FEATURES
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LT8335
Low I
Q
Boost/SEPIC/
Inverting Converter
with 2A, 28V Switch
DESCRIPTION
The
LT
®
8335
is a current mode DC/DC converter capable
of generating either positive or negative output voltages
using a single feedback pin. It can be configured as a
boost, SEPIC or inverting converter consuming as low as
6µA of quiescent current. Low ripple Burst Mode opera-
tion maintains high efficiency down to very low output
currents while keeping the output ripple below 15mV in
a typical application. The internally compensated current
mode architecture results in stable operation over a wide
range of input and output voltages. Integrated soft-start
and frequency foldback functions are included to control
inductor current during start-up. The 2MHz operation
combined with the small 8-lead DFN package, enables
low cost, area efficient solutions.
L,
LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
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3V to 25V Input Voltage Range
Ultralow Quiescent Current and Low Ripple Burst
Mode
®
Operation: I
Q
= 6µA
2A, 28V Power Switch
Positive or Negative Output Voltage Programming
with a Single Feedback Pin
Fixed 2MHz Switching Frequency
Programmable Undervoltage Lockout (UVLO)
Internal Compensation and Soft-Start
Low Profile (0.75mm) 8-Lead (3mm
×
2mm) DFN
Package
APPLICATIONS
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Industrial and Automotive
Telecom
Medical Diagnostic Equipment
Portable Electronics
TYPICAL APPLICATION
3V to 6V Input, 12V Boost Converter
V
IN
3V TO 6V
4.7µF
V
IN
EN/UVLO
LT8335
FBX
INTV
CC
1µF
8335 TA01
Efficiency and Power Loss
100
V
OUT
12V
275mA AT V
IN
= 3V
440mA AT V
IN
= 5V
520mA AT V
IN
= 6V
4.7pF
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
100
200
300
400
LOAD CURRENT (mA)
V
IN
= 3V
V
IN
= 5V
V
IN
= 6V
500
200
POWER LOSS
EFFICIENCY
800
POWER LOSS (mW)
1000
1.2µH
SW
GND
22µF
1M
600
400
154k
0
600
8335 TA01b
For more information
www.linear.com/LT8335
1
8335f
LT8335
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
FBX 1
NC 2
SW 3
SW 4
9
GND
8 EN/UVLO
7 INTV
CC
6 V
IN
5 GND
SW ............................................................................28V
V
IN
, EN/UVLO............................................................25V
EN/UVLO Pin Above V
IN
Pin........................................6V
INTV
CC
(Note 2) ..........................................................4V
FBX ...........................................................................±4V
Operating Junction Temperature (Note 3)
LT8335E, LT8335I ............................. –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
DDB PACKAGE
8-LEAD (3mm
×
2mm) PLASTIC DFN
θ
JA
= 80.5°C/W
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT8335EDDB#PBF
LT8335IDDB#PBF
TAPE AND REEL
LT8335EDDB#TRPBF
LT8335IDDB#TRPBF
http://www.linear.com/product/LT8335#orderinfo
PART MARKING
LGVM
LGVM
PACKAGE DESCRIPTION
8-Lead (3mm
×
2mm) Plastic DFN
8-Lead (3mm
×
2mm) Plastic DFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for information on 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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
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8335f
For more information
www.linear.com/LT8335
LT8335
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, EN/UVLO = 12V unless otherwise noted.
PARAMETER
V
IN
Operating Voltage Range
V
IN
Quiescent Current at Shutdown
V
EN/UVLO
= 0.2V
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
l
TYP
0.9
2
2
3.6
5.5
8.5
780
840
MAX
25
2
5
5
9.5
10
15
1100
1200
1.632
–0.780
0.015
0.015
10
UNITS
V
µA
µA
µA
µA
µA
µA
µA
µA
V
V
%/V
%/V
nA
MHz
ns
ns
A
mΩ
µA
V
V
nA
ms
3
V
EN/UVLO
= 1.5V
l
V
IN
Quiescent Current
Sleep Mode, Not Switching
l
Active Mode, Not Switching
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FBX Regulation
FBX Regulation Voltage
FBX Line Regulation
FBX Pin Current
Oscillator
Switching Frequency (f
OSC
)
Minimum On-Time
Minimum Off-Time
Switch
Maximum Switch Current Limit Threshold
Switch R
DS(ON)
Switch Leakage Current
EN/UVLO Logic
EN/UVLO Pin Threshold (Rising)
EN/UVLO Pin Threshold (Falling)
EN/UVLO Pin Current
Soft-Start
Soft-Start Time
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:
INTV
CC
cannot be externally driven. No additional components or
loading is allowed on this pin.
Note 3:
The LT8335E is guaranteed to meet performance specifications
from 0°C to 125°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
1.2
Start Switching
Stop Switching
V
EN/UVLO
= 1.6V
l
l
l
l
l
FBX > 0V
FBX < 0V
FBX > 0V, 3V < V
IN
< 25V
FBX < 0V, 3V < V
IN
< 25V
FBX = 1.6V, –0.8V
l
l
1.568
–0.820
1.6
–0.80
0.005
0.005
l
–10
1.80
2.0
74
47
2.0
2.5
170
0.1
1.620
1.556
–40
1.68
1.60
2.20
115
65
3.0
1
1.745
1.644
40
I
SW
= 0.5A
V
SW
= 28V
LT8335I is guaranteed over the full –40°C to 125°C operating junction
temperature range. High junction temperatures degrade operating
lifetimes. Operating lifetime is derated at junction temperatures greater
than 125°C.
Note 4:
The IC includes overtemperature protection that is intended to
protect the device during overload conditions. Junction temperature will
exceed 150°C when overtemperature protection is active. Continuous
operation above the specified maximum operating junction temperature
will reduce lifetime.
For more information
www.linear.com/LT8335
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8335f
LT8335
TYPICAL PERFORMANCE CHARACTERISTICS
FBX Positive Regulation Voltage
vs Temperature
1.630
1.620
FBX VOLTAGE (V)
FBX VOLTAGE (V)
1.610
1.600
1.590
1.580
1.570
–50 –25
V
IN
= 12V
–0.785
–0.790
EN/UVLO PIN VOLTAGE (V)
–0.795
–0.800
–0.805
–0.810
–0.815
–50 –25
FBX Negative Regulation Voltage
vs Temperature
V
IN
= 12V
1.74
1.72
1.70
1.68
1.66
1.64
1.62
1.60
1.58
1.56
EN/UVLO Pin Thresholds
vs Temperature
V
IN
= 12V
EN/UVLO RISING (TURN-ON)
EN/UVLO FALLING (TURN-OFF)
0 25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
8335 G01
0 25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
8335 G02
1.54
–50 –25
0 25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
8335 G03
Switching Frequency
vs Temperature
2.10
2.08
SWITCHING FREQUENCY (MHz)
2.06
2.04
2.02
2.00
1.98
1.96
1.94
1.92
1.90
–50 –25
0 25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
8335 G04
Switching Frequency vs V
IN
2.15
SWITCHING FREQUENCY (MHz)
2.10
2.05
2.00
1.95
1.90
1.85
NORMALIZED SWITCHING FREQUENCY (%)
125
Normalized Switching Frequency
vs FBX Voltage
V
IN
= 12V
V
IN
= 12V
100
75
50
25
0
5
10
15
V
IN
(V)
20
25
8335 G05
0
–0.8
–0.4
0.0
0.4
0.8
FBX VOLTAGE (V)
1.2
1.6
8335 G06
Switch Current Limit vs Duty
Cycle
2.9
V
IN
= 12V
MINIMUM ON–TIME (nS)
120
110
Switch Minimum On-Time
vs Temperature
V
IN
= 12V
60
55
MINIMUM OFF–TIME (ns)
50
45
40
35
Switch Minimum Off-Time
vs Temperature
V
IN
= 12V
SWITCH CURRENT LIMIT (A)
2.7
100
90
80
70
60
50
2.5
2.3
2.1
0
20
40
60
DUTY CYCLE (%)
80
100
8335 G07
40
–50 –25
0 25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
8335 G08
30
–50 –25
0 25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
8335 G09
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For more information
www.linear.com/LT8335
LT8335
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
Pin Current (Sleep Mode, Not
Switching) vs Temperature
10.00
8.75
V
IN
PIN CURRENT (µA)
V
IN
PIN CURRENT (µA)
7.50
6.25
5.00
3.75
2.50
1.25
0
–50 –25
0 25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
8335 G10
V
IN
Pin Current (Active Mode, Not
Switching) vs Temperature
1000
950
SWITCHING FREQUENCY (MHz)
900
850
800
750
700
650
600
–50 –25
0 25 50 75 100 125 150 175
JUNCTION TEMPERATURE (°C)
8335 G11
Burst Frequency vs Load Current
2.5
FRONT PAGE APPLICATION
V
IN
= 5V, V
OUT
= 12V
V
IN
= 12V
V
IN
= 12V
2.0
1.5
1.0
0.5
0
0
50
100
150
LOAD CURRENT (mA)
200
8335 G12
Switching Waveforms
(in CCM)
I
L
500mA/DIV
Switching Waveforms
(in DCM/Light Burst Mode)
Switching Waveforms
(in Deep Burst Mode)
I
L
500mA/DIV
I
L
500mA/DIV
V
SW
5V/DIV
V
SW
5V/DIV
V
SW
5A/DIV
1µs/DIV
FRONT PAGE APPLICATION
V
IN
= 5V, V
OUT
= 12V, I
LOAD
= 100mA
8335 G14
1µs/DIV
FRONT PAGE APPLICATION
V
IN
= 5V, V
OUT
= 12V, I
LOAD
= 440mA
8335 G13
1µs/DIV
FRONT PAGE APPLICATION
V
IN
= 5V, V
OUT
= 12V, I
LOAD
= 10mA
8335 G15
V
OUT
Transient Response: Load
Current Transients from 200mA to
440mA to 200mA
Front Page Application: V
IN
= 5V, V
OUT
= 12V
V
OUT
200mV/DIV
V
OUT
200mV/DIV
V
OUT
Transient Response: Load
Current Transients from 40mA to
440mA to 40mA
Front Page Application: V
IN
= 5V, V
OUT
= 12V
I
LOAD
200mA/DIV
I
LOAD
200mA/DIV
100µs/DIV
8335 G16
100µs/DIV
8335 G17
For more information
www.linear.com/LT8335
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8335f
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