LTC3788 Linear Technology, LTC3788 Datasheet
LTC3788
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LTC3788 Summary of contents
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... OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3788 features a precision 1.2V reference and dual power good output indicators. A 4.5V to 38V input supply range encompasses a wide range of system architectures and battery chemistries ...
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... TAPE AND REEL LTC3788EUH#PBF LTC3788EUH#TRPBF LTC3788IUH#PBF LTC3788IUH#TRPBF www.DataSheet4U.com Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. Consult LTC Marketing for information on non-standard lead based fi nish parts. ...
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... Float FB LIM V = 1.1V Float FB LIM C = 3300pF (Note 6) LOAD C = 3300pF (Note 6) LOAD C = 3300pF (Note 6) LOAD C = 3300pF (Note 6) LOAD C = 3300pF (Each Driver) LOAD C = 3300pF (Each Driver) LOAD LTC3788 MIN TYP MAX UNITS l 0.01 0 –0.01 –0 mmho 0.9 mA 1.2 mA 125 190 μA 200 300 μ μ ...
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... V SW1,2 BOOST1,2 FREQ = 0V, Forced Continuous or Pulse-Skipping Mode Note 4: The LTC3788 is tested in a feedback loop that servos V output of the error amplifi er while maintaining I current limit range. Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. ...
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... V OUT FIGURE 9 CIRCUIT 3788 G03 Load Step Pulse-Skipping Mode LOAD STEP 2A/DIV INDUCTOR CURRENT 5A/DIV V OUT 500mV/DIV 3788 G05 OUT FIGURE 9 CIRCUIT LTC3788 10000 1000 100 12V 24V OUT Burst Mode OPERATION FIGURE 9 CIRCUIT 0.1 0.01 0 0.0001 0.001 OUTPUT CURRENT (A) ...
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... LTC3788 TYPICAL PERFORMANCE CHARACTERISTICS Inductor Current at Light Load FORCED CONTINUOUS MODE Burst Mode OPERATION 5A/DIV PULSE-SKIPPING MODE V = 12V 24V OUT I = 200μA LOAD FIGURE 9 CIRCUIT Regulated Feedback Voltage vs Temperature 1.212 1.209 1.206 1.203 1.200 1.197 1.194 1.191 www.DataSheet4U.com 1.188 –45 – ...
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... G15 Load Current CC 6.0 5.8 5 5.4 5.2 5.0 4 4.6 4.4 4.2 4.0 100 120 200 140 160 180 3788 G17 LTC3788 Shutdown (RUN) Threshold vs Temperature RUN RISING RUN FALLING – 105 130 –45 30 TEMPERATURE (°C) 3788 G14 INTV Line Regulation ...
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... LTC3788 TYPICAL PERFORMANCE CHARACTERISTICS Oscillator Frequency vs Temperature 600 FREQ = INTV 550 500 450 400 FREQ = GND 350 300 –45 – TEMPERATURE (°C) Maximum Current Sense Threshold vs I 120 100 PULSE SKIPPING MODE 80 Burst Mode 60 OPERATION –20 FORCED CONTINUOUS MODE – ...
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... G25 CLKOUT (Pin 4): A Digital Output Used for Daisychaining Multiple LTC3788 ICs in Multiphase Systems. The PHASMD pin voltage controls the relationship between BG1, BG2 and CLKOUT. This pin swings between SGND and INTV PLLIN/MODE (Pin 5): Forced Continuous Mode, Burst Mode or Pulse-Skipping Mode Selection Pin and External Synchronization Input to Phase Detector Pin ...
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... LTC3788 PIN FUNCTIONS PGOOD2 (Pin 14): Power Good Indicator for Channel 2. Open-drain logic output that is pulled to ground when the output voltage is more than ±10% away from the regulated output voltage. To avoid false trips the output voltage must be outside the range for 25μs before this output is activated ...
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... CLK2 + CLK1 0.425V – – – 2.8V 0.7V SLOPE COMP + SENS LO – 2.5V SHDN 0.5μA/ 4.5μA 10μA + – 11V 3.8V SENS SHDN LO SGND RUN SS LTC3788 INTV CC D BOOST SHDN SWITCHING LOGIC SW AND CHARGE INTV PUMP CC BG SLEEP PGND + L + – – 2mV – SENSE R SENSE + ...
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... RUN1 and RUN2 pins. Pulling either of these pins below 1.28V shuts down the main control loop for that controller. Pulling both pins below 0.7V disables both controllers and most internal circuits, including the INTV LDOs. In this state, the LTC3788 draws only 8μ quiescent current ground) to OUT ...
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... Light Load Current Operation—Burst Mode Operation, Pulse-Skipping or Continuous Conduction (PLLIN/MODE Pin) The LTC3788 can be enabled to enter high effi ciency Burst Mode operation, constant-frequency pulse-skipping mode or forced continuous conduction mode at low load currents. To select Burst Mode operation, tie the PLLIN/ MODE pin to a ground (e ...
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... PLL to lock-in rapidly without deviating far from the desired frequency. The typical capture range of the LTC3788’s PLL is from approximately 55kHz to 1MHz, and is guaranteed to lock to an external clock source whose frequency is be- tween 75kHz and 850kHz. ...
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... The internal charge OUT Operation at Low SENSE Pin Common Voltage The current comparator in the LTC3788 is powered di- is between 100% and rectly from the SENSE mode voltage of SENSE low as 2.5V, which is below the UVLO threshold. The fi gure on the fi ...
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... The high impedance SENSE parators allow accurate DCR sensing. Filter components mutual to the sense lines should be placed close to the LTC3788, and the sense lines should run close together to a Kelvin connection underneath the current sense element (shown in Figure 1). Sensing cur- rent elsewhere can effectively add parasitic inductance ...
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... Inductor DCR Sensing For applications requiring the highest possible effi ciency at high load currents, the LTC3788 is capable of sensing the voltage drop across the inductor DCR, as shown in Figure 2b. The DCR of the inductor can be less than 1mΩ for high current inductors high current application requiring such an inductor, conduction loss through a sense resistor could reduce the effi ...
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... Do not allow the core to saturate! Power MOSFET Selection Two external power MOSFETs must be selected for each decreases with higher L controller in the LTC3788: one N-channel MOSFET for the : IN bottom (main) switch, and one N-channel MOSFET for the top (synchronous) switch. The peak-to-peak gate drive levels are set by the INTV voltage ...
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... IN V RIPPLE device DS(ON) where C The steady ripple due to the voltage drop across the ESR is given by: ΔV ESR LTC3788 vs Temperature curve, but DS(ON) Selection OUT function of the source impedance, IN must be capable of reducing the output voltage − I • ...
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... LTC3788 APPLICATIONS INFORMATION The LTC3788 can also be confi gured as a 2-phase single output converter where the outputs of the two channels are connected together and both channels have the same duty cycle. With 2-phase operation, the two channels of the dual switching regulator are operated 180 degrees out- of-phase ...
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... APPLICATIONS INFORMATION Setting Output Voltage The LTC3788 output voltages are each set by an external feedback resistor divider carefully placed across the out- put, as shown in Figure 4. The regulated output voltage is determined by: ⎛ ⎞ ⎝ ⎜ ⎠ ⎟ OUT R A Great care should be taken to route the V noise sources, such as the inductor or the SW line ...
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... Fault Conditions: Overtemperature Protection At higher temperatures cases where the internal power dissipation causes excessive self heating on-chip (such as an INTV rises above 4.7V, the shutdown circuitry will shut down the LTC3788. When the CC LDO is enabled. The junction temperature exceeds approximately 170°C, the CC ...
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... Typically, the external clock (on PLLIN/MODE pin) input high threshold is 1.6V, while the input low threshold is 1.2V. Note that the LTC3788 can only be synchronized to an external clock whose frequency is within range of the LTC3788’s internal VCO, which is nominally 55kHz to 1MHz. This is guaranteed to be between 75kHz and 850kHz. ...
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... LTC3788 APPLICATIONS INFORMATION Although all dissipative elements in the circuit produce losses, four main sources usually account for most of the losses in LTC3788 circuits regulator current losses, 4) Bottom MOSFET transition losses. 1. The V current is the DC supply current given in the IN Electrical Characteristics table, which excludes MOSFET driver and control currents small (< ...
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... OUT The maximum output current peak is 24V 4A, OUT MAX I OUT PEAK ( A low ESR (5mΩ) capacitor is suggested. This capacitor will limit output voltage ripple to 46.5mV (assuming ESR dominate ripple). LTC3788 ⎛ ⎞ − ⎜ ⎟ ⎝ ⎠ • ...
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... All of these nodes have very large and fast moving signals and, therefore, should be kept on the output side of the LTC3788 and occupy a minimal PC trace area. 7. Use a modifi ed “star ground” technique: a low imped- ...
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... CLKOUT CC f PLLIN/MODE INTV IN CC SGND RUN1 BG2 RUN2 C B2 VFB2 BOOST2 ITH2 TG2 SW2 SS2 PGOOD2 V PULL-UP + SENSE2 – SENSE2 Figure 7. Recommended Printed Circuit Layout Diagram LTC3788 R L1 SENSE1 V OUT1 + M1 M2 GND OUT2 R L2 SENSE2 3788 F07 27 3788f ...
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... LTC3788 APPLICATIONS INFORMATION BOLD LINES INDICATE HIGH SWITCHING CURRENT. KEEP LINES TO A MINIMUM LENGTH. www.DataSheet4U.com SENSE1 OUT1 C SW1 OUT1 SENSE2 OUT2 C SW2 OUT2 Figure 8. Branch Current Waveforms 3788 F08 3788f ...
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... SGND EXTV BG2 0.1μF B1 RUN1 BOOST2 RUN2 FREQ SW2 SS2 ITH2 TG2 VFB2 + SENSE2 – SENSE2 Figure 9. High Effi ciency Dual 12V/24V Boost Converter LTC3788 V OUT1 24V OUTA1 OUTB1 22μF 220μ SENSE1 MTOP1 3.3μH 4mΩ MBOT1 V IN ...
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... L1: PULSE PA2050.103NL L2: PULSE PA2050.163NL Figure 10. High Effi ciency Dual 24V/48V Boost Converter with Inductor DCR Current Sensing 30 R 53.6k INTV CC 100k – SENSE1 PGOOD2 100k + SENSE1 PGOOD1 LTC3788 VFB1 TG1 SW1 BOOST1 C , 0.1μF B1 BG1 ITH1 D1 VBIAS SS1 ILIM INTV CC C INT PHSMD 4.7μ ...
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... UH Package 32-Lead Plastic QFN (5mm × 5mm) (Reference LTC DWG # 05-08-1693 Rev D) 0.70 0.05 3.45 0.05 PACKAGE OUTLINE 0.25 0.05 0.50 BSC 0.75 0.05 5.00 0.10 (4 SIDES) 0.00 – 0.05 3.50 REF (4-SIDES) 0.200 REF LTC3788 BOTTOM VIEW—EXPOSED PAD PIN 1 NOTCH R = 0.30 TYP 0.115 OR 0.35 45° CHAMFER TYP TYP 31 32 3.45 0.10 3.45 0.10 0.25 0.05 0.50 BSC 0.40 0.10 1 ...
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... LTC3788 RELATED PARTS PART NUMBER DESCRIPTION LTC3788-1 2-Phase, Dual Output Synchronous Step-Up Controller LTC3862/LTC3862-1 Multiphase Current Mode Step-Up DC/DC Controller LTC3813 100V Maximum V Step-Up DC/DC Controller LTC3814-5 60V Maximum V OUT Step-Up DC/DC Controller LTC1871/LTC1871-1/ Wide Input Range LTC1871-7 Current Flyback, Boost and SEPIC Controller ...