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Linear Technology
Linear Technology

LTC3824 Datasheet

High Voltage Step-Down Controller


LTC3824 Datasheet Preview


FEATURESwww.datasheet4u.com
n Wide Input Range: 4V to 60V
n Current Mode Constant Frequency PWM
n Very Low Dropout Operation: 100% Duty Cycle
n Programmable Switching Frequency:
200kHz to 600kHz
n Selectable High Efficient Burst Mode® Operation:
40μA Quiescent Current
n Easy Synchronization
n 8V, 2A Gate Drive (VCC > 10V) for Industrial High
Voltage P-channel MOSFET
n Programmable Soft-Start
n Programmable Current Limit
n Available in a Small 10-Pin Thermally Enhanced
MSE Package
APPLICATIONS
n Industrial and Automotive Power Supplies
n Telecom Power Supplies
n Distributed Power Systems
LTC3824
High Voltage Step-Down
Controller With 40µA
Quiescent Current
DESCRIPTION
The LTC®3824 is a step-down DC/DC controller designed
to drive an external P-channel MOSFET. With a wide input
range of 4V to 60V and a high voltage gate driver, the
LTC3824 is suitable for many industrial and automotive
high power applications. Constant frequency current mode
operation provides excellent performance.
The LTC3824 can be configured for Burst Mode operation.
Burst Mode operation enhances low current efficiency
(only 40μA quiescent current) and extends battery run
time. The switching frequency can be programmed up to
600kHz and is easily synchronizable.
Other features include current limit, soft-start, micropower
shutdown, and Burst Mode disable.
The LTC3824 is available in a 10-lead MSE power package.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 5731964.
TYPICAL APPLICATION
VIN
5.5V TO 60V
CIN +
33μF
100V
5V/2A Buck Converter
CCAP
0.1μF
CAP
VCC
SENSE
LTC3824
RS
0.025Ω
392k
RSET
GND
GATE
22μH
100pF
VOUT
5V
COUT 2A
100μF
s2
SYNC/MODE
SS VC
VFB
0.1μF
10k
51Ω 422k
80.6k
3824 TA01
3.3nF
Efficiency and Power Loss vs Load Current
100 2.5
90 EFFICIENCY
80
VIN = 12V
VIN = 40V
2.0
1.5
70 1.0
60
50
10
POWER LOSS
VIN = 40V
VIN = 12V
100 1000
LOAD CURRENT (mA)
0.5
0
2000
3824 TA01a
3824fc
1
Page 1

LTC3824
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VCC ...........................................................................65V
wwwS.dSat,aRshSeEeTt,4uV.FcoBm..............................................................4V
VC ...............................................................................3V
SYNC/MODE ...............................................................6V
VCC – VSENSE ..............................................................1V
Maximum Temperatures (Note 2)
LTC3824E............................................. –40°C to 85°C
LTC3824I............................................ –40°C to 125°C
Storage Temperature Range..................... –65° to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
PIN CONFIGURATION
TOP VIEW
GND 1
10 CAP
SYNC/MODE 2
9 GATE
RSET 3 11 8 VCC
VC 4
7 SENSE
VFB 5
6 SS
MSE PACKAGE
10-LEAD PLASTIC MSOP
TJMAX = 125°C, θJA = 43°C/W, θJC = 3°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LTC3824EMSE#PBF
LTC3824EMSE#TRPBF LTBRZ
10-Lead Plastic MSOP
LTC3824IMSE#PBF
LTC3824IMSE#TRPBF LTCGZ
10-Lead Plastic MSOP
LEAD BASED FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LTC3824EMSE
LTC3824EMSE#TR
LTBRZ
10-Lead Plastic MSOP
LTC3824IMSE
LTC3824IMSE#TR
LTCGZ
10-Lead Plastic MSOP
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°C
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°C
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 12V, RSET = 392k, CCAP = 0.1μF. No load on any outputs, unless
otherwise specified.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Supply Voltage (VCC)
Supply Current (IVCC)
Supply Current (IVCC) Burst Mode Operation
Supply Current in Shutdown
VOLTAGE AMPLIFIER gm
VC ≤ 0.4V (Switching Off), VCC ≤ 60V
VSYNC = 0V (Burst Mode Operation Disable)
VCC ≤ 60V, SYNC/MODE Open, VC = 0.6V
VC ≤ 25mV, VCC ≤ 60V
l4
60
0.8 1.3
40 65
7
V
mA
μA
μA
Reference Voltage (VREF)
0.792 0.8
l 0.788
0.808
0.812
V
V
Transconductance
FB Input Current
VC High
VC Low
VC Source Current
VC Sink Current
VC = 0.8V, ΔIVC = ±2μA
VFB = VREF (Note 3)
IVC = 0
IVC = 0
VVC = 0.5V to 1.3V, VFB = VREF –100mV (VSYNC = 0V)
VVC = 0.7V to 1.3V, VFB = VREF +100mV (VSYNC = 0V)
220 260 370 μmho
l
10 30
nA
1.6 V
0.35 0.5
V
15 μA
15 μA
3824fc
2
Page 2

LTC3824
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 12V, RSET = 392k, CCAP = 0.1μF. No load on any outputs, unless
otherwise specified.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
wwwV.dCaTtahsrehseheotl4duf.ocroSmwitching Off
Soft-Start Current ISS
VC Burst Mode Threshold
VC Burst Mode Threshold Hysteresis
SENSE Voltage at Burst Mode Operation
VSYNC/MODE = 0V (Note 4)
VSS = 0.1V to 1.5V
VCC ≤ 60V, VC Rising, SYNC/MODE Open
VCC ≤ 60V
(VCC–VSENSE) at 30% Duty Cycle
70% Duty Cycle
l 0.4 V
5 μA
0.84 V
0.04 V
30 mV
20 mV
Current Limit Threshold (VCC–VSENSE)
FB Overvoltage Threshold
Sense Input Current
OSCILLATOR
VCC ≤ 60V
VC = 1.6V
VSENSE = VCC
l 80 100 120
8
0.1 2
mV
%
μA
Switching Frequency
Synchronization Pulse Threshold
on SYNC Pin
RSET = 392k
RSET = 200k
Rising Edge VSYNC
l 170 200 230
l 320 400 460
1.3
kHz
kHz
V
Synchronization Frequency Range
VRSET
Minimum On-Time (Measured at GATE Pin)
Switching Frequency Foldback
GATE DRIVER
RSET = 392k
RSET = 200k
RSET = 392k
3V Buck Converter Circuit, ILOAD > 2A
VFB = 0.3V
l 230
l 460
300
600
1.2
350
l 35
50
75
kHz
kHz
V
ns
kHz
GATE Bias Voltage (VCC–VCAP)
GATE Bias Voltage (VCAP–GND)
GATE High Voltage (VCC–VGATE)
GATE Peak Source Current
GATE Low Voltage (VGATE–VCAP)
GATE Peak Sink Current
9V ≤ VCC ≤ 60V, IGATE = 10mA
VCC = 12V, IGATE = 15mA
4V ≤ VCC ≤ 8V, IGATE = 10mA
6V ≤ VCC ≤ 8V, IGATE = 15mA, VCC = 12V
4V ≤ VCC ≤ 60V, IGATE = –15mA
CGATE = 10nF
8V ≤ VCC ≤ 60V, IGATE = 15mA
4V ≤ VCC < 8V, IGATE = 10mA
CGATE = 10nF
l 7.0
l 6.8
0.2
l
7.9
0.85
0.5
2.5
0.1
0.05
2.5
8.8
1.5
2.8
0.8
0.5
V
V
V
V
V
A
V
V
A
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 LTC3824E is guaranteed to meet performance specifications
from 0°C to 85°C junction temperature. Specifications over the –40°C
to 85°C temperature range are assured by design characterization and
correlation with statistical process controls. The LTC3824I grade is
guaranteed over the full –40°C to 125°C operating junction temperature
range.
Note 3: This parameter is tested in a feedback loop that servos VFB to the
reference voltage with the VC pin forced to 1V.
Note 4: This specification represents the maximum voltage on VC where
switching (GATE pin) is guaranteed to be off.
3824fc
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Page 3

LTC3824
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise noted.
(VCC-VCAP) vs IGATE at VDRIVE Low
www.data8s.5heet4u.com
8.4
8.3
8.2
8.1
8.0
7.9
7.8
7.7
7.6
0
10 20 30 40 50
IGATE (mA)
3824 G01
ICC vs VCC
3
2
VFB = 0.75V
1 VFB = 0.85V
0
0 10 20 30 40 50 60
VCC (V)
3824 G02
Switching Frequency Change
vs VCC at RSET = 392kΩ
3
2
1
0
–1
–2
–3
0
10 20 30 40
VCC (V)
50 60
3824 G03
VREF Change vs VCC
0.4
Switching Frequency vs RSET
700
ΔVREF vs Temperature
2
600
0.2
500
1
0 400
0
300
–0.2
200
–1
–0.4
0
10 20 30 40 50 60
VCC (V)
3824 G04
100
100
200 300
RSET(kΩ)
400
3824 G05
–2
–40 –20 0 25 50 75 100 125
DIE TEMPERATURE (°C)
3824 G06
Burst Mode Disabled at
ILOAD = 200mA, VOUT = 5V
ILOAD = 200mA
Burst Mode Operation VOUT = 3V
VIN =12V, VOUT= 3V, ILOAD = 200mA
VOUT
10mV/DIV
VOUT
50mV/DIV
INDUCTOR
CURRENT
1A/DIV
INDUCTOR
CURRENT
1A/DIV
4μs/DIV
3824 G10
20μs/DIV
3824 G08
3824fc
4
Page 4
Part Number LTC3824
Manufactur Linear Technology
Description High Voltage Step-Down Controller
Total Page 12 Pages
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