LTC1772 Linear Technology, LTC1772 Datasheet
LTC1772
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LTC1772 Summary of contents
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... In shutdown, the device draws a mere 8 A. High constant operating frequency of 550kHz allows the use of a small external inductor. The LTC1772 is available in a small footprint 6-lead SOT-23. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. ...
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... 3000pF LOAD C = 3000pF LOAD Note 4: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. Note 5: The LTC1772 is tested in a feedback loop that servos V output of the error amplifier. and power INFORMATION ORDER PART NUMBER TOP VIEW ...
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... SENSE (Pin 4): The Negative Input to the Current Com- parator. V (Pin 5): Supply Pin. Must be closely decoupled to GND IN Pin 2. PGATE (Pin 6): Gate Drive for the External P-Channel MOSFET. This pin swings from LTC1772 Undervoltage Lockout Trip Voltage vs Temperature 2. 4.2V IN 2.20 V FALLING IN 2 ...
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... U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC1772 is a constant frequency current mode switch- ing regulator. During normal operation, the external P-channel power MOSFET is turned on each cycle when the oscillator sets the RS latch (RS1) and turned off when the current comparator (ICMP) resets the latch. The peak ...
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... The inductor’s peak current is determined by: V ITH SENSE when the LTC1772 is operating below 40% duty cycle. However, once the duty cycle exceeds 40%, slope com- pensation begins and effectively reduces the peak induc- tor current. The amount of reduction is given by the curves in Figure 2. 110 100 90 ...
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... I = 0.4(I RIPPLE occurs at the maximum input voltage. In Burst Mode operation on the LTC1772, the ripple current is normally set such that the inductor current is continuous during the burst periods. Therefore, the peak- to-peak ripple current must not exceed: I ...
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... MOSFET (R guaranteed 2.5V) is required for applications that GS work close to this voltage. When these MOSFETs are used, make sure that the input supply to the LTC1772 is less than the absolute maximum V rating, typically 8V. GS The required minimum R of the MOSFET is gov- DS(ON) erned by its allowable power dissipation ...
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... RMS 4mm. Other capacitor types include Sanyo OS-CON, Nichicon PL series and Panasonic SP. Low Supply Operation Although the LTC1772 can function down to approxi- mately 2.0V, the maximum allowable output current is reduced when V amount of change as the supply is reduced down to 2V. Also shown in Figure 3 is the effect of V goes below 2 ...
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... Although all dissipative elements in the circuit produce losses, four main sources usually account for most of the losses in LTC1772 circuits: 1) LTC1772 DC bias current, 2) MOSFET gate charge current voltage drop of the output diode ...
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... TH For the selection of the external MOSFET, the R = 0V), the current OUT must be guaranteed at 2.5V since the LTC1772 has to work down to 2.7V. Let’s assume that the MOSFET dissipation limited C/W. Hence the junction temperature OUT will be 37.5 C and p = 0.005 (37.5 – 25) = 0.0625. The ...
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... IN R ITH C ITH BOLD LINES INDICATE HIGH CURRENT PATHS Figure 6. LTC1772 Layout Diagram (See PC Board Layout Checklist Connect the end of R possible. The V comparator the trace from SENSE kept short? Does the trace connect close ...
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... LTC1772 U TYPICAL APPLICATIONS LTC1772 High Efficiency, High Output Current 2.5V/2A Regulator R4 10k C3 220pF C1: TAIYO YUDEN CERAMIC EMK325BJ106MNT C2: SANYO POSCAP 6TPA47M D1: IR10BQ015 LTC1772 High Efficiency, Small Footprint 1.8V/0.5A Regulator R4 10k C3 220pF /RUN PGATE M1 TH 4.7 H LTC1772 + 2 5 GND – V SENSE ...
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... U TYPICAL APPLICATIONS R4 10k C3 220pF C1: AVXTPSE476M016R0047 C2: AVXTPSE107M010R0100 D1: MOTOROLA M516 LTC1772 3.3V to 5V/1A Boost Regulator R1 0.033 4.7 H 16V /RUN PGATE LTC1772 2 5 GND – V SENSE FB L1: MURATA LQN6C-4R7 U1: FAIRCHILD NC7SZ04 M1: Si9804DY R1: DALE 0.25W LTC1772 D1 V OUT ...
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... LTC1772 U TYPICAL APPLICATIONS R4 10k C3 220pF C1: AVXTPSE476M016R0047 C2: AVXTPSE107M010R0100 D1: MOTOROLA M516 14 LTC1772 5V/500mA Flyback Regulator R1 0.033 /RUN PGATE LTC1772 150pF CERAMIC GND V IN 100 3 4 – V SENSE • 100pF • CERAMIC M1: Si9803 R1: DALE 0.25W T1: COILTRONICS CTX10-4 ...
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... REF 1.50 – 1.75 0.00 – 0.15 (0.059 – 0.069) (0.00 – 0.006) 0.35 – 0.50 0.09 – 0.20 (0.014 – 0.020) (0.004 – 0.008) SIX PLACES (NOTE 2) (NOTE 2) LTC1772 0.95 (0.037) REF 0.90 – 1.45 (0.035 – 0.057) 0.90 – 1.30 (0.035 – 0.051) S6 SOT-23 0898 15 ...
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... LTC1772 RELATED PARTS PART NUMBER DESCRIPTION LTC1147 Series High Efficiency Step-Down Switching Regulator Controllers LT1375/LT1376 1.5A, 500kHz Step-Down Switching Regulators LTC1436/LTC1436-PLL High Efficiency, Low Noise, Synchronous Step-Down Converters LTC1438/LTC1439 Dual, Low Noise, Synchronous Step-Down Converters LTC1622 Low Input Voltage Current Mode Step-Down DC/DC Controller ...