LTC1628-PG Linear Technology, LTC1628-PG Datasheet

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... MOSFET until V can select among Burst Mode, constant frequency mode and continuous inductor current mode or regulate a secondary winding. The LTC1628-PG includes a power good output pin that replaces the FLTCPL, fault coupling control pin of the LTC1628. , LTC and LT are registered trademarks of Linear Technology Corporation. ...

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... V OSENSE2 – 13 SENSE2 + 14 SENSE2 28-LEAD PLASTIC SSOP T = 125 C, JMAX *PGOOD ON THE LTC1628-PG Consult factory for Military grade parts. The denotes the specifications which apply over the full operating = 15V unless otherwise noted RUN/SS1, 2 CONDITIONS (Note 3); I Voltage = 1.2V ...

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... FREQSET Input Current FREQSET 3.3V Linear Regulator V 3.3V Regulator Output Voltage 3.3OUT V 3.3V Regulator Load Regulation 3.3IL V 3.3V Regulator Line Regulation 3.3VL PGOOD Output (LTC1628-PG Only) V PGOOD Voltage Low PGL I PGOOD Leakage Current PGOOD V PGOOD Trip Level, Either Controller PG LTC1628/LTC1628-PG The denotes the specifications which apply over the full operating = 25 C ...

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... P according to the following formulas: D LTC1628/LTC1628-PG • Note 3: The LTC1628/LTC1628-PG are tested in a feedback loop that servos specified voltage and measures the resultant ITH1 OSENSE1 TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Output Current and Mode (Figure 13) ...

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... COMMON MODE VOLTAGE ( ITH RUN/SS 2 0.7V OSENSE 2.0 1.5 1.0 0 (V) RUN/SS LTC1628/LTC1628-PG Maximum Current Sense Threshold vs Percent of Nominal Output Voltage (Foldback 100 PERCENT ON NOMINAL OUTPUT VOLTAGE (%) 1628 G08 Current Sense Threshold vs I Voltage TH 90 ...

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... LTC1628/LTC1628- TYPICAL PERFOR A CE CHARACTERISTICS Maximum Current Sense Threshold vs Temperature –50 – 100 125 TEMPERATURE ( C) 1628 G17 Soft-Start Up (Figure 13) V OUT 5V/DIV V RUN/SS 5V/DIV I OUT 2A/DIV V = 15V 5ms/DIV IN 1628 G19 OUT Input Source/Capacitor Instantaneous Current (Figure 13) ...

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... TEMPERATURE ( C) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0 100 125 –50 1628 G29 LTC1628/LTC1628-PG Oscillator Frequency vs Temperature 350 FREQSET 300 250 V = OPEN FREQSET 200 150 FREQSET 100 50 0 125 – 50 – TEMPERATURE ( C) 1628 G27 Shutdown Latch Thresholds ...

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... LTC1628/LTC1628- CTIO S RUN/SS1, RUN/SS2 (Pins 1, 15): Combination of soft- start, run control inputs and short-circuit detection timers. A capacitor to ground at each of these pins sets the ramp time to full output current. Forcing either of these pins back below 1.0V causes the IC to shut down the circuitry required for that particular controller ...

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... 4.8V 5V – EXTV LDO CC REG INTV INTERNAL SGND SUPPLY STBYMD PGOOD (Pin 28): (LTC1628-PG Only) Open-Drain Logic Output. PGOOD is pulled to ground when the voltage on either V CC OSENSE W DUPLICATE FOR SECOND CONTROLLER CHANNEL DROP OUT DET BOT FCB TOP SWITCH R Q ...

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... LTC1628/LTC1628-PG U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC1628 uses a constant frequency, current mode step-down architecture with the two controller channels operating 180 degrees out of phase. During normal opera- tion, each top MOSFET is turned on when the clock for that channel sets the RS latch, and turned off when the main current comparator resets the RS latch ...

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... INTV . CC CC The PGOOD pin (LTC1628-PG only) is connected to an open drain of an internal MOSFET. The MOSFET turns on and pulls the pin low when both the outputs are not within 7.5% of their nominal output levels as determined by their resistive feedback dividers. When both outputs meet the 7 ...

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... LTC1628/LTC1628-PG U OPERATIO (Refer to Functional Diagram) overcurrent and/or short-circuit condition. Foldback cur- rent limiting is also activated when the output voltage falls below 70% of its nominal level whether or not the short- circuit latchoff circuit is enabled. Even if a short is present and the short-circuit latchoff is not enabled, a safe, low ...

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... This internal capacitor is charged by a fixed current plus an additional current that is proportional to the . voltage applied to the FREQSET pin graph for the voltage applied to the FREQSET pin vs frequency is given in Figure 5. As the operating frequency LTC1628/LTC1628- MAX 13 ...

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... LTC1628/LTC1628- APPLICATIO S I FOR ATIO 2.5 2.0 1.5 1.0 0.5 0 120 170 220 OPERATING FREQUENCY (kHz) Figure 5. FREQSET Pin Voltage vs Frequency is increased the gate charge losses will be higher, reducing efficiency (see Efficiency Considerations). The maximum switching frequency is approximately 310kHz. Inductor Value Calculation The operating frequency and inductor selection are inter- related in that higher operating frequencies allow the use of smaller inductor and capacitor values ...

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... The ESR of the capacitor is important for capacitor power dissipation as well as overall battery efficiency. All of the power (RMS ripple current • ESR) not only heats up the capacitor but wastes power from the battery. LTC1628/LTC1628-PG vs Temperature curve, but DS(ON) is usually specified in the MOS- RSS ...

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... LTC1628/LTC1628- APPLICATIO S I FOR ATIO Medium voltage (20V to 35V) ceramic, tantalum, OS-CON and switcher-rated electrolytic capacitors can be used as input capacitors, but each has drawbacks: ceramic voltage coefficients are very high and may have audible piezoelec- tric effects; tantalums need to be surge-rated; OS-CONs suffer from higher inductance, larger case size and limited surface-mount applicability ...

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... EXTV supplying internal power. The switch remains closed as long as the voltage applied to EXTV This allows the MOSFET driver and control power to be LTC1628/LTC1628-PG and 3.3V linear regulators also CC current can be supplied by CC ...

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... LTC1628/LTC1628- APPLICATIO S I FOR ATIO derived from the output during normal operation (4.7V < V < 7V) and from the internal regulator when the output OUT is out of regulation (start-up, short-circuit). If more cur- rent is required through the EXTV CC fied, an external Schottky diode can be added between the ...

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... Figure 7 reduces the start delay but allows C up slowly providing the soft-start function. Each RUN/SS pin has an internal 6V zener clamp (See Functional Diagram). 3. *OPTIONAL TO DEFEAT OVERCURRENT LATCHOFF LTC1628/LTC1628-PG ITH When the voltage on RUN/SS1 (RUN/SS2 The output current limit ramps SENSE 1 5 ...

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... LTC1628/LTC1628- APPLICATIO S I FOR ATIO Fault Conditions: Overcurrent Latchoff The RUN/SS pins also provide the ability to latch off the controller(s) when an overcurrent condition is detected. The RUN/SS capacitor used initially to turn on and SS limit the inrush current. After the controller has been ...

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... If the duty cycle drops below the minimum on-time limit in this and 3.3V) will CC situation, a significant amount of cycle skipping can occur with correspondingly larger current and voltage ripple. LTC1628/LTC1628- fix or modulate the CC is the smallest time duration ON(MIN) ...

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... LTC1628/LTC1628- APPLICATIO S I FOR ATIO FCB Pin Operation The FCB pin can be used to regulate a secondary winding logic level input. Continuous operation is forced when the FCB pin drops below 0.8V. During continuous mode, current flows continuously in the transformer pri- mary. The secondary winding(s) draw current only when the bottom, synchronous switch is on ...

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... IN quirement over competing solutions. Other losses includ- ing Schottky conduction losses during dead-time and inductor core losses generally account for less than 2% total additional loss. LTC1628/LTC1628-PG , then the resistance of one DS(ON losses. For example, if each = 50m , R = 10m and R ...

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... LTC1628/LTC1628- APPLICATIO S I FOR ATIO Checking Transient Response The regulator loop response can be checked by looking at the load current transient response. Switching regulators take several cycles to respond to a step in DC (resistive) load current. When a load step occurs, V amount equal to I (ESR), where ESR is the effective ...

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... Although the LTC1628 has a maximum input voltage of 36V, most applications will be limited to 30V by the MOSFET BVDSS. 50A I RATING 12V LTC1628 TRANSIENT VOLTAGE SUPPRESSOR GENERAL INSTRUMENT 1.5KA24A Figure 9. Automotive Application Protection LTC1628/LTC1628-PG 1628 F09 25 ...

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... LTC1628/LTC1628- APPLICATIO S I FOR ATIO Design Example As a design example for one channel, assume V 12V(nominal 22V(max OUT and f = 300kHz. The inductance value is chosen first based on a 30% ripple current assumption. The highest value of ripple current occurs at the maximum input voltage. Tie the FREQSET pin to the INTV pin for 300kHz operation ...

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... *PGOOD ON THE LTC1628-PG Figure 10. LTC1628 Recommended Printed Circuit Layout Diagram Are the signal and power grounds kept separate? The combined LTC1628 signal ground pin and the ground return of C terminals. The path formed by the top N-channel MOSFET, Schottky diode and the C leads and PC trace lengths. The output capacitor (– ...

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... LTC1628/LTC1628- APPLICATIO S I FOR ATIO BOLD LINES INDICATE HIGH, SWITCHING CURRENT LINES. KEEP LINES TO A MINIMUM LENGTH. signal ground and a small V OSENSE should be as close as possible to the LTC1628 SGND pin. The R2 and R4 connections should not be along the high current input feeds from the input capacitor(s). – ...

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... Compensation of the voltage loop will be much more sensitive to component selection. This behavior can be investigated by temporarily shorting out the current sensing resistor—don’t worry, the regulator will still maintain control of the output voltage. LTC1628/LTC1628-PG to prevent the short-circuit IN from its nominal level to verify operation of the IN ...

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... SENSE2 180pF 0 28V *PGOOD ON THE LTC1628- 5V, 3A/3.3V, 6A, 12V, 150mA OUT SWITCHING FREQUENCY = 300kHz MI, M2, M3, M4: NDS8410A L1: SUMIDA CEP123-6R3MC T1 1:1.8 — DALE LPE6562-A262 GAPPED E-CORE OR BH ELECTRONICS #501-0657 GAPPED TOROID Figure 12. LTC1628 High Efficiency Low Noise 5V/3A, 3.3V/5A, 12/120mA Regulator ...

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... DWG # 05-08-1640 – 8 0.65 (0.0256) BSC 0.25 – 0.38 (0.010 – 0.015) LTC1628/LTC1628-PG 10.07 – 10.33* (0.397 – 0.407 7.65 – 7.90 (0.301 – 0.311 1.73 – 1.99 (0.068 – 0.078) 0.05 – 0.21 (0.002 – 0.008) ...

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... M2B V OUT2 3.3V 0.015 3A; 4A PEAK 1628 F13 *PGOOD ON THE LTC1628-PG COMMENTS 100% DC, Logic Level MOSFETs, V < 40V IN POR, External Feedback Divider Auxiliary Regulator, 5V Standby 5V Standby, POR, Low-Battery, Aux Regulator High Efficiency 5V to 3.3V Conversion 15A 97% Efficiency, No Sense Resistor, 16-Pin SSOP ...