LT3782A Datasheet PDF - Linear

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LT3782A
Linear

Part Number LT3782A
Description 2-Phase Step-Up DC/DC Controller
Page 20 Pages


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Features
n 2-Phase Operation Reduces Required Input and
Output Capacitance
n Programmable Switching Frequency:
150kHz to 500kHz
n 6V to 40V Input Range
n 10V Gate Drive with VCC ≥13V
n High Current Gate Drive (4A)
n Programmable Soft-Start and Current Limit
n Programmable Slope Compensation for
High Noise Immunity
n MOSFET Gate Signals with Programmable
Falling Edge Delay for External Synchronous Drivers
n Programmable Undervoltage Lockout
n Programmable Duty Cycle Clamp (50% or Higher)
n Thermally Enhanced 28-Lead TSSOP and 4mm ×
5mm QFN Packages
Applications
n Industrial Equipment
n Telecom Infrastructure
n Interleaved Isolated Power Supply
LT3782A
2-Phase Step-Up
DC/DC Controller
Description
The LT®3782A is a current mode 2-phase step-up DC/DC
converter controller. Its high switching frequency (up to
500kHz) and 2-phase operation reduce system filtering
capacitance and inductance requirements.
With 10V gate drive (VCC ≥13V) and 4A peak drive current,
the LT3782A can drive most industrial grade high power
MOSFETs with high efficiency. For synchronous applica-
tions, the LT3782A provides synchronous gate signals
with programmable falling edge delay to avoid cross
conduction when using external MOSFET drivers. Other
features include programmable undervoltage lockout,
soft-start, current limit, duty cycle clamp (50% or higher)
and slope compensation. The LT3782A is identical to the
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.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks, ThinSOT
and No RSENSE are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 6144194.
Typical Application
VIN
10V TO 36V
10µF
×2
100pF
50V 4A Boost Converter
825k
VCC
1µF
RUN
GBIAS1
GBIAS2
GBIAS
BGATE1
274k
LT3782A
VEE1
59k
SLOPE
BGATE2
DELAY
80k DCL
RSET
SS
0.1µF
VEE2
SENSE1+
VC
13k
6.8nF
SENSE1
SENSE2+
SENSE2
GND FB
20µH
20µH
2µF
D1
D2
Q1
0.004Ω
10µF
×2 +
VOUT
50V, 4A
220µF
10Ω
10nF
Q2
0.004Ω
10Ω
10nF
475k
24.9k
D1, D2: 30BQ060PbF
Q1, Q2: Si7852DP-T1-E3
3782A TA01
For more information www.linear.com/LT3782A
Efficiency and Power Loss
vs Load Current
97 18
EFFICIENCY
VIN = 24V
95 15
VIN = 12V
93 12
91
VIN = 12V
9
89 VIN = 24V 6
POWER LOSS
87 3
85 0
012345
IOUT (A)
3782A TA01b
3782afc
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LT3782A
Absolute Maximum Ratings (Note 1)
VCC Supply Voltage....................................................40V
GBIAS, GBIAS1, GBIAS2 Pin
(Externally Forced)....................................................14V
SYNC, RUN Pin..........................................................30V
Operating Junction Temperature
Range (Notes 2, 3).................................. –40°C to 125°C
SS............................................................
SENSE1+, SENSE2+,
300µA
Max
ISS
SENSE1, SENSE2...................................... –0.3V to 2V
Storage Temperature Range...................– 65°C to 150°C
Lead Temperature (Soldering, 10 sec)
For FE Package...................................................... 300°C
Pin Configuration
TOP VIEW
SGATE2 1
28 GBIAS
SGATE1 2
27 VCC
NC 3
26 NC
GND 4
25 NC
SYNC 5
24 VEE1
DELAY 6
23 BGATE1
DCL
SENSE1+
SENSE1
7
8
9
29 22 GBIAS1
GND 21 GBIAS2
20 BGATE2
SLOPE 10
19 VEE2
RSET
SENSE2
SENSE2+
11
12
13
18 NC
17 RUN
16 FB
SS 14
15 VC
FE PACKAGE
28-LEAD PLASTIC TSSOP
TJMAX = 125°C, θJA = 30°C/ W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
TOP VIEW
28 27 26 25 24 23
SYNC 1
22 BGATE1
DELAY 2
21 GBIAS1
DCL 3
SENSE1+ 4
SENSE15
20 NC
29 19 NC
GND 18 GBIAS2
SLOPE 6
17 BGATE2
RSET 7
SENSE28
16 VEE2
15 NC
9 10 11 12 13 14
UFD PACKAGE
28-LEAD (4mm × 5mm) PLASTIC QFN
TJMAX = 125°C, θJA = 37°C/ W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
Order Information
LEAD FREE FINISH
LT3782AEFE#PBF
TAPE AND REEL
LT3782AEFE#TRPBF
PART MARKING*
LT3782AFE
PACKAGE DESCRIPTION
28-Lead Plastic TSSOP
TEMPERATURE RANGE
–40°C to 125°C
LT3782AIFE#PBF
LT3782AIFE#TRPBF
LT3782AFE
28-Lead Plastic TSSOP
–40°C to 125°C
LT3782AEUFD#PBF
LT3782AIUFD#PBF
LEAD BASED FINISH
LT3782AEFE
LT3782AIFE
LT3782AEUFD#TRPBF
LT3782AIUFD#TRPBF
TAPE AND REEL
LT3782AEFE#TR
LT3782AIFE#TR
3782A
3782A
PART MARKING*
LT3782AFE
LT3782AFE
28-Lead (4mm × 5mm) Plastic QFN
28-Lead (4mm × 5mm) Plastic QFN
PACKAGE DESCRIPTION
28-Lead Plastic TSSOP
28-Lead Plastic TSSOP
–40°C to 125°C
–40°C to 125°C
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
LT3782AEUFD
LT3782AEUFD#TR
3782A
28-Lead (4mm × 5mm) Plastic QFN
–40°C to 125°C
LT3782AIUFD
LT3782AIUFD#TR
3782A
28-Lead (4mm × 5mm) Plastic QFN
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
3782afc
2 For more information www.linear.com/LT3782A



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LT3782A
Electrical Characteristics The l denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at TJ = 25°C. VCC = 13V, RSET = 80k, no load on any outputs, unless otherwise noted.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Overall
Supply Voltage (VCC)
Supply Current (IVCC)
Shutdown
VC ≤ 0.5V (Switching Off), VCC ≤ 40V
l6
40
11 16
V
mA
RUN Threshold
l 2.3 2.44 2.6
V
RUN Threshold Hysteresis
80 mV
Supply Current in Shutdown
RUN Pin Input Current
Voltage Amplifier gm
Reference Voltage (VREF)
1V ≤ RUN ≤ VREF
RUN ≤ 0.3V, VCC ≤ 30V
VRUN = 2.3V
0.4 0.65
40 90
l –0.5 –2
2.42
l 2.4
2.44 2.464
2.488
mA
µA
µA
V
V
Transconductance
Input Current IFB
VC High
VC Low
Source Current IVC
Sink Current IVC
VC Threshold for Switching Off (BGATE1, BGATE2 Low)
Soft-Start Current ISS
Current Amplifier CA1, CA2
VVC = 1V, ∆IVC = ±2µA
VFB = VREF
IVC = 0
IVC = 0
VVC = 0.7V – 1V, VFB = VREF – 100mV
VVC = 0.7V – 1V, VFB = VREF + 100mV
VSS = 0.1V – 2.8V
l 200 260 370 µmho
l
0.2 0.6
µA
1.5 V
0.35 0.4
V
8 11 14
µA
13 20 28
µA
l 0.3
V
6 10 15
µA
Voltage Gain ∆VC/∆VSENSE
Current Limit (VSENSE1+ – VSENSE1–) (VSENSE2+ – VSENSE2–)
Current Limit Mismatch
Input Current (ISENSE1+, ISENSE1–, ISENSE2+, ISENSE2–)
Oscillator
VFB = 2.3V
(∆VSENSE1 – ∆VSENSE2), VFB = 2.3V
∆VSENSE = 0V
4
55 63
–10
60
70
10
mV
mV
µA
Switching Frequency
Synchronization Pulse Threshold on SYNC Pin
Synchronization Frequency Range
(Note: Operation Switching Frequency Equals
Half of the Synchronization Frequency)
VRSET
Maximum Duty Cycle
Duty Cycle Limit
DCL Pin Input Current
RSET = 130k
RSET = 80k
RSET = 40k
Rising Edge VSYNC
RSET = 130k
RSET = 80k
RSET = 40k
RSET = 80k
VFB = VREF – 25mV, RSET > 80k
RSET = 40k
RSET = 80k, VDCL ≤ 0.3V
VDCL = 1.2V
VDCL = VRSET
VDCL ≤ 0.3V
l 130 154 177
l 212 250 288
l 386 465 533
0.8 1.2
2
180 240
290 392
550 715
2.3
l 90
l 83
94
90
50
75
Max Duty Cycle
l –0.1 –0.3
kHz
kHz
kHz
V
kHz
kHz
kHz
V
%
%
%
%
µA
For more information www.linear.com/LT3782A
3782afc
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LT3782A
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at TJ = 25°C. VCC = 13V, RSET = 80k, no load on any outputs, unless otherwise noted.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Gate Driver
VGBIAS
BGATE1, BGATE2 High Voltage
BGATE1, BGATE2 Source Current (Peak)
IGBIAS < 70mA
13V
VCC
=
8VVC,CI≤BG2A4TEV,=IBG1A0T0Em=A–100mA
Capacitive Load >22µF
Capacitive Load >50µF
l 10.2 11 11.7
l 7.8
l 3.8
9.2 10.5
5
3
4
V
V
V
A
A
BGATE1, BGATE2 Low Voltage
BGATE1, BGATE2 Sink Current (Peak)
8V ≤ VCC ≤ 24V, IBGATE = 100mA
Capacitive Load >22µF
Capacitive Load >50µF
l
0.5 0.7
3
4
V
A
A
SGATE1, SGATE2 High Voltage
SGATE1, SGATE2 Low Voltage
SGATE1, SGATE2 Peak Current
8V ≤ VCC ≤ 24V, ISGATE = –20mA
8V ≤ VCC ≤ 24V, ISGATE = 20mA
500pF Load
l 4.5 5.5 6.7
0.5 0.7
100
V
V
mA
Delay of BGATE High
Delay Pin Input Current
DELAY Pin and RSET Pin Shorted
VDELAY = 1V
VDELAY = 0.5V
VDELAY = 0.25V
VDELAY = 0.25V
l
100
150
250
500
–0.1 –0.3
ns
ns
ns
ns
µA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT3782AE is guaranteed to meet performance specifications
from 0°C to 85°C operating junction temperature. Specifications over
the –40°C to 125°C operating junction temperature range are assured by
design, characterization and correlation with statistical process controls.
The LT3782AI is guaranteed to meet performance specifications over the
full –40°C to 125°C operating junction temperature range. The maximum
ambient temperature is determined by specific operating conditions in
conjunction with board layout, the rated package thermal resistance and
other environmental factors.
Note 3: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Typical Performance Characteristics TJ = 25°C unless otherwise noted.
VGBIAS vs IGBIAS
11.0
10.9
10.8
10.7
10.6
10.5
10.4
10.3
10.2
10.1
10.0
0
50
IGBIAS (mA)
4
100
3782A G01
ICC vs VCC
20
18
16
14
12
10
8
6
4
2
0
6 8 10 12 14 16 18 20 22 24 26 28 30
VCC (V)
3782A G02
∆(RVSREETF=vs80VkC)C, ∆Frequency vs VCC
3 12
2 10
1
0 ∆VREF
8
6
–1 4
–2
∆FREQUENCY
2
–3 0
–4 –2
–5
6
–4
9 12 15 18 21 24 27 30
VCC (V)
3782A G03
3782afc
For more information www.linear.com/LT3782A



LT3782A datasheet pdf
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