LTC3736 LINER [Linear Technology], LTC3736 Datasheet
LTC3736
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LTC3736 Summary of contents
Page 1
... Burst Mode operation is inhibited dur- ing synchronization or when the SYNC/FCB pin is pulled low in order to reduce noise and RF interference. Automatic soft- start is internally controlled. The LTC3736 is available in the tiny thermally enhanced (4mm package. , LTC and LT are registered trademarks of Linear Technology Corporation. ...
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... TG1, TG2, BG1, BG2 Peak Output Current (<10 s) ..... 1A Operating Temperature Range (Note 2) ... – Storage Temperature Range .................. – 125 C + 0.3V) Junction Temperature (Note 3) ............................ 125 C IN Lead Temperature (Soldering, 10 sec 10V Max (LTC3736EGN) ..................................................... 300 ORDER PART NUMBER SW1 LTC3736EUF ...
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... FB Note 4: Dynamic supply current is higher due to gate charge being delivered at the switching frequency. Note 5: The LTC3736 is tested in a feedback loop that servos I specified voltage and measures the resultant V Note 6: Peak current sense voltage is reduced dependent on duty cycle to a percentage of value as shown in Figure 1. ...
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... LTC3736 W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Load Current 100 FIGURE 15 CIRCUIT SYNC/FCB = 3.3V OUT 2.5V OUT V = 1.8V 55 OUT V = 1.2V OUT 100 1000 10000 LOAD CURRENT (mA) 3736 G01 Load Step (Pulse Skipping Mode) V OUT AC-COUPLED 100mV/DIV ...
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... TEMPERATURE ( C) 3736 G13 Undervoltage Lockout Threshold vs Temperature 2.50 2.45 2.40 2.35 2.30 2.25 2.20 2.15 2. 100 –60 –40 3736 G15 LTC3736 = 25 C unless otherwise noted. Regulated Feedback Voltage vs Temperature 0.609 0.607 0.605 0.603 0.601 0.599 0.597 0.595 0.593 0.591 –60 – – TEMPERATURE ( C) Maximum Current Sense Threshold ...
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... LTC3736 W U TYPICAL PERFOR A CE CHARACTERISTICS Shutdown Quiescent Current vs Input Voltage 20 RUN/ INPUT VOLTAGE ( CTIO S (UF/GN Package (Pins 1, 8/ Pins 4, 11): Current Threshold and TH1 TH2 Error Amplifier Compensation Point. Nominal operating range on these pins is from 0 ...
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... SLOPE2 – V FB1 FCB FCB + 0.54V VOLTAGE IPROG1 + MAXIMUM SELECT IPROG2 – V FB2 LTC3736 and SW pins (i.e., the maximum allowed drop , GND or float to select 204mV, 85mV or 125mV (Pins 24, 7/Pins 3, 10): Feedback Pins. Receives INTSS UV1 PGOOD OV1 SHDN 3736 FD OV2 UV2 3736f 7 ...
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... LTC3736 CTIO AL DIAGRA CLK1 – ICMP + IPROG1 BURSTDIS 0.3V SLEEP1 OV1 8 W (Controller 1) RS1 SWITCHING LOGIC ANTISHOOT AND THROUGH OV1 BLANKING CIRCUIT SC1 FCB SLEEP1 IREV1 SLOPE1 SW1 + SENSE1 SHDN + – – + SC1 BURSTDIS 0.15V – V FB1 OVP IREV1 + 0.68V ...
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... OV2 BLANKING SC2 CIRCUIT FCB SLEEP2 IREV2 SLOPE2 SW2 + SENSE2 + – – + SC2 BURSTDIS 0.15V TRACK – V FB2 OVP IREV2 + 0.68V IPROG2 LTC3736 SENSE2 TG2 MP2 PGND SW2 L2 + SENSE2 C BG2 OUT2 MN2 PGND SHDN – R2B V FB2 EAMP + R2A V OUT1 ...
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... Shutdown, Soft-Start and Tracking Start-Up (RUN/SS and TRACK Pins) The LTC3736 is shut down by pulling the RUN/SS pin low. In shutdown, all controller functions are disabled and the chip draws only 9 A. The TG outputs are held high (off) and the BG outputs low (off) in shutdown. Releasing RUN/SS allows an internal 0 ...
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... SYNC/FCB pin. In this case, a series RC should be connected between the PLLLPF pin 0.54V), the LTC3736 and SGND to serve as the PLL’s loop filter. The LTC3736 phase detector adjusts the voltage on the PLLLPF pin to align the turn-on of controller 1’s external P-channel MOSFET to the rising edge of the synchronizing signal. Thus, the turn-on of controller 2’ ...
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... Undervoltage Lockout To prevent operation of the external MOSFETs below safe input voltage levels, an undervoltage lockout is incorporated in the LTC3736. When the input supply voltage (V below 2.3V, the external P- and N-channel MOSFETs and all internal circuitry are turned off except for the undervolt- age block, which draws only a few microamperes. ...
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... U OPERATIO (Refer to Functional Diagram) With 2-phase operation, the two controllers of the LTC3736 are operated 180 degrees out of phase. This effectively interleaves the current pulses coming from the topside MOSFET switches, greatly reducing the time where they overlap and add together. The result is a significant ...
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... V = 2.5V) is required for applications that work close to GS this voltage. When these MOSFETs are used, make sure that the input supply to the LTC3736 is less than the abso- lute maximum MOSFET V rating, which is typically 8V. GS The P-channel MOSFET’s on-resistance is chosen based on the required load current ...
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... LTC3736 applications. Selecting the N-channel MOSFET is typically easier, since 2 for a given • off delays are much smaller than for a P-channel MOSFET. Table 1. Selected P-Channel MOSFETs Suitable for LTC3736 ) Applications • • R PART NUMBER Si7540DP ...
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... I V OSC RIPPLE IN Burst Mode Operation Considerations The choice of R and inductor value also determines DS(ON) the load current at which the LTC3736 enters Burst Mode operation. When bursting, the controller clamps the peak inductor current to approximately trade-off OSC I BURST PEAK The corresponding average current depends on the amount of ripple current ...
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... C duce undesirable voltage and current resonances small (0 bypass capacitor between the chip V pin and ground, placed close to the LTC3736, is also IN suggested resistor placed between C the V pin provides further isolation between the two IN channels ...
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... LTC3736. Pulling the RUN/SS pin below 0.7V puts the LTC3736 into a low quiescent current shutdown mode (I RUN/SS has been pulled all the way to ground, there will be a delay before the LTC3736 comes out of shutdown and is given by ...
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... FCB, is shown in Figure 8 and specified in the Electrical Characteristics table. Note that the LTC3736 can only be synchronized to an external clock whose frequency is within range of the LTC3736’s internal VCO, which is nominally 200kHz to 1MHz. This is guaranteed, over temperature and variations between 300kHz and 750kHz ...
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... LTC3736 U U APPLICATIO S I FOR ATIO SYNC/ FCB EXTERNAL OSCILLATOR If the external clock frequency is greater than the internal oscillator’s frequency then current is sourced con- OSC tinuously from the phase detector output, pulling up the PLLLPF pin. When the external clock frequency is less than ...
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... Maximum Sense Voltage for Low Input Supply Minimum On-Time Considerations Minimum on-time which the LTC3736 is capable of turning the top P-channel MOSFET on and then off determined by internal timing delays and the gate charge required to turn on the top MOSFET. Low duty cycle and high frequency ...
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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, five main sources usually account for most of the losses in LTC3736 circuits: 1) LTC3736 DC bias current, 2) MOSFET gate charge current transition losses. 1) The V ...
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... It is most important to keep the ground paths with high switching currents away from each other OUT1 V OUT1 The PGND pins on the LTC3736 IC should be shorted L1 together and connected to the common power ground connection (away from the switching currents). 3) Put the feedback resistors close to the V MN1 MP1 ...
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... IPRG1 PGND BG1 FB1 SYNC/FCB TH1 ITH1 IPRG2 TG1 3 16 15k PLLLPF PGND 4 15 SGND TG2 R 10 LTC3736EUF VIN RUN/ BG2 ITH2 PGND PGOOD 220pF SENSE2 FB2 8 MP2 I TH2 ITH2 TRACK SW2 ...
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... FB2 11 MP2 I TH2 ITH2 TRACK SW2 15k FB2B TRACKA TRACKB 59k 118k 118k OUT1 OUT2 L1, L2: VISHAY IHLP-2525CZ-01 C FF1 100pF LTC3736 L1 1 OUT1 2. MN1 C OUT1 Si3460DV OUT2 MN2 22 F Si3460DV 2 V OUT2 1. 1.5 H 3736 F16 L1 1 ...
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... SW1 SENSE1 23 20 IPRG1 PGND 24 19 MN1 V BG1 FB1 1 18 Si7540DP I SYNC/FCB TH1 17 2 IPRG2 TG1 3 16 PLLLPF PGND 4 15 SGND TG2 LTC3736EUF RUN/ MN2 BG2 9 12 Si7540DP PGND PGOOD SENSE2 FB2 8 MP2 I TH2 6 10 TRACK SW2 PGND 5 ...
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... TYP .015 .004 .053 – .068 45 (0.38 0.10) (1.351 – 1.727) 0 – 8 TYP .008 – .012 (0.203 – 0.305) LTC3736 BOTTOM VIEW—EXPOSED PAD R = 0.115 0.75 0.05 TYP 23 24 2.45 0.10 (4-SIDES) 0.200 REF 0.00 – 0.05 .337 – .344* (8.560 – 8.738) ...
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... MP1 SW1 SENSE1 23 20 IPRG1 PGND BG1 FB1 SYNC/FCB TH1 2 17 IPRG2 TG1 3 16 PLLLPF PGND 4 15 SGND TG2 LTC3736EUF RUN/ BG2 9 12 PGND PGOOD SENSE2 FB2 8 MP2 I TH2 6 10 TRACK SW2 PGND OUT1 ...