LTC1629 LINER [Linear Technology], LTC1629 Datasheet
LTC1629
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LTC1629 Summary of contents
Page 1
... OPTI-LOOP compensa- tion allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC1629-PG includes a power good output pin that re- places the AMPMD control pin of the LTC1629 ...
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... Peak Output Current <1 s(TGL1,2, BG1,2) ................ 5A INTV RMS Output Current ................................ 50mA CC Operating Ambient Temperature Range LTC1629C/LTC1629C-PG .......................... LTC1629I/LTC1629I-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 ...
Page 3
... Controller 2-Controller 1 Phase RELPHS CLKOUT Phase (Relative to Controller 1) CLK Clock High Output Voltage HIGH CLK Clock Low Output Voltage LOW PGOOD Output (LTC1629-PG Only) V PGOOD Voltage Low PGL I PGOOD Leakage Current PGOOD V PGOOD Trip Level, Either Controller PG Differential Amplifier/Op Amp Gain Block (Note 5) ...
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... T J dissipation P according to the following formulas: D LTC1629/LTC1629-PG • Note 3: The LTC1629/LTC1629-PG are tested in a feedback loop that servos specified voltage and measures the resultant V ITH W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Output Current (Figure 12) 100 80 V ...
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... Duty Factor DUTY FACTOR (%) Maximum Current Sense Threshold vs Sense Common Mode Voltage COMMON MODE VOLTAGE (V) LTC1629/LTC1629-PG INTV and EXTV Switch CC CC Voltage vs Temperature 5.05 INTV VOLTAGE CC 5.00 4.95 4.90 4.85 4.80 EXTV SWITCHOVER THRESHOLD CC 4.75 4.70 50 – 50 – ...
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... LTC1629/LTC1629- TYPICAL PERFOR A CE CHARACTERISTICS Load Regulation 0.0 FCB = 15V IN FIGURE 1 –0.1 –0.2 –0.3 –0 LOAD CURRENT (A) 1629 G13 Maximum Current Sense Threshold vs Temperature –50 – TEMPERATURE ( C) Soft-Start Up (Figure 12) V ITH 1V/DIV V OUT 2V/DIV ...
Page 7
... TH PLLFLTR (Pin 5): The Phase-Locked Loop’s Low Pass + and SENSE pins in Filter is tied to this pin. Alternatively, this pin can be driven with voltage source to vary the frequency of the internal oscillator. LTC1629/LTC1629-PG Oscillator Frequency vs Temperature 350 FREQSET 300 250 ...
Page 8
... Internal precision resistors capable of being elec- tronically switched in or out can configure differen- tial amplifier or an uncommitted Op Amp. AMPMD (Pin 15) (LTC1629 Only): This Logic Input pin controls the connections of internal precision resistors that configure the operational amplifier as a unity-gain differential amplifier ...
Page 9
... CTIO AL DIAGRA LTC1629-PG PGOOD CONNECTION DIFFOUT PGOOD – – THE AMPMD PIN ON THE LTC1629 IS REPLACED BY A PGOOD PIN IN THE LTC1629-PG PLLIN PHASE DET F IN 50k PLLLPF R LP CLKOUT CLK1 C LP OSCILLATOR CLK2 PHASMD PHASE LOGIC 2 A LTC1629 – ...
Page 10
... TH value continues to charge leased allowing normal operation to resume. When the RUN/SS pin is low, all LTC1629 functions are shut down has not reached 70% of its nominal value when C OUT has charged to 4.1V, an overcurrent latchoff can be invoked as described in the Applications Information section ...
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... RMS current typically up to 25mA. The amplifier is not capable U U APPLICATIO S I FOR ATIO The basic LTC1629 application circuit is shown in Figure 1 on the first page. External component selection is driven by the load requirement, and begins with the selection Once R ...
Page 12
... SENSE mode range of SGND to 1.5( INTV parator threshold sets the peak inductor current, yielding a maximum average output current I value less half the peak-to-peak ripple current, I Allowing a margin for variations in the LTC1629 and external component values yields (50mV/I )N SENSE MAX where N = number of stages ...
Page 13
... MOSFETs are limited to 30V or less. Selection criteria for the power MOSFETs include the “ON” resistance R input voltage, and maximum output current. When the LTC1629 is operating in continuous mode the duty factors for the top and bottom MOSFETs of each output stage are ® cores. Actual core ...
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... LTC1629/LTC1629- APPLICATIO S I FOR ATIO The MOSFET power dissipations at maximum output current are given by OUT MAX MAIN MAX RSS – OUT MAX P 1 SYNC where is the temperature dependency of R constant inversely related to the gate drive current and N is the number of stages ...
Page 15
... An internal P-channel low dropout regulator produces 5V /N assuming: at the INTV regulator powers the drivers and internal circuitry of the LTC1629. The INTV peak and must be bypassed to power ground with a minimum of 4.7 F tantalum or electrolytic capacitor. An additional 1 F ceramic capacitor placed very close to the IC is recommended due to the extremely high instanta- neous currents required by the MOSFET gate drivers ...
Page 16
... APPLICATIO S I FOR ATIO High input voltage applications in which large MOSFETs are being driven at high frequencies may cause the maxi- mum junction temperature rating for the LTC1629 to be exceeded. The supply current is dominated by the gate charge supply current, in addition to the current drawn from the differential amplifier output ...
Page 17
... If the input current does not change then the efficiency has not changed either. Output Voltage The LTC1629 has a true remote voltage sense capablity. The sensing connections should be returned from the load back to the differential amplifier’s inputs through a com- mon, tightly coupled pair of PC traces. The differential ...
Page 18
... RAMP pulling the RUN/SS pin below 0.8V the LTC1629 is put into low current shutdown (I < 40 A). RUN/SS can be Q driven directly from logic as shown in Figure 6. Diode D1 in Figure 6 reduces the start delay but allows C up slowly providing the soft-start function. The RUN/SS pin has an internal 6V zener clamp (see Functional Dia- gram) ...
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... Figure 7. Phase-Locked Loop Block Diagram Minimum On-Time Considerations Minimum on-time t that the LTC1629 is capable of turning on the top MOSFET determined by internal timing delays and the gate charge required to turn on the top MOSFET. Low duty cycle applications may approach this minimum on-time limit ...
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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, four main sources usually account for most of the losses in LTC1629 circuits: 1) LTC1629 V cluding loading on the differential amplifier output INTV regulator current ...
Page 21
... Note that the transient suppressor should not conduct during double-battery operation, but must still clamp the input voltage below breakdown of the converter. LTC1629/LTC1629-PG , causing a rapid drop regulator can OUT is greater than1:50, the switch rise time OUT ...
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... LTC1629/LTC1629- APPLICATIO S I FOR ATIO Although the LTC1629 has a maximum input voltage of 36V, most applications will be limited to 30V by the MOSFET BV . DSS 50A I RATING 12V TRANSIENT VOLTAGE SUPPRESSOR GENERAL INSTRUMENT 1.5KA24A Figure 8. Automotive Application Protection Design Example (Using Two Phases) ...
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... Keep the switching nodes, SW1 (SW2), away from sensitive small-signal nodes. Ideally the switch nodes should be placed at the furthest point from the LTC1629. 7) Use a low impedance source such as a logic gate to drive the PLLIN pin and keep the lead as short as possible. ...
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... LTC1629/LTC1629- APPLICATIO S I FOR ATIO 8) Minimize the capacitive load on the CLKOUT pin to minimize excess phase shift. Buffer if necessary with an NPN emitter follower. The diagram in Figure 9 illustrates all branch currents in a 2-phase switching regulator. It becomes very clear after studying the current waveforms why it is critical to keep the high-switching-current paths to a small physical size ...
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... V will significantly reduce the ripple voltage at the input and outputs and thereby improve efficiency, physical size, and heat generation of the overall switching power supply. /L discharge current Figure 10. Single and PolyPhase Current Waveforms LTC1629/LTC1629- )/L charging current IN OUT ...
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... SENSE2 TG2 0. SENSE2 AMPMD 28 RUN/SS CLKOUT 27 + SENSE1 TG1 0. – SENSE1 SW1 25 EAIN BOOST1 D11 10 24 PLLFLTR LTC1629 1 F PLLIN BG1 22 5V PHASMD EXTV CC 1 F,25V INTV 6. SGND PGND 19 V BG2 DIFFOUT 18 – V BOOST2 OS 17 ...
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... BSC 0.25 – 0.38 (0.010 – 0.015) LTC1629/LTC1629- 7.65 – 7.90 (0.301 – 0.311 1.73 – 1.99 (0.068 – 0.078) 0.05 – 0.21 (0.002 – 0.008) G28 SSOP 1098 27 ...
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... FAX: (408) 434-0507 www.linear-tech.com 28 CLKOUT 27 + TG1 0. – SW1 25 BOOST1 BG1 22 5V EXTV CC 1 F,25V 4 INTV 6. LTC1629-PG PGND 19 BG2 18 BOOST2 D4 17 100k SW2 POWER 16 – TG2 0.47 F GOOD 15 + PGOOD CON 2-16SP270M KEMET 3-T510 470 F OUT D3, D4: CENTRAL CMDSH-3TR L1 0.003 M1 ...