LTC1878 LINER [Linear Technology], LTC1878 Datasheet
LTC1878
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LTC1878 Summary of contents
Page 1
... Supply current during operation is only 10 A and drops to < shutdown. The 2.65V to 6V input voltage range makes the LTC1878 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems ...
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... RUN 0. < f PLLIN OSC f > f PLLIN OSC I = 100mA –100mA ORDER PART NUMBER 8 PLL LPF 7 SYNC/MODE LTC1878EMS8 MS8 PART MARKING = 150 LTNX MIN TYP MAX UNITS 4 30 0.784 0.8 0.816 0.74 0.8 0. 110 0.05 0.2 0.1 0.5 – 0.1 – 0.5 2 ...
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... RUN Rising SYNC/MODE V Rising RUN Note 4: The LTC1878 is tested in a feedback loop which servos V balance point for the error amplifier (V Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. and power A Efficiency vs Output Current 100 ...
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... LTC1878 W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Output Current 3. 4. 1.8V OUT 0 100 1000 OUTPUT CURRENT (mA) 1878 G04 Oscillator Frequency vs Supply Voltage 605 595 585 575 565 555 545 535 525 515 ...
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... OUT OUT 500mA LOAD 1878 G16 Load Step Response V OUT 100mV/DIV AC COUPLED I L 500mA/DIV I TH 1V/DIV OUT 1878 G18 LTC1878 Burst Mode Operation SW 5V/DIV V OUT 50mV/DIV AC COUPLED I L 200mA/DIV 8 10 s/DIV OUT ...
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... PI FU CTIO S RUN (Pin 1): Run Control Input. Forcing this pin below 0.4V shuts down the LTC1878. In shutdown all functions are disabled drawing < supply current. Forcing this pin above 1.2V enables the LTC1878. Do not leave RUN floating. I (Pin 2): Error Amplifier Compensation Point. The ...
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... When locked, the PLL aligns the turn-on of the top MOSFET to the rising edge of the synchronizing signal. When the LTC1878 is clocked by an external source, Burst Mode operation is disabled; the LTC1878 then operates in PWM pulse skipping mode. In this mode, when the output ...
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... Another important detail to remember is that at low input supply voltages, the R increases. Therefore, the user should calculate the power dissipation when the LTC1878 is used at 100% duty cycle with a low input voltage (see Thermal Considerations in the Applications Information section). Slope Compensation and Inductor Peak Current ...
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... OUT where f = operating frequency, C and I = ripple current in the inductor. The output ripple L is highest at maximum input voltage since I with input voltage. For the LTC1878, the general rule for proper operation is: C required ESR < 0.25 OUT The choice of using a smaller output capacitance increases the output ripple voltage due to the frequency ...
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... GND Figure 3. Setting the LTC1878 Output Voltage Phase-Locked Loop and Frequency Synchronization The LTC1878 has an internal voltage-controlled oscillator and phase detector comprising a phase-locked loop. This allows the top MOSFET turn- locked to the rising edge of an external frequency source. The frequency range of the voltage-controlled oscillator is 400kHz to 700kHz ...
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... L1, L2, etc. are the individual losses as a percentage of input power. Although all dissipative elements in the circuit produce losses, two main sources usually account for most of the losses in LTC1878 circuits: V quiescent current and I IN losses. The V quiescent current loss dominates the ...
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... where T is the ambient temperature example, consider the LTC1878 in dropout at an input voltage of 3V, a load current of 500mA, and an ambient temperature From the typical perfor- mance graph of switch resistance, the OPTIONAL P-channel switch approximately 0 ...
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... Keep the switching node SW away from sensitive small signal nodes Design Example As a design example, assume the LTC1878 is used in a single lithium-ion battery-powered cellular phone applica regulator can OUT tion. The input voltage will be operating from a maximum of 4.2V down to about 2.7V. The load current requirement is a maximum of 0 ...
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... SANYO POSCAP 6TPA47M Figure 8. Single Lithium-Ion to 2.5V/0.3A Regulator from Design Example U TYPICAL APPLICATIO S LTC1878 1 RUN 2 I SYNC/MODE TH 220pF GND * TOKO D62CB A920CY-100M ** TAIYO-YUDEN CERAMIC JMK325BJ226MM LTC1878 1 RUN 220pF GND * TOKO D62CB A920CY-100M ** TAIYO-YUDEN CERAMIC JMK325BJ226MM 2.65V TO 4 ...
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... SW + 887k 20pF 412k 1878 TA06 3- to 4-Cell NiCd/NiMH to 3.3V/0.5A Regulator Using All Ceramic Capacitors 20pF 887k 280k FOR 2.7V < V < 3. 1878 TA06 LTC1878 OUT IN 2. OUT 0.6A CER 22 F CER V IN 2.65V OUT IN 2 ...
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... Monolithic Synchronous Step-Down Switching Regulator LTC1772 Low Input Voltage Current Mode Step-Down DC/DC Controller LTC1877 High Efficiency Monolithic Step-Down Regulator Linear Technology Corporation 16 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear-tech.com 10k LTC1878 1 8 RUN PLL LPF SYNC/MODE TH ...