mode boost and SEPIC controller that drives N-channel
power MOSFETs. Two phase operation reduces system
filtering capacitance and inductance requirements. The 5V
gate drive is optimized for most automotive and industrial
grade power MOSFETs.
Adjustable slope compensation gain allows the user to fine-
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 5V LDO with undervoltage
lockout protection for the gate drivers, a precision RUN
pin threshold with programmable hysteresis, soft-start
and programmable leading edge blanking and maximum
duty cycle
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.
Wide V
IN
Range: 4V to 36V Operation
2-Phase Operation Reduces Input and Output
Capacitance
Fixed Frequency, Peak Current Mode Control
5V Gate Drive for Logic-Level 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 5V LDO Regulator
24-Lead Narrow SSOP Package
5mm
×
5mm QFN with 0.65mm Lead Pitch and
24-Lead Thermally Enhanced TSSOP Packages
APPLICATIONS
n
Automotive, Telecom and Industrial Power Supplies
TYPICAL APPLICATION
84.5k
24.9k
RUN
INTV
CC
4.7μF
66.5k
10nF
10k
10nF
1nF
V
IN
GATE1
SENSE1
+
220μF
0.006Ω
50V
EFFICIENCY (%)
19.4μH
19.4μH
22μF
50V
V
IN
5V TO 36V
V
OUT
48V
5A (MAX)
98
96
94
92
90
88
86
84
82
80
100
1000
LOAD CURRENT (mA)
10000
3862 TA01b
3862 TA01
Efficiency vs Output Current
V
OUT
= 48V
V
IN
= 12V
LTC3862
BLANK
SENSE1
–
FREQ
GATE2
SYNC
SENSE2
+
PLLFLTR
V
IN
= 24V
V
IN
= 5V
0.006Ω
SS
3V8
FB
ITH
SENSE2
PGND
CLKOUT
SLOPE
D
MAX
PHASEMODE
SGND
–
10nF
475k
12.4k
68.1k
100pF
3862fb
1
LTC3862
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Input Supply Voltage (V
IN
) ......................... –0.3V to 40V
INTV
CC
Voltage ............................................ –0.3V to 6V
INTV
CC
LDO RMS Output Current .........................50mA
RUN Voltage ................................................ –0.3V to 8V
SYNC Voltage ............................................... –0.3V to 6V
SLOPE, PHASEMODE, D
MAX
,
BLANK Voltage ........................................... –0.3V to 3V8
SENSE1
+
, SENSE1
–
, SENSE2
+
,
SENSE2
–
Voltage ....................................... –0.3V to 3V8
SS, PLLFLTR Voltage ................................. –0.3V to 3V8
ITH Voltage ............................................... –0.3V to 2.7V
FB Voltage .................................................. –0.3V to 3V8
FREQ Voltage ............................................ –0.3V to 1.5V
Operating Junction Temperature Range (Notes 3, 4)
LTC3862E............................................. –40°C to 85°C
LTC3862I............................................ –40°C to 125°C
LTC3862H .......................................... –40°C to 150°C
Storage Temperature Range................... –65°C to 150°C
Reflow Peak Body Temperature ........................... 260°C
PIN CONFIGURATION
TOP VIEW
D
MAX
SLOPE
BLANK
PHASEMODE
FREQ
SS
ITH
FB
SGND
1
2
3
4
5
6
7
8
9
25
24 3V8
23 SENSE1
+
22 SENSE1
21 RUN
20 V
IN
19 INTV
CC
18 GATE1
17 PGND
16 GATE2
15 NC
14 SENSE2
–
13 SENSE2
+
–
TOP VIEW
SLOPE
D
MAX
SLOPE
BLANK
PHASEMODE
FREQ
SS
ITH
FB
SGND
1
2
3
4
5
6
7
8
9
24 3V8
23 SENSE1
+
22 SENSE1
–
21 RUN
20 V
IN
19 INTV
CC
18 GATE1
17 PGND
16 GATE2
15 NC
14 SENSE2
–
13 SENSE2
+
BLANK 1
PHASEMODE 2
FREQ 3
SS 4
ITH 5
FB 6
7
SGND
8
TOP VIEW
SENSE1
+
SENSE1
–
DMAX
RUN
18 V
IN
17 INTV
CC
25
16 GATE1
15 PGND
14 GATE2
13 NC
9 10 11 12
SENSE2
+
SENSE2
–
SYNC
PLLFLTR
3V8
24 23 22 21 20 19
CLKOUT 10
SYNC 11
PLLFLTR 12
CLKOUT 10
SYNC 11
PLLFLTR 12
FE PACKAGE
24-LEAD PLASTIC TSSOP
T
JMAX
= 150°C,
θ
JA
= 38°C/W
EXPOSED PAD (PIN 25) IS PGND, MUST BE SOLDERED TO PCB
GN PACKAGE
24-LEAD NARROW PLASTIC SSOP
T
JMAX
= 150°C,
θ
JA
= 85°C/W
UH PACKAGE
24-LEAD (5mm 5mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 34°C/W
EXPOSED PAD (PIN 25) IS PGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3862EFE#PBF
LTC3862EFE#TRPBF
3862FE
24-Lead Plastic TSSOP
–40°C to 85°C
LTC3862IFE#PBF
LTC3862IFE#TRPBF
3862FE
24-Lead Plastic TSSOP
–40°C to 125°C
LTC3862HFE#PBF
LTC3862HFE#TRPBF
3862FE
24-Lead Plastic TSSOP
–40°C to 150°C
LTC3862EGN#PBF
LTC3862EGN#TRPBF
LTC3862GN
24-Lead Plastic SSOP
–40°C to 85°C
LTC3862IGN#PBF
LTC3862IGN#TRPBF
LTC3862GN
24-Lead Plastic SSOP
–40°C to 125°C
LTC3862HGN#PBF
LTC3862HGN#TRPBF
LTC3862GN
24-Lead Plastic SSOP
–40°C to 150°C
LTC3862EUH#PBF
LTC3862EUH#TRPBF
3862
–40°C to 85°C
24-Lead (5mm
×
5mm) Plastic QFN
LTC3862IUH#PBF
LTC3862IUH#TRPBF
3862
–40°C to 125°C
24-Lead (5mm
×
5mm) Plastic QFN
LTC3862HUH#PBF
LTC3862HUH#TRPBF
3862
–40°C to 150°C
24-Lead (5mm
×
5mm) Plastic QFN
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
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/
CLKOUT
3862fb
2
LTC3862
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN
I
VIN
PARAMETER
V
IN
Supply Voltage Range
V
IN
Supply Current
Normal Mode, No Switching
Shutdown
LDO Regulator Output Voltage
Line Regulation
INTV
CC
UVLO Voltage
LDO Regulator Output Voltage
Reference Voltage
Feedback Voltage V
IN
Line Regulation
Feedback Voltage Load Regulation
Transconductance Amplifier Gain
Error Amplifier Unity-Gain Crossover
Frequency
Error Amplifier Maximum Output Voltage
(Internally Clamped)
Error Amplifier Minimum Output Voltage
I
ITH
I
FB
V
ITH(PSKIP)
I
SENSE(ON)
V
SENSE(MAX)
V
SENSE(MATCH)
RUN/Soft-Start
I
RUN
V
RUN
V
RUNHYS
I
SS
R
SS
Oscillator
f
OSC
Oscillator Frequency
Oscillator Frequency Range
V
FREQ
Nominal FREQ Pin Voltage
R
FREQ
= 45.6k
R
FREQ
= 45.6k
R
FREQ
= 45.6k
l
l
(Notes 2, 3) The
l
denotes the specifications which apply over the full
operating junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, RUN = 2V and SS = open, unless
otherwise noted.
CONDITIONS
MIN
4
(Note 5)
V
RUN
= 0V
6V < V
IN
< 36V
Load = 0mA to 20mA
Rising INTV
CC
Falling INTV
CC
–2
3.3
2.9
3.8
V
ITH
= 0.8V (Note 6)
E-Grade (Note 3)
I-Grade and H-Grade (Note 3)
V
IN
= 4V to 36V (Note 6)
V
ITH
= 0.5V to 1.2V (Note 6)
V
ITH
= 0.8V (Note 6), ITH Pin Load = ±5μA
(Note 7)
V
FB
= 1V, No Load
V
FB
= 1.5V, No Load
l
l
l
l
TYP
MAX
36
UNITS
V
mA
μA
V
%/V
%
V
V
V
Supply Input and INTV
CC
Linear Regulator
1.8
30
4.8
5.0
0.002
3.0
80
5.2
0.02
INTV
CC
dV
INTVCC(LINE)
V
UVLO
3V8
V
FB
dV
FB
/dV
IN
dV
FB
/dV
ITH
g
m
f
0dB
V
ITH
dV
INTVCC(LOAD)
Load Regulation
Switcher Control Loop
1.210
1.199
1.223
1.223
±0.002
0.01
660
1.8
2.7
50
–30
30
(Note 6)
Rising ITH Voltage (Note 6)
Hysteresis
V
SLOPE
= Float, Low Duty Cycle
(Note 3)
V
SLOPE
= Float, Low Duty Cycle (Note 3)
(V
SENSE1
– V
SENSE2
)
V
RUN
= 0V
V
RUN
= 1.5V
65
60
–10
–50
0.275
25
0.01
l
l
1.235
1.248
0.01
0.1
V
V
%/V
%
μMho
MHz
V
mV
μA
μA
Error Amplifier Output Source Current
Error Amplifier Output Sink Current
Error Amplifier Input Bias Currents
Pulse Skip Mode Operation ITH Pin Voltage
SENSE Pin Current
Maximum Current Sense Input Threshold
CH1 to CH2 Maximum Current Sense
Threshold Matching
RUN Source Current
High Level RUN Channel Enable Threshold
RUN Threshold Hysteresis
SS Pull-Up Current
SS Pull-Down Resistance
V
SS
= 0V
V
RUN
= 0V
280
260
75
–200
nA
V
mV
2
85
90
10
μA
mV
mV
mV
75
75
–0.5
–5
1.22
80
–5
10
300
300
1.223
320
340
500
μA
μA
V
mV
μA
kΩ
kHz
kHz
kHz
V
3862fb
3
LTC3862
ELECTRICAL CHARACTERISTICS
SYMBOL
f
SYNC
V
SYNC
I
PLLFLTR
CH1-CH2
PARAMETER
SYNC Minimum Input Frequency
SYNC Maximum Input Frequency
SYNC Input Threshold
Phase Detector Sourcing Output Current
Phase Detector Sinking Output Current
Channel 1 to Channel 2 Phase Relationship
(Notes 2, 3) The
l
denotes the specifications which apply over the full
operating junction temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, RUN = 2V and SS = open, unless
otherwise noted.
CONDITIONS
V
SYNC
= External Clock
V
SYNC
= External Clock
Rising Threshold
f
SYNC
> f
OSC
f
SYNC
< f
OSC
V
PHASEMODE
= 0V
V
PHASEMODE
= Float
V
PHASEMODE
= 3V8
V
PHASEMODE
= 0V
V
PHASEMODE
= Float
V
PHASEMODE
= 3V8
V
DMAX
= 0V
V
DMAX
= Float
V
DMAX
= 3V8
V
BLANK
= 0V (Note 8)
V
BLANK
= Float (Note 8)
V
BLANK
= 3V8 (Note 8)
l
l
MIN
650
TYP
MAX
50
UNITS
kHz
kHz
V
μA
μA
Deg
Deg
Deg
Deg
Deg
Deg
%
%
%
ns
ns
ns
Ω
Ω
1.5
–15
15
180
180
120
90
60
240
96
84
75
180
260
340
2.1
0.7
CH1-CLKOUT
Channel 1 to CLKOUT Phase Relationship
D
MAX
Maximum Duty Cycle
t
ON(MIN)1
t
ON(MIN)2
t
ON(MIN)3
Gate Driver
R
DS(ON)
Overvoltage
V
FB(OV)
Minimum On-Time
Minimum On-Time
Minimum On-Time
Driver Pull-Up R
DS(ON)
Driver Pull-Down R
DS(ON)
V
FB
, Overvoltage Lockout Threshold
V
FB(OV)
– V
FB(NOM)
in Percent
8
10
12
%
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:
All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
Note 3:
The LTC3862E is guaranted to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3862I is guaranteed
over the full –40°C to 125°C operating junction temperature range and
the LTC3862H is guaranteed over the full –40°C to 150°C operating
junction temperature range. High junction temperatures degrade operating
lifetimes. Operating lifetime is derated at junction temperatures greater
than 125°C.
Note 4:
This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Continuous
operation above the specified maximum operating junction temperature
may impair device reliability.
Note 5:
Supply current in normal operation is dominated by the current
needed to charge the external MOSFET gates. This current will vary with
supply voltage and the external MOSFETs used.
Note 6:
The IC is tested in a feedback loop that adjusts V
FB
to achieve a
specified error amplifier output voltage.
Note 7:
Guaranteed by design, not subject to test.
Note 8:
The minimum on-time condition is specified for an inductor peak-
to-peak ripple current = 30% (see Minimum On-Time Considerations in the
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