LT8410IDC#TRPBF [Linear]
LT8410 - Ultralow Power Boost Converter with Output Disconnect; Package: DFN; Pins: 8; Temperature Range: -40°C to 85°C;型号: | LT8410IDC#TRPBF |
厂家: | Linear |
描述: | LT8410 - Ultralow Power Boost Converter with Output Disconnect; Package: DFN; Pins: 8; Temperature Range: -40°C to 85°C 开关 光电二极管 输出元件 |
文件: | 总16页 (文件大小:309K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT8410/LT8410-1
Ultralow Power Boost
Converter with Output
Disconnect
FEATURES
DESCRIPTION
TheLT ®8410/LT8410-1areultralowpowerboostconverters
with integrated power switch, Schottky diode and output
disconnect circuitry. The parts control power delivery by
varying both the peak inductor current and switch off-
time. This control scheme results in low output voltage
ripple as well as high efficiency over a wide load range.
The quiescent current is a low 8.5μA, which is further
reduced to 0μA in shutdown. The internal disconnect
circuitry allows the output voltage to be blocked from the
input during shutdown. High value (12.4M/0.4M) resis-
tors are integrated on chip for output voltage detection,
significantlyreducinginputreferredquiescentcurrent.The
LT8410/LT8410-1alsofeaturesacomparatorbuiltintothe
n
Ultralow Quiescent Current
8.5μA in Active Mode
0μA in Shutdown Mode
n
Comparator Built into SHDN Pin
n
Low Noise Control Scheme
n
Adjustable FB Reference Voltage
n
Wide Input Range: 2.5V to 16V
n
Wide Output Range: Up to 40V
n
Integrated Power NPN Switch
25mA Current Limit (LT8410)
8mA Current Limit (LT8410-1)
n
Integrated Schottky Diode
n
Integrated Output Disconnect
n
High Value (12.4M/0.4M) Feedback Resistors
SHDN pin, overvoltage protection for the CAP and V
OUT
Integrated
pins, built in soft-start and comes in a tiny 8-pin 2mm ×
2mm DFN package.
n
Built in Soft-Start (Optional Capacitor from V
to GND)
REF
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5481178, 6580258, 6304066, 6127815, 6498466,
6611131.
n
n
Overvoltage Protection for CAP and V
Tiny 8-Pin 2mm × 2mm DFN Package
Pins
OUT
APPLICATIONS
n
Sensor Power
n
RF Mems Relay Power
n
General Purpose Bias
TYPICAL APPLICATION
General Purpose Bias with Wide Input Voltage
Output Voltage Ripple
vs Load Current
Efficiency vs Load Current
10
8
100
90
80
70
60
50
40
V
IN
V
= 3.6V
100µH
IN
2.5V to 16V
V
= 12V
IN
2.2µF
0.1µF
V
SW
CAP
V
= 5V
IN
= 16V
OUT
V
V
CC
OUT
6
V
= 3.6V
IN
LT8410
V
0.1µF*
CHIP
ENABLE
REF
SHDN
4
604k
0.1µF
GND
FBP
2
412k
*HIGHER VALUE CAPACITOR IS REQUIRED
WHEN THE V IS HIGHER THAN 5V
8410-1 TA01a
IN
0
0.01
0.1
1
10
0.01
0.1
1
10
100
LOAD CURRENT (mA)
8410-1 TA02
LOAD CURRENT (mA)
8410-1 TA03
84101fc
1
For more information www.linear.com/LT8410
LT8410/LT8410-1
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
TOP VIEW
V
Voltage................................................–0.3V to 16V
CC
8
7
6
5
SHDN
1
2
3
4
FBP
SW Voltage ................................................–0.3V to 42V
CAP Voltage ...............................................–0.3V to 40V
V
CC
V
REF
9
GND
SW
CAP
V
Voltage..............................................–0.3V to 40V
OUT
V
OUT
SHDN Voltage ............................................–0.3V to 16V
REF
FBP Voltage ..............................................–0.3V to 2.5V
Maximum Junction Temperature .......................... 125°C
Operating Temperature Range (Note 2)..–40°C to 125°C
Storage Temperature Range...................–65°C to 150°C
DC PACKAGE
V
Voltage..............................................–0.3V to 2.5V
8-LEAD (2mm × 2mm) PLASTIC DFN
T
= 125°C, θ = 88°C/W
JMAX JA
EXPOSED PAD (PIN #9) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
(http://www.linear.com/product/LT8410#orderinfo)
LEAD FREE FINISH
LT8410EDC#PBF
LT8410IDC#PBF
TAPE AND REEL
PART MARKING*
LDQR
PACKAGE DESCRIPTION
8-Lead (2mm × 2mm) Plastic DFN
TEMPERATURE RANGE
–40°C to 125°C
LT8410EDC#TRPBF
LT8410IDC#TRPBF
LT8410EDC-1#TRPBF
LT8410IDC-1#TRPBF
LDQR
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
8-Lead (2mm × 2mm) Plastic DFN
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
LT8410EDC-1#PBF
LT8410IDC-1#PBF
LFCC
LFCC
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.
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 3V, VSHDN = VCC unless otherwise noted. (Note 2)
PARAMETER
CONDITIONS
MIN
TYP
MAX
2.5
UNITS
V
Minimum Operating Voltage
Maximum Operating Voltage
Reference Voltage
2.2
16
V
l
1.220
1.235
10
1.255
V
V
REF
V
REF
V
REF
Current Limit
(Note 3)
µA
µS
%/V
µA
µA
µA
Discharge Time
Line Regulation
70
0.01
8.5
0
l
l
Quiescent Current
Not Switching
12
1
Quiescent Current in Shutdown
V = 0V
SHDN
Quiescent Current from V
and CAP
V
= 16V
OUT
3
OUT
Minimum Switch Off Time
After Start-Up (Note 4)
During Start-Up (Note 4)
240
600
nS
nS
l
l
Switch Current Limit
LT8410
LT8410-1
20
6
25
8
30
10
mA
mA
84101fc
2
For more information www.linear.com/LT8410
LT8410/LT8410-1
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 3V, VSHDN = VCC unless otherwise noted. (Note 2)
PARAMETER
Switch V
CONDITIONS
LT8410, I = 10mA
MIN
TYP
MAX
UNITS
150
100
mV
mV
CESAT
SW
LT8410-1, I = 4mA
SW
Switch Leakage Current
Schottky Forward Voltage
Schottky Reverse Leakage
V
= 5V
0
1
µA
SW
I
= 10mA
650
850
mV
DIODE
V
CAP
V
CAP
– V = 5
0
0
0.5
1
µA
µA
SW
– V = 40
SW
PMOS Disconnect Current Limit
LT8410
LT8410-1
14
2.5
19
4
25
5
mA
mA
PMOS Disconnect V
– V
I = 1mA
OUT
50
31.85
1.3
mV
CAP
OUT
l
l
l
V
OUT
Resistor Divider Ratio
31.6
1.20
0.08
32.2
30
FBP Pin Bias Current
V
FBP
= 0.5V, Current Flows Out of Pin
nA
V
SHDN Minimum Input Voltage High
SHDN Input Voltage High Hysteresis
SHDN Hysteresis Current
SHDN Rising
1.30
60
1.45
mV
µA
V
0.1
0.14
0.3
(Note 3)
SHDN Input Voltage Low
SHDN Pin Bias Current
V
SHDN
V
SHDN
= 3V
= 16V
0
2
1
3
µA
µA
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 3: See the Applications Information section for more information.
Note 4: Start-up mode occurs when V is less than V • 64/3.
OUT
FBP
Note 2: The LT8410E/LT8410E-1 are 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 LT8410I/LT8410I-1 are guaranteed over the full –40°C to 125°C
operating junction temperature range.
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.
Switching Frequency
vs Load Current
Load Regulation
VOUT vs FBP Voltage
1000
800
600
400
200
0
0.6
50
40
30
20
10
0
V
V
= 3.6V
V
V
= 3.6V
CC
CC
= 16V
= 16V
OUT
OUT
0.4
0.2
0
FIGURE 4 CIRCUIT
FIGURE 4 CIRCUIT
–0.2
–0.4
–0.6
0
1
2
3
0
1
2
3
0
0.5
1
1.5
2
LOAD CURRENT (mA)
LOAD CURRENT (mA)
FBP VOLTAGE (V)
8410-1 G01
8410-1 G02
8410-1 G03
84101fc
3
For more information www.linear.com/LT8410
LT8410/LT8410-1
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage vs Temperature
Quiescent Current—Not Switching
Quiescent Current vs Temperature
1.00
0.75
12
10
8
10
8
V
= 3.6V, V
= 16V
OUT
CC
LOAD = 0.5mA
FIGURE 4 CIRCUIT
0.50
0.25
6
0
6
4
–0.25
–0.50
–0.75
–1.00
4
2
2
V
= 3.6V
0
CC
0
0
–40
0
40
80
120
0
4
8
12
16
–40
40
80
120
TEMPERATURE (°C)
V
VOLTAGE (V)
TEMPERATURE (°C)
CC
8410-1 G04
8410-1 G05
8410-1 G06
Quiescent Current
vs SHDN Voltage
Quiescent Current in Regulation
with No Load
SHDN Current vs SHDN Voltage
10
8
1000
100
10
2.5
2.0
1.5
1.0
0.5
0
V
= 3.6V
V
= 3.6V
CC
CC
6
4
2
V
CC
= 3.6V
0
–0.5
0
1
2
3
4
5
0
10
20
30
40
0
4
8
12
16
SHDN VOLTAGE (V)
OUTPUT VOLTAGE (V)
SHDN VOLTAGE (V)
8410-1 G07
8410-1 G08
8410-1 G09
Peak Inductor Current
vs Temperature (LT8410)
Peak Inductor Current
vs Temperature (LT8410-1)
VREF Voltage vs Temperature
40
36
32
28
24
20
15
13
11
9
1.235
1.234
1.233
1.232
1.231
1.230
V
V
= 3.6V
= 16V
V
V
= 3.6V
= 16V
CC
OUT
CC
OUT
FIGURE 4 CIRCUIT
FIGURE 5 CIRCUIT
7
V
= 3.6V
CC
5
–40
0
40
TEMPERATURE (°C)
80
120
–40
0
40
TEMPERATURE (°C)
80
120
–40
0
40
TEMPERATURE (°C)
80
120
8410-1 G10
8410-1 G11
8410-1 G12
84101fc
4
For more information www.linear.com/LT8410
LT8410/LT8410-1
TYPICAL PERFORMANCE CHARACTERISTICS
LT8410 Switching Waveform
at No Load
LT8410 Switching Waveform
at 0.5mA Load
V
VOLTAGE
2mV/DIV
V
VOLTAGE
10mV/DIV
OUT
OUT
AC COUPLED
AC COUPLED
SW VOLTAGE
10V/DIV
SW VOLTAGE
10V/DIV
INDUCTOR
CURRENT
20mA/DIV
INDUCTOR
CURRENT
10mA/DIV
8410-1 G13
8410-1 G14
V
V
= 3.6V
OUT
50µs/DIV
V
V
= 3.6V
OUT
2µs/DIV
CC
CC
= 16V
= 16V
LT8410 Switching Waveform
at 3mA Load
UVLO vs Temperature
2.6
2.4
V
VOLTAGE
10mV/DIV
OUT
AC COUPLED
V
RISING
CC
2.2
2.0
1.8
1.6
SW VOLTAGE
10V/DIV
V
FALLING
CC
INDUCTOR
CURRENT
20mA/DIV
8410-1 G15
V
V
= 3.6V
OUT
500ns/DIV
CC
= 16V
1.4
–40
0
40
TEMPERATURE (°C)
80
120
8410-1 G16
SHDN Minimum Input Voltage
High vs Temperature
Line Regulation
0.30
0.25
0.20
0.15
0.10
0.05
0
1.5
1.4
1.3
1.2
1.1
1.0
V
= 16V
OUT
SHDN RISING
SHDN FALLING
0
4
8
12
16
–40
0
40
80
120
V
VOLTAGE (V)
TEMPERATURE (°C)
CC
8410-1 G17
8410-1 G18
84101fc
5
For more information www.linear.com/LT8410
LT8410/LT8410-1
TYPICAL PERFORMANCE CHARACTERISTICS
Output Disconnect PMOS Current
vs CAP to VOUT Voltage Difference
LT8410 Start-Up Waveforms
without Capacitor at VREF Pin
25
SHDN VOLTAGE
V
= 16V
CAP
5V/DIV
LT8410
INDUCTOR
CURRENT
20mA/DIV
20
15
10
5
CAP VOLTAGE
5V/DIV
V
OUT
VOLTAGE
5V/DIV
LT8410-1
8
8410-1 G20
V
V
= 3.6V
OUT
200µs/DIV
CC
= 16V
0
0
4
CAP TO V
12
16
VOLTAGE DIFFERENCE (V)
OUT
8410-1 G19
LT8410 Start-Up Waveforms with
0.1μF Capacitor at VREF Pin
LT8410 Transient Response
0.5mA→1.5mA→0.5mA Load Pulse
SHDN VOLTAGE
V
VOLTAGE
5V/DIV
OUT
200mV/DIV
INDUCTOR
CURRENT
20mA/DIV
AC COUPLED
INDUCTOR
CURRENT
20mA/DIV
LOAD
CURRENT
0.5mA/DIV
CAP VOLTAGE
5V/DIV
V
VOLTAGE
5V/DIV
OUT
8410-1 G21
8410-1 G22
V
V
= 3.6V
OUT
2ms/DIV
V
V
= 3.6V
OUT
2ms/DIV
CC
CC
= 16V
= 16V
SW Saturation Voltage
vs Switch Current (LT8410)
300
250
200
150
100
50
0
0
5
10
15
20
25
SWITCH CURRENT (mA)
8410-1 G24
84101fc
6
For more information www.linear.com/LT8410
LT8410/LT8410-1
PIN FUNCTIONS
SHDN (Pin 1): Shutdown Pin. This pin is used to enable/
disablethechip.Drivebelow0.3Vtodisablethechip.Drive
above 1.45V to activate the chip. Do not float this pin.
V
(Pin 7): Reference Pin. Soft-start can be achieved
REF
by placing a capacitor from this pin to GND. This cap
will be discharged for 70µs (typical) at the beginning
of start-up and then be charged to 1.235V with a 10μA
current source.
V
(Pin 2): Input Supply Pin. Must be locally bypassed
CC
to GND. See the Typical Applications section.
FBP (Pin 8): Positive Feedback Pin. This pin is the error
GND (Pin 3): Ground. Tie directly to local ground plane.
amplifier’s positive input terminal. To achieve the desired
SW (Pin 4): Switch Pin. This is the collector of the inter-
nal NPN power switch. Minimize the metal trace area
connected to this pin to minimize EMI.
output voltage, choose the FBP pin voltage (V ) accord-
FBP
ing to the following formula:
VOUT
31.85
V
=
FBP
V
(Pin 5): Drain of Output Disconnect PMOS. Place
OUT
a bypass capacitor from this pin to GND.
Forprotectionpurposes,theoutputvoltagecannotexceed
40V even if V is driven higher than V
CAP (Pin 6): Cathode of the Internal Schottky Diode. Place
a bypass capacitor from this pin to GND.
.
REF
FBP
ExposedPad(Pin9):Pin9isfloatingbutmustbeground-
ed for proper shielding.
BLOCK DIAGRAM
2
1
5
6
4
V
V
OUT
SHDN
CAP
SW
CC
ENABLE
CHIP
MAX
10µA
12.4M
400k
1.235V
+
–
+
–
OUTPUT DISCONNECT
CONTROL
V
REF
1.235V
7
DISCHARGE
CONTROL
SWITCH
CONTROL
TIMING AND PEAK
CURRENT CONTROL
–
+
+
FB
FBP
VC
+
8
1.235V
–
EXPOSED PAD
(GND)
GND
9
3
84101fc
7
For more information www.linear.com/LT8410
LT8410/LT8410-1
OPERATION
The LT8410 series utilizes a variable peak current, variable
off-time control scheme to provide high efficiency over a
wide output current range.
the circuit, special precautions are taken to ensure that
the inductor current remains under control
The LT8410 series also has a PMOS output disconnect
switch. The PMOS switch is turned on when the part is
enabled via the SHDN pin. When the part is in shutdown,
The operation of the part can be better understood by
referring to the Block Diagram. The part senses the output
voltage by monitoring the internal FB node, and servoing
the FB node voltage to be equal to the FBP pin voltage.
The chip integrates an accurate high value resistor divider
the PMOS switch turns off, allowing the V
node to
OUT
go to ground. This type of disconnect function is often
required in power supplies.
(12.4M/0.4M) from the V
pin. The output voltage is set
OUT
The differences between the LT8410 and LT8410-1 are
the SW current limit and the output disconnect PMOS
current limit. For the LT8410, the SW current limit and
PMOS current limit are approximately 25mA and 19mA,
respectively,whilethoseoftheLT8410-1areapproximately
8mA and 4mA, respectively.
by the FBP pin voltage, which in turn is set by an external
resistor divider from the V pin. The FBP pin voltage can
REF
also bedirectly biasedwith anexternalreference, allowing
full control of the output voltage during operation.
The switch control block senses the output of the ampli-
fier and adjusts the switching frequency as well as other
parameters to achieve regulation. During the start-up of
APPLICATIONS INFORMATION
Inductor Selection
Table 1. Recommended Inductors for LT8410/ LT8410-1
L
DCR
SIZE
(mm)
Several inductors that work well with the LT8410 and
LT8410-1arelistedinTable1. Thetablesarenotcomplete,
and there are many other manufacturers and devices that
can be used. Consult each manufacturer for more detailed
information and for their entire selection of related parts,
as many different sizes and shapes are available.
PART
(µH) (Ω)
VENDOR
LQH2MCN680K02 68
6.6 2.0 × 1.6 × 0.9 Murata
LQH32CN101K53 100 3.5 3.2 × 2.5 × 2.0 www.murata.com
DO2010-683ML
LPS3015-104ML
LPS3015-154ML
LPS3314-154ML
68
8.8 2.0 × 2.0 × 1.0 Coilcraft
100 3.4 3.0 × 3.0 × 1.4 www.coilcraft.com
150 6.1 3.0 × 3.0 × 1.4
150 4.1 3.3 × 3.3 × 1.3
Inductorswithavalueof47μHorhigherarerecommended
for most LT8410 series designs. Inductors with low core
losses and small DCR (copper wire resistance) are good
choices for LT8410 series applications. For full output
power,theinductorshouldhaveasaturationcurrentrating
higher than the peak inductor current. The peak inductor
current can be calculated as:
Capacitor Selection
The small size and low ESR of ceramic capacitors make
them suitable for most LT8410 applications. X5R and
X7R types are recommended because they retain their
capacitance over wider voltage and temperature ranges
than other types such as Y5V or Z5U. A 2.2μF or higher
input capacitor, and a 0.1μF to 1μF output capacitor, are
sufficient for most applications. Always use a capacitor
with a sufficient voltage rating. Many ceramic capacitors
rated at 0.1μF to 1μF have greatly reduced capacitance
when bias voltages are applied. Be sure to check actual
capacitanceatthedesiredoutputvoltage.Generally,a0603
V • 150 • 10–6
IN
IPK = ILIMIT
+
mA
L
where the worst case I
is 30mA and 10mA for LT8410
LIMIT
and LT8410-1, respectively. L is the inductance value in
henrys and V is the input voltage to the boost circuit.
IN
84101fc
8
For more information www.linear.com/LT8410
LT8410/LT8410-1
APPLICATIONS INFORMATION
or 0805 size capacitor will be adequate. A 0.1μF to 1μF
capacitorplacedontheCAPnodeisrecommendedtofilter
the inductor current, while a 0.1μF to 1μF capacitor placed
Connecting the Load to the CAP Node
The efficiency of the converter can be improved by con-
necting the load to the CAP pin instead of the V pin.
OUT
on the V
node will give excellent transient response
OUT
The power loss in the PMOS disconnect circuit is then
made negligible. No quiescent current will be consumed
in the internal feedback resistor divider string during
shutdown since the PMOS transistor will be open and the
and stability. To make the V pin less sensitive to noise,
REF
REF
puttingacapacitorontheV pinisrecommended,butnot
required.A47nFto220nF0402capacitorwillbesufficient.
Table 2 shows a list of several capacitor manufacturers.
Consult the manufacturers for more detailed information
and for their entire selection of related parts.
internal feedback resistor divider is connected at the V
OUT
pin. The disadvantage of this method is that the CAP node
cannot go to ground during shutdown, but will be limited
Table 2. Recommended Ceramic Capacitor Manufacturers
to around a diode drop below V . Loads connected to the
CC
MANUFACTURER
Taiyo Yuden
Murata
PHONE
WEB SITE
www.t-yuden.com
part should only sink current. Never force external power
(408) 573-4150
(814) 237-1431
(843) 448-9411
(408) 986-0424
(847) 803-6100
supplies onto the CAP or V
pins.
OUT
www.murata.com
www.avxcorp.com
www.kemet.com
www.tdk.com
AVX
Maximum Output Load Current
Kemet
ThemaximumoutputcurrentofaparticularLT8410series
circuitisafunctionofseveralcircuitvariables.Thefollowing
method can be helpful in predicting the maximum load
current for a given circuit:
TDK
Setting Output Voltage
The output voltage is set by the FBP pin voltage. V
is
OUT
Step 1. Calculate the peak inductor current:
equal to 31.85 • V
when the output is regulated, as
FBP
V •150 •10–6
shown in Figure 1. Since the V
pin provides a good
REF
IN
IPK =ILIMIT
where I
+
mA
reference (1.235V), the FBP voltage can be easily set by
L
a resistor divider from the V pin to ground. The series
REF
is 25mA and 8mA for LT8410 and LT8410-1
LIMIT
resistanceofthisresistordividershouldbekeptlargerthan
respectively. L is the inductance value in henrys and V
is the input voltage to the boost circuit.
200KΩ to prevent loading down the V pin. The FBP pin
IN
REF
can also be biased directly by an external reference. For
overvoltage protection, the output voltage is limited to
Step 2. Calculate the inductor ripple current:
40V. Therefore, if V
voltage will stay at 40V.
is higher than 1.235V, the output
FBP
V
+ 1– V • 200 •10–6
(
)
OUT
IN
IRIPPLE
=
mA
L
50
where V
is the desired output voltage. If the inductor
OUT
40
30
20
10
0
ripple current is less than the peak current, then the circuit
will only operate in discontinuous conduction mode. The
inductor value should be increased so that I
< I .
RIPPLE
PK
An application circuit can be designed to operate only in
discontinuous mode, but the output current capability
will be reduced.
Step 3. Calculate the average input current:
0
0.5
1
1.5
2
I
RIPPLE mA
2
FBP VOLTAGE (V)
IIN(AVG) =IPK
–
8410-1 F01
Figure 1. FBP to VOUT Transfer Curve
84101fc
9
For more information www.linear.com/LT8410
LT8410/LT8410-1
APPLICATIONS INFORMATION
Step 4. Calculate the nominal output current:
protection against pin glitches and slow ramping), then
an internal 10μA current source pulls the V pin slowly
REF
I
•V •0.7
IN
IN(AVG)
to 1.235V. Since the V
voltage is set by the FBP pin
OUT
IOUT(NOM)
=
mA
VOUT
Step 5. Derate output current:
= I • 0.8
voltage, the V
voltage will also slowly increase to the
OUT
regulated voltage, which results in lower peak inductor
current. The voltage ramp rate on the pin can be set by
I
OUT
OUT(NOM)
the value of the V pin capacitor.
REF
For low output voltages the output current capability will
beincreased. Whenusingoutputdisconnect(loadcurrent
Output Disconnect
taken from V ), these higher currents will cause the
The LT8410 series has an output disconnect PMOS that
blocks the load from the input during shutdown. The
maximumcurrentthroughthePMOSislimitedbycircuitry
inside the chip, helping the chip survive output shorts.
OUT
drop in the PMOS switch to be higher resulting in lower
output current capability than predicted by the preceding
equations.
Inrush Current
SHDN Pin Comparator and Hysteresis Current
WhenV issteppedfromgroundtotheoperatingvoltage
CC
An internal comparator compares the SHDN pin voltage
with an internal voltage reference (1.3V) which gives a
preciseturn-onvoltagelevel.Theinternalhysteresisofthis
turn-onvoltageisabout60mV.Whenthechipisturnedon,
and the SHDN pin voltage is close to this turn-on voltage,
0.1μA current flows out of the SHDN pin. This current is
calledSHDNpinhysteresiscurrent, andwillgoawaywhen
the chip is off. By connecting the external resistors as in
Figure 2, a user-programmable enable voltage function
can be realized.
while the output capacitor is discharged, a high level of
inrushcurrentmayflowthroughtheinductorandSchottky
diode into the output capacitor. Conditions that increase
inrush current include a larger more abrupt voltage step
at V , a larger output capacitor tied to the CAP pin and
CC
an inductor with a low saturation current. While the chip is
designed to handle such events, the inrush current should
not be allowed to exceed 0.3A. For circuits that use output
capacitor values within the recommended range and have
input voltages of less than 6V, inrush current remains low,
posing no hazard to the device. In cases where there are
The turn-on voltage for the configuration is:
large steps at V (more than 6V) and/or a large capacitor
CC
R1
R2
1.30 • 1+
is used at the CAP pin, inrush current should be measured
to ensure safe operation.
and the turn-off voltage is:
Soft-Start
R1
R2
−7
1.24−R3•10−7 • 1+
−(R1•10 )
The LT8410 series contains a soft-start circuit to limit
peak switch currents during start-up. High start-up cur-
rent is inherent in switching regulators, in general, since
where R1, R2 and R3 are resistance value in Ω.
the feedback loop is saturated due to V
being far from
OUT
ENABLE VOLTAGE
its final value. The regulator tries to charge the output
capacitor as quickly as possible, which results in large
peak current.
R1
R3
CONNECT TO
SHDN PIN
WhentheFBPpinvoltageisgeneratedbyaresistordivider
from the V
pin, the start-up current can be limited by
R2
REF
connecting an external capacitor (typically 47nF to 220nF)
84101 F02
to the V pin. When the part is brought out of shutdown,
REF
Figure 2. Programming Enable Voltage by Using External Resistors
thiscapacitorisfirstdischargedforabout70μs(providing
84101fc
10
For more information www.linear.com/LT8410
LT8410/LT8410-1
APPLICATIONS INFORMATION
Board Layout Considerations
V
IN
SHDN
As with all switching regulators, careful attention must
be paid to the PCB layout and component placement. To
maximize efficiency, switch rise and fall times are made as
shortaspossible.Topreventelectromagneticinterference
(EMI) problems, proper layout of the high frequency
switchingpathisessential.ThevoltagesignaloftheSWpin
hassharprisingandfallingedges.Minimizethelengthand
area of all traces connected to the SW pin and always use
a ground plane under the switching regulator to minimize
SHDN
FBP
V
CC
V
REF
GND
SW
CAP
GND
interplane coupling. In addition, the FBP pin and V pin
REF
V
OUT
are sensitive to noise. Minimize the length and area of all
traces to these two pins is recommended. Recommended
component placement is shown in Figure 3.
8410-1 F03
CAPACITOR GROUNDS MUST BE
RETURNED DIRECTLY TO IC GROUND
Figure 3. Recommended Board Layout
84101fc
11
For more information www.linear.com/LT8410
LT8410/LT8410-1
TYPICAL APPLICATIONS
L1
Efficiency vs Load Current
V
IN
100µH
2.5V to 16V
100
90
80
70
60
50
40
C2
0.1µF
C1
2.2µF
V
= 12V
IN
SW
CAP
V
= 16V
C3
OUT
C4
V
V
CC
OUT
V
= 5V
IN
LT8410
V
0.1µF
V
= 3.6V
REF
IN
TURN ON/OFF
SHDN
604k
0.1µF
GND
FBP
412k
C1: 2.2μF, 16V, X5R, 0603
C2: 0.1μF, 25V, X5R, 0603
8410-1 TA05
C3: 0.1μF, 25V, X5R, 0603 *
C4: 0.1μF, 16V, X7R, 0402
L1: MURATA LQH32CN101K53
0.01
0.1
1
10
100
8410-1 TA07
LOAD CURRENT (mA)
* HIGHER CAPACITANCE VALUE IS REQUIRED FOR
C3 WHEN THE V IS HIGHER THAN 5V
IN
V
(V)
I
(mA)
IN
OUT
Figure 4. 16V Output Converter with Wide Input Voltage
3.6
2.2
5
3.6
13
16V Output Converter with 2mm × 2mm Inductor
12
L1
68µH
V
IN
2.5V to 16V
C2
C1
Efficiency vs Load Current
0.1µF
2.2µF
90
80
70
60
50
40
SW
CAP
V
= 16V
C3
OUT
C4
V
IN
= 12V
V
V
CC
OUT
LT8410
V
V
= 5V
IN
0.1µF
REF
TURN ON/OFF
SHDN
R1
301k
V
= 3.6V
IN
0.1µF
GND
FBP
R2
210k
C1: 2.2μF, 16V, X5R, 0603
C2: 0.1μF, 25V, X5R, 0603
C3: 0.1μF, 25V, X5R, 0603 *
C4: 0.1μF, 16V, X7R, 0402
L1: COILCRAFT DO2010-683ML
8410 TA06
* HIGHER CAPACITANCE VALUE IS REQUIRED FOR
C3 WHEN THE V IS HIGHER THAN 5V
0.01
0.1
1
10
100
IN
LOAD CURRENT (mA)
8410-1 TA08
LT8410 Maximum Output Current vs Output Voltage
RESISTOR DIVIDER
MAXIMUM OUTPUT CURRENT (mA)
FROM V
REF
V
(V)
R1 (kΩ) / R2 ( kΩ)
V
IN
= 2.8V
0.5
0.7
0.8
1
V
= 3.6V
0.7
0.9
1
V
IN
= 5V
V
IN
= 12V
3.6
4.4
5.5
7.2
9.7
14
OUT
IN
40
NA
1.1
35
30
25
20
15
10
5
110/887
237/768
365/634
487/511
619/383
750/255
866/127
1.4
1.5
2.1
2.9
4
1.4
1.9
2.4
4.6
11
1.4
1.6
3.3
8
7
NA
17
NA
84101fc
12
For more information www.linear.com/LT8410
LT8410/LT8410-1
TYPICAL APPLICATIONS
34V Output Converter with Wide Input Voltage
Efficiency vs Load Current
90
80
70
60
50
40
L1
V
IN
V
= 12V
IN
150µH
2.5V to 16V
C2
C1
V
= 5V
IN
0.1µF
2.2µF
SW
CAP
V
= 34V
C3
OUT
C4
V
V
CC
OUT
V
= 3.6V
IN
LT8410
V
0.1µF
REF
TURN ON/OFF
SHDN
133k
0.1µF
GND
FBP
866k
C1: 2.2μF, 16V, X5R, 0603
8410-1 TA09
C2: 0.1μF, 100V, X5R, 0603
C3: 0.1μF, 100V, X5R, 0603 *
C4: 0.1μF, 16V, X7R, 0402
0.01
0.1
1
10
LOAD CURRENT (mA)
8410-1 TA10
L1: COILCRAFT LPS3314-154ML
* HIGHER CAPACITANCE VALUE IS REQUIRED FOR
V
IN
(V)
I
(mA)
OUT
C3 WHEN THE V IS HIGHER THAN 8V
IN
3.6
0.8
5
1.2
4
12
L1
220µH
V
IN
2.5V to 16V
C2
1.0µF
C1
2.2µF
SW
CAP
V
= 16V
OUT
V
V
SHDN VOLTAGE
CC
OUT
C3
10000µF
2V/DIV
LT8410-1
V
REF
TURN ON/OFF
SHDN
R1
604k
C4
V
OUT
VOLTAGE
10V/DIV
0.1µF
GND
FBP
R2
412k
INPUT CURRENT
5mA/DIV
C1: 2.2μF, 16V, X5R, 0603
C2: 1.0μF, 25V, X5R, 0603 *
8410-1 TA10a
INDUCTOR
CURRENT
10mA/DIV
C3: 10000μF, ELECTROLYTIC CAPACITOR
C4: 0.1μF, 16V, X7R, 0402
8410-1 G10b
V
= 3.6V
20s/DIV
IN
L1: COILCRAFT LPS3008-224ML
* HIGHER CAPACITANCE VALUE IS REQUIRED FOR
C2 WHEN THE V IS HIGHER THAN 12V
IN
Figure 5. Capacitor Charger with the LT8410-1
LT8410-1 Maximum Output Current vs Output Voltage
FEEDBACK RESISTOR
DIVIDER
R1 (kΩ) / R2 ( kΩ)
MAXIMUM OUTPUT CURRENT (mA)
V
(V)
V
IN
= 2.8V
V
= 3.6V = 5V
V
V = 12V
IN
OUT
IN
IN
40
NA
0.12
0.14
0.18
0.25
0.34
0.48
0.84
2.3
0.16
0.19
0.25
0.35
0.48
0.69
1.2
0.24
0.89
35
30
25
20
15
10
5
110/887
237/768
365/634
487/511
619/383
750/255
866/127
0.3
0.38
0.55
0.76
1.1
1.1
1.5
2
2.9
3.5
NA
NA
2.1
3.3
3.5
84101fc
13
For more information www.linear.com/LT8410
LT8410/LT8410-1
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/product/LT8410#packaging for the most recent package drawings.
DC8 Package
8-Lead Plastic DFN (2mm × 2mm)
(Reference LTC DWG # 05-08-1719 Rev A)
0.70 ±0.05
2.55 ±0.05
0.64 ±0.05
1.15 ±0.05
(2 SIDES)
PACKAGE
OUTLINE
0.25 ±0.05
0.45 BSC
1.37 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
R = 0.115
TYP
5
8
R = 0.05
TYP
0.40 ±0.10
PIN 1 NOTCH
2.00 ±0.10 0.64 ±0.10
(4 SIDES)
(2 SIDES)
R = 0.20 OR
0.25 × 45°
CHAMFER
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
(DC8) DFN 0409 REVA
4
1
0.23 ±0.05
0.45 BSC
0.75 ±0.05
0.200 REF
1.37 ±0.10
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
NOTE:
1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE
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
84101fc
14
For more information www.linear.com/LT8410
LT8410/LT8410-1
REVISION HISTORY (Revision history begins at Rev B)
REV
DATE
DESCRIPTION
PAGE NUMBER
B
01/11 Corrected Pin Configuration.
2
3
2
Revised Note 2 in Electrical Characteristics.
04/16 Changed SW pin voltage Absolute Maximum to 42V.
C
84101fc
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LT8410/LT8410-1
TYPICAL APPLICATION
High Voltage Power Supply Does Not Need a Transformer
DANGER HIGH VOLTAGE! OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY
C3, 0.1µF
C5, 0.1µF
D2
L1
100µH
V
IN
2.5V to 16V
D1
C4
D3
C6
D4
C2
0.1µF
C1
2.2µF
0.1µF
0.1µF
SW
CAP
V
V
OUT
CC
C7
LT8410
OUTPUT = 100V
0.1µF
0.4mA (V = 5V)
IN
V
TURN ON/OFF
C1: 2.2μF, 16V, X5R, 0603
REF
SHDN
1.4mA (V = 12V)
IN
C8
0.1µF
143k
787k
C2 – C7: 0.1μF, 100V, X5R, 0603
C8: 0.1μF, 16V, X7R, 0402
GND
FBP
D1 – D4: ON SEMI RB751S40T1G
L1: MURATA LQH32CN101K53
8410-1 TA11
Output Voltage vs FBP Voltage
Efficiency vs Load Current
140
120
100
90
80
70
60
50
40
V
= 5V
IN
V
= 100V
OUT
V
= 12V
IN
80
60
40
20
V
= 5V
IN
0
0
0.5
1
1.5
2
0.01
0.1
1
10
FBP VOLTAGE (V)
LOAD CURRENT (mA)
8410-1 TA12
8410-1 TA13
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
: 2.45V to 16V, V
LT1946/LT1946A
1.5A (I ), 1.2MHz/2.7MHz, High Efficiency Step-Up DC/DC
V
= 34V, I = 3.2mA, I < 1µA,
OUT(MAX) Q SD
SW
IN
Converters
8-Lead MS Package
LT3464
85mA (I ), High Efficiency Step-Up DC/DC Converter with
V
: 2.3V to 10V, V
= 34V, I = 25µA, I < 1µA,
OUT(MAX) Q SD
SW
IN
Integrated Schottky and PNP Disconnect
ThinSOT™ Package
LT3471
Dual Output, Boost/Inverter, 1.3A (I ), High Efficiency
V
: 2.4V to 16V, V
= 40V, I = 2.5mA, I < 1µA,
Q SD
SW
IN
OUT(MAX)
OUT(MAX)
OUT(MAX)
Boost-Inverting DC/DC Converter
DFN Package
LT3473/LT3473A
LT3494/LT3494A
LT3495/LT3495B/
1A (I ), 1.2MHz, High Efficiency Step-Up DC/DC Converter
V
: 2.2V to 16V, V
= 36V, I = 100µA, I < 1µA,
Q SD
SW
IN
with Integrated Schottky Diode and Output Disconnect
DFN Package
180mA/350mA (I ), High Efficiency, Low Noise Step-Up
V
: 2.1V to 16V, V
= 40V, I = 65µA, I < 1µA,
Q SD
SW
IN
DC/DC Converter with Output Disconnect
DFN Package
650mA/350mA (I ), High Efficiency, Low Noise Step-Up
V
: 2.3 V to 16V, V
= 40V, I = 60µA, I < 1µA,
OUT(MAX) Q SD
SW
IN
LT3495-1/LT3495B-1 DC/DC Converter with Output Disconnect
DFN Package
84101fc
LT 0416 REV C • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
LINEAR TECHNOLOGY CORPORATION 2008
(408)432-1900 FAX: (408) 434-0507 www.linear.com/LT8410
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