FeaTures
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LTC3897
PolyPhase™ Synchronous
Boost Controller with Input/
Output Protection
DescripTion
The
LTC
®
3897
is a synchronous boost DC/DC controller
with surge stopper and ideal diode controller.
The boost controller drives two N-channel power MOSFET
stages out-of-phase to reduce input and output capacitor
requirements, allowing the use of smaller inductors than
the single-phase equivalent. Synchronous rectification
reduces power loss and eases thermal requirements.
The surge stopper controls the gate of an external N-channel
MOSFET to protect against high voltage input transients and
provides in-rush current control, overcurrent protection and
output disconnect for the boost converter. The integrated
ideal diode controller drives another N-channel MOSFET to
replace a Schottky diode for reverse input protection and
voltage holdup or peak detection. It controls the forward
voltage drop across the MOSFET and minimizes reverse
current flow.
The LTC3897 is available in thermally-enhanced 38-pin
leadless QFN or 38-lead TSSOP packages.
L,
LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, LTspice, OPTI-LOOP and
PolyPhase are registered trademarks and No R
SENSE
is a trademark of Linear Technology
Corporation. All other trademarks are the property of their respective owners. Protected by U. S.
Patents, including 5408150, 5481178, 5705919, 5929620, 6144194, 6177787, 6580258.
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Input Supply Range: 4.5V to 65V (Up to 75V Surge)
Reverse Input Protection to –40V
In-Rush Current Control, Overcurrent Protection
and Output Disconnect for Boost Converter
Input Voltage Surge Protection with Adjustable
Clamp Voltage
Onboard Ideal Diode Controller
Low Quiescent Current: 55µA
2-Phase Operation Reduces Required Input and
Output Capacitance and Noise
Output Voltage Up to 60V
Adjustable Gate Drive Level 5V to 10V (OPTI-DRIVE)
for Logic-Level or Standard Threshold FETs
No External Bootstrap Diodes Required
applicaTions
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Industrial
Automotive
Military/Avionics
Typical applicaTion
24V/10A 2-Phase Synchronous Boost Converter with Surge Protection and Reverse Protection
INPUT VOLTAGE SURGE PROTECTION
IN-RUSH/OVERCURRENT PROTECTION
V
IN
6V TO
55V
10
10nF
2m
33µF
549k
SPFB
12.1k
IS–
IS+
DG
CS
SG
V
IN
RUN
SS
I
TH
INTV
CC
DRV
CC
DRVSET
DRVUV FREQ
GND
REVERSE CURRENT PROTECTION (IDEAL DIODE)
REVERSE INPUT VOLTAGE PROTECTION
SENSE1+
SENSE1–
0.1µF
EFFICIENCY (%)
BG1
BOOST1
SW1
TG1
SENSE2+
SENSE2–
BG2
BOOST2
SW2
TG2
V
FB
DTC
TMR
1nF
475k
3897 TA01a
5m
3.5µH
100
90
80
70
60
50
40
30
20
10
Efficiency and Power Loss
vs Output Current
BURST EFFICIENCY
100k
V
BIAS
10k
POWER LOSS (mW)
BURST LOSS
1k
100
V
IN
= 12V
V
OUT
= 24V
Burst Mode OPERATION
FIGURE 17 CIRCUIT
0.01
0.1
1
OUTPUT CURRENT (A)
10
3897 G02
5m
3.5µH
LTC3897
V
OUT
24V
10A
220µF
10
0.1µF
15nF
0.1µF
0
0.001
1
8.66k
1µF
PINS NOT SHOWN IN THIS CIRCUIT:
PLLIN/MODE, I
LIM
, PHASMD,
CLKOUT, EXTV
CC
, SGEN, DGEN
V
IN
OPERATES THROUGH TRANSIENTS UP TO 75V.
WHEN V
IN
> 24V, V
OUT
FOLLOWS V
IN
UP TO 57V.
4.7µF
24.9k
For more information
www.linear.com/LTC3897
1
3897f
LTC3897
absoluTe MaxiMuM raTings
(Note 1)
V
IN
, SGEN .................................................. –40V to 76 V
V
BIAS
, IS
+
, IS
–
, .........................................................76V
SENSE1
+
, SENSE2
+
, SENSE1
–
, SENSE2
–
..................65V
CS ............................................................... –40V to 76V
SG, DG (Note 8) ...........................CS – 0.3V to CS + 10V
BOOST1 and BOOST2 .................................–0.3V to 71V
SW1 and SW2............................................... –5V to 65V
BG1, BG2, TG1, TG2 ........................................... (Note 9)
RUN, DGEN ................................................ –0.3V to 76V
PLLIN/MODE, TMR, V
FB
, SPFB .................... –0.3V to 6V
INTV
CC
......................................................... –0.3V to 6V
EXTV
CC
...................................................... –0.3V to 14V
DRV
CC
, (BOOST1-SW1), (BOOST2-SW2) ....–0.3V to 11V
(SENSE1
+
-SENSE1
–
),
(SENSE2
+
-SENSE2
–
)............................. –0.3V to 0.3V
I
LIM
, SS, I
TH
, FREQ,
PHASMD, DTC ....................... –0.3V to INTV
CC
+ 0.3V
DRVUV, DRVSET........................–0.3V to INTV
CC
+ 0.3V
Operating Junction Temperature Range
(Notes 2, 3) ........................................ –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
pin conFiguraTion
SGEN
DGEN
PLLIN/MODE
FREQ
PHASMD
I
LIM
SENSE1
+
SENSE1
–
DTC
1
2
3
4
5
6
7
8
9
39
GND
38
TMR
37
SPFB
36
IS –
35
IS+
34 DG
33 CS
32 SG
31 V
IN
30 TG1
29 SW1
28 BOOST1
27 BG1
26 V
BIAS
25 EXTV
CC
24 DRV
CC
23 BG2
22 BOOST2
21 SW2
20 TG2
FREQ 1
PHASMD 2
I
LIM
3
SENSE1
+
SENSE1
–
PLLIN/MODE
TOP VIEW
TOP VIEW
DGEN
SGEN
SPFB
IS –
TMR
38 37 36 35 34 33 32
31 DG
30 CS
29 SG
28 V
IN
27 TG1
39
GND
26 SW1
25 BOOST1
24 BG1
23 V
BIAS
22 EXTV
CC
21 DRV
CC
20 BG2
13 14 15 16 17 18 19
SENSE2
+
V
FB
SS
CLKOUT
TG2
SW2
BOOST2
4
5
DTC 6
DRVUV 7
DRVSET 8
INTV
CC
9
RUN 10
I
TH
11
SENSE2 12
–
DRVUV
10
DRVSET
11
INTV
CC
12
RUN
13
I
TH
14
SENSE2
–
15
SENSE2
+
16
V
FB
17
SS 18
CLKOUT 19
FE PACKAGE
38-LEAD PLASTIC TSSOP
θ
JA
= 28°C/W
EXPOSED PAD (PIN 39) IS GND, MUST BE SOLDERED TO PCB
UHF PACKAGE
38-LEAD (5mm
×
7mm) PLASTIC QFN
θ
JA
= 34°C/W
EXPOSED PAD (PIN 39) IS GND, MUST BE SOLDERED TO PCB
IS+
2
3897f
For more information
www.linear.com/LTC3897
LTC3897
orDer inForMaTion
LEAD FREE FINISH
LTC3897EUHF#PBF
LTC3897IUHF#PBF
LTC3897HUHF#PBF
LTC3897EFE#PBF
LTC3897IFE#PBF
LTC3897HFE#PBF
TAPE AND REEL
LTC3897EUHF#TRPBF
LTC3897IUHF#TRPBF
LTC3897HUHF#TRPBF
LTC3897EFE#TRPBF
LTC3897IFE#TRPBF
LTC3897HFE#TRPBF
http://www.linear.com/product/LTC3897#orderinfo
PART MARKING
3897
3897
3897
LTC3897FE
LTC3897FE
LTC3897FE
PACKAGE DESCRIPTION
38-Lead (5mm x 7mm) Plastic QFN
38-Lead (5mm x 7mm) Plastic QFN
38-Lead (5mm x 7mm) Plastic QFN
38-Lead Plastic TSSOP
38-Lead Plastic TSSOP
38-Lead Plastic TSSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
–40°C to 125°C
–40°C to 125°C
–40°C to 150°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/ .
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 12V, V
BIAS
= 12V, unless otherwise noted.
SYMBOL
V
BIAS
PARAMETER
Bias Voltage Operating Range
SENSE Pins Common Mode Range
(BOOST Converter Input Supply Voltage)
V
IN
I
Q
Input Supply Voltage Operating Range
Reverse Input Current
Input DC Supply Current
Pulse-Skipping or Forced Continuous Mode
Burst Mode (Sleep)
V
IN
= –30V
(Note 5)
RUN = 12V, V
FB
= 1.25V (No Load)
RUN = 12V, DGEN = SGEN = 0V, V
FB
= 1.25V
(No Load), CS = IS
+
= IS
–
= V
SPFB
= 0V
RUN = DGEN = 12V, SGEN = 0V, V
FB
= 1.25V
(No Load), CS = 12V, IS
+
= IS
–
= CS – 0.1V
RUN = 12V, DGEN = 0V, SGEN = 12V,
V
FB
= 1.25V (No Load), CS = IS
+
= IS
–
= 12V
RUN = DGEN = SGEN = 12V, V
FB
= 1.25V
(No Load), CS = 12V, IS
+
= IS
–
= CS – 0.1V
Shutdown
BOOST Controller Main Control Loop
V
OUT
V
FB
I
FB
Regulated Boost Output Voltage in
Synchronous Configuration
Regulated Feedback Voltage
Feedback Current
Reference Line Voltage Regulation
Output Voltage Load Regulation
I
TH
= 1.2 V (Note 4)
(Note 4)
(Note 4) V
IN
= 6V to 75V
(Note 4)
(Note 4) Measured in Servo Loop,
I
TH
Voltage = 1V to 0.6V
(Note 4) Measured in Servo Loop,
I
TH
Voltage = 1V to 1.4V
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elecTrical characTerisTics
CONDITIONS
MIN
4.5
2.3
4.2
TYP
MAX
75
65
75
UNITS
V
V
V
µA
mA
Supply Voltage and Operating Current
0
1.32
55
125
260
325
15
–10
90
175
350
450
22
60
µA
µA
µA
µA
µA
V
V
nA
%/V
%
%
RUN = DGEN = SGEN = 0V
1.188
1.200
±10
0.002
0.01
–0.01
1.212
±50
0.02
0.1
–0.1
For more information
www.linear.com/LTC3897
3
3897f
LTC3897
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 12V, V
BIAS
= 12V, unless otherwise noted.
SYMBOL
g
m
UVLO
PARAMETER
Error Amplifier Transconductance
Undervoltage Lockout
CONDITIONS
I
TH
= 1.2 V
DRV
CC
Ramping Up
DRVUV = 0V
DRVUV = INTV
CC
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elecTrical characTerisTics
MIN
TYP
2
4.0
7.5
MAX
UNITS
mmho
4.2
7.8
4.0
7.0
1.38
13
155
105
55
12
10
9
350
±2
V
V
V
V
V
mV
µA
mV
mV
mV
mV
mV
mV
µA
µA
Ω
Ω
Ω
Ω
Ω
DRV
CC
Ramping Down
DRVUV = 0V
DRVUV = INTV
CC
V
RUN
I
SS
RUN Pin ON Threshold
RUN Pin Hysteresis
Soft-Start Charge Current
V
SS
= GND
V
FB
= 1.15V, I
LIM
= INTV
CC
, V
SENSE
+ = 12V
V
FB
= 1.15V, I
LIM
= Float, V
SENSE
+ = 12V
V
FB
= 1.15V, I
LIM
= GND, V
SENSE
+ = 12V
Matching Between V
SENSE1(MAX)
and
V
SENSE2(MAX)
SENSE
+
Pin Current
SENSE
–
Pin Current
Top Gate Pull-Up Resistance
Top Gate Pull-Down Resistance
Bottom Gate Pull-Up Resistance
Bottom Gate Pull-Down Resistance
BDSW
BOOST to DRV
CC
Switch On-Resistance
Top Gate Off to Bottom Gate On Switch-On
Delay Time
V
FB
= 1.15V, I
LIM
= INTV
CC
, V
SENSE
+ = 12V
V
FB
= 1.15V, I
LIM
= Float, V
SENSE
+ = 12V
V
FB
= 1.15V, I
LIM
= GND, V
SENSE
+ = 12V
V
FB
= 1.1V, I
LIM
= Float
V
FB
= 1.1V, I
LIM
= Float
DRV
CC
= 10V
DRV
CC
= 10V
DRV
CC
= 10V
DRV
CC
= 10V
V
SW
= 0V, V
DRVSET
= INTV
CC
DTC = 0V
DTC = Float
DTC = INTV
CC
Bottom Gate Off to Top Gate On Switch-On
Delay Time
DTC = 0V
DTC = Float
DTC = INTV
CC
Maximum BG Duty Factor
t
ON(MIN)
Minimum BG On-Time
DRV
CC
Voltage from Internal V
BIAS
LDO
DRV
CC
Load Regulation from V
BIAS
LDO
DRV
CC
Voltage from Internal EXTV
CC
LDO
DRV
CC
Load Regulation from
Internal EXTV
CC
LDO
(Note 7) V
DRVSET
= INTV
CC
V
EXTVCC
= 0V
7V < V
BIAS
< 75V, DRVSET = 0V
11V < V
BIAS
< 75V, DRVSET = INTV
CC
I
CC
= 0mA to 50mA, V
EXTVCC
= 0V,
V
DRVSET
= INTV
CC
7V < V
EXTVCC
< 13V, DRVSET = 0V
11V < V
EXTVCC
< 13V, DRVSET = INTV
CC
I
CC
= 0mA to 50mA, V
EXTVCC
= 8.5V,
V
DRVSET
= 0V
DRV
CC
LDO Regulator
V
RUN
Rising
3.6
6.4
1.18
7
3.8
6.7
1.28
100
10
140
95
48
0
0
0
250
2.5
1.5
2.5
1
V
SENSE1,2(MAX)
Maximum Current Sense Threshold
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125
85
41
–12
–10
–9
2.6
3.7
55
90
170
55
90
170
96
90
70
120
235
70
120
235
ns
ns
ns
ns
ns
ns
%
ns
5.8
9.6
6.0
10.0
0.7
6.2
10.4
2
6.2
10.4
2
V
V
%
V
V
%
5.8
9.6
6.0
10.0
0.7
4
3897f
For more information
www.linear.com/LTC3897
LTC3897
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 12V, V
BIAS
= 12V, unless otherwise noted.
SYMBOL
PARAMETER
EXTV
CC
LDO Switchover Voltage
EXTV
CC
Hysteresis
Programmable DRV
CC
Programmable DRV
CC
Programmable DRV
CC
Oscillator and Phase-Locked Loop
Programmable Frequency
R
FREQ
= 25k
R
FREQ
= 60k
R
FREQ
= 100k
Lowest Fixed Frequency
Highest Fixed Frequency
f
SYNC
Synchronizable Frequency
PLLIN/MODE Input High Level
PLLIN/MODE Input Low Level
BOOST1 and BOOST2 Charge Pump
BOOST Charge Pump Available Output
Current
FREQ = 0V, Forced Continuous or
Pulse-Skipping Mode
V
SW1,2
= 12V; V
BOOST1,2
= 16.5V
V
SW1,2
= 12V; V
BOOST1,2
= 19.5V
V
SGEN
Rising
V
IN
= 4.2V, I
SG
= 0, –1µA, DG – CS = 1V
V
IN
= 8V to 75V, I
SG
= 0, −1µA
SG Pin Pull-Up Current
SG Pin Pull-Down Current
V
IN
= SG = DG = CS = 12V
Overvoltage: SPFB = 1.5V, SG – CS = 5V
Overcurrent: ΔV
IS
= 100mV, SG – CS = 5V
Shutdown: DGEN = SGEN = 0V, SG – CS = 5V
CS Pin Input Current
V
IN
= CS = 12V, IS
+
= IS
–
= 11.9V, SGEN = Float
V
IN
= CS = 12V, SGEN = 0V
V
CS
= –30V
V
SPFB
ΔV
IS
Regulated Surge Protection Feedback Voltage
Overcurrent Fault Threshold, (V
IS+
– V
IS
–)
IS
+
Pin Input Current
SPFB Pin Input Current
IS
–
Pin Input Current
IS
–
> 2.5V
IS
–
< 1.5V
IS
+
= IS
–
= V
IN
= CS = 12V, SGEN = DGEN = Float
IS
+
= IS
–
= V
IN
= CS = 12V, SGEN = DGEN = 0V
SPFB = 1.235V
IS
+
= IS
–
= V
IN
= CS = 12V, SGEN = DGEN = Float
IS
+
= IS
–
= V
IN
= CS = 12V, SGEN = DGEN = 0V
l
elecTrical characTerisTics
CONDITIONS
EXTV
CC
Ramping Positive
DRVUV = 0V
DRVUV = INTV
CC
R
DRVSET
= 50kΩ, V
EXTVCC
= 0V
R
DRVSET
= 70kΩ, V
EXTVCC
= 0V
R
DRVSET
= 90kΩ, V
EXTVCC
= 0V
MIN
4.5
7.4
TYP
4.7
7.7
250
5.0
MAX
4.9
8.0
UNITS
V
V
mV
V
6.4
7.0
9.0
105
7.6
V
V
kHz
335
320
488
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400
760
350
535
465
380
585
850
kHz
kHz
kHz
kHz
V
V
FREQ
= 0V
V
FREQ
= INTV
CC
PLLIN/MODE = External Clock
PLLIN/MODE = External Clock
PLLIN/MODE = External Clock
75
2.5
0.5
V
70
30
1.16
4.5
10
–5
50
50
0.4
12
–10
130
130
1
2
25
–2.5
1.205
45
21
1.235
50
27
35
1
±20
20
5
6
100
–3.5
1.265
55
33
100
15
±500
100
15
1.26
100
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µA
µA
1.36
8
16
–15
V
mV
V
V
µA
mA
mA
mA
µA
µA
mA
V
mV
mV
µA
µA
nA
µA
µA
Surge Stopper
SGEN Pin ON Threshold
SGEN Pin Hysteresis
SG Pin Output High Voltage (V
SG
– V
CS
)
For more information
www.linear.com/LTC3897
5
3897f
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