation at Light Load (LT1308A) Continuous Switching at Light Loads (LT1308B) Low VCESAT Switch: 300mV at 2A Pin-for-Pin Upgrade Compatible with LT1308 Lower Quiescent Current in Shutdown: 1µA (Max) Improved Accuracy Low-Battery Detector Reference: 200mV ± 2% The LT ®1308A/LT1308B are micropower, fixed frequency step-up DC/DC converters that operate over a 1V to 10V input voltage range. They are improved versions of the LT1308 and are recommended for use in new designs. The LT1308A features automatic shifting to power saving Burst Mode operation at light loads and consumes just 140µA at no load. The LT1308B features continuous switching at light loads and operates at a quiescent current of 2.5mA. Both devices consume less than 1µA in shutdown. Low-battery detector accuracy is significantly tighter than the LT1308. The 200mV reference is specified at ± 2% at room and ± 3% over temperature. The shutdown pin enables the device when it is tied to a 1V or higher source and does not need to be tied to VIN as on the LT1308. An internal VC clamp results in improved transient response and the switch voltage rating has been increased to 36V, enabling higher output voltage applications. The LT1308A/LT1308B are available in the 8-lead SO and 14-lead TSSOP packages. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. APPLICATIONS s s s s s s s GSM/CDMA Phones Digital Cameras LCD Bias Supplies Answer-Back Pagers GPS Receivers Battery Backup Supplies Handheld Computers TYPICAL APPLICATION L1 4.7µH D1 5V 1A SW LBO LT1308B SHDN VC 47k 100pF C1: AVX TAJC476M010 C2: AVX TPSD227M006 D1: IR 10BQ015 L1: MURATA LQH6N4R7 *R1: 169k FOR VOUT = 3.3V 887k FOR VOUT = 12V FB GND R2 100k R1* 309k 95 90 85 EFFICIENCY (%) Converter Efficiency V IN = 3.6V V IN = 4.2V + Li-Ion CELL VIN C1 47µF SHUTDOWN LBI + C2 220µF 80 75 70 65 60 55 V IN = 1.5V 1308A/B F01 50 1 10 100 LOAD CURRENT (mA) 1000 1308A/B F01a Figure 1. LT1308B Single Li-Ion Cell to 5V/1A DC/DC Converter 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 U U V IN = 2.5V 1 LT1308A/LT1308B ABSOLUTE AXI U RATI GS VIN, SHDN, LBO Voltage ......................................... 10V SW Voltage ............................................... – 0.4V to 36V FB Voltage ....................................................... VIN + 1V VC Voltage ................................................................ 2V LBI Voltage ................................................. – 0.1V to 1V Current into FB Pin .............................................. ±1mA PACKAGE/ORDER I FOR ATIO TOP VIEW VC FB SHDN GND GND GND GND 1 2 3 4 5 6 7 14 LBO 13 LBI 12 VIN 11 VIN 10 SW 9 8 SW SW ORDER PART NUMBER LT1308ACF LT1308BCF VC 1 FB 2 SHDN 3 GND 4 F PACKAGE 14-LEAD PLASTIC TSSOP (Note 6) TJMAX = 125°C, θJA = 80°C/W Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. Commercial Grade 0°C to 70°C. VIN = 1.1V, VSHDN = VIN, unless otherwise noted. SYMBOL PARAMETER IQ Quiescent Current CONDITIONS Not Switching, LT1308A Switching, LT1308B VSHDN = 0V (LT1308A/LT1308B) q VFB IB Feedback Voltage FB Pin Bias Current Reference Line Regulation Minimum Input Voltage (Note 3) 1.1V ≤ VIN ≤ 2V 2V ≤ VIN ≤ 10V ∆I = 5µA VIN = 1.2V Duty Cyle = 30% (Note 4) ISW = 2A (25°C, 0°C), VIN = 1.5V ISW = 2A (70°C), VIN = 1.5V VIN = 2.5V, Circuit of Figure 1 gm AV fOSC Error Amp Transconductance Error Amp Voltage Gain Switching Frequency Maximum Duty Cycle Switch Current Limit Switch VCESAT Burst Mode Operation Switch Current Limit (LT1308A) 2 U U W WW U W (Note 1) Operating Temperature Range Commercial ............................................ 0°C to 70°C Extended Commerial (Note 2) ........... – 40°C to 85°C Industrial ........................................... – 40°C to 85°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C TOP VIEW 8 7 6 5 LBO LBI VIN SW ORDER PART NUMBER LT1308ACS8 LT1308AIS8 LT1308BCS8 LT1308BIS8 S8 PART MARKING 1308A 1308AI 1308B 1308BI S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125°C, θJA = 80°C/W MIN TYP 140 2.5 0.01 MAX 240 4 1 1.24 80 0.4 0.2 1 UNITS µA mA µA V nA %/V %/V V µmhos V/V 1.20 1.22 27 0.03 0.01 0.92 60 100 q q q q 500 82 2 600 90 3 290 330 400 700 4.5 350 400 kHz % A mV mV mA LT1308A/LT1308B The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. Commercial Grade 0°C to 70°C. VIN = 1.1V, VSHDN = VIN, unless otherwise noted. SYMBOL PARAMETER Shutdown Pin Current CONDITIONS VSHDN = 1.1V VSHDN = 6V VSHDN = 0V q q q q ELECTRICAL CHARACTERISTICS MIN TYP 2 20 0.01 MAX 5 35 0.1 204 206 0.25 0.1 100 10 UNITS µA µA µA mV mV V µA nA V/V µA LBI Threshold Voltage LBO Output Low LBO Leakage Current LBI Input Bias Current (Note 5) Low-Battery Detector Gain Switch Leakage Current VSW = 5V q 196 194 200 200 0.1 0.01 33 3000 0.01 ISINK = 50µA VLBI = 250mV, VLBO = 5V VLBI = 150mV q q The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. Industrial Grade – 40°C to 85°C. VIN = 1.2V, VSHDN = VIN, unless otherwise noted. SYMBOL PARAMETER IQ Quiescent Current CONDITIONS Not Switching, LT1308A Switching, LT1308B VSHDN = 0V (LT1308A/LT1308B) (Note 3) 1.1V ≤ VIN ≤ 2V 2V ≤ VIN ≤ 10V ∆I = 5µA q q q q q q q q q MIN TYP 140 2.5 0.01 MAX 240 4 1 1.25 80 0.4 0.2 1 UNITS µA mA µA V nA %/V %/V V µmhos V/V VFB IB Feedback Voltage FB Pin Bias Current Reference Line Regulation Minimum Input Voltage 1.19 1.22 27 0.05 0.01 0.92 60 100 gm AV fOSC Error Amp Transconductance Error Amp Voltage Gain Switching Frequency Maximum Duty Cycle Switch Current Limit Switch VCESAT Burst Mode Operation Switch Current Limit (LT1308A) Shutdown Pin Current 500 82 2 600 90 3 290 330 400 750 4.5 350 400 kHz % A mV mV mA Duty Cyle = 30% (Note 4) ISW = 2A (25°C, – 40°C), VIN = 1.5V ISW = 2A (85°C), VIN = 1.5V VIN = 2.5V, Circuit of Figure 1 VSHDN = 1.1V VSHDN = 6V VSHDN = 0V q q 2 20 0.01 196 193 200 200 0.1 0.01 33 3000 5 35 0.1 204 207 0.25 0.1 100 10 µA µA µA mV mV V µA nA V/V µA LBI Threshold Voltage q LBO Output Low LBO Leakage Current LBI Input Bias Current (Note 5) Low-Battery Detector Gain Switch Leakage Current ISINK = 50µA VLBI = 250mV, VLBO = 5V VLBI = 150mV VSW = 5V q q q 0.01 3 LT1308A/LT1308B ELECTRICAL CHARACTERISTICS Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1308ACS8 and LT1308BCS8 are designed, characterized and expected to meet the industrial temperature limits, but are not tested at –40°C and 85°C. I grade devices are guaranteed. Note 3: Bias current flows into FB pin. Note 4: Switch current limit guaranteed by design and/or correlation to static tests. Duty cycle affects current limit due to ramp generator (see Block Diagram). Note 5: Bias current flows out of LBI pin. Note 6: Connect the four GND pins (Pins 4–7) together at the device. Similarly, connect the three SW pins (Pins 8–10) together and the two VIN pins (Pins 11, 12) together at the device. TYPICAL PERFORMANCE CHARACTERISTICS LT1308B 3.3V Output Efficiency 95 90 85 EFFICIENCY (%) V IN = 1.8V V IN = 2.5V EFFICIENCY (%) 75 70 65 60 55 50 1 V IN = 1.2V EFFICIENCY (%) 80 100 10 LOAD CURRENT (mA) LT1308B 12V Output Efficiency 90 85 80 V IN = 5V V IN = 3.3V SWITCH VCESAT (mV) EFFICIENCY (%) 75 70 65 60 55 50 1 10 100 LOAD CURRENT (mA) 1000 1308A/B G04 4 UW 1308A/B G01 LT1308A 3.3V Output Efficiency 95 90 85 80 75 70 65 60 55 50 1000 1 100 10 LOAD CURRENT (mA) 1000 1308A/B G02 LT1308A 5V Output Efficiency 95 90 V IN = 4.2V V IN = 3.6V V IN = 1.8V V IN = 2.5V 85 80 75 70 65 60 55 50 1 V IN = 1.2V V IN = 1.5V V IN = 2.5V 10 100 LOAD CURRENT (mA) 1000 1308A/B G03 LT1308A Transient Response Circuit of Figure 1 500 Switch Saturation Voltage vs Current VOUT 100mV/DIV AC COUPLED ILOAD 1A 0A VIN = 3.6V VOUT = 5V COUT = 220µF 100µs/DIV 1308 G05 400 85°C 300 25°C –40°C 200 100 0 0 1.0 0.5 1.5 SWITCH CURRENT (A) 2.0 1308 G06 LT1308A/LT1308B PIN FUNCTIONS VC (Pin 1): Compensation Pin for Error Amplifier. Connect a series RC from this pin to ground. Typical values are 47kΩ and 100pF. Minimize trace area at VC. FB (Pin 2): Feedback Pin. Reference voltage is 1.22V. Connect resistive divider tap here. Minimize trace area at FB. Set VOUT according to: VOUT = 1.22V(1 + R1/R2). SHDN (Pin 3): Shutdown. Ground this pin to turn off switcher. To enable, tie to 1V or more. SHDN does not need to be at VIN to enable the device. GND (Pin 4): Ground. Connect directly to local ground plane. Ground plane should enclose all components associated with the LT1308. PCB copper connected to Pin 4 also functions as a heat sink. Maximize this area to keep chip heating to a minimum. SW (Pin 5): Switch Pin. Connect inductor/diode here. Minimize trace area at this pin to keep EMI down. VIN (Pin 6): Supply Pin. Must have local bypass capacitor right at the pin, connected directly to ground. LBI (Pin 7): Low-Battery Detector Input. 200mV reference. Voltage on LBI must stay between –100mV and 1V. Low-battery detector does not function with SHDN pin grounded. If not used, float LBI pin. LBO (Pin 8): Low-Battery Detector Output. Open collector, can sink 50µA. A 1MΩ pull-up is recommended. LBO is high impedance when SHDN is grounded. BLOCK DIAGRAM VIN 6 R5 40k VOUT R1 (EXTERNAL) FB R2 (EXTERNAL) FB 2 R4 140k RAMP GENERATOR 600kHz OSCILLATOR *HYSTERESIS IN LT1308A ONLY Figure 2. LT1308A/LT1308B Block Diagram + + Σ + – W U U U VIN Q4 2VBE SHDN VIN R6 40k + gm VC 1 LBI ERROR AMPLIFIER BIAS SHUTDOWN 3 – Q1 Q2 ×10 R3 30k + * ENABLE 200mV 7 + – A4 LBO 8 – A1 COMPARATOR SW FF R Q S DRIVER 5 Q3 A2 + A=3 0.03Ω – 4 GND 1308 BD 5 LT1308A/LT1308B APPLICATIONS INFORMATION OPERATION The LT1308A combines a current mode, fixed frequency PWM architecture with Burst Mode micropower operation to maintain high efficiency at light loads. Operation can be best understood by referring to the block diagram in Figure 2. Q1 and Q2 form a bandgap reference core whose loop is closed around the output of the converter. When VIN is 1V, the feedback voltage of 1.22V, along with an 80mV drop across R5 and R6, forward biases Q1 and Q2’s base collector junctions to 300mV. Because this is not enough to saturate either transistor, FB can be at a higher voltage than VIN. When there is no load, FB rises slightly above 1.22V, causing VC (the error amplifier’s output) to decrease. When VC reaches the bias voltage on hysteretic comparator A1, A1’s output goes low, turning off all circuitry except the input stage, error amplifier and lowbattery detector. Total current consumption in this state is 120µA. As output loading causes the FB voltage to decrease, A1’s output goes high, enabling the rest of the IC. Switch current is limited to approximately 400mA initially after A1’s output goes high. If the load is light, the output voltage (and FB voltage) will increase until A1’s output goes low, turning off the rest of the LT1308A. Low frequency ripple voltage appears at the output. The ripple frequency is dependent on load current and output capacitance. This Burst Mode operation keeps the output regulated and reduces average current into the IC, resulting in high efficiency even at load currents of 1mA or less. If the output load increases sufficiently, A1’s output remains high, resulting in continuous operation. When the LT1308A is running continuously, peak switch current is controlled by VC to regulate the output voltage. The switch is turned on at the beginning of each switch cycle. When the summation of a signal representing switch current and a ramp generator (introduced to avoid subharmonic oscillations at duty factors greater than 50%) exceeds the VC signal, comparator A2 changes state, resetting the flip-flop and turning off the switch. Output voltage increases as switch current is increased. The output, attenuated by a resistor divider, appears at the FB pin, closing the overall loop. Frequency compensation is provided by an external series RC network connected between the VC pin and ground. Low-battery detector A4’s open-collector output (LBO) pulls low when the LBI pin voltage drops below 200mV. There is no hysteresis in A4, allowing it to be used as an amplifier in some applications. The entire device is disabled when the SHDN pin is brought low. To enable the converter, SHDN must be at 1V or greater. It need not be tied to VIN as on the LT1308. The LT1308B differs from the LT1308A in that there is no hysteresis in comparator A1. Also, the bias point on A1 is set lower than on the LT1308B so that switching can occur at inductor current less than 100mA. Because A1 has no hysteresis, there is no Burst Mode operation at light loads and the device continues switching at constant frequency. This results in the absence of low frequency output voltage ripple at the expense of efficiency. The difference between the two devices is clearly illustrated in Figure 3. The top two traces in Figure 3 shows an LT1308A/LT1308B circuit, using the components indicated in Figure 1, set to a 5V output. Input voltage is 3V. Load current is stepped from 50mA to 800mA for both circuits. Low frequency Burst Mode operation voltage ripple is observed on Trace A, while none is observed on Trace B. At light loads, the LT1308B will begin to skip alternate cycles. The load point at which this occurs can be decreased by increasing the inductor value. However, output ripple will continue to be significantly less than the LT1308A output ripple. Further, the LT1308B can be forced into micropower mode, where IQ falls from 3mA to 200µA by sinking 40µA or more out of the VC pin. This stops switching by causing A1’s output to go low. 6 U W U U TRACE A: LT1308A VOUT, 100mV/DIV AC COUPLED TRACE B: LT1308B VOUT, 100mV/DIV AC COUPLED 800mA ILOAD 50mA VIN = 3V 200µs/DIV (CIRCUIT OF FIGURE 1) 1308 F03 Figure 3. LT1308A Exhibits Burst Mode Operation Output Voltage Ripple at 50mA Load, LT1308B Does Not LT1308A/LT1308B APPLICATIONS INFORMATION LAYOUT HINTS The LT1308A/LT1308B switch current at high speed, mandating careful attention to layout for proper performance. You will not get advertised performance with careless layouts. Figure 4 shows recommended component placement for a boost (step-up) converter. Follow this closely in your PC layout. Note the direct path of the switching loops. Input capacitor C1 must be placed close (< 5mm) to the IC package. As little as 10mm of wire or PC trace from CIN to VIN will cause problems such as inability to regulate or oscillation. The negative terminal of output capacitor C2 should tie close to Pin 4 of the LT1308A/LT1308B. Doing this reduces dI/dt in the ground copper which keeps high frequency spikes to a minimum. The DC/DC converter ground should tie to the PC board ground plane at one place only, to avoid introducing dI/dt in the ground plane. A SEPIC (Single-Ended Primary Inductance Converter) schematic is shown in Figure 5. This converter topology produces a regulated output over an input voltage range that spans (i.e., can be higher or lower than) the output. Recommended component placement for a SEPIC is shown in Figure 6. COMPONENT SELECTION Inductors Suitable inductors for use with the LT1308A/LT1308B must fulfill two requirements. First, the inductor must be able to handle current of 2A steady-state, as well as support transient and start-up current over 3A without inductance decreasing by more than 50% to 60%. Second, the DCR of the inductor should have low DCR, under 0.05Ω so that copper loss is minimized. Acceptable inductance values range between 2µH and 20µH, with 4.7µH best for most applications. Lower value inductors are physically smaller than higher value inductors for the same current capability. Table 1 lists some inductors we have found to perform well in LT1308A/LT1308B application circuits. This is not an exclusive list. Table 1 VENDOR Murata Sumida Coiltronics PART NO. LQH6C4R7 CDRH734R7 CTX5-1 VALUE 4.7µH 4.7µH 5µH PHONE NO. 770-436-1300 847-956-0666 561-241-7876 U W U U Capacitors Equivalent Series Resistance (ESR) is the main issue regarding selection of capacitors, especially the output capacitors. The output capacitors specified for use with the LT1308A/ LT1308B circuits have low ESR and are specifically designed for power supply applications. Output voltage ripple of a boost converter is equal to ESR multiplied by switch current. The performance of the AVX TPSD227M006 220µF tantalum can be evaluated by referring to Figure 4. When the load is 800mA, the peak switch current is approximately 2A. Output voltage ripple is about 60mVPP, so the ESR of the output capacitor is 60mV/2A or 0.03Ω. Ripple can be further reduced by paralleling ceramic units. Table 2 lists some capacitors we have found to perform well in the LT1308A/LT1308B application circuits. This is not an exclusive list. Table 2 VENDOR AVX AVX Taiyo Yuden Taiyo Yuden SERIES TPS TPS X5R X5R PART NO. TPSD227M006 TPSD107M010 LMK432BJ226 TMK432BJ106 VALUE 220µF, 6V 22µF, 10V 10µF, 25V PHONE NO. 803-448-9411 100µF, 10V 803-448-9411 408-573-4150 408-573-4150 Diodes We have found Motorola MBRS130 and International Rectifier 10BQ015 to perform well. For applications where VOUT exceeds 30V, use 40V diodes such as MBRS140 or 10BQ040. 7 LT1308A/LT1308B APPLICATIONS INFORMATION GROUND PLANE LBI LBO L1A CTX10-2 C2 4.7µF CERAMIC C1 VIN 3V TO 10V D1 + VIN R1 R2 SHUTDOWN 1 2 3 4 LT1308A LT1308B 8 7 6 5 L1 MULTIPLE VIAs GND C2 + D1 VOUT Figure 4. Recommended Component Placement for Boost Converter. Note Direct High Current Paths Using Wide PC Traces. Minimize Trace Area at Pin 1 (VC) and Pin 2 (FB). Use Multiple Vias to Tie Pin 4 Copper to Ground Plane. Use Vias at One Location Only to Avoid Introducing Switching Currents into the Ground Plane GROUND PLANE C1 + R1 R2 SHUTDOWN 1 2 3 4 LT1308A LT1308B MULTIPLE VIAs GND C3 + Figure 6. Recommended Component Placement for SEPIC 8 U W U U + VIN C1 47µF SHUTDOWN LT1308B SHDN VC 47k 680pF SW L1B R1 309k FB GND R2 100k VOUT 5V 500mA + C3 220µF 6.3V C1: AVX TAJC476M016 C2: TAIYO YUDEN EMK325BJ475(X5R) C3: AVX TPSD227M006 D1: IR 10BQ015 L1: COILTRONICS CTX10-2 1308A/B F05 1308 F04 Figure 5. SEPIC (Single-Ended Primary Inductance Converter) Converts 3V to 10V Input to a 5V/500mA Regulated Output LBI LBO VIN 8 7 6 5 L1A L1B C2 D1 VOUT 1308 F06 LT1308A/LT1308B APPLICATIONS INFORMATION SHDN PIN The LT1308A/LT1308B SHDN pin is improved over the LT1308. The pin does not require tying to VIN to enable the device, but needs only a logic level signal. The voltage on the SHDN pin can vary from 1V to 10V independent of VIN. Further, floating this pin has the same effect as grounding, which is to shut the device down, reducing current drain to 1µA or less. LOW-BATTERY DETECTOR The low-battery detector on the LT1308A/LT1308B features improved accuracy and drive capability compared to the LT1308. The 200mV reference has an accuracy of ± 2% and the open-collector output can sink 50µA. The LT1308A/ LT1308B low-battery detector is a simple PNP input gain stage with an open-collector NPN output. The negative input of the gain stage is tied internally to a 200mV reference. The positive input is the LBI pin. Arrangement as a low-battery detector is straightforward. Figure 7 details hookup. R1 and R2 need only be low enough in value so that the bias current of the LBI pin doesn’t cause large errors. For R2, 100k is adequate. The 200mV reference can also be accessed as shown in Figure 8. A cross plot of the low-battery detector is shown in Figure 9. The LBI pin is swept with an input which varies from 195mV to 205mV, and LBO with a 100k pull-up resistor, is displayed. START-UP The LT1308A/LT1308B can start up into heavy loads, unlike many CMOS DC/DC converters that derive operating voltage from the output (a technique known as “bootstrapping”). Figure 10 details start-up waveforms of Figure 1’s circuit with a 20Ω load and VIN of 1.5V. Inductor current rises to 3.5A as the output capacitor is charged. After the output reaches 5V, inductor current is about 1A. In Figure 11, the load is 5Ω and input voltage is 3V. Output voltage reaches 5V 500µs after the device is enabled. Figure 12 shows start-up behavior of Figure 5’s SEPIC circuit, driven from a 9V input with a 10Ω load. The output reaches 5V in about 1ms after the device is enabled. GSM AND CDMA PHONES The LT1308A/LT1308B are suitable for converting a single Li-Ion cell to 5V for powering RF power stages in GSM or CDMA phones. Improvements in the LT1308A/LT1308B error amplifiers allow external compensation values to be reduced, resulting in faster transient response compared to the LT1308. The circuit of Figure 13 (same as Figure 1, printed again for convenience) provides a 5V, 1A output from a Li-Ion cell. Figure 14 details transient response at the LT1308A operating at a VIN of 4.2V, 3.6V and 3V. Ripple voltage in Burst Mode operation can be seen at 10mA load. Figure 15 shows transient response of the LT1308B under the same conditions. Note the lack of Burst Mode ripple at 10mA load. 5V R1 LBI R2 100k VIN LT1308A LT1308B LBO + – 200mV INTERNAL REFERENCE GND 100k 200k TO PROCESSOR VBAT VREF 200mV R1 = VLB – 200mV 2µA 10k 2N3906 LBO VIN LT1308A LT1308B GND 1308 F08 VBAT 1308 F07 Figure 7. Setting Low-Battery Detector Trip Point U W U U + LBI 10µF Figure 8. Accessing 200mV Reference 9 LT1308A/LT1308B APPLICATIONS INFORMATION VOUT 1V/DIV VLBO 1V/DIV 195 200 VLBI (mV) 205 1308 F09 Figure 9. Low-Battery Detector Input/Output Characteristic VOUT 2V/DIV IL1 1A/DIV VSHDN 5V/DIV 1ms/DIV 1308 F10 Figure 10. 5V Boost Converter of Figure 1. Start-Up from 1.5V Input into 20Ω Load + Li-Ion CELL C1 47µF SHUTDOWN C1: AVX TAJC476M010 C2: AVX TPSD227M006 Figure 13. Li-Ion to 5V Boost Converter Delivers 1A 10 U W U U IL1 2A/DIV VSHDN 5V/DIV 500µs/DIV 1308 F11 Figure 11. 5V Boost Converter of Figure 1. Start-Up from 3V Input into 5Ω Load VOUT 2V/DIV ISW 2A/DIV VSHDN 5V/DIV 500µs/DIV 1308 F12 Figure 12. 5V SEPIC Start-Up from 9V Input into 10Ω Load L1 4.7µH D1 5V 1A SW LBO R1 309k VIN LBI LT1308B SHDN VC 47k 100pF FB GND R2 100k + C2 220µF D1: IR 10BQ015 L1: MURATA LQH6N4R7 1308A/B F13 LT1308A/LT1308B APPLICATIONS INFORMATION VOUT VIN = 4.2V VOUT VIN = 3.6V VOUT VIN = 3V ILOAD 1A 10mA VOUT VIN = 4.2V VOUT VIN = 3.6V VOUT VIN = 3V ILOAD 1A 10mA 1308 F14 VOUT TRACES = 200mV/DIV 200µs/DIV Figure 14. LT1308A Li-Ion to 5V Boost Converter Transient Response to 1A Load Step PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. F Package 14-Lead Plastic TSSOP (4.4mm) (LTC DWG # 05-08-1650) 4.90 – 5.10* (0.193 – 0.201) 14 13 12 11 10 9 8 4.30 – 4.48** (0.169 – 0.176) 0° – 8° 0.65 (0.0256) BSC 0.18 – 0.30 (0.0071 – 0.0118) 0.09 – 0.18 (0.0035 – 0.0071) 0.50 – 0.70 (0.020 – 0.028) NOTE: DIMENSIONS ARE IN MILLIMETERS *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.152mm (0.006") PER SIDE **DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.254mm (0.010") PER SIDE U U W U U VOUT TRACES = 200mV/DIV 100µs/DIV 1308 F15 Figure 15. LT1308B Li-Ion to 5V Boost Converter Transient Response to 1A Load Step 6.25 – 6.50 (0.246 – 0.256) 1234567 1.10 (0.0433) MAX 0.05 – 0.15 (0.002 – 0.006) F14 TSSOP 1299 11 LT1308A/LT1308B TYPICAL APPLICATION SEPIC Converts 3V to 10V Input to a 5V/500mA Regulated Output L1A CTX10-2 C2 4.7µF CERAMIC D1 VIN 3V TO 10V + VIN C1 47µF SHUTDOWN LT1308B SHDN VC 47k 680pF SW L1B R1 309k FB GND R2 100k VOUT 5V 500mA C1: AVX TAJC476M016 C2: TAIYO YUDEN EMK325BJ475(X5R) C3: AVX TPSD227M006 D1: IR 10BQ015 L1: COILTRONICS CTX10-2 PACKAGE DESCRIPTION 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0°– 8° TYP 0.014 – 0.019 (0.355 – 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 0.016 – 0.050 (0.406 – 1.270) RELATED PARTS PART NUMBER LT1302 LT1304 LT1316 LTC 1474 LTC1516 LTC1522 LT1610 LT1611 LT1613 LT1615 LTC1682 LT1949 ® DESCRIPTION High Output Current Micropower DC/DC Converter 2-Cell Micropower DC/DC Converter Burst Mode Operation DC/DC with Programmable Current Limit Micropower Step-Down DC/DC Converter 2-Cell to 5V Regulated Charge Pump Micropower, 5V Charge Pump DC/DC Converter Single-Cell Micropower DC/DC Converter Inverting 1.4MHz Switching Regulator in 5-Lead SOT-23 1.4MHz Switching Regulator in 5-Lead SOT-23 Micropower Step-Up DC/DC in 5-Lead SOT-23 Doubler Charge Pump with Low Noise LDO 600kHz, 1A Switch PWM DC/DC Converter LT1307/LT1307B Single Cell, Micropower, 600kHz PWM DC/DC Converters LT1317/LT1317B Micropower, 600kHz PWM DC/DC Converters 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com U U 3.3V to 12V/300mA Step-Up DC/DC Converter L1 4.7µH D1 12V 300mA SW LBO R1 887k + Li-Ion CELL VIN C1 47µF SHUTDOWN LBI LT1308B SHDN VC 47k 100pF FB GND R2 100k + C2 100µF + C3 220µF 6.3V 1308A/B F05 C1: AVX TAJC476M010 C2: AVX TPSD107M016 D1: IR 10BQ015 L1: MURATA LQH6N4R7 1308A/B TA01 Dimensions in inches (millimeters) unless otherwise noted. S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.053 – 0.069 (1.346 – 1.752) 8 0.004 – 0.010 (0.101 – 0.254) 0.228 – 0.244 (5.791 – 6.197) 0.150 – 0.157** (3.810 – 3.988) 0.189 – 0.197* (4.801 – 5.004) 7 6 5 0.050 (1.270) BSC 1 2 3 4 SO8 1298 COMMENTS 5V/600mA from 2V, 2A Internal Switch, 200µA IQ 5V/200mA, Low-Battery Detector Active in Shutdown 3.3V at 75mA from One Cell, MSOP Package 1.5V Minimum, Precise Control of Peak Current Limit 100µA IQ, Operate with VIN as Low as 1.5V 94% Efficiency, 10µA IQ, 9V to 5V at 250mA 12µA IQ, No Inudctors, 5V at 50mA from 3V Input Regulated 5V ± 4% Output, 20mA from 3V Input 3V at 30mA from 1V, 1.7MHz Fixed Frequency – 5V at 150mA from 5V Input, Tiny SOT-23 package 5V at 200mA from 4.4V Input, Tiny SOT-23 package 20µA IQ, 36V, 350mA Switch Adjustable or Fixed 3.3V, 5V Outputs, 60µVRMS Output Noise 1.1A, 0.5Ω, 30V Internal Switch, VIN as Low as 1.5V 1308abis, sn1308ab LT/TP 0899 4K • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 1999