background image

24

LTC1624

TYPICAL APPLICATIO

N

S

U

+

+

SENSE

I

TH

/RUN

V

FB

GND

V

IN

BOOST

TG

SW

LTC1624

1000pF

100pF

C

C

330pF

R

C

6.8k

D1

MBRS130LT3

D2

CMDSH-3

C

B

0.1

µ

F

8

7

6

5

1

2

3

4

+

R2

35.7k

1%

R1

11k

1%

C

OUT

100

µ

F

16V

×

 2

M1
Si6426DQ

L1b*

L1a*

R

SENSE

0.05

 

C

IN

22

µ

F

35V

×

 2

22

µ

F

35V

V

OUT

5V
1A

V

OUT

V

IN

3.6V TO 18V

1624 F17

  * COILTRONICS CTX20-4

0.1

µ

F

Figure 17. 5V/1A SEPIC Converter with Output Derived Boost Voltage

Figure 18. 24V to 12V/10A Buck Converter with Output-Derived Boost Voltage

+

SENSE

I

TH

/RUN

V

FB

GND

V

IN

BOOST

TG

SW

LTC1624

C

IN1

, C

IN2

1000

µ

F

35V

×

 2

V

IN

13V TO

28V

D1*

C

B

0.1

µ

F

C5
3.3

µ

F

50V

C4, 0.1

µ

F

8

7

6

5

1

2

3

4

R

SENSE2

, 0.015

R1
11k
1%

R

C

20k

C

C

100pF

M1*

C

OUT

2700

µ

F

16V

R5
220

R2
100k
1%

Z1
IN 755

L1

V

OUT

12V
10A

1624 F18

C

IN1

, C

IN2

 = SANYO 35MV1000GX

C5, C7 = WIMA MKS2
C

OUT

 = SANYO 16MV2700GX

D1 = MOTOROLA MBR2535CT
L1 = PULSE ENGINEERING PO472

M1 = INTERNATIONAL RECTIFIER  IRL3803
R

SENSE1

, R

SENSE2

 = IRC LR2010-01-R015-F

* BOTH D1 AND M1 MOUNTED TO SAME
   THERMALLOY #6399B HEAT SINK

R

SENSE1

, 0.015

+

C7
3.3

µ

F

50V

C9
0.1

µ

F

C10
220pF

D2
MBR0540

Содержание LTC1624

Страница 1: ...oost step down inverting and SEPIC Burst ModeTM operation provides high efficiency at low load currents A maximum highdutycyclelimitof95 provideslowdropoutoperation whichextendsoperatingtimeinbattery...

Страница 2: ...Regulation VIN 3 6V to 20V Note 2 0 002 0 01 V VLOAD REG Output Voltage Load Regulation Note 2 ITH Sinking 5 A 0 5 0 8 ITH Sourcing 5 A 0 5 0 8 VOVL Output Overvoltage Lockout 1 24 1 28 1 32 V IQ Inpu...

Страница 3: ...ge Boost Line Regulation INPUT VOLTAGE V 0 BOOST VOLTAGE V 6 5 4 3 2 1 0 15 25 1624 G04 5 10 20 30 35 IBOOST 1mA VSW 0V BOOST LOAD CURRENT mA 0 BOOST VOLTAGE V 6 5 4 3 2 1 0 15 25 1624 G06 5 10 20 30...

Страница 4: ...0 10 60 85 1448 G12 15 35 110 135 VOUT IN REGULATION VFB 0V PIN FUNCTIONS U U U SENSE Pin 1 Connects to the input for the current comparator Built in offsets between the SENSE and VIN pinsinconjunctio...

Страница 5: ...charged during each off cycle The dropout detector counts the number of oscillator cycles that the top MOSFET remains on and periodically forces a brief off period to allow CB to recharge Themaincontr...

Страница 6: ...RIVER TG SW D1 L1 N CHANNEL MOSFET N CHANNEL MOSFET INTV CC R SENSE SENSE D B 5 6V INTV CC REG V IN 0 8V 1 19V 200kHz 200kHz 1 19V I TH RUN 1 28V 1 19V 180k 1 5V 3 A 30k 8k 2 3 4 5 6 7 GND 1624 FD 2 5...

Страница 7: ...esults in higher output voltage ripple and greater core losses A reasonable starting point for setting ripple current is IL 0 4 IMAX Remember the maximum IL occurs at the maximum input voltage The ind...

Страница 8: ...eterm 1 isgenerallygivenforaMOSFETintheform of a normalized RDS ON vs Temperature curve but 0 005 C can be used as an approximation for low voltageMOSFETs CRSSisusuallyspecifiedintheMOSFET APPLICATION...

Страница 9: ...will be scaled by a factor of Duty Cycle Efficiency For 5V regulators this simply means connecting the BOOST monlyusedfordesignbecauseevensignificantdeviations donotoffermuchrelief Notethatcapacitorma...

Страница 10: ...at approximately 10mV RSENSE at VITH RUN 1 4V and ends at 160mV RSENSE VITH RUN 2 4V The output current thus ramps up slowly charging the outputcapacitor Thepeakinductorcurrentandmaximum output curren...

Страница 11: ...ed in the sense resistor only when the topside MOSFET is on The I2R loss is thus reduced by the duty cycle For example at 50 DC if RDS ON 0 05 RL 0 15 and RSENSE 0 05 then the effective total resistan...

Страница 12: ...Note that the transient suppressor should not conduct during double battery operation but must still clamptheinputvoltagebelowbreakdownoftheconverter Although the LTC1624 has a maximum input voltage o...

Страница 13: ...VIN In this case the worst case dissipation rises to P I V V V V D SC AVG D IN IN D APPLICATIONS INFORMATION W U U U With the 0 05 sense resistor ISC AVG 2A will result increasing the 0 5V Schottky di...

Страница 14: ...the peak inductor current occuring at VIN MIN and IOUT MAX I V V V V kHz L V V L IN OUT D IN OUT D P P 200 with IL MAX IL P P at VIN VIN MIN Remember boost converters are not short circuit pro tected...

Страница 15: ...The input voltage source imped ance determines the size of the capacitor that is typically 10 F to 100 F A low ESR is recommended although not as critical as the output capacitor and can be on the or...

Страница 16: ...tional term for transition losses that are highest at high total input plus output voltages For VIN VOUT 20V the high current efficiency generally improves with larger MOSFETs while for VIN VOUT 20V t...

Страница 17: ...UT D IN MIN L 1 1 Schottky diodes such as MBR130LT3 are recommended SEPIC Converter Input and Output Capacitors The output capacitor is normally chosen by its effective series resistance ESR because t...

Страница 18: ...h Duty Cycle V V OUT IN with VOUT being the absolute value of VOUT The MOSFET power dissipation and maximum switch current are given by that the voltage across C1 is constant such that VC1 VIN at full...

Страница 19: ...N I I V V V V I L PEAK OUT MAX IN OUT D IN L 2 The ripple current in the inductor IL is typically 20 to 50 of the peak inductor current occuring at VIN MIN and IOUT MAX to minimize output ripple Maxim...

Страница 20: ...624 ground pin referenced to VOUT the nonimal range on the ITH RUN pin is VOUT in shutdown to VOUT 2 4V at Max IOUT Referring to Figure15 M2 M3andR3providealevelshiftfromtypical TTL levels to the LTC1...

Страница 21: ...8 7 6 5 1 2 3 4 R2 35 7k 1 R1 11k 1 COUT 100 F 10V 2 M1 Si4412DY L1 10 H RSENSE 0 033 CIN 22 F 35V 2 VOUT 5V 3A VIN 5 3V TO 28V 1624 F10 COILTRONICS CTX10 4 0 1 F Figure 10 5V 3A Converter with Outpu...

Страница 22: ...ST TG SW LTC1624 1000pF 100pF CC 470pF RC 6 8k D1 MBRS140T3 CB 0 1 F 8 7 6 5 1 2 3 4 R2 35 7k 1 R1 3 92k 1 COUT 100 F 16V 2 M1 Si4412DY L1 47 H RSENSE 0 068 CIN 22 F 35V 2 VOUT 12V 1A VIN 12 3V TO 28V...

Страница 23: ...F 8 7 6 5 1 2 3 4 R2 35 7k 1 R1 20k 1 COUT 100 F 10V 2 M1 Si6426DQ L1 20 H RSENSE 0 068 CIN 22 F 35V 2 VOUT 3 3V 1 5A VIN 3 5V TO 18V 1624 F16 COILTRONICS CTX20 4 0 1 F Figure 16 Low Dropout 3 3V 1 5A...

Страница 24: ...12V 10A Buck Converter with Output Derived Boost Voltage SENSE ITH RUN VFB GND VIN BOOST TG SW LTC1624 CIN1 CIN2 1000 F 35V 2 VIN 13V TO 28V D1 CB 0 1 F C5 3 3 F 50V C4 0 1 F 8 7 6 5 1 2 3 4 RSENSE2...

Страница 25: ...MOTOROLA MBR2535CT L1 MAGNETICS CORE 55930AZ WINDING 8T 14BIF M1 INTERNATIONAL RECTIFIER IRL 3803 RSENSE IRC OAR 3 0 005 5 BOTH D1 AND Q1 MOUNTED ON THERMALLOY MODEL 6399 HEAT SINK SENSE ITH RUN VFB...

Страница 26: ...RRENT ADJ R2 35 7k RC 10k CC 330pF M1 COUT 100 F 16V 2 L1 27 H R4 0 025 VOUT 12V 3A 1624 F21 CIN1 CIN2 KEMET T495X226M035AS L1 SUMIDA CDRH127 270 RSENSE IRC LR2010 01 R033 F R4 IRC LR2010 01 R025 F M1...

Страница 27: ...2 0 014 0 019 0 355 0 483 0 004 0 010 0 101 0 254 0 050 1 270 TYP DIMENSION DOES NOT INCLUDE MOLD FLASH MOLD FLASH SHALL NOT EXCEED 0 006 0 152mm PER SIDE DIMENSION DOES NOT INCLUDE INTERLEAD FLASH IN...

Страница 28: ...LT 1375 LT1376 1 5A 500kHz Step Down Switching Regulators High Frequency LTC1433 LTC1434 Monolithic 0 45A Low Noise Current Mode Step Down Switching Regulators 16 and 20 Pin Narrow SSOP LTC1435 High...

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