manualshive.com logo in svg

Linear Technology LTC3729, Manual, Page: 26 / 28

Share
Download
Linear Technology LTC3729 Manual Download Page 26

26

LTC3729

sn3729 3729fas

Figure 11. High Current 3.3V/90A 6-Phase Application

TYPICAL APPLICATIO S

U

V

IN

: 12V

V

OUT

: 3.3V/90A

SWITCHING FREQUENCY = 400kHz

MI – M18: Si7440DP 
L1 – L6: 1

µ

H PANASONIC ETQP6F1R0S

D7 – D12: CENTROL CMDSH-3TR

OUTPUT CAPACITORS: SANYO 6TPB330M 

28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

CLKOUT

TG1

SW1

BOOST1

V

IN

BG1

EXTV

CC

INTV

CC

PGND

BG2

BOOST2

SW2

TG2

PGOOD

RUN/SS

SENSE1

+

SENSE1

–

EAIN

PLLFLTR

PLLIN

PHASMD

I

TH

SGND

V

DIFFOUT

V

OS

–

V

OS

+

SENSE2

–

SENSE2

+

LTC3729

M5

M6

M4

0.33

µ

F

0.33

µ

F

OPTIONAL

SYNC

CLOCK IN

8.06k, 1%

47k

25.5k, 1%

1000pF

1000pF

6800pF

470pF

100pF

2X150

µ

F

16V

GND

M2

M3

M1

D1
MBRS
340T3

D2
MBRS
340T3

0.47

µ

F

22

µ

F

6.3V 

+

+

1

µ

F

1

µ

F,6.3V

5V

10

Ω

0.47

µ

F

3X330

µ

F, 6.3V

POSCAP

V

OUT

3.3V/90A

+

L1

0.003

Ω

24k

75k

L2

0.003

Ω

28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

CLKOUT

TG1

SW1

BOOST1

V

IN

BG1

EXTV

CC

INTV

CC

PGND

BG2

BOOST2

SW2

TG2

PGOOD

RUN/SS

SENSE1

+

SENSE1

–

EAIN

PLLFLTR

PLLIN

PHASMD

I

TH

SGND

V

DIFFOUT

V

OS

–

V

OS

+

SENSE2

–

SENSE2

+

LTC3729

M11

M12

M10

1nF

10k

1000pF

1000pF

100pF

NC

2X150

µ

F

16V

GND

M8

M9

M7

D3
MBRS
340T3

D4
MBRS
340T3

0.47

µ

F

1

µ

F

10

Ω

0.47

µ

F

3X330

µ

F, 6.3V

POSCAP

V

IN

12V

+

L3

0.003

Ω

3X330

µ

F, 6.3V

POSCAP

L4

0.003

Ω

3729 TA03

0.01

µ

F

47pF

28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

CLKOUT

TG1

SW1

BOOST1

V

IN

BG1

EXTV

CC

INTV

CC

PGND

BG2

BOOST2

SW2

TG2

PGOOD

RUN/SS

SENSE1

+

SENSE1

–

EAIN

PLLFLTR

PLLIN

PHASMD

I

TH

SGND

V

DIFFOUT

V

OS

–

V

OS

+

SENSE2

–

SENSE2

+

LTC3729

M17

M18

M16

1nF

10k

1000pF

1000pF

NC

2X150

µ

F

16V

GND

M14

M15

M13

D5
MBRS
340T3

D6
MBRS
340T3

0.47

µ

F

D8

D10

D12

1

µ

F

10

Ω

0.47

µ

F

D7

D9

D11

+

L5

0.003

Ω

L6

0.003

Ω

0.01

µ

F

47pF

100pF

22

µ

F

6.3V 

+

1

µ

F,6.3V

5V

22

µ

F

6.3V 

+

1

µ

F,6.3V

5V

+

+

Summary of Contents for LTC3729

Page 1: ...ercurrent latchoff is disabled OPTI LOOP compensa tion allows the transient response to be optimized over a wide range of output capacitance and ESR values The LTC3729 includes a power good output pin...

Page 2: ...5 C to 150 C Lead Temperature Soldering 10 sec G Package Only 300 C 32 31 30 29 28 27 26 25 9 10 11 12 13 TOP VIEW UH PACKAGE 32 LEAD 5mm 5mm PLASTIC QFN 14 15 16 17 18 19 20 21 22 23 24 8 7 6 5 4 3 2...

Page 3: ...85 60 A DFMAX Maximum Duty Factor In Dropout 98 99 5 Top Gate Transition Time TG1 2 tr Rise Time CLOAD 3300pF 30 90 ns TG1 2 tf Fall Time CLOAD 3300pF 40 90 ns Bottom Gate Transition Time BG1 2 tr Ris...

Page 4: ...PD 34 C W Note 3 The LTC3729 is tested in a feedback loop that servos VITH to a specified voltage and measures the resultant VEAIN TYPICAL PERFOR A CE CHARACTERISTICS U W Efficiency vs Output Current...

Page 5: ...30 35 ON SHUTDOWN CURRENT mA 0 EXTV CC VOLTAGE DROP mV 150 200 250 40 3729 G05 100 50 0 10 20 30 50 TEMPERATURE C 50 INTV CC AND EXTV CC SWITCH VOLTAGE V 4 95 5 00 5 05 25 75 3729 G06 4 90 4 85 25 0 5...

Page 6: ...s Temperature TYPICAL PERFOR A CE CHARACTERISTICS U W LOAD CURRENT A 0 NORMALIZED V OUT 0 2 0 1 4 3729 G13 0 3 0 4 1 2 3 5 0 0 FCB 0V VIN 15V FIGURE 1 VRUN SS V 0 0 V ITH V 0 5 1 0 1 5 2 0 2 5 1 2 3 4...

Page 7: ...connected to a resistive divider from the output of the differential amplifier DIFFOUT PI FU CTIO S U U U Current Sense Pin Input Current vs Temperature EXTVCC Switch Resistance vs Temperature Oscill...

Page 8: ...ts set point TG2 TG1 Pins 16 27 Pins 14 26 High Current Gate Drives for Top N Channel MOSFETS These are the out puts of floating drivers with a voltage swing equal to INTVCC superimposed on the switch...

Page 9: ...BOT BG INTVCC INTVCC VIN VOUT 3729 FBD R1 EAIN DROP OUT DET RUN SOFT START BOT FCB FORCE BOT S R Q Q OSCILLATOR PLLLPF 50k EA 0 86V 0 80V OV 1 2 A 6V R2 RC 4 VFB RST SHDN RUN SS ITH CC CSS 4 VFB 0 86...

Page 10: ...resume When the RUN SS pin is low all LTC3729 functions are shut down IfVOUT hasnotreached70 ofitsnominalvaluewhenCSS has charged to 4 1V an overcurrent latchoff can be invoked as described in the Ap...

Page 11: ...nal output voltage the RUN SS capacitor begins discharging assuming that the output is in a severe overcurrent and or short circuit condition If the condition lasts for a long enough period as determi...

Page 12: ...al output stagestorunatalowerfundamentalfrequency enhancing efficiency Theinductorvaluehasadirecteffectonripplecurrent The inductor ripple current IL per individual section N decreases with higher ind...

Page 13: ...onous SwitchDuty Cycle V V V IN OUT IN The MOSFET power dissipations at maximum output current are given by Kool M is a registered trademark of Magnetics Inc APPLICATIO S I FOR ATIO W U U U Figure 3 N...

Page 14: ...on output current Schottky diode is generally a good compromise for both regions of operation due to the relatively small average current Larger diodes result in additional transition losses due to t...

Page 15: ...raintsonoutputcapacitor ESR The impedance characteristics of each capacitor type are significantly different than an ideal capacitor and therefore require accurate modeling or bench evaluation during...

Page 16: ...ternal voltage source is applied to the EXTVCC pin when the VIN supply is not present a diode can be placed in series with the LTC3729 s VIN pin and a Schottky diode between the EXTVCCandtheVINpin top...

Page 17: ...external resistive divider according to the following formula V V R R OUT 0 8 1 2 1 where R1 and R2 are defined in Figure 2 Soft Start Run Function The RUN SS pin provides three functions 1 Run Shut...

Page 18: ...vere overcurrent and or short circuit condition When deriving the 5 A current from VIN as in the figure current latchoff is always defeated Diode connecting this pull up resistor to INTVCC as in Figur...

Page 19: ...e slave oscillator s ability to lock onto the master s frequency A DC voltage of 0 7V to 1 7V applied to the master oscillator s PLLFLTR pin is recommended in order to meet this requirement The result...

Page 20: ...percent 3 I2R losses are predicted from the DC resistances of the fuse if used MOSFET inductor current sense resistor and input and output capacitor ESR In continuous mode the average output current...

Page 21: ...ersystem phasemarginand ordampingfactorcanbe estimated using the percentage of overshoot seen at this pin The bandwidth can also be estimated by examining the rise time at the pin The ITH external com...

Page 22: ...ication with some accomodation for tolerances R mV A SENSE 50 11 5 0 005 Choosing 1 resistors R1 16 5k and R2 13 2k yields an output voltage of 1 80V The power dissipation on the topside MOSFET can be...

Page 23: ...o the plate of COUT separately The power ground returns to the sourcesofthebottomN channelMOSFETs anodesofthe Schottky diodes and plates of CIN which should have as short lead lengths as possible 2 Do...

Page 24: ...SFETs and Schottky diodes should return to the bottom plate s of the input capacitor s with a short isolated PC trace since very high switched currents are present A separate isolated path from the bo...

Page 25: ...factor of four A ceramic input capacitor with its unbeatably low ESR characteristic can be used Figure 4 illustrates the RMS input current drawn from the input capacitance versus the duty cycle as de...

Page 26: ...0 003 24k 75k L2 0 003 28 27 26 25 24 23 22 21 20 19 18 17 16 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 CLKOUT TG1 SW1 BOOST1 VIN BG1 EXTVCC INTVCC PGND BG2 BOOST2 SW2 TG2 PGOOD RUN SS SENSE1 SENSE1 EAIN PL...

Page 27: ...er no responsibility is assumed for its use Linear Technology Corporation makes no represen tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights UH Package 3...

Page 28: ...ck Divider LTC1530 High Power Step Down Switching Regulator Controller High Efficiency 5V to 3 3V Conversion at Up to 15A LTC1538 AUX Dual Low Noise Synchronous Step Down Switching Regulators 5V Stand...

Reviews:

No comments