lt3782aeufd Linear Technology Corporation, lt3782aeufd Datasheet

Page 1

... LT3782 except that the LT3782A has a tighter current sense mismatch tolerance. The LT3782A is available in thermally enhanced 28-lead TSSOP and 4mm × 5mm QFN packages. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6144194. 20μH 10μ ...

Page 2

... LT3782AEFE LT3782AEFE#TR LT3782AIFE LT3782AIFE#TR LT3782AEUFD LT3782AEUFD#TR LT3782AIUFD LT3782AIUFD#TR Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: ...

Page 3

ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T PARAMETER Overall Supply Voltage ( Supply Current (I ) VCC Shutdown RUN Threshold RUN Threshold Hysteresis Supply Current in Shutdown RUN Pin Input Current Voltage Amplifi ...

Page 4

LT3782A ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T PARAMETER Gate Driver V GBIAS BGATE1, BGATE2 High Voltage BGATE1, BGATE2 Source Current (Peak) BGATE1, BGATE2 Low Voltage BGATE1, BGATE2 Sink Current (Peak) SGATE1, SGATE2 High Voltage SGATE1, SGATE2 ...

Page 5

TYPICAL PERFORMANCE CHARACTERISTICS Switching Frequency vs R FREQ 600 500 400 300 200 100 100 120 140 160 180 R (kΩ) FREQ 3782A G04 Start-Up GBIAS GBIAS (Charging 2μ ...

Page 6

LT3782A PIN FUNCTIONS (FE/UFD) SGATE2 (Pin 1/Pin 26): Second Phase Synchronous Drive Signal. An external driver buffer is needed to drive the top synchronous power FET. SGATE1 (Pin 2/Pin 27): First Phase Synchronous Drive Signal. An external driver buffer is ...

Page 7

BLOCK DIAGRAM – 1V AND CLAMPED AT 11V C GBIAS REGULATOR 20μF + LOW POWER SHUTDOWN R6 A5 RUN – 0. – + 2.44V BGATE1 ...

Page 8

LT3782A APPLICATIONS INFORMATION Operation The LT3782A is a two phase constant frequency current mode boost controller. Switching frequency can be pro- grammed up to 500kHz. During normal switching cycles, the two channels are controlled by internal fl ip-fl ops and ...

Page 9

APPLICATIONS INFORMATION With a 200ns one-shot timer on chip, the LT3782A provides fl exibility on the external sync pulse width. The sync pulse threshold is about 1.2V (Figure 1). This pin can be fl oated when the sync function is ...

Page 10

LT3782A APPLICATIONS INFORMATION then should be 80k and V FREQ1 FREQ2 be 1V, with V = 2.3V then R RSET FREQ1 = 32.5k (see Figure 3). Duty Cycle Limit When DCL pin is shorted to R pin ...

Page 11

APPLICATIONS INFORMATION The Peak and Average Input Currents The control circuit in the LT3782A measures the input cur- rent by using a sense resistor in each MOSFET source, so the output current needs to be refl ected back to the ...

Page 12

LT3782A APPLICATIONS INFORMATION The gate drive voltage is set by the 10V GBIAS regulator. Consequently, 10V rated MOSFETs are required in most high voltage LT3782A applications. Pay close attention to the BV DSS MOSFETs relative to the maximum actual switch ...

Page 13

APPLICATIONS INFORMATION From a known power dissipated in the power MOSFET, its junction temperature can be obtained using the following formula • FET TH(JA) The used in this equation ...

Page 14

LT3782A APPLICATIONS INFORMATION For a given V and can calculate the duty cycle D IN OUT and then derive the output RMS ripple current from Figure 6. After choosing output capacitors with suffi cient RMS ripple current ...

Page 15

APPLICATIONS INFORMATION 2 3. The I R losses in the sense resistor can be calculated almost by inspection O(MAX • R • R(SENSE) 1– D MAX 4. The losses in the inductor are simply ...

Page 16

LT3782A TYPICAL APPLICATIONS 1 SGATE2 2 SGATE1 GND 5 SYNC 6 DELAY 7 DCL 10Ω CS1 SENSE1 10nF 9 – SENSE1 59k 10 SLOPE 82k 11 R SET 12 – SENSE2 10nF 10Ω ...

Page 17

TYPICAL APPLICATIONS LT3782A 3782af 17 ...

Page 18

LT3782A PACKAGE DESCRIPTION 4.75 (.187) 6.60 ±0.10 4.50 ±0.10 SEE NOTE 4 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.09 – 0.20 0.50 – 0.75 (.0035 – .0079) (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS 2. ...

Page 19

... ON THE TOP AND BOTTOM OF PACKAGE Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. UFD Package 28-Lead Plastic QFN (4mm × ...

Page 20

... Synchronous Flyback Controller LTC3850 Dual, 250kHz to 750kHz, 2-Phase Synchronous Step-Down Controller LTC3862/LTC3862-1 Multiphase High Power Current Mode Step-Up Controller PolyPhase is a registered trademark of Linear Technology Corporation. ThinSOT and No R Linear Technology Corporation 20 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● ...