LINER LT8613 60v, 1.2a synchronous monolithic buck regulator with 6î¼a quiescent current Datasheet

LT8619/LT8619-5
60V, 1.2A Synchronous Monolithic Buck
Regulator with 6µA Quiescent Current
FEATURES
DESCRIPTION
Wide Input Voltage Range: 3V to 60V
nn Fast Minimum Switch-On Time: 30ns
nn Ultralow Quiescent Current Burst Mode Operation:
nn 6μA I Regulating 12V to 3.3V
Q
IN
OUT
nn 10mV
Output
Ripple
at
No
Load
P-P
nn Synchronizable/Programmable Fixed Frequency
Forced Continuous Mode Operation: 300kHz
to 2.2MHz
nn High Efficiency Synchronous Operation:
nn 92% Efficiency at 0.5A, 5V
OUT from 12VIN
nn 90% Efficiency at 0.5A, 3.3V
OUT from 12VIN
nn Low Dropout: 360mV at 0.5A
nn Low EMI
nn Accurate 1V Enable Pin Threshold
nn Internal Soft-Start and Compensation
nn Power Good Flag
nn Small Thermally Enhanced 16-Lead MSOP Package
and 10-Lead (3mm × 3mm) DFN Packages
The LT®8619 is a compact, high efficiency, high speed
synchronous monolithic step-down switching regulator
that consumes only 6μA of quiescent current. The LT8619
can deliver 1.2A of continuous current. Top and bottom
power switches are included with all necessary circuitry
to minimize the need for external components. Low ripple
Burst Mode® operation enables high efficiency down to
very low output currents while keeping the output ripple
to 10mVP-P. A SYNC pin allows forced continuous mode
operation synchronized to an external clock. Internal compensation with peak current mode topology allows the use
of small inductors and results in fast transient response
and good loop stability. The EN/UV pin has an accurate 1V
threshold and can be used to program VIN undervoltage
lockout or to shut down the LT8619, reducing the input
supply current to below 0.6μA. The PG flag signals when
VOUT is within ±7.5% of the programmed output voltage.
The LT8619 is available in a small 16-lead MSOP and
10-lead 3mm × 3mm DFN packages with exposed pad
for low thermal resistance.
nn
APPLICATIONS
12V Automotive Systems
nn 12V and 24V Commercial Vehicles
nn 48V Electric and Hybrid Vehicles
nn Industrial Supplies
All registered trademarks and trademarks are the property of their respective owners.
nn
TYPICAL APPLICATION
5V, 1.2A Step-Down Converter
2.2µF
VIN
BST
LT8619-5
0.1µF 10µH
SW
EN/UV
1µF
66.5k
100k
INTVCC
PG
PG
BIAS
RT
SYNC
fOSC = 700kHz
L = VISHAY IHLP-2020BZ-01
COUT = TDK C3225X7R1C226K250
OUT
GND
8619 TA01a
22µF
10
70
1
EFFICIENCY
0.1
60
50
40
30
20
10
0
0.001 0.01
POWER LOSS
0.01
POWER LOSS (W)
OFF ON
VOUT
5V
1.2A
Efficiency
at =VOUT
Efficiency
at V OUT
5V = 5V
fOSC = 700kHz
90 Burst Mode
OPERATION
80
EFFICIENCY (%)
VIN
6V TO 60V
100
VIN = 48V
VIN = 24V 0.001
VIN = 12V
L = 10µH, IHLP-2020BZ-01
0.0001
0.1
1
10 100 1k 10k
LOAD CURRENT (mA)
8619 TA01b
8619f
For more information www.linear.com/LT8619
1
LT8619/LT8619-5
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
VIN, EN/UV.................................................................60V
BIAS...........................................................................30V
BST Pin Above SW Pin................................................4V
PG, SYNC, OUT............................................................6V
FB ................................................................................2V
Operating Junction Temperature (Note 3)
LT8619E, LT8619E-5........................... –40°C to 125°C
LT8619I, LT8619I-5............................. –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
PIN CONFIGURATION
TOP VIEW
VIN
1
EN/UV
2
RT
3
PG
4
SYNC
5
TOP VIEW
NC
VIN
NC
EN/UV
RT
PG
SYNC
GND
10 SW
11
GND
9 BST
8 INTVCC
7 BIAS
6 FB*
1
2
3
4
5
6
7
8
17
GND
16
15
14
13
12
11
10
9
SW
SW
BST
NC
INTVCC
BIAS
FB/OUT*
FB/OUT*
MSE PACKAGE
16-LEAD PLASTIC MSOP
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
θJA = 43°C/W, θJC = 10°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
θJA = 40°C/W, θJC = 10°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
*FB FOR LT8619, OUT FOR LT8619-5
ORDER INFORMATION
http://www.linear.com/product/LT8619#orderinfo
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT8619EDD#PBF
LT8619EDD#TRPBF
LGNP
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LT8619IDD#PBF
LT8619IDD#TRPBF
LGNP
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LT8619EMSE#PBF
LT8619EMSE#TRPBF
8619
16-Lead Plastic MSOP
–40°C to 125°C
LT8619IMSE#PBF
LT8619IMSE#TRPBF
8619
16-Lead Plastic MSOP
–40°C to 125°C
LT8619EMSE-5#PBF
LT8619EMSE-5#TRPBF
86195
16-Lead Plastic MSOP
–40°C to 125°C
LT8619IMSE-5#PBF
LT8619IMSE-5#TRPBF
86195
16-Lead Plastic MSOP
–40°C to 125°C
Consult ADI 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.
2
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VEN/UV = 2V unless otherwise noted (Notes 2, 3)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Switching Loop
VIN Minimum Input Voltage
VIN Quiescent Current at No Load
VIN = 12V, VEN/UV = 0V
0.6
0.6
1.0
3.0
µA
µA
l
6
6
10
18
µA
µA
VIN = 12V, VOUT = 3.3V, RT = 66.5k, VEN/UV = 2V, Floats SYNC
10
µA
VIN = 12V, VOUT = 3.3V, RT = 66.5k, VEN/UV = 2V, VSYNC = INTVCC
3
mA
VIN = 12V, VOUT = 3.3V, RT = 66.5k, VEN/UV = 2V, VSYNC = 0V
ILOAD = 100µA
ILOAD = 1mA
BIAS Pin Current Consumption
VIN = 12V, VBIAS = 3.3V, ILOAD = 0.5A, fOSC = 700kHz
Regulated Output Voltage
LT8619-5, VIN = 12V, VSYNC = INTVCC, No Load
Feedback Voltage
V
l
VIN = 12V, VOUT = 3.3V, RT = 66.5k, VEN/UV = 2V, VSYNC = 0V
VIN Current in Regulation
3.0
Feedback Voltage Line Regulation
VIN = 4V to 50V, VSYNC = INTVCC
LT8619, VFB = 0.8V
Minimum On-Time
LT8619, ILOAD = 0.5A, VSYNC = INTVCC
µA
µA
mA
4.975
4.925
5.0
5.0
5.025
5.075
V
l
l
0.796
0.788
0.8
0.8
0.804
0.812
V
V
±0.004
±0.03
%/V
±20
nA
30
60
ns
100
150
180
ns
1.5
1.75
2.0
A
l
l
Minimum Off-Time
Top Switch Peak Current Limit
65
400
2.2
LT8619, VIN = 12V, VSYNC = INTVCC, No Load
Feedback Pin Input Current
38
320
l
l
l
Bottom Switch Current Limit
1.8
A
Bottom Switch Reverse Current Limit
VSYNC = INTVCC
0.55
A
Soft-Start Duration
VIN = 12V, VOUT = 3.3V, No Load, COUT = 22µF
0.2
ms
EN/UV to PG High Delay
CINTVCC = 1µF, VOUT = 3.3V, No Load, COUT = 22µF
0.66
ms
10
µs
EN/UV to PG Low Delay
Oscillator and SYNC
Operating Frequency
RT = 162k
l
260
300
340
kHz
RT = 66.5k
l
630
700
770
kHz
2.0
2.1
MHz
2.2
MHz
RT = 20k
l
1.9
Synchronization Frequency
fSYNC ≥ fOSC
l
0.3
SYNC Threshold
Frequency Synchronization
Burst Mode Operation
Floats SYNC Pin, Pulse-Skipping Mode
Forced Continuous Mode
SYNC Pin Current
Built-In Sourcing Current, VSYNC = 0V
Built-In Sinking Current, VSYNC = 3.3V
0.35
1.6
1
0.6
1.2
2.0
–0.2
3.0
0.95
2.4
V
V
V
B
µA
µA
8619f
For more information www.linear.com/LT8619
3
LT8619/LT8619-5
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VEN/UV = 2V unless otherwise noted (Notes 2, 3)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Switch, Logic and Power Good
Top Switch On-Resistance
ILOAD = 0.1A
Bottom Switch On-Resistance
ILOAD = 0.1A
EN/UV Power-On Threshold
EN/UV Rising
l
0.94
EN/UV Power-On Hysteresis
0.45
Ω
0.22
Ω
1.0
1.1
40
0.34
0.56
V
mV
0.92
V
100
nA
EN/UV Shutdown Threshold
EN/UV Falling
EN/UV Pin Current
VEN/UV = 2V
Overvoltage Threshold
VFB Rising Wrt. Regulated VFB
Positive Power Good Threshold
VFB Rising Wrt. Regulated VFB
l
5
7.5
10
%
Negative Power Good Threshold
VFB Falling Wrt. Regulated VFB
l
–5
–7.5
–10
%
Positive Power Good Delay
VFB = 0.8V ↑ 0.9V to PG Low
VFB = 0.9V ↓ 0.8V to PG High
60
35
µs
µs
Negative Power Good Delay
VFB = 0.8V ↓ 0.7V to PG Low
VFB = 0.7V ↑ 0.8V to PG High
60
35
µs
µs
PG Leakage
VPG = 3.3V, Power Good
PG VOL
IPG = 100µA
l
–100
l
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 LT8619 is tested under pulse load conditions such that
TJ ≈ TA. The LT8619E 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,
4
3.75
0.01
%
±100
nA
0.3
V
characterization, and correlation with statistical process controls. The
LT8619I 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: This 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.
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
TYPICAL PERFORMANCE CHARACTERISTICS
Burst Mode
OPERATION
90
80
80
70
70
PULSESKIPPING
MODE
60
50
FORCED
CONTINUOUS
MODE
40
30
VIN = 12V
fOSC = 700kHz
L = 10µH
IHLP-2020BZ-01
20
10
0
0.001 0.01
700kHz Efficiency at V OUT = 3.3V
0.1
1
10 100
LOAD CURRENT (mA)
1k
90
60
50
FORCED
CONTINUOUS
MODE
40
30
VIN = 12V
fOSC = 700kHz
L = 10µH
IHLP-2020BZ-01
10
0
0.001 0.01
0.1
1
10 100
LOAD CURRENT (mA)
1k
2MHz Efficiency
Efficiency at
at VVOUT = 3.3V
100
40
30
VIN = 12V
fOSC = 2MHz
L = 3.3µH
IHLP-2020AB-01
20
10
0
0.001 0.01
0.1
1
10 100
LOAD CURRENT (mA)
1k
90
10k
80
10k
0.2
90
1.2A LOAD
70
60
50
40
0.4
0.6
0.8
LOAD CURRENT (A)
1.0
0
0.001 0.01
1.2
70
20
FORCED CONTINUOUS MODE
VOUT:
10
PULSESKIPPING
MODE
3.3V
5V
3.3V
3.3V
10
20
30
VIN (V)
40
50
60
8619 G07
0.1
1
10
VIN (V)
10k
No Load IVIN
VINvs Temperature
fOSC = 700kHz
Burst Mode OPERATION
60V
60V
SHUTDOWN
Burst Mode OPERATION
SHUTDOWN
1k
12V
10
1
0
0.1
1
10 100
LOAD CURRENT (mA)
8619 G06
80
75
fOSC = 700kHz
Burst Mode OPERATION
VIN = 48V
VIN = 24V
VIN = 12V
L = 10µH, IHLP-2020BZ-01
30
10
No Load IVIN at 700kHz
100
10k
Efficiency at VOUT
OUT = 3.3V
20
fOSC = 700kHz
L = 10µH, IHLP-2020BZ-01
0
1k
80
FORCED CONTINUOUS MODE
1k
0.5A LOAD
0.1
1
10 100
LOAD CURRENT (mA)
8619 G05
VOUT = 3.3V
fSW = 700kHz
FORCED CONTINUOUS MODE
L = 10µH IHLP-2020BZ-01
85
VIN = 12V
fOSC = 2MHz
L = 4.7µH
IHLP-2020AB-01
90
85
70
IVIN (µA)
EFFICIENCY (%)
100
12V
75
Efficiency vs VIN
95
30
8619 G03
48V
24V
8619 G04
100
FORCED
CONTINUOUS
MODE
40
IVIN (µA)
50
EFFICIENCY (%)
EFFICIENCY (%)
FORCED
CONTINUOUS
MODE
50
0
0.001 0.01
10k
Burst Mode OPERATION
60
60
10
95
PULSESKIPPING
MODE
PULSESKIPPING
MODE
70
20
Efficiency at VOUT = 5V
90
80 Burst Mode
OPERATION
70
Burst Mode
OPERATION
8619 G02
8619 G01
100
2MHz Efficiency at VOUT = 5V
80
PULSESKIPPING
MODE
20
10k
100
Burst Mode
OPERATION
90
EFFICIENCY (%)
EFFICIENCY (%)
100
EFFICIENCY (%)
700kHz Efficiency
Efficiency at
at VVOUT = 5V
EFFICIENCY (%)
100
fOSC = 700kHz
NO LOAD
100
8619 G08
12V
1
0.5
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
8619 G09
8619f
For more information www.linear.com/LT8619
5
LT8619/LT8619-5
TYPICAL PERFORMANCE CHARACTERISTICS
VOUT = 3.3V
VIN = 12V
fOSC = 700kHz
NO LOAD
FORCED CONTINUOUS MODE
0.75
0.50
0.25
0
–0.25
–0.50
Line Regulation
0.10
VIN = 12V
VOUT = 3.3V
fSW = 700kHz
FORCED CONTINUOUS MODE
0.1
∆VOUT (%)
∆VOUT (%)
Load Regulation
0.2
VOUT = 2.4V, NO LOAD
fSW = 400kHz
FORCED CONTINUOUS MODE
0.05
∆VOUT (%)
1.00
0
0
–0.05
–0.1
–0.75
–0.2
25 50 75 100 125 150
TEMPERATURE (°C)
0
0.2
0.4
0.6
0.8
LOAD CURRENT (A)
8619 G10
1.9
CURRENT LIMIT (A)
VEN/UV (V)
1000
900
POWER–ON THRESHOLD
EN/UV FALLING
0.6
SHUTDOWN THRESHOLD
0
1.7
1.5
25 50 75 100 125 150
TEMPERATURE (°C)
VIN = 12V
VOUT = 3.3V
fSW = 700kHz
L = 10µH
IHLP-2020BZ-01
0
20
40
60
DUTY CYCLE (%)
0.4
0.2
0
0.2
0.4
0.6
0.8
LOAD CURRENT (A)
1.0
1.2
8619 G16
6
400
300
200
BOTTOM SWITCH
100
80
0
–50 –25
100
0
25 50 75 100 125 150
TEMPERATURE (°C)
8619 G15
5
L = 10µH, IHLP-2020BZ-01
1.75 VOUT = 3.3V, ∆VOUT = –1%
fOSC = 700kHz
1.50 FORCED CONTINUOUS MODE
(CONTINUOUS OPERATION
ABOVE MAX JUNCTION
1.25 TEMPERATURE MAY
PERMANENTLY
1.00 DAMAGE THE
DEVICE)
0.75
0.50
4
0
–50 –25
3
1.2A LOAD
1.0A LOAD
0.5A LOAD
fSW
VIN = 12V
VOUT = 3.3V, NO LOAD
FORCED CONTINUOUS MODE
2
1
fSW = 700kHz
0
fSW = 2MHz
–1
–2
–3
0.25
0
500
Dropout vs Temperature
0.6
TOP SWITCH
600
2.00
DROPOUT VOLTAGE (V)
DROPOUT VOLTAGE (V)
0.8
LOAD CURRENT = 100mA
8619 G14
Dropout
VOUT = 3.3V
∆VOUT = –1%
fSW = 2MHz
L = 3.3µH, IHLP-2020AB-01
FORCED CONTINUOUS MODE
100
8619 G12
700
1.8
8619 G13
1.0
10
VIN (V)
800
1.6
0.2
0
–50 –25
1
Switch Resistance
2.0
1.0
0.4
–0.10
Top FET Current Limit vs
Duty Cycle
EN/UV RISING
0.8
1.2
8619 G11
EN/UV Threshold
1.2
1.0
RDS(ON) (mΩ)
0
∆fSW (%)
–1.00
–50 –25
NO LOAD
0
25 50 75 100 125 150
TEMPERATURE (°C)
8619 G17
–4
–5
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
8619 G18
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
TYPICAL PERFORMANCE CHARACTERISTICS
60
0.2A LOAD
40
0.5A LOAD
20
0
–50 –25
0
160
0.5A LOAD
NO LOAD
150
140
–50 –25
25 50 75 100 125 150
TEMPERATURE (°C)
0
8619 G19
Power Good Delay
25
10
20
40
60
VFB – VPGTH (mV)
80
IBIAS vs fSW
10
IBIAS (mA)
IBIAS (mA)
NO LOAD
4
2
0.6
1.0
1.4
fSW (MHz)
1.8
2.2
8619 G25
NPG VFB RISING
–7.5
NPG VFB FALLING
–10.0
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
8619 G21
12
IBIAS vs Load
VIN = 12V
VOUT = 3.3V
FORCED CONTINUOUS MODE
10
6
fSW = 2MHz
4
VIN FALLING
0
2
0
25 50 75 100 125 150
TEMPERATURE (°C)
fSW = 700kHz
0
0.2
0.4
0.6
0.8
LOAD CURRENT (A)
1.0
VIN = 12V
VOUT = 3.3V
BIAS = VOUT
8
FORCED CONTINUOUS MODE
(CONTINUOUS OPERATION
ABOVE MAX JUNCTION
6 TEMPERATURE MAY
PERMANENTLY
DAMAGE THE
DEVICE)
4
0
–50 –25
24
1.2A LOAD
1A LOAD
0.5A LOAD
IIBIAS
at 2MHz
2MHz vs
vs Temperature
Temperature
BIAS at
VIN = 12V
VOUT = 5V
20 BIAS = VOUT
FORCED CONTINUOUS MODE
(CONTINUOUS OPERATION
16 ABOVE MAX JUNCTION
TEMPERATURE MAY
PERMANENTLY
12 DAMAGE THE
DEVICE)
8
NO LOAD
25 50 75 100 125 150
TEMPERATURE (°C)
8619 G26
0
–50 –25
1.2A LOAD
1A LOAD
0.5A LOAD
NO LOAD
4
0
1.2
8619 G24
IBIAS at 700kHz vs Temperature
2
0.2
–5.0
8619 G23
VIN = 12V
VOUT = 3.3V
L = 10µH
8 FORCED CONTINUOUS MODE
0
2.7
8619 G22
1A LOAD
–2.5
8
VIN RISING
2.8
2.5
–50 –25
100
6
0
VOUT = 1.6V, NO LOAD
fSW = 700kHz
FORCED CONTINUOUS MODE
2.6
0
OV
2.5
VIN UVLO
2.9
VIN UVLO (V)
POWER GOOD DELAY (µs)
3.0
75
0
25 50 75 100 125 150
TEMPERATURE (°C)
PPG VFB FALLING
5.0
8619 G20
100
50
POWER GOOD, OVERVOLTAGE THRESHOLD (%)
80
170
PPG VFB RISING
7.5
IBIAS (mA)
NO LOAD
10.0
IBIAS (mA)
MINIMUM ON-TIME (ns)
180
VOUT = 3.3V
fSW = 2MHz
FORCED CONTINUOUS MODE
100
Power Good, Overvoltage
Power Good, Overvoltage Threshold
Threshold
Minimum Off-Time
MINIMUM OFF TIME (ns)
120
Minimum On-Time
On Time
Minimum
0
25 50 75 100 125 150
TEMPERATURE (°C)
8619 G27
8619f
For more information www.linear.com/LT8619
7
LT8619/LT8619-5
TYPICAL PERFORMANCE CHARACTERISTICS
Forced Continuous Mode No Load
Switching Waveform
Forced Continuous Mode Switching
Waveform at Minimum On-time
IL
200mA/DIV
VOUT (AC)
2mV/DIV
SW
20V/DIV
IL
200mA/DIV
SW
(ZOOM IN)
10V/DIV
SW
10V/DIV
200ns/DIV
TOP = 200ns/DIV, BOT = 5ns/DIV,
PERSISTENCE MODE
8619 G28
VIN = 12V, VOUT = 3.3V
fSW = 2MHz, L = 3.3μH, COUT = 22μF
VIN = 53.7V, VOUT = 3.3V, 0.5A LOAD
fSW = 2MHz, L = 3.3μH, COUT = 22μF
Forced Continuous Mode Transient
Load Step from 10mA to 1A
Pulse-Skipping Mode Transient
Load Step from 10mA to 1A
VOUT
200mV/DIV
VOUT
200mV/DIV
ILOAD
1A/DIV
ILOAD
1A/DIV
SW
10V/DIV
SW
10V/DIV
20μs/DIV
20μs/DIV
8619 G30
VIN = 12V, VOUT = 3.3V
fOSC = 2MHz, L = 3.3μH, COUT = 22μF
VIN = 12V, VOUT = 3.3V
fOSC = 2MHz, L = 3.3μH, COUT = 22μF
Bust Mode Transient Load Step
from 10mA to 1A
Forced Continuous Mode
Frequency Synchronization
8619 G31
VOUT (AC)
20mV/DIV
SYNC
2V/DIV
SW
10V/DIV
VOUT
200mV/DIV
ILOAD
1A/DIV
SW
10V/DIV
20μs/DIV
8619 G32
VOUT (AC, ZOOM IN)
20mV/DIV
SYNC (ZOOM IN)
2V/DIV
SW (ZOOM IN)
10V/DIV
TOP = 10μs/DIV, BOT = 200ns/DIV
8619 G33
VIN = 12V, VOUT = 3.3V, NO LOAD
fOSC = 700kHz, L = 10μH, COUT = 22μF
fSW (FREE RUNNING) = 700kHZ, fSYNC = 1.2MHz
VIN = 12V, VOUT = 3.3V
fOSC = 2MHz, L = 3.3μH, COUT = 22μF
8
8619 G29
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
TYPICAL PERFORMANCE CHARACTERISTICS
VOUT = 2.4V Start-Up Dropout
Performance
VIN
1V/DIV
VOUT
1V/DIV
PG
2V/DIV
SW
5V/DIV
VOUT = 5V Start-Up Dropout
Performance
VIN
1V/DIV
VIN
VOUT
1V/DIV
VOUT
VOUT
1s/DIV
VIN
8619 G34
PG
2V/DIV
SW
5V/DIV
VOUT = 2.4V, 10Ω LOAD
fSW = 400kHz, L = 15μH, COUT = 47μF
PG 100k PULL-UP BY INTVCC
FORCED CONTINUOUS MODE
1s/DIV
8619 G35
VOUT = 5V, 10Ω LOAD
fSW = 700kHz, L = 10μH, COUT = 22μF
PG 100k PULL-UP BY INTVCC
FORCED CONTINUOUS MODE
EN/UV Shut Down
EN/UV Start-Up
EN/UV
2V/DIV
EN/UV
2V/DIV
VOUT
1V/DIV
VOUT
1V/DIV
PG
2V/DIV
PG
2V/DIV
SW
10V/DIV
SW
10V/DIV
100μs/DIV
8619 G36
VIN = 12V, VOUT = 3.3V, NO LOAD
fOSC = 2MHz, L = 3.3μH, COUT = 22μF
FORCED CONTINUOUS MODE
2μs/DIV
8619 G37
VIN = 12V, VOUT = 3.3V, NO LOAD
fOSC = 2MHz, L = 3.3μH, COUT = 22μF
FORCED CONTINUOUS MODE
8619f
For more information www.linear.com/LT8619
9
LT8619/LT8619-5
PIN FUNCTIONS
(DFN/MSOP)
NC (Pin 1, 3, 13, MSOP Only): No Connect. These pins
are not connected to the internal circuitry.
VIN (Pin 1/Pin 2): The VIN pin supplies current to the
LT8619 internal circuitry and to the internal topside power
switch. Be sure to place the positive terminal of the input
bypass capacitor as close as possible to the VIN pin, and
the negative capacitor terminal as close as possible to
the GND pin.
EN/UV (Pin 2/Pin 4): The LT8619 is shut down when this
pin is low and active when this pin is high. The EN/UV pin
power-on threshold is 1V. When forced below 0.56V, the
IC is put into a low current shutdown mode. Tie to VIN if
shutdown feature is not used. An external resistor divider
from VIN can be used to program the VIN UVLO.
RT (Pin 3/Pin 5): A resistor is tied between RT and ground
to set the switching frequency. When synchronizing, the
RT resistor should be chosen to set the LT8619 switching frequency equal to or below the synchronization frequency. Do not apply external voltage to this pin.
PG (Pin 4/Pin 6): Open-Drain Power Good Output. PG
remains low until the FB pin is within ±7.5% of the final
regulation voltage. The PG pull-up resistor can be connected to the INTVCC, VOUT or an external supply voltage
that is lower than 6V.
SYNC (Pin 5/Pin 7): External Clock Synchronization Input.
Tie to a clock source for synchronization to an external
frequency. During clock synchronization, the controller
enters forced continuous mode. Ground the SYNC pin for
Burst Mode operation. Connect to INTVCC to enable forced
continuous mode operation. Floating this pin will enable
pulse-skipping mode operation. During start-up, the controller is forced to run in pulse-skipping mode. When in
pulse-skipping or forced continuous mode operation, the
IQ will be much higher compared to Burst Mode operation.
10
FB (Pin 6/Pin 9, 10, LT8619 Only): The LT8619 regulates
the FB pin to 0.8V. Connect the feedback resistor divider
tap to this pin. Also, connect a phase lead capacitor
between FB and VOUT. Typically, this capacitor is between
4.7pF to 10pF. Do not apply an external voltage to this pin.
OUT (Pin 9, 10, LT8619-5 MSOP Only): Connect to the
regulator output VOUT. The LT8619-5 regulates the OUT
pin to 5V. This pin connects to the internal 10MΩ feedback divider that programs the fixed output voltage.
BIAS (Pin 7/Pin 11): The internal regulator will draw current from BIAS instead of VIN when the BIAS pin is tied
to a voltage higher than 3.1V. For switching regulator
output voltages of 3.3V and above, this pin should be tied
to VOUT. If this pin is tied to a supply other than VOUT, use
a 1μF local bypass capacitor on this pin.
INTVCC (Pin 8/Pin 12): Internal 3.3V Regulator Output.
The internal power drivers and control circuits are powered from this voltage. INTVCC maximum output current
is 20mA. INTVCC current will be supplied from BIAS if
VBIAS > 3.1V, otherwise current will be drawn from VIN.
Voltage on INTVCC will vary between 2.8V and 3.3V when
VBIAS is between 3.0V and 3.5V. Decouple this pin to GND
with at least a 1μF low ESR ceramic capacitor. Do not load
the INTVCC pin with external circuitry.
BST (Pin 9/Pin 14): This pin is used to provide a drive
voltage, higher than the input voltage, to the topside
power switch. Place a 0.1μF boost capacitor as close as
possible to the IC.
SW (Pin 10/Pin 15, 16): The SW pin is the output of the
internal power switches. Connect this pin to the inductor
and boost capacitor. This node should be kept small on
the PCB for good performance.
GND (Exposed Pad Pin 11/Pin 8, Exposed Pad Pin 17):
Ground. The exposed pad must be connected to the negative terminal of the input capacitor and soldered to the
PCB in order to lower the thermal resistance.
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
BLOCK DIAGRAM
VIN
CIN
R3
OPT
VIN
EN/UV
+
1V
–
R4
OPT
+
ENABLE
–
ICMP
SYNC
UVLO
CLK
OSC
0.3MHz–2.2MHz
SLOPE
COMP
RT
RT
S
BURST
DETECT
RC
VIN
BIAS
3.3V
LDO
INTVCC
R
CINTVCC
Q
BST
CB
VC
CC
INTVCC
SW
OV
L
VOUT
LOGIC
COUT
R1
C1
EA
+ – +
ISS
GND
0.8V VREF
FB/OUT
CSS
R2
–
NPG
+
0.74V
VOUT = 5V
GLITCH
FILTER
+
PPG
–
OV
0.83V
–
0.86V
OV
+
PG
PG
8619 BD
8619f
For more information www.linear.com/LT8619
11
LT8619/LT8619-5
OPERATION
The LT8619 is a monolithic, constant frequency current
mode step-down DC/DC converter. An oscillator, with frequency set using a resistor on the RT pin, turns on the
internal top power switch at the beginning of each clock
cycle. Current in the inductor then increases until the current comparator trips and turns off the top power switch.
The peak inductor current at which the top switch turns off
is controlled by the voltage on the internal VC node. The
error amplifier servos the VC node by comparing the voltage on the FB pin with an internal 0.8V reference. When
the load current increases, it causes a reduction in the
feedback voltage relative to the reference leading the error
amplifier to raise the VC voltage until the average inductor current matches the new load current. When the top
power switch turns off, the bottom power switch turns on
until the next clock cycle begins or inductor current falls
to zero (Burst Mode operation or pulse-skipping mode).
If overload conditions result in more than 1.8A flowing
through the bottom switch, the next clock cycle will be
delayed until the switch current returns to a safe level.
If the EN/UV pin is low, the LT8619 is shut down and
draws less than 0.6µA from the input. When the EN/UV
pin is above 1V, the switching regulator starts operation.
First, the internal LDO powers up, followed by the switching regulator 200μs soft-start ramp. During the soft-start
phase, the switcher operates in pulse-skipping mode and
gradually switches to forced continuous mode when VOUT
approaches the set point (if SYNC pin is forced high or
connected to an external clock). Typically, upon EN/UV
rising edge, it takes about 660μs for the switcher output
voltage to reach regulation and PG to be asserted.
To optimize efficiency at light loads, configure the LT8619
to operate in Burst Mode by grounding the SYNC pin.
At light load, in between bursts, all circuitry associated
with controlling the output switch is shut down, reducing
12
the input supply current. In a typical application, 6μA will
be consumed from the supply when regulating with no
load. Float the SYNC pin to enable pulse-skipping mode
operation. While in pulse-skipping mode, the oscillator
operates continuously and the bottom power switch turns
off when the inductor current falls to zero. During light
loads, switch pulses are skipped to regulate the output
and the quiescent current will be higher than Burst Mode
operation. Connecting the SYNC pin to INTVCC enables
forced continuous mode operation. In forced continuous
mode, the inductor current is allowed to reverse and the
switcher operates at a fixed frequency. If a clock is applied
to the SYNC pin, the part operates in forced continuous
mode and synchronizes to the external clock frequency;
with the rising SW signal synchronized to the external
clock positive edge.
To improve efficiency across all loads, supply current
to internal circuitry can be sourced from the BIAS pin
when biased above 3.1V. Else, the internal circuitry will
draw current from VIN. The BIAS pin should be connected
to VOUT if the LT8619 output is programmed to 3.3V or
above.
An overvoltage comparator, OV, guards against transient
overshoots. If VFB is higher than 0.83V, the OV comparator trips, disables the top MOSFET and turns on the bottom power switch until the next clock cycle begins or the
inductor reverse current reaches 0.55A. With high reverse
current, both top and bottom MOSFETs shut off till the
next cycle. Positive and negative power good comparators pull the PG pin low if the FB voltage varies more than
±7.5% (typical) from the set point.
The oscillator reduces the LT8619’s operating frequency
when the voltage at the FB pin is low. This frequency
foldback helps to control the inductor current when the
output voltage is lower than the programmed value which
occurs during overcurrent conditions.
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
APPLICATIONS INFORMATION
Achieving Ultralow Quiescent Current
1k
As the output load decreases, the frequency of single current pulses decreases (see Figure 1) and the percentage
of time the LT8619 is in sleep mode increases, resulting in much higher light load efficiency than for typical
converters. For a typical application, when the output is
not loaded, by maximizing the time between pulses, the
regulator quiescent approaches 6µA. Therefore, to optimize the quiescent current performance at light loads,
the current in the feedback resistor divider must be minimized as it appears to the output as load current (See FB
Resistor Network section).
While in Burst Mode operation, the current limit of the
top switch is approximately 380mA resulting in output
voltage ripple shown in Figure 2. Increasing the output
capacitance will decrease the output ripple proportionally.
As load ramps upward from zero, the switching frequency
will increase but only up to the switching frequency
programmed by the resistor at the RT pin as shown in
Figure 1. The output load at which the LT8619 reaches
the programmed frequency varies based on input voltage,
output voltage, and inductor choice.
For some applications it is desirable for the LT8619 to
operate in pulse-skipping mode, offering two major differences from Burst Mode operation. First, the minimum
inductor current clamp present in Burst Mode operation
is removed, providing a smaller packet of charge to the
output capacitor and reduce the output ripple voltage.
For a given load, the chip awake more often, resulting in
higher supply current compared to Burst Mode operation. Second is that full switching frequency is reached
at lower output load than in Burst Mode operation (see
Figure 3). To enable pulse-skipping mode, leave the SYNC
pin floating. Tying the SYNC pin to INTVCC node enables
the programmed switching frequency at no load.
100
fSW (kHz)
10
1
0.1
0.01
0.001
0.01
0.1
1
10
LOAD CURRENT (mA)
100
1k
8619 F01
Figure 1. Burst Frequency vs Load Current
VOUT (AC)
10mV/DIV
IL
200mA/DIV
SW
10V/DIV
VOUT (AC, ZOOM IN)
10mV/DIV
IL (ZOOM IN)
200mA/DIV
SW (ZOOM IN)
10V/DIV
TOP = 20ms/DIV, BOT = 1μs/DIV
8619 F02
Figure 2. Burst Mode Operation Waveform with
VIN = 12V, VOUT = 3.3V at No Load, RT = 66.5k,
L = 10μH, COUT = 22μF
400
VOUT = 3.3V
fOSC = 700kHz
L = 10µH
350
LOAD CURRENT (mA)
To enhance efficiency at light loads, the LT8619 enters into
Burst Mode operation, which keeps the output capacitor
charged to the desired output voltage while minimizing the
input quiescent current and output ripple voltage. In Burst
Mode operation the LT8619 delivers single small pulses of
current to the output capacitor followed by sleep periods
where the output power is supplied by the output capacitor.
While in sleep mode the LT8619 consumes less than 6μA.
VIN = 12V
VOUT = 3.3V
fOSC = 700kHz
L = 10µH
Burst Mode OPERATION
300
Burst Mode OPERATION
250
200
150
100
PULSE-SKIPPING MODE
50
0
0
10
20
30
VIN (V)
40
50
60
8619 F03
Figure 3. Minimum Load for Full Frequency Operation
vs VIN in Burst Mode Operation and Pulse-Skipping
Mode Setting
8619f
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13
LT8619/LT8619-5
APPLICATIONS INFORMATION
FB Resistor Network
The output voltage is programmed with a resistor divider
between VOUT and the FB pin. Choose the resistor values
according to:
⎛V
⎞
R1= R2 ⎜ OUT – 1⎟
⎝ 0.8V ⎠
Reference designators refer to the Block Diagram. 1%
resistors are recommended to maintain output voltage
accuracy.
If low input quiescent current and good light-load efficiency are desired, use a large resistor value for the FB
resistor divider. The current flowing in the divider acts as
a load current, and will increase the no-load input current
to the converter, which is approximately:
⎞
⎛ V
⎜ OUT ⎟
⎜⎜
⎟⎟
⎝ VIN ⎠
When using large FB resistors, a 4.7pF to 10pF phase
lead capacitor, C1, should be connected from VOUT to FB.
Setting the Switching Frequency
The LT8619 uses a constant frequency PWM architecture that can be programmed to switch from 300kHz to
2.2MHz by using a resistor tied from the RT pin to ground.
The RT resistor required for a desired oscillator frequency
can be roughly obtain using:
RT =
fOSC
–5
where RT is in kΩ and fOSC is the desired switching frequency in MHz.
14
fOSC (MHz)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.2
RT (kΩ)
162
121
95.3
78.7
66.5
57.6
51.1
45.3
36.5
fOSC (MHz)
1.4
1.6
1.8
2.0
2.2
RT (kΩ)
30.9
26.1
22.6
20.0
17.8
2.2
1.8
⎛ 1⎞
⎜ ⎟
⎜ η⎟
⎝ ⎠
where 5.2μA is the quiescent current of the LT8619 and
the second term is the current in the feedback divider
reflected to the input of the buck operating at its light load
efficiency, η. For a 3.3V application with R1 = 1M and
R2 = 316k, the feedback divider draws 2.5μA from VOUT.
With VIN = 12V and η = 85%, this adds 0.8μA to the 5.2μA
quiescent current resulting in 6μA quiescent current from
the 12V supply. Note that this equation implies that the
no-load current is a function of VIN; this is plotted in the
Typical Performance Characteristics section.
50.07
Table 1. Oscillator Frequency vs RT Value (1% Standard Value)
fOSC (MHz)
⎞
⎛ V
IQ = 5.2µA + ⎜⎜ OUT ⎟⎟
⎝ R1+ R2 ⎠
Table 1 and Figure 4 show the typical RT value for a
desired oscillator frequency.
1.4
1.0
0.6
0.2
0
20
40
60
80 100 120 140 160
RT (kΩ)
8619 F04
Figure 4. Oscillator Frequency vs RT Value
Operating Frequency Selection and Trade-Offs
Selection of the operating frequency is a trade-off between
efficiency, component size, and input voltage range. The
advantage of high frequency operation is that smaller
inductor and capacitor values may be used. The disadvantages are lower efficiency and a smaller input voltage range.
For force continuous mode operation, the highest oscillator frequency (fOSC(MAX)) for a given application can be
approximately given by the 1st order equation:
fOSC(MAX) =
ILOADR SW(BOT) + VOUT
(
t ON(MIN) VIN – ILOADR SW(TOP) +ILOADR SW(BOT)
)
Where VIN is the input voltage, VOUT is the output voltage, RSW(TOP) and RSW(BOT) are the internal switch on
resistance (~0.45Ω, ~0.22Ω, respectively) and tON(MIN)
8619f
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LT8619/LT8619-5
APPLICATIONS INFORMATION
is the minimum top switch on-time at the loading condition as shown in Figure 5. Figure 6 shows the relationship between the maximum input voltage vs the switching
frequency. If a smaller RT is selected, to ensure that the
regulator is switching at the higher frequency as illustrated in Figure 4, the maximum input supply voltage has
to be lowered; and it needs to be further reduced if the
load is decreased or removed.
80
VOUT = 3.3V
fSW = 2MHz
L = 3.3µH
FORCED CONTINUOUS MODE
MINIMUM ON-TIME (ns)
70
60
50
40
30
20
10
0
0
0.2
0.4
0.6
0.8
LOAD CURRENT (A)
1.0
1.2
8619 F05
Figure 5. Minimum On-Time vs Load Current
60
0.5A
LOAD
MAXIMUM VIN (V)
50
40
0.2A LOAD
30
NO LOAD
20
10
0
FORCED CONTINUOUS MODE
VOUT = 3.3V
L = 10µH
0.2
0.6
1.0
1.4
fSW (MHz)
1.8
2.2
8619 F06
Figure 6. Forced Continuous Mode Maximum Input
Voltage vs Switching Frequency
High Supply Operation
For Burst Mode operation or pulse-skipping mode, VIN
voltage may go as high as the absolute maximum rating
of 60V regardless of the frequency setting; however, the
LT8619 will reduce the switching frequency as necessary
to regulate the output voltage.
For forced continuous mode, if there is a momentarily VIN
voltage surge higher than the voltage shown in Figure 6,
resulting in minimum on-time operation, an overvoltage
comparator guards against transient overshoots as well
as other more serious conditions that may overvoltage the
output. When the VFB voltage rises by more than 3.75%
above its nominal value, the top MOSFET is turned off
and the bottom MOSFET is turned on. At this moment,
the output voltage continues to increase until the inductor
current reverses. The actual peak output voltage will be
higher than 3.75%, depending on external components
value, loading condition and output voltage setting. The
bottom MOSFET remains on continuously until the inductor current exceeds the bottom MOSFET reverse current
or overvoltage condition is cleared. With high reverse current, both top and bottom MOSFETs shut off till the next
clock cycle.
Low Supply Operation
The LT8619 is designed to remain operational during
short line transients when the input voltage may briefly
dip below 3.0V. Below this voltage, the INTVCC voltage
might drop to a point that is not able to provide adequate
gate drive voltage to turn on the MOSFET. The LT8619 has
two circuits to detect this undervoltage condition. A UVLO
comparator monitors the INTVCC voltage to ensure that it
is above 2.8V during startup; once in regulation, the chip
continues to operate as long as INTVCC stays above 2.65V.
If this UVLO comparator trips, the chip is shut down until
INTVCC recovers. Another comparator monitors the VIN
supply voltage, add a resistor divider from VIN to EN/UV
to turn off the regulator if VIN dips below the undesirable
voltage.
The LT8619 is capable of a maximum duty cycle of greater
than 99%, and the VIN-to-VOUT dropout is limited by the
RDS(ON) of the top switch. In deep dropout, the loop
attempt to turn on the top switch continuously. However,
the top switch gate drive is biased from the floating bootstrap capacitor CB, which normally recharges during each
off cycle; in dropout, this capacitor loses its refresh cycle
and charge depleted. A comparator detects the drop in
boot-strap capacitor voltage, forces the top switch off and
recharges the capacitor.
8619f
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15
LT8619/LT8619-5
APPLICATIONS INFORMATION
For low VIN applications that cannot allow deviation from
the programmed oscillator frequency, use the following
formula to set the switching frequency:
VIN(MIN) =
VSW(BOT) + VOUT
1– t OFF(MIN) • fOSC
+ VSW(TOP) – VSW(BOT)
where VIN(MIN) is the minimum input voltage without
skipped cycles, VOUT is the output voltage, VSW(TOP) and
VSW(BOT) are the internal switch drops (~0.54V, ~0.264V,
respectively at maximum load), fOSC is the oscillating frequency (set by RT), and tOFF(MIN) is the minimum switching off-time. Note that higher switching frequency will
increase the minimum input voltage below which cycles
will be dropped to achieve higher duty cycle.
Inductor Selection and Maximum Output Current
The LT8619 is designed to minimize solution size by
allowing the inductor to be chosen based on the output
load requirements of the application. During overload or
short-circuit conditions the LT8619 safely tolerates operation with a saturated inductor through the use of a high
speed peak-current mode architecture.
A good first choice for the inductor value is:
L=2
VOUT + VSW(BOT)
fOSC
where fOSC is the switching frequency in MHz, VOUT is
the output voltage, VSW(BOT) is the bottom switch drop
(~0.264V) and L is the inductor value in μH.
To avoid overheating and poor efficiency, an inductor
must be chosen with an RMS current rating that is greater
than the maximum expected output load of the application. In addition, the saturation current (typically labeled
ISAT) rating of the inductor must be higher than the load
current plus one-half of inductor ripple current:
ISAT > ILOAD(MAX) +
16
ΔIL(MAX)
2
where ILOAD(MAX) is the maximum output load for a given
application and ∆IL(MAX) is the inductor ripple current as
calculated in the following equation:
ΔIL(MAX) =
⎡
VOUT ⎤
VOUT ⎢ 1–
⎥
fOSC • L
⎢⎣ VIN(MAX) ⎥⎦
1
As a quick example, an application requiring 1A output
current should use an inductor with an RMS rating of
greater than 1A and an ISAT of greater than 1.5A. During
long duration overload or short-circuit conditions, the
inductor RMS rating requirement is greater to avoid overheating of the inductor. To push for high efficiency, select
an inductor with low series resistance (DCR), preferably
below 0.04Ω, and the core material should be intended
for high frequency application. However, achieving this
requires a large size inductor. An inductor with DCR
around 0.1Ω is generally a good compromise for both
efficiency and board area, at the expense of trimming 1%
to 2% from the efficiency number.
The LT8619 limits the peak switch current in order to protect the switches and the system from overload faults. The
top switch current limit (ILIM) is at least 1.5A. The inductor value must then be sufficient to supply the desired
maximum output current (ILOAD(MAX)), which is a function
of the switch current limit (ILIM) and the ripple current:
ILOAD(MAX) = ILIM –
ΔIL
2
Therefore, the maximum output current that the LT8619
will deliver depends on the switch current limit, the inductor value, and the input and output voltages. The inductor
value may have to be increased if the inductor ripple current does not allow sufficient maximum output current
(ILOAD(MAX)) given the switching frequency, and maximum
input voltage used in the desired application.
In order to achieve higher light load efficiency, more
energy must be delivered to the output during single small
pulses in Burst Mode operation such that the LT8619 can
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APPLICATIONS INFORMATION
stay in sleep mode longer between each pulse. This can
be achieved by using a larger value inductor, and should
be considered independent of switching frequency when
choosing an inductor. For example, while a lower inductor
value would typically be used for a high switching frequency application, if high light load efficiency is desired,
a higher inductor value should be chosen.
The optimum inductor for a given application may differ
from the one indicated by this design guide. A larger value
inductor provides a higher maximum load current and
reduces the output voltage ripple. For applications requiring smaller load currents, the value of the inductor may
be lower and the LT8619 may operate with higher ripple
current. This allows you to use a physically smaller inductor, or one with a lower DCR resulting in higher efficiency.
Be aware that low inductance may result in discontinuous
mode operation, which further reduces maximum load
current.
For details of maximum output current and discontinuous
operation, see Analog Devices’s Application Note 44.
Input Capacitor
Step-down regulators draw current from the input supply in pulses with very fast rise and fall times. The input
capacitor is required to reduce the resulting voltage ripple at the LT8619 and to force this very high frequency
switching current into a tight local loop, minimizing EMI.
In continuous mode, the input capacitor RMS current is
given by:
IRMS(MAX) ≈ ILOAD(MAX)
VOUT ( VIN – VOUT )
VIN
This equation has a maximum RMS current at VIN =
2VOUT, where IRMS(MAX) = ILOAD(MAX)/2.
Bypass the input of the LT8619 circuit with a 2.2μF to
10μF ceramic capacitor of X7R or X5R type placed as
close as possible to the VIN and GND pin. Y5V types have
poor performance over temperature and applied voltage,
and should not be used. Note that larger input capacitance
is required when a lower switching frequency is used.
If the input power source has high impedance, or there
is significant inductance due to long wires or cables, a
ceramic input capacitor combined with the trace or cable
inductance forms a high quality (underdamped) tank circuit. If the LT8619 circuit is plugged into a live supply, the
input voltage can ring to twice its nominal value, possibly
exceeding the LT8619’s voltage rating. This situation is
easily avoided (see Analog Devices Application Note 88),
by adding a lossy electrolytic capacitor in parallel with the
ceramic capacitor.
Output Capacitor and Output Ripple
The output capacitor has two essential functions. Along
with the inductor, it filters the square wave generated
by the LT8619 to produce the DC output. In this role it
determines the output ripple, thus low impedance at the
switching frequency is important. The second function
is to store energy in order to satisfy transient loads and
stabilize the LT8619’s control loop. The current slew rate
of a regulator is limited by the inductor and feedback loop.
When the amount of current required by the load changes,
the initial current deficit must be supplied by the output
capacitor until the feedback loop reacts and compensates
for the load changes. Ceramic capacitors have very low
equivalent series resistance (ESR) and provide the best
ripple performance. For good starting values, see the
Typical Applications section.
Transient performance can be improved with a higher
value capacitor and the addition of a feedforward capacitor placed between VOUT and FB. Increasing the output
capacitance will also decrease the output voltage ripple. A
lower value of output capacitor can be used to save space
and cost but transient performance will suffer and may
cause loop instability. See the Typical Applications in this
data sheet for suggested capacitor values.
Ceramic Capacitors
When choosing a capacitor, special attention should be
given to the manufacturer’s data sheet in order to accurately calculate the effective capacitance under the relevant bias voltage and operating temperature conditions.
Ceramic dielectrics can offer near ideal performance as
8619f
For more information www.linear.com/LT8619
17
LT8619/LT8619-5
APPLICATIONS INFORMATION
an output capacitor, i.e. high volumetric efficiency with
extremely low equivalent resistance. There is a downside
however; the high K dielectric material exhibits a substantial temperature and voltage coefficient, meaning that its
capacitance varies depending on the operating temperature and applied voltage. X7R capacitors provide a range
intermediate capacitance values which varies only ±15%
over the temperature range of –55°C to 125°C. The Y5V
capacitance can vary from 22% to –82% over the –30°C
to 85°C temperature range and should not be used for the
LT8619 application.
Ceramic capacitors can also cause problems due to their
piezoelectric nature. During Burst Mode operation, the
switching frequency depends on the load current, and at
very light loads the LT8619 can excite the ceramic capacitor at frequencies that may generate audible noise. Since
the LT8619 operates at a lower inductor current during
Burst Mode operation, the noise is typically very quiet
to a casual ear. If this is unacceptable, consider using
a high performance tantalum or electrolytic capacitor at
the output instead. Low noise ceramic capacitors are also
available.
Figure 7 shows the voltage coefficient of four different
ceramic 22μF capacitors, all of which are rated for 16V
operation. Note that with the exception of the X7R in the
1210 and 1812 package, the capacitors lose more than
30% of their capacitance when biased at more than half of
the rated voltage. Typically, as the package size increases,
the bias voltage coefficient decreases. If the voltage coefficient of a big ceramic capacitor in a particular package size is not acceptable; multiple smaller capacitors
with less voltage coefficient can be placed in parallel as
an effective means of meeting the capacitance requirement. Not All Capacitors are Interchangeable. A wrong
capacitor selection can degrade the circuit performance
considerably.
Ceramic capacitors are also susceptible to mechanical
stress which can result in significant loss of capacitance.
The most common sources of mechanical stress includes
bending or flexure of the PCB, contact pressure during in
circuit parameter testing, and direct contact by a soldering iron tip. Consult the manufacturer’s application notes
for additional information regarding ceramic capacitor
handling.
20
CAPACITANCE CHANGE (%)
0
–20
X7R, 1210
X5R, 1206
–40
X7R, 1812
–60
–80
–100
X5R, 0805
0
2
4
6
8
10 12
DC BIAS VOLTAGE (V)
C3225X7R1C226K250
C4532X7R1C226M200
C3216X5R1C226M160
C2012X5R1C226K125
14
16
8619 F09
Figure 7. Ceramic Capacitor Voltage Coefficient
18
Enable Pin
The LT8619 is in shutdown when the EN/UV pin is low
and active when the pin is high. The power-on threshold
of the EN comparator is 1.0V, with 40mV of hysteresis,
once EN/UV drops below this power-on threshold, the
MOSFETs are disabled, but the internal biasing circuit
stays alive. When forced below 0.56V, all the internal
blocks are disabled and the IC is put into a low current
shutdown mode. The EN/UV pin can be tied to VIN if the
shutdown feature is not used.
Adding a resistor divider from VIN to EN/UV programs the
LT8619 to regulate the output only when VIN is above a
desired voltage (see the Block Diagram). Typically, this
threshold, VIN(EN/UV), is used in situations where the input
supply is current limited, or has a relatively high source
resistance. A switching regulator draws constant power
from the source, so source current increases as source
voltage drops. This looks like a negative resistance load
to the source and can cause the source to current limit
or latch low under low source voltage conditions. The
VIN(EN/UV) threshold prevents the regulator from operating
at source voltages where the problems might occur. This
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
APPLICATIONS INFORMATION
threshold can be adjusted by setting the values R3 and
R4 such that they satisfy the following equation:
⎛ R3 ⎞
VIN(EN/UV) = ⎜ 1+
• 1V
⎝ R4 ⎟⎠
where the LT8619 will remain off until VIN is above
VIN(EN/UV). Due to the comparator’s hysteresis, switching
will not stop until the input falls slightly below VIN(EN/UV).
When in Burst Mode operation for light load currents,
the current through the VIN(EN/UV) resistor network can
easily be greater than the supply current consumed by
the LT8619. Therefore, the VIN(EN/UV) resistors should
be large enough to minimize their impact on efficiency
at low loads.
INTVCC Regulator
An internal low dropout (LDO) regulator produces the 3.3V
supply from VIN that powers the drivers and the internal
bias circuitry. The INTVCC can supply enough current for
the LT8619’s circuitry and must be bypassed to ground
with at least a 1μF ceramic capacitor. Good bypassing is
necessary to supply the high transient currents required
by the power MOSFET gate drivers. To improve efficiency
the internal LDO can draw current from the BIAS pin when
the BIAS pin is at 3.1V or higher. Typically the BIAS pin can
be tied to the output of the switching regulator, or can be
tied to an external supply which must also be at 3.3V or
above. If BIAS is connected to a supply other than VOUT,
be sure to bypass with a local ceramic capacitor. If the
BIAS pin is below 3.0V, the internal LDO will consume
current from VIN. Applications with high input voltage and
high switching frequency where the internal LDO pulls
current from VIN will increase die temperature because
of the higher power dissipation across the LDO. Do not
connect an external load to the INTVCC pin.
Output Power Good
When the LT8619’s output voltage is within the ±7.5%
window of the regulation point, the open-drain PG pin
goes high impedance and is typically pulled high with an
external resistor. Otherwise, the internal open-drain transistor will pull the PG pin low. The PG pin is also actively
pulled low during several fault conditions: EN/UV pin is
below 1V, INTVCC drops below its UVLO threshold, VIN is
too low, or thermal shutdown.
Synchronization
Synchronizing the LT8619 oscillator to an external frequency can be done by connecting a square wave (with
20% to 80% duty cycle) to the SYNC pin. The square wave
amplitude should have valleys that are below 0.4V and
peaks above 2V (up to 6V). During frequency synchronization, the part operates in forced continuous mode with
the SW rising edge synchronized to the SYNC positive
edge. The LT8619 may be synchronized over a 300kHz
to 2.2MHz range. The RT resistor must be chosen to set
the LT8619 switching frequency equal or below the lowest
synchronization input. For example, if the synchronization signal will be 500kHz and higher, the RT should be
selected for 500kHz.
Start-Up Inrush Current, Short-Circuit Protection
Upon start-up, the internal soft-start action regulates
the VOUT slew rate; the LT8619 provides the maximum
rated output current to charge up the output capacitor
as quickly as possible. During start-up, if the output is
overloaded, the regulator continues to provide the maximum sourcing current to overcome the output load, but
at the same time, the bottom switch current is monitored
such that if the inductor current is beyond the safe levels,
switching of the top switch will be delay until such time
as the inductor current falls to safe levels.
Once the soft-start period has expired and the FB voltage
is higher than 0.74V, the LT8619 switching frequency will
be folded back if the external load pulls down the output.
At the same time, the bottom switch current will continue
to be monitored to limit the short-circuit current. Figure 8
shows the frequency foldback transfer curve and Figure 9
shows the short circuit waveform. During this overcurrent
condition, if the SYNC pin is connected to a clock source,
the LT8619 will get out from the synchronization mode.
8619f
For more information www.linear.com/LT8619
19
LT8619/LT8619-5
APPLICATIONS INFORMATION
2.5
RT = 20kΩ
VIN
VIN
LT8619
2.0
EN/UV
fSW (MHz)
GND
1.5
8619 F10
1.0
Figure 10. Reverse VIN Protection
0.5
0
PCB Layout
0
0.1
0.2
0.3
0.4 0.5
VFB (V)
0.6
0.7
0.8
8619 F08
Figure 8. Frequency Foldback Transfer Function
VOUT
1V/DIV
ISHORT
10A/DIV
IL
0.5A/DIV
SW
10V/DIV
5μs/DIV
8619 F09
Figure 9. Short-Circuit Waveform with VIN = 12V,
VOUT = 3.3V, fOSC = 2MHz, L = 4.7μH, COUT = 22μF
Reversed Input Protection
Load protection may be necessary in systems where the
output will be held high when the input to the LT8619 is
absent. This may occur in battery charging applications or
in battery backup systems where a battery or some other
supply is diode ORed with the LT8619’s output. If the VIN
pin is allowed to float and the EN/UV pin is held high (either
by a logic signal or because it is tied to VIN), then the
LT8619’s internal circuitry will pull its quiescent current
through its SW pin. This is acceptable if the system can tolerate several μA in this state. If the EN/UV pin is grounded
the SW pin current will drop to near 1µA. However, if the
VIN pin is grounded while the output is held high, regardless of EN/UV, parasitic body diodes inside the LT8619
can pull current from the output through the SW pin and
the VIN pin. Figure 10 shows a connection of the VIN and
EN/UV pins that will allow the LT8619 to run only when
the input voltage is present and that protects against a
shorted or reversed input.
20
For proper operation and minimum EMI, care must be
taken during printed circuit board (PCB) layout. Figure 11
and Figure 12 show the recommended component placement with trace, ground plane and via locations. Note that
large, switched currents flow in the LT8619’s VIN, SW,
GND pins, and the input capacitor. The loop formed by
these components should be as small as possible by placing the capacitor adjacent to the VIN and GND pins. When
using a physically large input capacitor, the resulting loop
may become too large in which case using a small case/
value capacitor placed close to the VIN and GND pins plus
a larger capacitor further away is preferred. These components, along with the inductor and output capacitor,
should be placed on the same side of the circuit board,
and their connections should be made on that layer. Place
a local, unbroken ground plane under the application circuit on the layer closest to the surface layer. The SW and
BST nodes should be as small as possible. Finally, keep
the FB and RT nodes small so that the ground traces will
shield them from the SW and BST nodes. The exposed
pad on the bottom of the package must be soldered to
ground so that the pad is connected to ground electrically
and also acts as a heat sink thermally. To keep thermal
resistance low, extend the ground plane as much as possible, and add thermal vias under and near the LT8619 to
additional ground planes within the circuit board and on
the bottom side.
High Temperature Output Current Considerations
The maximum practical continuous load that the LT8619
can drive, while rated at 1.2A, actually depends upon both
the internal current limit (refer to the Typical Performance
Characteristics section) and the internal temperature
which depends on operating conditions, PCB layout and
airflow.
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
APPLICATIONS INFORMATION
VOUT
SW
+
GND
EN/UV
RT
PG
VIN
SYNC
BST
INTVCC
BIAS
FB/OUT
RT
VOUT
8619 F11
Figure 11. Recommended PCB Layout for LT8619 10-Pin DFN
VOUT
SW
+
GND
EN/UV
VIN
PG
SYNC
BST
INTVCC
BIAS
FB/OUT
VOUT
RT
8619 F12
Figure 12. Recommended PCB Layout for LT8619 16-Pin MSOP
8619f
For more information www.linear.com/LT8619
21
LT8619/LT8619-5
APPLICATIONS INFORMATION
For higher ambient temperatures, care should be taken in
the layout of the PCB to ensure good heat sinking of the
LT8619. The exposed pad on the bottom of the package
must be soldered to a ground plane. This ground should
be tied to large copper layers below with thermal vias;
these layers will spread heat dissipated by the LT8619.
Placing additional vias can reduce thermal resistance further. Figure 13 shows the rise in case temperature vs load
current. Note that a higher ambient temperature will result
in bigger case temperature rise as shown in Figure 14.
Power dissipation within the LT8619 can be estimated
by calculating the total power loss from an efficiency
measurement and subtracting the inductor loss. The
die temperature is calculated by multiplying the LT8619
power dissipation by the thermal resistance from junction
to ambient.
Figure 15 shows the typical derating maximum output
current curve. As with any monolithic switching regulator, the PCB layout, thermal resistance, air flow, other
heat sources in the vicinity affect how efficiently heat can
be removed from the die and radically change the die
junction temperature. The actual LT8619 switcher output
voltage and current sourcing capability might deviate from
the performance curve stated in this data sheet. When
pushing the LT8619 to its limit, verify its operation in the
actual environment. AT HIGH AMBIENT TEMPERATURE,
CONTINUOUS OPERATION ABOVE THE MAXIMUM
OPERATION JUNCTION TEMPERATURE MAY IMPAIR
DEVICE RELIABILITY OR PERMANENTLY DAMAGE THE
DEVICE.
35
VIN = 12V
VOUT = 5V
fSW = 700kHz
15 TA = 25°C
FORCED CONTINUOUS MODE
10
5
0
0
0.2
0.4
0.6
0.8
LOAD CURRENT (A)
1.0
VIN = 12V
VOUT = 5V, 1.2A LOAD
fSW = 700kHz
30
CASE TEMPERATURE RISE (°C)
CASE TEMPERATURE RISE (°C)
20
25
20
15
10
CONTINUOUS OPERATION ABOVE
MAXIMUM JUNCTION TEMPERATURE
MAY PERMANENTLY DAMAGE THE DEVICE
5
0
1.2
25
50
75
100
AMBIENT TEMPERATURE (°C)
8619 F13
125
8619 F14
Figure 13. Case Temperature Rise vs Load Current
Figure 14. Case Temperature Rise vs Ambient Temperature
MAXIMUM OUTPUT CURRENT (A)
1.4
1.2
fSW = 700kHz
1.0
fSW = 2MHz
0.8
0.6
0.4
0.2
0
VIN = 12V
VOUT = 3.3V
TJ(MAX) ≤ 125°C
FORCED CONTINUOUS MODE
90
95
100 105 110 115 120
AMBIENT TEMPERATURE (°C)
125
8619 F15
Figure 15. LT8619 Derating Maximum Output
Current with Junction Temperature Less Than 125°C
22
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
TYPICAL APPLICATIONS
3.3V 400kHz Step-Down Converter
VIN
4V TO 60V
2.2µF
OFF ON
BST
VIN
1.8V 2MHz Step-Down Converter
0.1µF 15µH
SW
LT8619
PG
INTVCC
INTVCC
LT8619
6.8pF
FB
GND
8619 TA02
EN/UV
OFF ON
1M
SYNC
VIN
PG
BIAS
RT
121k
1µF
2.2µF
100k
EN/UV
1µF
VIN
3.3V TO 12V
VOUT
3.3V
1.2A
316k
0.1µF 2.2µH
1.87M
FB
SYNC
20k
SW
PG
BIAS
RT
22µF
PG
BST
100k
5.6pF
VOUT
1.8V
1.2A
22µF
GND
1.5M
8619 TA03
fOSC = 2MHz
fOSC = 400kHz
L = VISHAY IHLP-2020AB-01
COUT = TDK C3225X7R1C226K250
L = VISHAY IHLP-3232CZ-11
COUT = TDK C3225X7R1C226K250
5V 2MHz Step-Down Converter
VIN
6V TO 36V
(60V TRANSIENT)
2.2µF
OFF ON
VIN
BST
LT8619-5
0.1µF 4.7µH
SW
100k
EN/UV
1µF
20k
INTVCC
VOUT
5V
1.2A
PG
PG
BIAS
RT
SYNC
OUT
GND
22µF
8619 TA04
fOSC = 2MHz
L = VISHAY IHLP-2020BZ-01
COUT = TDK C3225X7R1C226K250
12V 700kHz Step-Down Converter
VIN
13V TO 60V
1µF
2.2µF
VIN
INTVCC
PG
BST
LT8619
OFF ON
EN/UV
RT
66.5k
SYNC
100k
PG
0.1µF
SW
BIAS
22µH
0.931M
22pF
FB
GND
8619 TA05
401k
VOUT
12V
1.2A
66.5k
10µF
×2
fOSC = 700kHz
L = VISHAY IHLP-2020CZ-11
COUT = MURATA GRM32ER7YA106K
8619f
For more information www.linear.com/LT8619
23
LT8619/LT8619-5
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LT8619#packaging for the most recent package drawings.
DD Package
DD Package
10-Lead10-Lead
Plastic DFN
(3mm
Plastic
DFN× 3mm)
(3mm × 3mm)
(Reference
LTC DWGLTC
# 05-08-1699
Rev C) Rev C)
(Reference
DWG # 05-08-1699
0.70 ±0.05
3.55 ±0.05
1.65 ±0.05
2.15 ±0.05 (2 SIDES)
PACKAGE
OUTLINE
0.25 ±0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
3.00 ±0.10
(4 SIDES)
R = 0.125
TYP
6
0.40 ±0.10
10
1.65 ±0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
0.35 × 45°
CHAMFER
PIN 1
TOP MARK
(SEE NOTE 6)
0.200 REF
5
0.75 ±0.05
0.00 – 0.05
1
(DD) DFN REV C 0310
0.25 ±0.05
0.50 BSC
2.38 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
24
8619f
For more information www.linear.com/LT8619
LT8619/LT8619-5
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LT8619#packaging for the most recent package drawings.
MSE Package
16-Lead Plastic
, Exposed Die Pad
MSEMSOP
Package
(Reference
LTCMSOP,
DWG # 05-08-1667
RevPad
F)
16-Lead
Plastic
Exposed Die
(Reference LTC DWG # 05-08-1667 Rev F)
BOTTOM VIEW OF
EXPOSED PAD OPTION
2.845 ±0.102
(.112 ±.004)
5.10
(.201)
MIN
2.845 ±0.102
(.112 ±.004)
0.889 ±0.127
(.035 ±.005)
8
1
1.651 ±0.102
(.065 ±.004)
1.651 ±0.102 3.20 – 3.45
(.065 ±.004) (.126 – .136)
0.305 ±0.038
(.0120 ±.0015)
TYP
16
0.50
(.0197)
BSC
4.039 ±0.102
(.159 ±.004)
(NOTE 3)
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
0.35
REF
0.12 REF
DETAIL “B”
CORNER TAIL IS PART OF
DETAIL “B” THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
9
NO MEASUREMENT PURPOSE
0.280 ±0.076
(.011 ±.003)
REF
16151413121110 9
DETAIL “A”
0° – 6° TYP
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
GAUGE PLANE
0.53 ±0.152
(.021 ±.006)
DETAIL “A”
1.10
(.043)
MAX
0.18
(.007)
SEATING
PLANE
0.17 – 0.27
(.007 – .011)
TYP
1234567 8
0.50
NOTE:
(.0197)
1. DIMENSIONS IN MILLIMETER/(INCH)
BSC
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL
NOT EXCEED 0.254mm (.010") PER SIDE.
0.86
(.034)
REF
0.1016 ±0.0508
(.004 ±.002)
MSOP (MSE16) 0213 REV F
8619f
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog
Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications
For ismore
information
www.linear.com/LT8619
subject to change without notice. No license
granted
by implication
or otherwise under any patent or patent rights of Analog Devices.
25
LT8619/LT8619-5
TYPICAL APPLICATION
Ultralow EMI 5V 2MHz Step-Down Converter
VIN
6V TO 36V
(60V TRANSIENT)
FB1
BEAD
LIN
4.7µH
4.7µF
4.7µF
4.7µF
BST
VIN
0.1µF 4.7µH
LT8619-5
VOUT
5V
1.2A
SW
OFF ON
1µF
PG
INTVCC
PG
BIAS
RT
SYNC
20k
FB1 = TDK MPZ2012S221A
LIN = XFL4020
L = VISHAY IHLP-2020BZ-01
COUT = TDK C3225X7R1C226K250
100k
EN/UV
OUT
GND
22µF
8619 TA06
fOSC = 2MHz
RELATED PARTS
PART
DESCRIPTION
COMMENTS
LT8602
42V, Quad Output (2.5A + 1.5A + 1.5A + 1.5A) 95% Efficiency,
2.2MHz Synchronous Micropower Step-Down DC/DC
Converter with IQ = 25μA
VIN(MIN) = 3V, VIN(MAX) = 42V, VOUT(MIN) = 0.8V, IQ = 2.5μA,
ISD < 1μA, 6mm × 6mm QFN-40
LT8609/LT8609A
42V, 2A, 94% Efficiency, 2.2MHz Synchronous Micropower
Step-Down DC/DC Converter with IQ = 2.5μA
VIN(MIN) = 3V, VIN(MAX) = 42V, VOUT(MIN) = 0.8V, IQ = 2.5μA,
ISD < 1μA, MSOP-10E
LT8610
42V, 2.5A, 96% Efficiency, 2.2MHz Synchronous Micropower
Step- Down DC/DC Converter with IQ = 2.5μA
VIN(MIN) = 3.4V, VIN(MAX) = 42V, VOUT(MIN) = 0.97V, IQ = 2.5μA,
ISD < 1μA, MSOP-16E
LT8610A/LT8610AB 42V, 3.5A, 96% Efficiency, 2.2MHz Synchronous Micropower
Step- Down DC/DC Converter with IQ = 2.5μA
VIN(MIN) = 3.4V, VIN(MAX) = 42V, VOUT(MIN) = 0.97V, IQ = 2.5μA,
ISD < 1μA, MSOP-16E
LT8610AC
42V, 3.5A, 96% Efficiency, 2.2MHz Synchronous Micropower
Step- Down DC/DC Converter with IQ = 2.5μA
VIN(MIN) = 3V, VIN(MAX) = 42V, VOUT(MIN) = 0.8V, IQ = 2.5μA,
ISD < 1μA, MSOP-16E
LT8611
VIN(MIN) = 3.4V, VIN(MAX) = 42V, VOUT(MIN) = 0.97V, IQ = 2.5μA,
42V, 2.5A, 96% Efficiency, 2.2MHz Synchronous Micropower
Step- Down DC/DC Converter with IQ = 2.5μA and Input/Output ISD < 1μA, 3mm × 5mm QFN-24
Current Limit/Monitor
LT8612
42V, 6A, 96% Efficiency, 2.2MHz Synchronous Micropower
Step-Down DC/DC Converter with IQ = 2.5μA
VIN(MIN) = 3.4V, VIN(MAX) = 42V, VOUT(MIN) = 0.97V, IQ = 3.0μA,
ISD < 1μA, 3mm × 6mm QFN-28
LT8613
42V, 6A, 96% Efficiency, 2.2MHz Synchronous Micropower
Step- Down DC/DC Converter with Current Limiting
VIN(MIN) = 3.4V, VIN(MAX) = 42V, VOUT(MIN) = 0.97V, IQ = 3.0μA,
ISD < 1μA, 3mm × 6mm QFN-28
LT8614
42V, 4A, 96% Efficiency, 2.2MHz Synchronous Silent Switcher
Step- Down DC/DC Converter with IQ = 2.5μA
VIN(MIN) = 3.4V, VIN(MAX) = 42V, VOUT(MIN) = 0.97V, IQ = 2.5μA,
ISD < 1μA, 3mm × 4mm QFN-18
LT8616
42V, Dual 2.5A + 1.5A, 95% Efficiency, 2.2MHz Synchronous
Micropower Step-Down DC/DC Converter with IQ = 5μA
VIN(MIN) = 3.4V, VIN(MAX) = 42V, VOUT(MIN) = 0.8V, IQ = 5μA,
ISD < 1μA, TSSOP-28E, 3mm × 6mm QFN-28
LT8620
65V, 2.5A, 94% Efficiency, 2.2MHz Synchronous Micropower
Step- Down DC/DC Converter with IQ = 2.5μA
VIN(MIN) = 3.4V, VIN(MAX) = 65V, VOUT(MIN) = 0.97V, IQ = 2.5μA,
ISD < 1μA, MSOP-16E, 3mm × 5mm QFN-24
LT8640/LT8640-1
42V, 5A, 96% Efficiency, 3MHz Synchronous Micropower
Step-Down DC/DC Converter with IQ = 2.5μA
VIN(MIN) = 3.4V, VIN(MAX) = 42V, VOUT(MIN) = 0.97V, IQ = 2.5μA,
ISD < 1μA, 3mm × 4mm QFN-18
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8619f
LT 0118 • PRINTED IN USA
www.linear.com/LT8619
For more information www.linear.com/LT8619
 ANALOG DEVICES, INC. 2018