ltc3862gn-1 Linear Technology Corporation, ltc3862gn-1 Datasheet

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ltc3862gn-1

Manufacturer Part Number
ltc3862gn-1
Description
Multi-phase Current Mode Step-up Dc/dc Controller
Manufacturer
Linear Technology Corporation
Datasheet
FEATURES
APPLICATIONS
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TYPICAL APPLICATION
324k
Wide V
2-Phase Operation Reduces Input and Output
Capacitance
Fixed Frequency, Peak Current Mode Control
10V Gate Drive for High Voltage MOSFETs
Adjustable Slope Compensation Gain
Adjustable Max Duty Cycle (Up to 96%)
Adjustable Leading Edge Blanking
±1% Internal Voltage Reference
Programmable Operating Frequency with One
External Resistor (75kHz to 500kHz)
Phase-Lockable Fixed Frequency 50kHz to 650kHz
SYNC Input and CLKOUT for 2-, 3-, 4-, 6- or
12-Phase Operation (PHASEMODE Programmable)
Internal 10V LDO Regulator
24-Lead Narrow SSOP Package
5mm × 5mm QFN Package with 0.65mm Lead Pitch
24-Lead Thermally Enhanced TSSOP Package
Automotive, Telecom and Industrial Power Supplies
5.62k
IN
45.3k
Range: 8.5V to 36V Operation
1.5nF
4.7μF
1nF
45.3k
24.9k
100pF
0.1μF
150k
RUN
INTV
BLANK
FREQ
SYNC
PLLFLTR
SS
3V8
FB
ITH
CC
LTC3862-1
PHASEMODE
SGND
V
IN
SENSE1
SENSE1
SENSE2
SENSE2
CLKOUT
SLOPE
GATE1
GATE2
PGND
D
MAX
+
+
0.020Ω
56μH
110μF
100V
0.020Ω
56μH
38621 TA01a
22μF
50V
DESCRIPTION
The LTC
mode boost and SEPIC controller that drives N-channel
power MOSFETs. Two phase operation reduces system
fi ltering capacitance and inductance requirements. The 10V
gate drive is optimized for most automotive and industrial
grade power MOSFETs.
Adjustable slope compensation gain allows the user to fi ne-
tune the current loop gain, improving noise immunity.
The operating frequency can be set with an external resistor
over a 75kHz to 500kHz range and can be synchronized
to an external clock using the internal PLL. Multi-phase
operation is possible using the SYNC input, the CLKOUT
output and the PHASEMODE control pin allowing 2-, 3-,
4-, 6- or 12-phase operation.
Other features include an internal 10V LDO with
undervoltage lockout protection for the gate drivers, a
precision RUN pin threshold with programmable hyster-
esis, soft-start and programmable leading edge blanking
and maximum duty cycle. The LTC3862 is a 5V gate drive
version of the LTC3862-1.
L, 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, 6498466, 6611131.
Step-Up DC/DC Controller
Multi-Phase Current Mode
V
8.5V TO 36V
V
72V
2A (MAX)
IN
OUT
®
3862-1 is a two phase constant frequency, current
100
98
96
94
92
90
88
86
84
82
80
100
V
Effi ciency vs Output Current
OUT
= 72V
V
IN
LOAD CURRENT (mA)
= 9V
LTC3862-1
V
IN
1000
= 32V
V
IN
= 24V
38621 TA01b
10000
38621f
1

Related parts for ltc3862gn-1

ltc3862gn-1 Summary of contents

Page 1

... The LTC3862 gate drive version of the LTC3862-1. L, 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, 6498466, 6611131. ...

Page 2

... JMAX JA PART MARKING* PACKAGE DESCRIPTION LTC3862FE-1 24-Lead Plastic TSSOP LTC3862FE-1 24-Lead Plastic TSSOP LTC3862FE-1 24-Lead Plastic TSSOP LTC3862GN-1 24-Lead Plastic SSOP LTC3862GN-1 24-Lead Plastic SSOP LTC3862GN-1 24-Lead Plastic SSOP TOP VIEW + – BLANK 1 PHASEMODE 2 FREQ ...

Page 3

ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL LTC3862EUH-1#PBF LTC3862EUH-1#TRPBF LTC3862IUH-1#PBF LTC3862IUH-1#TRPBF LTC3862HUH-1#PBF LTC3862HUH-1#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. Consult ...

Page 4

LTC3862-1 ELECTRICAL CHARACTERISTICS operating temperature range, otherwise specifi cations are at T SYMBOL PARAMETER RUN/Soft-Start I RUN Source Current RUN V High Level RUN Channel Enable Threshold RUN V RUN Threshold Hysteresis RUNHYS I SS Pull-Up Current ...

Page 5

TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency vs Output Current 100 V = 72V OUT 32V 24V 100 LOAD CURRENT (mA) Load Step ...

Page 6

LTC3862-1 TYPICAL PERFORMANCE CHARACTERISTICS INTV Line Regulation CC 10.2 10.1 10.0 9.9 9 INPUT VOLTAGE (V) 38621 G09 INTV LDO Dropout CC vs Load Current, Temperature 1200 1000 150°C 125°C 800 85°C 600 ...

Page 7

TYPICAL PERFORMANCE CHARACTERISTICS Maximum Current Sense Threshold vs Duty Cycle 80 75 SLOPE = 0.625 70 65 SLOPE = 1. SLOPE = 100 ...

Page 8

LTC3862-1 TYPICAL PERFORMANCE CHARACTERISTICS Oscillator Frequency vs Input Voltage 320 315 310 305 300 295 290 285 280 INPUT VOLTAGE (V) 38621 G27 Frequency Pin Voltage vs Temperature 1.235 1.233 1.231 1.229 1.227 ...

Page 9

PIN FUNCTIONS 3V8: Output of the Internal 3.8V LDO from INTV pin for the low voltage analog and digital circuits. A low ESR 1nF ceramic bypass capacitor should be connected between 3V8 and SGND, as close as possible to the ...

Page 10

LTC3862-1 PIN FUNCTIONS + + SENSE1 , SENSE2 : Positive Inputs to the Current Comparators. The ITH pin voltage programs the current comparator offset in order to set the peak current trip threshold. This pin is normally connected to a ...

Page 11

FUNCTIONAL DIAGRAM CLKOUT SYNC PLLFLTR MAX PHASEMODE FREQ R FREQ SLOPE SLOPE COMPENSATION BLANK BLANK BLOGIC LOGIC 3V8 5μ ITH PSKIP PSKIP – + 0.275V ...

Page 12

LTC3862-1 OPERATION The Control Loop The LTC3862-1 uses a constant frequency, peak current mode step-up architecture with its two channels operat- ing 180 degrees out of phase. During normal operation, each external MOSFET is turned on when the clock for ...

Page 13

OPERATION In multi-phase applications, all of the FB pins are connected together and all of the error amplifi er output pins (ITH) are connected together. The INTV pins, however, should not CC be connected together. The INTV CC sourcing current ...

Page 14

LTC3862-1 OPERATION To prevent the maximum junction temperature from be- ing exceeded, the input supply current to the IC should be checked when operating in continuous mode (heavy load) at maximum tradeoff between the operating IN frequency ...

Page 15

OPERATION Operation at High Supply Voltage At high input voltages, the LTC3862-1’s internal LDO can dissipate a signifi cant amount of power, which could cause the maximum junction temperature to be exceeded. Conditions such as a high operating frequency, or ...

Page 16

LTC3862-1 OPERATION Operation of the RUN Pin The control circuitry in the LTC3862-1 is turned on and off using the RUN pin. Pulling the RUN pin below 1.22V forces shutdown mode and releasing it allows a 0.5μA current source to ...

Page 17

OPERATION The LTC3862-1 uses a constant frequency architecture that can be programmed over a 75kHz to 500kHz range using a single resistor from the FREQ pin to ground. Figure 6 illustrates the relationship between the FREQ pin resistance and the ...

Page 18

LTC3862-1 OPERATION Table 1 CH-1 to CH-2 CH-1 to CLKOUT PHASEMODE PHASE PHASE SGND 180° 90° Float 180° 60° 3V8 120° 240° Using the LTC3862-1 Transconductance (g Amplifi Multi-Phase Applications The LTC3862-1 error amplifi transconductance, ...

Page 19

OPERATION LTC3862-1 chip, connect all of the SS pins together and use one external capacitor to program the soft-start time. In this case, the current into the soft-start capacitor will • 5μA, where n is the ...

Page 20

LTC3862-1 OPERATION the slope compensation is too low the converter can suffer from excessive jitter or, worst case, sub-harmonic oscillation. When excess slope compensation is applied to the internal current sense signal, the phase margin of the control loop suffers. ...

Page 21

OPERATION MINIMUM ON-TIME AT LIGHT LOAD WITH BLANK = SGND INDUCTOR CURRENT 200mA/DIV GATE 5V/DIV SW NODE 20V/DIV 500ns/DIV V = 36V 72V OUT MEASURED ON-TIME = 210ns MINIMUM ON-TIME AT LIGHT LOAD WITH BLANK = FLOAT ...

Page 22

LTC3862-1 OPERATION + – The SENSE and SENSE Pins + – The SENSE and SENSE pins are high impedance inputs to the CMOS current comparators for each channel. Nominally, there current into or out of these pins. ...

Page 23

OPERATION The ITH series R • C fi lter sets the dominant pole-zero C C loop compensation. The transfer function for boost and fl yback converters contains a right half plane zero that normally requires the loop crossover frequency to ...

Page 24

LTC3862-1 APPLICATIONS INFORMATION Typical Boost Applications Circuit A basic 2-phase, single output LTC3862-1 application circuit is shown in Figure 18. External component selec- tion is driven by the characteristics of the load and the input supply. Duty Cycle Considerations For ...

Page 25

APPLICATIONS INFORMATION Maximum Duty Cycle Limitations Another operating extreme occurs at high duty cycle, when the input voltage is low and the output voltage is high. In this case – IN(MIN MAX ...

Page 26

LTC3862-1 APPLICATIONS INFORMATION The inductor saturation current rating needs to be higher than the worst-case peak inductor current during an overload condition the maximum rated load O(MAX) current, then the maximum current limit value (I would normally ...

Page 27

APPLICATIONS INFORMATION result, some iterative calculation is normally required to determine a reasonably accurate value. The power dissipated by the MOSFET in a multi-phase boost converter with n phases is O(MAX • FET ...

Page 28

LTC3862-1 APPLICATIONS INFORMATION For a boost converter where the current limit value is chosen to be 30% higher than the maximum load current, the peak current in the MOSFET and sense resistor is • 1+ SW(MAX) ...

Page 29

APPLICATIONS INFORMATION additional power dissipation is important when deciding on a diode current rating, package type, and method of heat sinking close approximation, the power dissipated by the diode is • V • (1 – ...

Page 30

LTC3862-1 APPLICATIONS INFORMATION For the bulk capacitance, which we assume contributes 1% to the total output ripple, the minimum required ca- pacitance is approximately: I O(MAX) C ≥ OUT 0.01• n • V • f OUT For many designs it ...

Page 31

APPLICATIONS INFORMATION The value of the input capacitor is a function of the source impedance, and in general, the higher the source impedance, the higher the required input capacitance. The required amount of input capacitance is also greatly affected by ...

Page 32

LTC3862-1 APPLICATIONS INFORMATION D MAX SLOPE BLANK PHASEMODE 45.3k FREQ 0.1μF SS LTC3862-1 1.5nF 45.3k ITH 100pF FB 5.62k SGND 324k V OUT CLKOUT SYNC PLLFLTR Figure 25a. A 8.5V to 36V Input, 72V/2A Output 2-Phase Boost Converter Application Circuit ...

Page 33

APPLICATIONS INFORMATION The inductor value chosen was 57.8μH and the part number is PA2050-583, manufactured by Pulse Engi- neering. This inductor has a saturation current rating of 5A. 8. The power MOSFET chosen for this application is a Renesas HAT2267H. ...

Page 34

LTC3862-1 APPLICATIONS INFORMATION For the bulk capacitance, which we assume contributes 1% to the total output ripple, the minimum required capacitance is approximately: I O(MAX) C ≥ = OUT 0.01• n • V • f 0.01• 2 • 72V • ...

Page 35

APPLICATIONS INFORMATION 10. The output resistor divider should be located as close as possible to the IC, with the bottom resistor connected between FB and SGND. The PCB trace connecting the top resistor to the upper terminal of the output ...

Page 36

LTC3862-1 TYPICAL APPLICATION A 24V Input, 48V/6A Output 2-Phase Boost Converter Application Circuit D MAX SLOPE BLANK PHASEMODE 45.3k FREQ 0.1μF SS 4.7nF LTC3862-1 30.1k ITH 100pF FB 7.87k SGND 301k V OUT CLKOUT SYNC PLLFLTR Start-Up RUN 5V/DIV I ...

Page 37

TYPICAL APPLICATION A 24V Input, 107V/1.5A Output 2-Phase Boost Converter Application Circuit D MAX SLOPE BLANK PHASEMODE 68.1k FREQ 0.1μF SS 44pF LTC3862-1 43.5k ITH 2200pF FB 6.65k SGND 576k V OUT CLKOUT SYNC PLLFLTR L1, L2: CHAMPS TECHNOLOGIES HRPQA2050-57 ...

Page 38

LTC3862-1 PACKAGE DESCRIPTION 6.60 0.10 4.50 0.10 RECOMMENDED SOLDER PAD LAYOUT 0.09 – 0.20 (.0035 – .0079) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS 2. DIMENSIONS ARE IN 3. DRAWING NOT TO SCALE .254 MIN .0165 .0015 RECOMMENDED SOLDER PAD LAYOUT .0075 ...

Page 39

... 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. UH Package 24-Lead Plastic QFN (5mm × ...

Page 40

... Constant Frequency Current Mode SENSE LTC3873-5 Flyback, Boost and SEPIC DC/DC Controllers LTC3780 High Effi ciency, Synchronous, 4-Switch Buck-Boost Controller PolyPhase is a registrated treademark of Linear Technology Corporation Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● ...

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