LTC3114-1 40V, 1A Synchronous Buck-Boost DC/DC Converter with Programmable Output Current DESCRIPTION FEATURES n n n n n n n n n n n n n n Regulates VOUT Above, Below or Equal to VIN Single Inductor Wide VIN Range: 2.2V to 40V Wide VOUT Range: 2.7V to 40V 1A Output Current in Buck Mode 0.5A Output Current, VIN = 3.6V, VOUT = 5V Programmable Average Output Current Up to 96% Efficiency Burst Mode® Operation, 30µA No-Load IQ Current Mode Control 1.
LTC3114-1 ABSOLUTE MAXIMUM RATINGS (Note 1) VIN, PVIN, PVOUT......................................... –0.3V to 45V VBST1......................................VSW1 – 0.3V to VSW1 + 6V VBST2......................................VSW2 – 0.3V to VSW2 + 6V VRUN.............................................. –0.3V to (VIN + 0.3V) Voltage, All Other Pins.................................. –0.3V to 6V Operating Junction Temperature Range (Notes 2, 4) LTC3114E-1/LTC3114I-1......................
LTC3114-1 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3114MPFE-1#PBF LTC3114MPFE-1#TRPBF 3114FE-1 16-Lead Plastic TSSOP –55°C to 150°C AUTOMOTIVE PRODUCTS** LTC3114EDHC-1#WPBF LTC3114EDHC-1#WTRPBF 31141 16-Lead (5mm × 3mm) Plastic DFN –40°C to 125°C LTC3114IDHC-1#WPBF LTC3114IDHC-1#WTRPBF 16-Lead (5mm × 3mm) Plastic DFN –40°C to 125°C 31141 Contact the factory for parts specified with wider operating temperature ranges.
LTC3114-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 24V, VOUT = 5V, unless otherwise noted.
LTC3114-1 TYPICAL PERFORMANCE CHARACTERISTICS 95 90 90 85 85 80 80 70 65 60 55 40 0.001 75 70 65 60 VIN = 5V VIN = 12V VIN = 24V VIN = 36V 50 45 0.01 0.1 LOAD CURRENT (A) 40 0.001 1 0.01 0.1 LOAD CURRENT (A) 31141 G01 90 OUTPUT CURRENT (A) EFFICIENCY (%) 75 70 VIN = 5V VIN = 12V VIN = 24V VIN = 36V 65 60 0.0001 0.001 0.01 0.1 LOAD CURRENT (A) 70 1 1 1.35 1.25 1.15 1.05 0.95 0.85 0.75 0.65 0.55 0.45 0.35 0.25 0.15 0.
LTC3114-1 TYPICAL PERFORMANCE CHARACTERISTICS (TA = 25°C unless otherwise specified) VIN = 12V 0.75 VIN = 12V RPROG = 64.7k 10 OUTPUT VOLTAGE (V) 0 Output Voltage Load Regulation 0.50 0.25 0 –0.25 –0.50 –1.25 –1.50 –0.1 10 INPUT VOLTAGE (V) 1 7.25 7.00 6.75 6.50 6.25 1 10 INPUT VOLTAGE (V) VIN = 40V LDO DROPOUT VOLTAGE (mV) LDO VOLTAGE (V) 40 4.430 VIN = 5V 0 30 60 90 TEMPERATURE (°C) 6.50 6.00 5.50 5.00 4.50 4.00 120 150 31141 G15 1.
LTC3114-1 TYPICAL PERFORMANCE CHARACTERISTICS (TA = 25°C unless otherwise specified) RUN Pin Threshold vs Temperature 8 VIN = 24V VIN = 12V 7 RUN PIN CURRENT (µA) RUN PIN THRESHOLD (V) 1.228 1.226 1.224 1.222 1.220 1.218 6 5 –30 0 30 60 90 TEMPERATURE (°C) 120 –0.32 5 0 10 15 20 25 30 RUN PIN VOLTAGE (V) 0.35 0.33 0.31 0.29 0.27 0.25 0.23 0.21 120 150 1.800 –30 0 30 60 90 TEMPERATURE (°C) 1.750 1.725 1.700 1.675 1.650 –60 –30 0 30 60 90 TEMPERATURE (°C) 120 31141 G21 2.
LTC3114-1 TYPICAL PERFORMANCE CHARACTERISTICS (TA = 25°C unless otherwise specified) Load Transient in Buck Mode, 100mA to 600mA Load Transient in Boost Mode, 100mA to 600mA LOAD CURRENT 500mA/DIV LOAD CURRENT 500mA/DIV VOUT 200mV/DIV VOUT 200mV/DIV VIN = 14V VOUT = 5V 1ms/DIV 31141 G28 VOUT 50mV/DIV VIN = 3.
LTC3114-1 BLOCK DIAGRAM VIN PVIN SW2 SW1 LDO 4.4V PLDO REVERSE BLOCKING LDO PVOUT INDUCTOR ISENSE MA MD MB PGND OUTPUT CURRENT SENSE MC 0.1A – + PGND 10µA IZERO LTC3114-1 GATE DRIVERS BST1 IOUT 25k + – BST2 RUN 1.2V VIN 2.1V LDO 2.5V + – + – + – AVERAGE CURRENT AMP + – PWM VOLTAGE ERROR AMP + – MODE PROG 1V FB 1V VC 1.2MHz OSCILLATOR SOFT-START 1V BIAS GENERATOR BANDGAP REFERENCE POR OVERTEMPERATURE PROTECTION GND PGND 31141 BD Rev. C For more information www.analog.
LTC3114-1 PIN FUNCTIONS PGND (Pin 1, Exposed Pad Pin 17): Power Ground Connections. The PGND pin must be electrically connected to a power ground plane in the application. The exposed pad is an additional power ground connection in parallel with Pin 1. Optimal thermal performance requires that the exposed pad be soldered to the PC board and preferably to a ground plane. functions. Refer to the Applications Information section for complete details on how to select the proper values for RPROG and CPROG.
LTC3114-1 PIN FUNCTIONS BST1 (Pin 13): Flying Capacitor Pin for SW1. This pin must be connected to SW1 through a 68nF capacitor. BST1 is used to generate the gate driver rail for power switch A. Make the PCB trace from BST2 to the boost capacitor as short and direct as possible. PVIN (Pin 14): Power Input for the Buck-Boost Converter. A 10µF or larger capacitor must be connected between PVIN and GND as close to the IC as possible.
LTC3114-1 OPERATION plifying the PCB layout and design. Factory trimming of the output current limit offset and gain provide a high degree of accuracy, typically within ±5% of the setpoint. The applications section provides details on how to select the programming resistor, RPROG, for the desired average output current level from the LTC3114-1.
LTC3114-1 OPERATION Current Mode Control in the Applications Information section of this data sheet. VC is internally connected to the noninverting input of a high gain, integrating, operational amplifier, referred to in Figure 2, as the average current amp. The inverting input of the average current amplifier is connected to the inductor current sense circuit through a gain setting resistor (RCS1) and to its output (VIA) through an internal frequency compensation network comprised of RCS2, CCS1 and CCS2.
LTC3114-1 OPERATION sensing circuitry produces a voltage across resistor RX that resembles the inductor current waveform transformed to a voltage. If there is an increase in the power converter load on VOUT, the instantaneous level of VOUT will drop slightly, which will increase the voltage level on VC by the inverting action of the voltage error amplifier. When the increase on VC first occurs, the output of the current averaging amplifier, VIA, will also increase momentarily to command a larger duty cycle.
LTC3114-1 OPERATION The SW1/SW2 forced low time on each switching cycle briefly disconnects the inductor from VOUT and VIN resulting in slightly less output current in either buck or boost mode for a given inductor current. In boost mode, the output current is related to average inductor current and duty cycle by: IOUT(BOOST) ≈ IL • (1 – D) where D is the converter duty cycle.
LTC3114-1 OPERATION or small inductor resulting in a small amount of residual energy left in the inductor following a zero current event. In this case the LTC3114-1 SW1 waveform will display a characteristic half sine wave between the time at which Izero is detected and when the next switching cycle commences. This is because SWC is the only active (on) switch following an IZERO event and this behavior is not harmful to the LTC3114-1.
LTC3114-1 OPERATION is disabled until LDO rises above 2.5V (typical) as long as VIN is above its nominal UVLO threshold level. Depending on the particular application, either of these UVLO thresholds could be the limiting factor affecting the minimum input voltage required for operation. The LTC3114-1 LDO regulator uses VIN for its power input. If LDO is not bootstrapped, then there exists a voltage drop or dropout voltage between VIN and LDO.
LTC3114-1 OPERATION The RUN comparator is relatively noise insensitive, but there may be cases dues to PCB layout, very large value resistors for R1 and R2 or proximity to noisy components where noise pickup is unavoidable and may cause the turn on or turn off of the IC to be intermittent. In these cases, a filter capacitor can be added across R2 to ensure proper operation.
LTC3114-1 OPERATION Top Layer 2nd Layer Bottom Layer 3rd Layer Figure 4. Typical 4 Layer PC Board Layout Rev. C For more information www.analog.com Downloaded from Arrow.com.
LTC3114-1 APPLICATIONS INFORMATION A standard application circuit for the LTC3114-1 is shown on the front page of this data sheet. The appropriate selection of external components is dependent upon the required performance of the IC in each particular application given considerations and trade-offs such as PCB area, input and output voltage range, output voltage ripple, required efficiency, thermal considerations and cost.
LTC3114-1 APPLICATIONS INFORMATION threshold defined by VC. However, in boost mode, especially at large step-up ratios, the output current capability can also be limited by the total resistive losses in the power stage. These losses include, switch resistances, inductor DC resistance and PCB trace resistance.
LTC3114-1 APPLICATIONS INFORMATION the series resistance of the output capacitor and all other terms as previously defined. Table 2. Representative Bypass and Output Capacitors VALUE (µF) VOLTAGE (V) SIZE L × W × H (mm), TYPE, ESR 22 25 TPME226K050R0075 22 50 3.2 × 2.5 × 2.79 X5R Ceramic 7.3 × 4.3 × 4.1 Tantalum, 75mΩ Kemet C2220X226K3RACTU 22 25 A700D226M016ATE030 22 16 Murata GRM32ER71E226KE15L 22 25 3.2 × 2.5 × 2.5 X7R Ceramic Nichicon PLV1E121MDL1 82 25 8 × 8 × 12 Alum.
LTC3114-1 APPLICATIONS INFORMATION applications are generally similar except that voltage ripple is generally not a concern. Some capacitors exhibit a high DC leakage current which may preclude their consideration for applications that require a very low quiescent current in Burst Mode operation. Ceramic capacitors are often utilized in switching converter applications due to their small size, low ESR and low leakage currents.
LTC3114-1 APPLICATIONS INFORMATION A simplified diagram of the average output current programming circuitry is shown in the Block Diagram. An internal sense resistor, RS, and low offset amplifier directly measure current in the VOUT path and produce a small fraction of this current out of the PROG pin. Accordingly, a resistor and filtering capacitor connected from PROG to ground produce a voltage proportional to average output current on PROG.
LTC3114-1 APPLICATIONS INFORMATION + – VOUT VOLTAGE ERROR AMP gm + – VOLTAGE CONTROLLED CURRENT SOURCE FB 1V RTOP 1.7M RBOT 100k COUT 22µF RCOSER 0.01Ω RLOAD 18Ω 1V GND RZ CP1 2π • R LOAD • C OUT CP2 31141 F06 Figure 6. Simplified Representation of Average Current Mode Control Loop verter for a transconductance gain of 1.97A/V.
LTC3114-1 APPLICATIONS INFORMATION is simply a matter of substituting different values in the equations provided and reviewing the Bode plots, making minor adjustments as needed. Since the compensation design procedure uses a simplified model of the LTC3114-1, the results from the following compensation design should always be verified with time domain step load response tests to validate the effectiveness of the compensation design.
LTC3114-1 APPLICATIONS INFORMATION Assuming the error amp zero is designed as just described, at frequencies above P2 (and Z1), the closed-loop gain of our system simplifies to: • g •R G •R G CL = CS LOAD m Z VOUT GCS is the inner current loop closed-loop transconductance = 1.
LTC3114-1 TYPICAL APPLICATIONS 9V to 36V VIN to 12V VOUT Regulator OPTIONAL D1 10µH 68nF VIN 9V TO 36V SW1 SW2 BST2 BST1 LTC3114-1 VIN PVOUT 10µF 33nF PVIN RUN PROG MODE 20k GND LDO PLDO 68nF FB VC PGND 2M 4.7µF 10nF 10pF VOUT 12V AT 1A, VIN > 12V 44µF 12V AT 0.7A, VIN > 9V 182k 56.
LTC3114-1 TYPICAL APPLICATIONS 6V to 40V VIN to 24V VOUT Regulator OPTIONAL D1 15µH 68nF VIN 6V TO 40V SW1 SW2 BST1 BST2 LTC3114-1 VIN PVOUT 10µF 33nF PVIN RUN PROG MODE 20k GND LDO PLDO 68nF 2M 4.7µF FB VC PGND 10nF 10pF VOUT 24V AT 1A, VIN > 24V 22µF 24V AT 0.2A, VIN = 6V 86.6k 39.
LTC3114-1 TYPICAL APPLICATIONS Constant Current/Constant Voltage Lead-Acid Battery Charger OPTIONAL D2 VBATT FLOAT LEVEL –30°C 14.5V 0°C 14.03V 25°C 13.8V 50°C 13.48V 6.8µH 68nF VIN 2.7V TO 40V 10µF 33nF 24.9k 68nF SW1 SW2 BST2 BST1 LTC3114-1 VIN PVOUT PVIN RUN D1 LDO PLDO 4.7µF NTC 68k FB VC PROG MODE GND + 44µF 2M 6-CELL LEAD-ACID BATTERY 220k 10nF PGND 1A CONSTANT CHARGING CURRENT WHEN BELOW FLOAT LEVEL 31141 TA04a 56.
LTC3114-1 PACKAGE DESCRIPTION DHC Package 16-Lead Plastic DFN (5mm × 3mm) (Reference LTC DWG # 05-08-1706 Rev Ø) 0.65 ±0.05 3.50 ±0.05 1.65 ±0.05 2.20 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 4.40 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 5.00 ±0.10 (2 SIDES) R = 0.20 TYP 3.00 ±0.10 (2 SIDES) 9 R = 0.115 TYP 0.40 ±0.10 16 1.65 ±0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) PIN 1 NOTCH 0.200 REF 0.75 ±0.05 0.00 – 0.05 8 1 0.25 ±0.05 0.50 BSC (DHC16) DFN 1103 4.
LTC3114-1 PACKAGE DESCRIPTION FE Package 16-Lead Plastic TSSOP (4.4mm) (Reference LTC DWG # 05-08-1663 Rev J) Exposed Pad Variation BB 4.70 (.185) 3.58 (.141) DETAIL A 4.90 – 5.10* (.193 – .201) 0.56 (.022) REF 3.58 (.141) NOTE 5 16 1514 13 12 1110 9 NOTE 5 6.60 ±0.10 2.94 3.05 (.116) (.120) 4.50 ±0.10 DETAIL A SEE NOTE 4 2.94 6.40 (.116) (.252) BSC 0.53 (.021) REF DETAIL A IS THE PART OF THE LEAD FRAME FEATURE FOR REFERENCE ONLY NO MEASUREMENT PURPOSE 1.05 ±0.10 0.65 BSC 0.45 ±0.
LTC3114-1 REVISION HISTORY REV DATE DESCRIPTION A 11/14 Corrected Part Marking Table for TSSOP Package Option. 2 B 3/16 Clarified Min VIN on Electrical Characteristics. 3 Clarified FB (Pin 7) description, BST2 (Pin 12) and BST1 (Pin 13) description. 9 Added High Transient Input Voltage Applications section. 17 Clarified Average Output Current Limit Programming section. 23 Added optional diode to Typical Applications. C 07/19 PAGE NUMBER 17-30 Added LTC3118 to Related Parts.
LTC3114-1 TYPICAL APPLICATION Wide VIN Range 5V, 1A Regulator with Bootstrapped LDO and Custom UVLO Threshold OPTIONAL D1 VIN 3.75V TO 40V ON: VIN > 4V OFF: VIN < 3.75V 6.8µH 68nF 10µF SW1 SW2 BST1 BST2 LTC3114-1 VIN PVOUT 1.4M PVIN RUN LDO PLDO 68nF 4.7µF IMPROVES EFFICIENCY AT HIGH VIN BAT54 604k 10nF 2M FB VC PROG MODE 20k VOUT 5V AT 1A 30µF VIN > 5V GND PGND 499k 4700pF 27.
