LTC3859 Linear Technology, LTC3859 Datasheet
LTC3859
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LTC3859 Summary of contents
Page 1
... DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Constant frequency current mode architecture allows a phase-lockable switching frequency 850kHz. The LTC3859 operates from a wide 4.5V to 38V input supply ≤ 24V OUT range. When biased from the output of the boost converter or another auxiliary supply, the LTC3859 can operate from an input supply as low as 2 ...
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... LTC3859 ABSOLUTE MAXIMUM RATINGS Bias Input Supply Voltage (V ) .............. –0.3V to 40V BIAS Buck Top Side Driver Voltages (BOOST1, BOOST2) ............................. –0.3V to 46V Boost Top Side Driver Voltages (BOOST3) ............................................ –0.3V to 76V Buck Switch Voltage (SW1, SW2) ................ –5V to 40V Boost Switch Voltage (SW3) ........................ –5V to 70V INTV , (BOOST1– ...
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... LTC3859EUHF#PBF LTC3859EUHF#TRPBF LTC3859IUHF#PBF LTC3859IUHF#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi ...
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... LTC3859 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T SYMBOL PARAMETER UVLO Undervoltage Lockout V Buck Feedback Overvoltage Protection OVL1 SENSE Pin Current SENSE1 SENSE Pin Current SENSE3 – I – SENSE Pin Current SENSE1,2 – I – SENSE Pin Current SENSE3 ...
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... BOOST3 SW3 Forced Continuous Mode Note 4: The LTC3859 is tested in a feedback loop that servos V specifi ed voltage and measures the resultant V 85°C is not tested in production. This specifi cation is assured by design, characterization and correlation to production testing at 125°C. ≈ T ...
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... LTC3859 TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency and Power Loss vs Output Current (Buck) 100 CCM EFFICIENCY 40 PULSE-SKIPPING 30 EFFICIENCY BURST LOSS 20 BURST EFFICIENCY CCM LOSS 10 PULSE-SKIPPING LOSS 0 0.0001 0.001 0.01 0 OUTPUT CURRENT (A) 3859 G01 FIGURE 12 CIRCUIT V = 10V OUT Load Step (Buck) ...
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... V = 10V OUT FIGURE 12 CIRCUIT Soft Start-Up (Boost) V OUT3 2V/DIV GND 3859 G16 2ms/DIV FIGURE 12 CIRCUIT www.DataSheet4U.com LTC3859 Effi ciency vs Input Voltage (Boost) 100 FIGURE 12 CIRCUIT BIAS 10V OUT LOAD ...
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... LTC3859 TYPICAL PERFORMANCE CHARACTERISTICS INTV Line Regulation CC 5.5 5.4 5.3 5.2 5.1 5 INPUT VOLTAGE (V) 3859 G19 SENSE Pins Total Input Current vs V Voltage SENSE 800 700 SENSE1, 2 PINS 600 500 400 300 200 SENSE3 PIN 100 COMMON MODE VOLTAGE (V) ...
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... OPERATING FREQUENCY (kHz) www.DataSheet4U.com LTC3859 Quiescent Current vs Temperature 100 90 ALL CHANNELS ONE CHANNEL –45 – TEMPERATURE (°C) 3859 G29 Undervoltage Lockout Threshold vs Temperature 4 ...
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... RUN1, RUN2, RUN3 (Pins 9, 10, 11/Pins 13, 14, 15): Digital Run Control Inputs for Each Controller. Forcing either of these pins below 1.2V shuts down that controller. Forcing all of these pins below 0.7V shuts down the entire LTC3859, reducing quiescent current to approximately 14μA. OV3 (Pin 17/Pin 21): Overvoltage Open-Drain Logic Output for the Boost Regulator ...
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... A capacitor to ground at this pin sets the ramp time to fi nal regulated output voltage. Alternatively, a resistor divider on another voltage supply connected to the TRACK/SS pins of the buck channels allow the LTC3859 buck outputs to track the other supply during start-up ...
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... LTC3859 FUNCTIONAL DIAGRAM 12 www.DataSheet4U.com 3859f ...
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... FUNCTIONAL DIAGRAM www.DataSheet4U.com LTC3859 3859f 13 ...
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... C Shutdown and Start-Up (RUN1, RUN2, RUN3 and pin, TH TRACK/SS1, TRACK/SS2, SS3 Pins) The three channels of the LTC3859 can be independently shut down using the RUN1, RUN2 and RUN3 pins. Pull OUT ing any of these pins below 1.2V shuts down the main control loop for that channel ...
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... Light Load Current Operation (Burst Mode Operation, Pulse-Skipping, or Continuous Conduction) (PLLIN/MODE Pin) The LTC3859 can be enabled to enter high effi ciency Burst Mode operation, constant frequency pulse-skipping mode or forced continuous conduction mode at low load cur- rents. To select Burst Mode operation, tie the PLLIN/ MODE pin to ground ...
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... The typical capture range of the LTC3859’s phase-locked loop is from approximately 55kHz to 1MHz, with a guar- antee over all manufacturing variations to be between 75kHz and 850kHz. In other words, the LTC3859’s PLL is guaranteed to lock to an external clock source whose frequency is between 75kHz and 850kHz. ...
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... EMI and losses in the input capacitor and battery. With 2-phase operation, the two buck controllers of the LTC3859 are operated 180 degrees out of phase. This effectively interleaves the current pulses drawn by the switches, greatly reducing the overlap time where they add together. The result is a signifi ...
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... The schematic on the fi rst page is a basic LTC3859 ap- plication circuit. External component selection is driven by the load requirement, and begins with the selection of R and the inductor value ...
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... APPLICATIONS INFORMATION The Typical Application on the fi rst page is a basic LTC3859 application circuit. LTC3859 can be confi gured to use either DCR (inductor resistance) sensing or low value resistor sensing. The choice between the two current sensing schemes is largely a design trade-off between cost, power consumption, and accuracy ...
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... Figure 4. Current Sensing Methods Inductor DCR Sensing For applications requiring the highest possible effi ciency at high load currents, the LTC3859 is capable of sensing the voltage drop across the inductor DCR, as shown in Figure 4b. The DCR of the inductor represents the small amount of DC winding resistance of the copper, which can be less than 1mΩ ...
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... Power MOSFET and Schottky Diode (Optional) Selection Two external power MOSFETs must be selected for each controller in the LTC3859: one N-channel MOSFET for the L top switch (main switch for the buck, synchronous for the boost), and one N-channel MOSFET for the bottom switch (main switch for the boost, synchronous for the buck) ...
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... LTC3859 APPLICATIONS INFORMATION The peak-to-peak drive levels are set by the INTV This voltage is typically 5.4V during start-up (see EXTV Pin Connection). Consequently, logic-level threshold MOSFETs must be used in most applications. Pay close attention to the BV specifi cation for the MOSFETs as DSS well; many of the logic level MOSFETs are limited to 30V or less ...
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... LTC3859, ceramic capacitors can also be used for C if there is any question. The benefi the LTC3859 2-phase operation can be calcu- lated by using Equation (1) for the higher power controller and then calculating the loss that would have resulted if both controller channels switched on at the same time ...
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... The output ripple is highest at maximum input voltage since I increases with input voltage. L Setting Output Voltage The LTC3859 output voltages are each set by an external feedback resistor divider carefully placed across the output, as shown in Figure 5. The regulated output voltages are determined by ...
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... MOSFET gate drivers and to prevent interaction between the channels. High input voltage applications in which large MOSFETs are being driven at high frequencies may cause the maxi- mum junction temperature rating for the LTC3859 to be exceeded. The INTV gate charge current, may be supplied by either the V LDO or the EXTV pin is less than 4 ...
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... CC Using the EXTV LDO allows the MOSFET driver and CC control power to be derived from one of the LTC3859’s switching regulator outputs (4.7V ≤ V ing normal operation and from the V output is out of regulation (e.g., startup, short-circuit). If more current is required through the EXTV is specifi ...
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... INTV ing the INTV down the entire LTC3859 chip. Once the junction tempera- ture drops back to approximately 155°C, the INTV turns back on. Long term overstress (T be avoided as it can degrade the performance or shorten the life of the part ...
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... Any of the Above Minimum On-Time Considerations Minimum on-time t that the LTC3859 is capable of turning on the top MOSFET (bottom MOSFET for the boost controller determined by internal timing delays and the gate charge required to turn on the top MOSFET. Low duty cycle applications may ...
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... L1, L2, etc. are the individual losses as a percent- age of input power. Although all dissipative elements in the circuit produce losses, four main sources usually account for most of the losses in LTC3859 circuits regulator current losses, 4) Topside MOSFET transition losses. ...
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... LTC3859 APPLICATIONS INFORMATION amount equal where ESR is the effective LOAD(ESR) series resistance also begins to charge or OUT LOAD discharge C generating the feedback error signal that OUT forces the regulator to adapt to the current change and return V to its steady-state value. During this recovery ...
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... Schottky loop described above the LTC3859 V the (+) terminals of C connected between the (+) terminal of C ground. The feedback resistor connections should not be along the high current input feeds from the input capacitor(s) ...
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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 LTC3859 and occupy minimum PC trace area. 7. Use a modifi ed star ground technique: a low impedance, ...
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... APPLICATIONS INFORMATION BOLD LINES INDICATE HIGH SWITCHING CURRENT. KEEP LINES TO A MINIMUM LENGTH. SW1 L1 R SENSE1 D1 SW2 L2 R SENSE2 D2 Figure 11. Branch Current Waveforms for Bucks www.DataSheet4U.com LTC3859 V OUT1 C R OUT1 L1 V OUT2 C R OUT2 L2 3859 F11 3859f 33 ...
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... L2: WÜRTH 744314650 L3: WÜRTH 744325120 C : SANYO 6TPB220ML OUT1 C : SANYO 10TPC68M OUT2 SANYO 50CE220LX IN OUT3 D1, D2: CMDH-4E D3: BAS140W Figure 12. High Effi ciency Wide Input Range Dual 5V/8.5V Converter 34 LTC3859 – SENSE1 C1 1nF + SENSE1 100k PGOOD1 TG1 SW1 C B1 0.1μF BOOST1 BG1 D1 ...
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... SENSE2 C2 1nF – SENSE2 D3 L3 MTOP3 TG3 1.2μH SW3 C B3 0.1μF BOOST3 BG3 MBOT3 – SENSE3 C3 1nF + SENSE3 3859 F13 www.DataSheet4U.com LTC3859 C1 10μ MTOP1 SENSE1 V 8.8μH 9mΩ OUT1 12V 3A C OUT1 47μF MBOT1 C2 10μF MTOP2 L2 R SENSE2 3.2μH V 6mΩ ...
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... MTOP3, MBOT3: RENESAS HAT2169H L1, L2: SUMIDA CDEP105-0R4 L3: PULSE PA1494.362NL SANYO 2R5TPE220M OUT1 OUT2 SANYO 50CE220AX IN OUT3 D1, D2: CMDH-4E D3: BAS140W Figure 14. High Effi ciency Triple 24V/1V/1.2V Converter from 12V V 36 LTC3859 – SENSE1 C1 1nF + SENSE1 100k PGOOD1 TG1 SW1 C B1 0.1μF BOOST1 BG1 D1 ...
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... MBOT2 + SENSE2 C2 1nF – SENSE2 TG3 C3 SW3 10μF 50V BOOST3 L3 BG3 MBOT3 10μH – SENSE3 C3 1nF + SENSE3 3859 F15 www.DataSheet4U.com LTC3859 C1 10μ SENSE1 2.2μH V 9mΩ OUT1 1. OUT1 220μF C2 10μ SENSE2 6.5μH V 9mΩ OUT2 3.3V ...
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... LTC3859 PACKAGE DESCRIPTION 4.75 REF 6.60 ±0.10 4.50 REF SEE NOTE 4 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.09 – 0.20 0.50 – 0.75 (.0035 – .0079) (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS 2. DIMENSIONS ARE IN MILLIMETERS (INCHES) 3. DRAWING NOT TO SCALE 38 FE Package 38-Lead Plastic TSSOP (4.4mm) ...
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... DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE www.DataSheet4U.com LTC3859 0.70 0.05 PACKAGE OUTLINE PIN 1 NOTCH R = 0.30 TYP OR ...
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... Low I , High Voltage Synchronous Step-Down DC/DC Q Controller LTC3824 Low I , High Voltage DC/DC Controller, 100% Duty Cycle Q 40 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● B1 LTC3859 – V SENSE1 FB1 C1 1nF + SENSE1 100k I PGOOD1 TH1 SS1 TG1 TRACK/SS1 ...