LTC1628 LINER [Linear Technology], LTC1628 Datasheet
LTC1628
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LTC1628 Summary of contents
Page 1
... 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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... Peak Output Current <10 s (TG1, TG2, BG1, BG2) ... 3A INTV Peak Output Current ................................ 50mA CC Operating Temperature Range LTC1628C/LTC1628C-PG ........................ LTC1628I/LTC1628I-PG ..................... – Junction Temperature (Note 2) ............................. 125 C Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T ...
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... RUN/SS2 V Rising from 3V RUN/SS1, RUN/SS2 Soft Short Condition V = 0.5V; OSENSE1 4.5V RUN/SS1 0.5V OSENSE1 0.7V SENSE1 – – OSENSE1 0.7V,V = 5V, LTC1628 Only SENSE1 – – OSENSE1, 2 (Note 3300pF LOAD C = 3300pF LOAD (Note 3300pF LOAD C = 3300pF LOAD C = 3300pF Each Driver LOAD 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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... CTIO S FLTCPL (Pin 28): (LTC1628 Only) Fault Coupling Control Pin that determines if fault/normal conditions on one controller will act on the other controller. FLTCPL = INTV to couple channels; FLTCPL = 0V to decouple CTIO AL DIAGRA 1.19V 1M FREQSET CLK1 OSCILLATOR CLK2 FLTCPL RUN/SS1 MERGE LOGIC ...
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... I SS gradually released allowing normal, full-current opera- tion. When both RUN/SS1 and RUN/SS2 are low, all LTC1628 controller functions are shut down, and the STBYMD pin determines if the standby 5V and 3.3V regulators are kept alive. Low Current Operation The FCB pin is a multifunction pin providing two func- ...
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... If the condition lasts for a long enough period as determined by the size of the RUN/SS capacitor, the controller (or both controllers as determined by the FLTCPL pin, LTC1628 only) will be shut down until the RUN/SS pin(s) voltage(s) are recycled. This built-in latchoff can be overridden by providing a > ...
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... Figure 3. Input Waveforms Comparing Single-Phase (a) and 2-Phase (b) Operation for Dual Switching Regulators Converting 12V to 5V and 3. Each. The Reduced Input Ripple with the LTC1628 2-Phase Regulator Allows Less Expensive Input Capacitors, Reduces Shielding Requirements for EMI and Improves Efficiency 12 With 2-phase operation, the two channels of the dual- switching regulator are operated 180 degrees out of phase ...
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... U U APPLICATIO S I FOR ATIO Figure 1 on the first page is a basic LTC1628 application circuit. External component selection is driven by the load requirement, and begins with the selection of R and the inductor value. Next, the power MOSFETs and D1 are selected ...
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... However, designs for surface mount are available that do not increase the height significantly. Power MOSFET and D1 Selection Two external power MOSFETs must be selected for each controller with the LTC1628: One N-channel MOSFET for ). Remember, the the top (main) switch, and one N-channel MOSFET for the MAX bottom (synchronous) switch ...
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... Selection criteria for the power MOSFETs include the “ON” resistance R , reverse transfer capacitance C DS(ON) input voltage and maximum output current. When the LTC1628 is operating in continuous mode the duty cycles for the top and bottom MOSFETs are given by: V OUT Main Switch Duty Cycle ...
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... Always consult the manufacturer if there is any question. The benefit of the LTC1628 multiphase can be calculated by using the equation above for the higher power control- ler and then calculating the loss that would have resulted if both controller channels switch on at the same time. The ...
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... An internal P-channel low dropout regulator produces 5V at the INTV pin from the V supply pin. INTV CC IN the drivers and internal circuitry within the LTC1628. The INTV pin regulator can supply a peak current of 50mA CC and must be bypassed to ground with a minimum of 4.7 F tantalum special polymer, or low ESR type electrolytic capacitor ...
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... If a change is made and the input current decreases, then the efficiency has improved. If there is no change in input current, then there is no change in efficiency SEC + LTC1628 SENSE V OUT T1 EXTV CC ...
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... U U APPLICATIO S I FOR ATIO Output Voltage The LTC1628 output voltages are each set by an external feedback resistive divider carefully placed across the output capacitor. The resultant feedback signal is com- pared with the internal precision 0.800V voltage reference by the error amplifier. The output voltage is given by the ...
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... CC maximum sense voltage is progressively lowered from 75mV to 25mV. Under short-circuit conditions with very low duty cycles, the LTC1628 will begin cycle skipping in order to limit the short-circuit current. In this situation the bottom MOSFET will be dissipating most of the power but less than in normal operation. The short-circuit ripple ...
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... INTV oscillator frequency as shown in Figure 5. Minimum On-Time Considerations Minimum on-time t that the LTC1628 is capable of turning on the top MOSFET. returns to a safe level determined by internal timing delays and the gate charge required to turn on the top MOSFET. Low duty cycle ...
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... V again above its minimum. In order to prevent erratic operation if no external connec- tions are made to the FCB pin, the FCB pin has a 0.18 A Figure 8. Active Voltage Positioning Applied to the LTC1628 internal current source pulling the pin high. Include this current when choosing resistor values R5 and R6 ...
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... adequate charge storage and very low ESR at the switch- ing frequency. A 25W supply will typically require a minimum capacitance having a maxi- mum of 20m to 50m of ESR. The LTC1628 2-phase switch input CC architecture typically halves this input capacitance re- current IN quirement over competing solutions. Other losses includ- ...
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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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... Note that the transient suppressor should not conduct during double-battery operation, but must still clamp the input voltage below breakdown of the converter. Although the LTC1628 has a maximum input voltage of 36V, most applications will be limited to 30V by the MOSFET BVDSS. 50A I ...
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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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... PC Board Layout Checklist When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the LTC1628. These items are also illustrated graphically in the layout diagram of Figure 10. The Figure 11 illustrates the current waveforms present in the various branches of the 2-phase synchronous regulators operating in the continuous mode ...
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... 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). – Are the SENSE ...
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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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... TO 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 30 1M FLTCPL 100k MBRS1100T3 V PULL-UP (<7V) 28 ...
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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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... I BOOST2 TH2 0 SW2 OSENSE2 13 16 – SENSE2 TG2 SENSE2 RUN/SS2 L1, L2 SUMIDA CEP1238R0MC OUTPUT CAPACITORS: PANASONIC SP SERIES Figure 13. LTC1628 5V/4A, 3.3V/4A Regulator Synchronous Controller 0.015 V OUT1 5V 3A; 4A PEAK M1A M1B D1 MBRM 140T3 50V 0.1 F GND ...