LTC1877 Linear Technology, LTC1877 Datasheet
LTC1877
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LTC1877 Summary of contents
Page 1
... Supply current during operation is only 10 A and drops to < shutdown. The 2.65V to 10V input voltage range makes the LTC1877 ideally suited for both single and dual Li-Ion battery-powered applica- tions. 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 INFORMATION ORDER PART NUMBER 8 PLL LPF 7 SYNC/MODE LTC1877EMS8 MS8 PART MARKING = 150 LTLU MIN TYP MAX 4 30 0.784 0.8 0.816 0.74 0.8 0. 110 0.05 0.15 0.1 0.5 – 0.1 – 0.5 2.65 10 ...
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... Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC1877 is guaranteed to meet specified performance from Specifications over the – operating temperature range are assured by design, characterization and correlation with statistical process controls ...
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... LTC1877 W U TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Output Current 3. 10V 7. 2.5V OUT 50 0.1 1.0 10 100 1000 OUTPUT CURRENT (mA) 1877 • G04 Oscillator Frequency vs Supply Voltage 605 595 585 575 565 555 545 535 ...
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... OUT I = 500mA LOAD 1877 • G15 V OUT 50mV/DIV AC COUPLED 500mA/DIV 1V/DIV OUT I = 50mA TO 500mA LOAD Burst Mode OPERATION 1877 • G17 LTC1877 Burst Mode Operation SW 5V/DIV V OUT 20mV/DIV AC COUPLED I L 200mA/DIV 10 s/DIV 1.5V C OUT OUT 1877 • ...
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... PIN FUNCTIONS RUN (Pin 1): Run Control Input. Forcing this pin below 0.4V shuts down the LTC1877. In shutdown all functions are disabled drawing <1 A supply current. Forcing this pin above 1.2V enables the LTC1877. Do not leave RUN floating. I (Pin 2): Error Amplifier Compensation Point. The TH current comparator threshold increases with this control voltage ...
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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 LTC1877 is clocked by an external source, Burst Mode operation is disabled; the LTC1877 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 LTC1877 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 LTC1877, 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 LTC1877 Output Voltage Phase-Locked Loop and Frequency Synchronization The LTC1877 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 LTC1877 circuits: V quiescent current and I IN losses. The V quiescent current loss dominates the ...
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... A R where T is the ambient temperature example, consider the LTC1877 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 R P-channel switch approximately 0.9 . There- fore, power dissipated by the part is: ...
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... MOSFETs. 4. Keep the switching node SW away from sensitive small signal nodes. Design Example As a design example, assume the LTC1877 is used in a single lithium-ion battery-powered cellular phone applica- 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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... LTC1877 CER GND 20pF 4-to 6-Cell NiCd/NiMH to 1.8V/0.6A Regulator Using All Ceramic Capacitors 1 8 RUN PLL LPF SYNC/MODE 220pF LTC1877 CER GND 20pF 2.5V OUT 1.0 10 ...
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... SEATING PLANE 0.012 0.006 0.004 (0.30) (0.15 0.102) 0.0256 REF (0.65) TYP LTC1877 Low Noise 2.5V/0.3A Regulator 8 RUN PLL LPF 7 I SYNC/MODE TH LTC1877 GND 20pF 887k 412k 0.118 0.004* (3.00 0.102 0.118 0.004** 0.192 0.004 (3.00 0.102) (4.88 0.10) ...
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... Linear Technology Corporation 16 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear-tech.com Single Lithium-Ion to 3.3V/0.3A Regulator + F** – RUN PLL LPF SYNC/MODE TH LTC1877 GND 20pF 887k 280k COMMENTS Monolithic Switching Regulators, I Burst Mode Operation ...