FEATURES
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LTC3779
150V V
IN
and V
OUT
Synchronous
4-Switch Buck-Boost Controller
DESCRIPTION
The
LTC
®
3779
is a high performance buck-boost switching
regulator controller that operates from input voltages
above, below or equal to the output voltage. The constant
frequency current mode architecture allows a phase-
lockable frequency of up to 600kHz, while an input/
output constant-current loop provides support for battery
charging.
With a wide 4.5V to 150V input and output range and
seamless transfers between operating regions, the
LTC3779 is ideal for automotive, telecom and battery-
powered systems.
The LTC3779 features a precision 1.2V reference and
power good output indicator. The MODE pin can select
between pulse-skipping mode or forced continuous mode
of operation. Pulse-skipping mode offers high efficiency
at light load while forced continuous mode operates at
a constant frequency for noise sensitive applications.
The PLLIN pin allows the IC to be synchronized to an
external clock. The SS pin ramps the output voltage
during start-up. Current foldback limits MOSFET heat
dissipation during short-circuit conditions.
All registered trademarks and trademarks are the property of their respective owners.
4-Switch Current Mode Single Inductor Architecture
Allows V
IN
Above, Below or Equal to V
OUT
Wide V
IN
Range: 4.5V to 150V
Wide Output Voltage Range: 1.2V ≤ V
OUT
≤ 150V
Synchronous Rectification: Up to 99% Efficiency
±1% 1.2V Voltage Reference
Input or Output Average Current Limit
Onboard LDO or External NMOS LDO for DRV
CC
36V EXTV
CC
LDO Powers Drivers
Programmable 6V to 10V DRV
CC
Optimizes Efficiency
No Top FET Refresh Noise in Boost or Buck Mode
V
OUT
Disconnected from V
IN
During Shutdown
Phase-Lockable Fixed Frequency (50kHz to 600kHz)
No Reverse Current During Start-Up
Power Good Output Voltage Monitor
150V Rated RUN Pin with Accurate Turn-On Threshold
Programmable Input Overvoltage Lockout
Thermally Enhanced FE38 TSSOP Package Modified
for High Voltage Operation
Industrial, Automotive, Medical, Military, Avionics
APPLICATIONS
n
TYPICAL APPLICATION
V
IN
20V TO 120V
20µF
5µF
1k
5Ω
0.1µF
10k
133k
1.21k
NDRV
DRV
CC
10µF
LTC3779
30µF
V
INSNS
V
IN
SW1
TG1
RUN
V
INOV
SENSEP
BG1
BOOST1
0.22µF
15µH
4mΩ
V
OUT
48V
10A
56µF
Efficiency and Power Loss
vs Input Voltage
100
30
98
EFFICIENCY (%)
100
220pF
4m
475k
EFFICIENCY
24
POWER LOSS (W)
96
18
SENSEN
SGND
PGND
BG2
100
94
12
V5
2.2µF
0.1µF
56.2k
SS
FREQ
BOOST2
0.22µF
SW2
TG2
I
AVGSNSP
100
4.7µF
I
AVGSNSN
V
OUTSNS
V
FB
12.1k
1k
100
92
V
OUT
= 48V
I
OUT
= 10A
0
POWER LOSS
6
90
0
12
24
36 48 60 72 84 96 108 120
VIN VOLTAGE (V)
3779 TA01b
I
TH
100pF
10k
10nF
3779 TA01a
Rev A
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1
LTC3779
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
BG1
VINOV
DRVSET
SGND
EXTV
CC
NDRV
DRV
CC
V5
SS
1
2
3
4
5
6
7
8
9
39
PGND
30 V
OUTSNS
28 I
AVGSNSN
26 I
AVGSNSP
24 RUN
22 BOOST2
21 TG2
20 SW2
32 V
INSNS
34 V
IN
38 SW1
37 TG1
36 BOOST1
Input Supply Voltage (V
IN
) ....................... 150V to –0.3V
Topside Driver Voltage
BOOST1, BOOST2 .....................................161V to –0.3V
Switch Voltage SW1, SW2 .......................... 150V to –5V
RUN ......................................................... 150V to –0.3V
I
AVGSNSP
, I
AVGSNSN
....................................150V to –10V
V
INSNS
, V
OUTSNS
...................................... 150V to –0.3V
EXTV
CC
Voltage ........................................ 36V to –0.3V
NDRV Voltage .................................................... (Note 9)
DRV
CC
Voltage ............................................11V to –0.3V
BOOST1-SW1, BOOST2-SW2......................11V to –0.3V
TG1-SW1, TG2-SW2, BG1, BG2.......................... (Note 8)
V5 Voltage.................................................... 6V to –0.3V
MODE, PLLIN, SS, PGOOD .......................... V5 to –0.3V
ITH, FREQ, DRVSET ..................................... V5 to –0.3V
SENSEP, SENSEN, VINOV ............................ V5 to –0.3V
V
FB
Voltage ............................................... 2.7V to –0.3V
Operating Junction Temperature
Range (Notes 2, 3) ................................. –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
EXTV
CC
/DRV
CC
Peak Current ..............................100mA
V
FB
10
SENSEP 11
SENSEN 12
ITH 13
SGND 14
MODE 15
PLLIN 16
FREQ 17
PGOOD 18
BG2 19
FE PACKAGE
VARIATION: FE38(31)
38-LEAD PLASTIC TSSOP
T
JMAX
= 150°C,
θ
JA
= 28°C/W
EXPOSED PAD (PIN 39) IS PGND, MUST BE SOLDERED TO PCB
FOR RATED ELECTRICAL AND THERMAL CHARACTERISTICS
ORDER INFORMATION
LEAD FREE FINISH
LTC3779EFE#PBF
LTC3779IFE#PBF
LTC3779HFE#PBF
TAPE AND REEL
LTC3779EFE#TRPBF
LTC3779IFE#TRPBF
LTC3779HFE#TRPBF
http://www.linear.com/product/LTC3779#orderinfo
PART MARKING
LTC3779FE
LTC3779FE
LTC3779FE
PACKAGE DESCRIPTION
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
Consult ADI 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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
Rev A
2
For more information
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LTC3779
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
= 15V, V
RUN
= 5V, V
EXTVCC
= 0V, V
DRVSET
= 0V,
V
VINOV
= 0V unless otherwise noted.
SYMBOL
V
IN
V
OUT
PARAMETER
Input Supply Operating Voltage Range
Output Supply Operating Voltage Range
Regulated Feedback Voltage
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
Transconductance Amplifier gm
I
Q
Input DC Supply Current
Shutdown
Undervoltage Lockout
RUN Pin ON Threshold
RUN Pin Hysteresis
RUN Pin Source Current
RUN Pin Hysteresis Current
V
IN
Overvoltage Lockout Threshold
(Rising)
V
IN
Overvoltage Hysteresis
SENSE Pins Current
I
AVGSNSP
I
AVGSNSN
V
SENSE(MAX)
I
AVGSNS
Pins Current
Soft-Start Charge Current
Maximum Current Sense Threshold
(Buck Region Valley Current Mode)
Maximum Current Sense Threshold
(Boost Region Peak Current Mode)
Maximum Input / Output Average
Current Sense Threshold
DC
(MAX, BOOST)
Maximum Duty Factor
V
SENSEP
= V
SENSEN
= 0
V
IAVGSNSP
= V
IAVGSNSN
= 10V
V
SS
= 0V
V
FB
= 1V
V
FB
= 1V
V
IAVGSNSP
= V
IAVGSNSN
= 10V, V
FB
= 1V
% Switch C On
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
(Note 4)
(Note 5); ITH Voltage = 1.4V
(Note 5)
(Note 5); V
IN
= 7V to 100V
(Note 5); Measured in Servo Loop; ∆ITH
Voltage = 1.5V to 2V
(Note 5); ITH = 1.4V; Sink/Source 5µA
(Note 6)
RUN = 0V
V5 Ramping Up
V5 Ramping Down
V
RUN
Rising
V
RUN
< 1.2V
V
RUN
> 1.2V
V
VINOV
Rising
l
l
MIN
4.5
1.2
1.188
TYP
MAX
150
150
UNITS
V
V
V
nA
%
%
mmho
1.2
–15
0.02
0.01
1.5
3.6
40
1.212
-50
0.2
0.2
5.5
75
4.6
4.1
1.3
mA
µA
V
V
V
mV
µA
µA
4.1
3.6
1.1
4.35
3.85
1.2
100
2.5
6.5
1.18
1.28
50
1.38
V
mV
±2
15
4
70
120
47.5
5
90
140
50
90
9
9
6
110
160
52.5
µA
µA
µA
mV
mV
mV
%
%
%
DC
ON(MIN, BOOST)
Minimum Duty Factor for Main Switch in % Switch C On
Boost Operation
DC
ON(MIN, BUCK)
Gate Driver
TG Pull-Up On Resistance
TG Pull-Down On Resistance
BG Pull-Up On Resistance
BG Pull-Down On Resistance
TG Transition Time:
Rise Time
Fall Time
BG Transition Time:
Rise Time
Fall Time
V
DRVCC
= 9V
V
DRVCC
= 9V
V
DRVCC
= 9V (Note 7)
C
LOAD
= 3300pF
V
DRVCC
= 9V (Note 7)
C
LOAD
= 3300pF
Minimum Duty Factor for Main Switch in % Switch B On
Buck Operation
3.1
1.3
5.5
3
60
Ω
Ω
ns
60
ns
Rev A
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3
LTC3779
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
= 15V, V
RUN
= 5V, V
EXTVCC
= 0V, V
DRVSET
= 0V,
V
VINOV
= 0V unless otherwise noted.
SYMBOL
PARAMETER
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
DRV
CC
LDO Regulator
V
DRVCC
DRV
CC
Regulation Voltage from NDRV
Regulator
NDRV Driving External NFET, V
EXTVCC
= 0V
7V < V
IN
< 150V, V
DRVSET
= 0V
8V < V
IN
< 150V, V
DRVSET
= 1/4 V
V5
9V < V
IN
< 150V, V
DRVSET
= Float
10V < V
IN
< 150V, V
DRVSET
= 3/4 V
V5
11V < V
IN
< 150V, V
DRVSET
= V
V5
V
NDRV
= V
DRVCC
, V
EXTVCC
= 0V
7V < V
IN
< 150V, V
DRVSET
= 0V
8V < V
IN
< 150V, V
DRVSET
= 1/4 V
V5
9V < V
IN
< 150V, V
DRVSET
= Float
10V < V
IN
< 150V, V
DRVSET
= 3/4 V
V5
11V < V
IN
< 150V, V
DRVSET
= V
V5
I
CC
= 0mA to 50mA, V
EXTVCC
= 0V
7V < V
EXTVCC
< 30V, V
DRVSET
= 0V
8V < V
EXTVCC
< 30V, V
DRVSET
= 1/4 V
V5
9V < V
EXTVCC
< 30V, V
DRVSET
= Float
10V < V
EXTVCC
< 30V, V
DRVSET
= 3/4 V
V5
11V < V
EXTVCC
< 30V, V
DRVSET
= V
V5
I
CC
= 0mA to 50mA, V
EXTVCC
= 12V
V
DRVSET
= 0V
EXTV
CC
Ramping Positive
% of DRV
CC
Regulation Voltage
6V < V
DRVCC
< 10V
I
V5
= 0mA to 20mA, V
DRVCC
= 10V
R
FREQ
= 68.5kΩ
R
FREQ
≤ 20kΩ
R
FREQ
= 135kΩ
V
PLLIN
Rising
V
PLLIN
Falling
PLLIN = External Clock
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ELECTRICAL CHARACTERISTICS
CONDITIONS
C
LOAD
= 3300pF Each Driver, V
DRVSET
= V5
C
LOAD
= 3300pF Each Driver, V
DRVSET
= V5
MIN
TYP
60
60
MAX
UNITS
ns
ns
5.8
6.8
7.8
8.75
9.65
5.5
6.5
7.5
8.45
9.15
5.8
6.8
7.8
8.75
9.65
6.1
7.1
8.1
9.1
10
5.8
6.8
7.8
8.8
9.5
0.5
6.1
7.1
8.1
9.1
10
0.5
DRV
CC
– 0.5
10
6.4
7.4
8.4
9.45
10.35
6.1
7.1
8.1
9.15
9.85
2
6.4
7.4
8.4
9.45
10.35
2
V
V
V
V
V
V
V
V
V
V
%
V
V
V
V
V
%
V
%
DRV
CC
Regulation Voltage from Internal
V
IN
LDO
V
EXTVCC
DRV
CC
Load Regulation from V
IN
LDO
DRV
CC
Regulation Voltage from Internal
EXTV
CC
LDO
DRV
CC
Load Regulation from Internal
EXTV
CC
LDO
EXTV
CC
LDO Switchover Voltage
EXTV
CC
Hysteresis
V5 Linear Regulator
V5 Regulation Voltage
V5 Load Regulation
Oscillator and Phase-Locked Loop
Nominal Frequency
Low Fixed Frequency
High Fixed Frequency
PLLIN Input Threshold
PLLIN Input Resistance
Synchronizable Oscillator Frequency
I
FREQ
PGOOD Output
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level
Frequency Setting Current
5.3
5.5
0.5
5.7
1
275
50
550
1.2
V
%
kHz
kHz
kHz
V
V
kΩ
kHz
µA
V
µA
%
%
µs
Rev A
225
30
450
2
250
40
500
200
50
18
20
0.1
600
22
0.3
±1
–10
10
125
I
PGOOD
= 2mA
V
PGOOD
= 5.5V
V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Negative
V
FB
Ramping Positive
PGOOD delay
V
PGOOD
High to Low
4
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LTC3779
ELECTRICAL CHARACTERISTICS
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 LTC3779 is tested under pulsed load conditions such that T
J
≈ T
A
. The LTC3779E is guaranteed to meet performance specifications
from 0°C to 85°C 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
LTC3779I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LTC3779H is guaranteed over the full –40°C to
150°C operating junction temperature range. High junction temperature
degrades operating lifetimes; operating lifetime is derated for junction
temperatures greater than 125°C. Note that the maximum ambient
temperature consistent with these specifications is determined by
specific operating conditions in conjunction with board layout, the rated
package thermal impedance and other environmental factors. The junction
temperature T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the formula:
T
J
= T
A
+ (P
D
•
θ
JA
),
where
θ
JA
= 28°C/W for the TSSOP package.
Note 3:
This IC includes over temperature protection that is intended to
protect the device during momentary overload conditions. The maximum
rated junction temperature will be exceeded when this protection is active.
Continuous operation above the specified absolute maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 4:
When biased from an auxiliary supply through the EXTV
CC
pin, the
LTC3779 can operate from a V
IN
voltage lower than 4.5V. Otherwise the
minimum V
IN
operational voltage is 4.5V after startup.
Note 5:
The LTC3779 is tested in a feedback loop that servos V
ITH
to a
specified voltage and measures the resultant V
FB
.
Note 6:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See
Applications Information.
Note 7:
Rise and fall times are measured using 10% and 90% levels.
Delay times are measured using 50% levels.
Note 8:
Do not apply a voltage or current source to these pins. They must
be connected to capacitive loads only, otherwise permanent damage may
occur. These pins are rated for an absolute maximum voltage of –0.3V to
11V.
Note 9:
Do not apply a voltage or current source to the NDRV pin, other
than tying NDRV to DRV
CC
when not used. If used it must be connected
to capacitive loads only (see
DRVCC Regulator
in the Applications
Information section), otherwise permanent damage may occur.
Rev A
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5
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