LT8410IDC-1#TRPBF - Linear Technology Corporation

LT8410/LT8410-1

84101fb

APPLICATIONS

n Sensor Power

n RF Mems Relay Power

n General Purpose Bias

TYPICAL APPLICATION

DESCRIPTION

Ultralow Power Boost

Converter with Output

Disconnect

The LT

8410/LT8410-1 are ultralow power boost converters

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,

signiﬁcantly reducing input referred quiescent current. The

LT8410/ LT8410-1 also features a comparator built into the

SHDN pin, overvoltage protection for the CAP and VOUT

pins, built in soft-start and comes in a tiny 8-pin 2mm ×

2mm DFN package.

General Purpose Bias with Wide Input Voltage

FEATURES

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

Integrated

n Built in Soft-Start (Optional Capacitor from VREF

to GND)

n Overvoltage Protection for CAP and VOUT Pins

n Tiny 8-Pin 2mm × 2mm DFN Package

SW CAP

GND

CHIP

ENABLE

FBP

8410-1 TA01a

LT8410

2.2µF

0.1µF

100µH

0.1µF

0.1µF*

VOUT = 16V

VIN

2.5V to 16V

VCC VOUT

VREF

SHDN

604k

412k

*HIGHER VALUE CAPACITOR IS REQUIRED

WHEN THE VIN IS HIGHER THAN 5V

LOAD CURRENT (mA)

0.01

VOUT PEAK-TO-PEAK RIPPLE (mV)

8410-1 TA02

1010.1

VIN = 3.6V

LOAD CURRENT (mA)

0.01

EFFICIENCY (%)

100

8410-1 TA03

100100.1 1

VIN = 12V

VIN = 5V

VIN = 3.6V

Output Voltage Ripple

vs Load Current Efﬁciency vs Load Current

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. Hot Swap is a trademark 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.

LT8410/LT8410-1

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PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS

VCC Voltage ................................................–0.3V to 16V

SW Voltage ................................................–0.3V to 40V

CAP Voltage ...............................................–0.3V to 40V

VOUT Voltage ..............................................–0.3V to 40V

SHDN Voltage ............................................–0.3V to 16V

VREF Voltage ..............................................–0.3V to 2.5V

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

(Note 1)

TOP VIEW

SHDN

VCC

GND

FBP

VREF

CAP

VOUT

DC PACKAGE

8-LEAD (2mm × 2mm) PLASTIC DFN

TJMAX = 125°C, θJA = 88°C/W

EXPOSED PAD (PIN #9) IS GND, MUST BE SOLDERED TO PCB

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS

Minimum Operating Voltage 2.2 2.5 V

Maximum Operating Voltage 16 V

Reference Voltage l1.220 1.235 1.255 V

VREF Current Limit (Note 3) 10 µA

VREF Discharge Time 70 µS

VREF Line Regulation 0.01 %/V

Quiescent Current Not Switching l8.5 12 µA

Quiescent Current in Shutdown VSHDN = 0V l0 1 µA

Quiescent Current from VOUT and CAP VOUT = 16V 3 µA

Minimum Switch Off Time After Start-Up (Note 4)

During Start-Up (Note 4)

240

600

Switch Current Limit LT8410

LT8410-1

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)

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT8410EDC#PBF LT8410EDC#TRPBF LDQR 8-Lead (2mm × 2mm) Plastic DFN –40°C to 125°C

LT8410IDC#PBF LT8410IDC#TRPBF LDQR 8-Lead (2mm × 2mm) Plastic DFN –40°C to 125°C

LT8410EDC-1#PBF LT8410EDC-1#TRPBF LFCC 8-Lead (2mm × 2mm) Plastic DFN –40°C to 125°C

LT8410IDC-1#PBF LT8410IDC-1#TRPBF LFCC 8-Lead (2mm × 2mm) Plastic DFN –40°C to 125°C

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container.

Consult LTC Marketing for information on non-standard lead based ﬁnish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel speciﬁcations, go to: http://www.linear.com/tapeandreel/

LT8410/LT8410-1

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Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: The 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.

Note 3: See the Applications Information section for more information.

Note 4: Start-up mode occurs when VOUT is less than VFBP • 64/3.

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 UNITS

Switch VCESAT LT8410, ISW = 10mA

LT8410-1, ISW = 4mA

150

100

Switch Leakage Current VSW = 5V 0 1 µA

Schottky Forward Voltage IDIODE = 10mA 650 850 mV

Schottky Reverse Leakage VCAP – VSW = 5

VCAP – VSW = 40

0.5

µA

PMOS Disconnect Current Limit LT8410

LT8410-1

2.5

PMOS Disconnect VCAP – VOUT IOUT = 1mA 50 mV

VOUT Resistor Divider Ratio l31.6 31.85 32.2

FBP Pin Bias Current VFBP = 0.5V, Current Flows Out of Pin l1.3 30 nA

SHDN Minimum Input Voltage High SHDN Rising l1.20 1.30 1.45 V

SHDN Input Voltage High Hysteresis 60 mV

SHDN Hysteresis Current (Note 3) 0.08 0.1 0.14 µA

SHDN Input Voltage Low 0.3 V

SHDN Pin Bias Current VSHDN = 3V

VSHDN = 16V

µA

TYPICAL PERFORMANCE CHARACTERISTICS

TA = 25°C, unless otherwise noted.

Switching Frequency

vs Load Current Load Regulation VOUT vs FBP Voltage

LOAD CURRENT (mA)

SWITCHING FREQUENCY (kHz)

1000

800

600

200

400

8410-1 G01

321

VCC = 3.6V

VOUT = 16V

FIGURE 4 CIRCUIT

LOAD CURRENT (mA)

OUTPUT VOLTAGE CHANGE (%)

0.6

0.4

0.2

–0.4

–0.2

–0.6

8410-1 G02

321

VCC = 3.6V

VOUT = 16V

FIGURE 4 CIRCUIT

FBP VOLTAGE (V)

OUTPUT VOLTAGE (V)

8410-1 G03

21 1.50.5

LT8410/LT8410-1

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TYPICAL PERFORMANCE CHARACTERISTICS

Quiescent Current

vs SHDN Voltage

Quiescent Current in Regulation

with No Load SHDN Current vs SHDN Voltage

Peak Inductor Current

vs Temperature (LT8410)

Peak Inductor Current

vs Temperature (LT8410-1) VREF Voltage vs Temperature

Output Voltage vs Temperature Quiescent Current—Not Switching Quiescent Current vs Temperature

TEMPERATURE (°C)

–40

OUTPUT VOLTAGE CHANGE (%)

1.00

0.75

0.25

0.50

–0.25

–0.75

–0.50

–1.00

8410-1 G04

12080400

VCC = 3.6V, VOUT = 16V

LOAD = 0.5mA

FIGURE 4 CIRCUIT

VCC VOLTAGE (V)

QUIESCENT CURRENT (µA)

8410-1 G05

161284

TEMPERATURE (°C)

–40

QUIESCENT CURRENT (µA)

8410-1 G06

12080400

VCC = 3.6V

SHDN VOLTAGE (V)

QUIESCENT CURRENT (µA)

8410-1 G07

52 3 41

VCC = 3.6V

OUTPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

1000

100

8410-1 G08

4020 3010

VCC = 3.6V

SHDN VOLTAGE (V)

SHDN PIN BIAS CURRENT (µA)

2.5

2.0

1.5

1.0

0.5

–0.5

8410-1 G09

168 124

VCC = 3.6V

TEMPERATURE (°C)

–40

PEAK INDUCTOR CURRENT (mA)

8410-1 G10

12040 800

VCC = 3.6V

VOUT = 16V

FIGURE 4 CIRCUIT

TEMPERATURE (°C)

–40

VREF VOLTAGE (V)

1.235

1.234

1.233

1.231

1.232

1.230

8410-1 G12

12040 800

VCC = 3.6V

TEMPERATURE (°C)

–40

PEAK INDUCTOR CURRENT (mA)

8410-1 G11

12040 800

VCC = 3.6V

VOUT = 16V

FIGURE 5 CIRCUIT

LT8410/LT8410-1

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TYPICAL PERFORMANCE CHARACTERISTICS

UVLO vs Temperature

Line Regulation

SHDN Minimum Input Voltage

High vs Temperature

LT8410 Switching Waveform

at No Load

LT8410 Switching Waveform

at 0.5mA Load

LT8410 Switching Waveform

at 3mA Load

VCC = 3.6V

VOUT = 16V

50µs/DIV

INDUCTOR

CURRENT

10mA/DIV

SW VOLTAGE

10V/DIV

VOUT VOLTAGE

2mV/DIV

AC COUPLED

8410-1 G13 VCC = 3.6V

VOUT = 16V

2µs/DIV

INDUCTOR

CURRENT

20mA/DIV

SW VOLTAGE

10V/DIV

VOUT VOLTAGE

10mV/DIV

AC COUPLED

8410-1 G14

VCC = 3.6V

VOUT = 16V

500ns/DIV

INDUCTOR

CURRENT

20mA/DIV

SW VOLTAGE

10V/DIV

VOUT VOLTAGE

10mV/DIV

AC COUPLED

8410-1 G15

TEMPERATURE (°C)

–40

UVLO VOLTAGE (V)

2.6

2.4

2.2

2.0

1.6

1.8

1.4

8410-1 G16

12080400

VCC RISING

VCC FALLING

VCC VOLTAGE (V)

OUTPUT VOLTAGE CHANGE (%)

0.30

0.25

0.20

0.15

0.05

0.10

8410-1 G17

16124 8

VOUT = 16V

TEMPERATURE (°C)

–40

SHDN MINIMUM INPUT

VOLTAGE HIGH (V)

1.5

1.4

1.3

1.1

1.2

1.0

8410-1 G18

12080400

SHDN RISING

SHDN FALLING

LT8410/LT8410-1

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TYPICAL PERFORMANCE CHARACTERISTICS

Output Disconnect PMOS Current

vs CAP to VOUT Voltage Difference

LT8410 Start-Up Waveforms

without Capacitor at VREF Pin

LT8410 Start-Up Waveforms with

0.1μF Capacitor at VREF Pin

CAP TO VOUT VOLTAGE DIFFERENCE (V)

PMOS CURRENT (mA)

8410-1 G19

161284

VCAP = 16V

LT8410

LT8410-1

SHDN VOLTAGE

5V/DIV

INDUCTOR

CURRENT

20mA/DIV

CAP VOLTAGE

5V/DIV

VOUT VOLTAGE

5V/DIV

VCC = 3.6V

VOUT = 16V

2ms/DIV 8410-1 G21

SHDN VOLTAGE

5V/DIV

INDUCTOR

CURRENT

20mA/DIV

CAP VOLTAGE

5V/DIV

VOUT VOLTAGE

5V/DIV

VCC = 3.6V

VOUT = 16V

200µs/DIV 8410-1 G20

VOUT VOLTAGE

200mV/DIV

AC COUPLED

INDUCTOR

CURRENT

20mA/DIV

LOAD

CURRENT

0.5mA/DIV

VCC = 3.6V

VOUT = 16V

2ms/DIV 8410-1 G22

SWITCH CURRENT (mA)

SWITCH VCESAT (mV)

300

250

200

150

100

8410-1 G24

252015105

LT8410 Transient Response

0.5mA→1.5mA→0.5mA Load Pulse

SW Saturation Voltage

vs Switch Current (LT8410)

LT8410/LT8410-1

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PIN FUNCTIONS

SHDN (Pin 1): Shutdown Pin. This pin is used to enable/

disable the chip. Drive below 0.3V to disable the chip. Drive

above 1.45V to activate the chip. Do not ﬂoat this pin.

VCC (Pin 2): Input Supply Pin. Must be locally bypassed

to GND. See the Typical Applications section.

GND (Pin 3): Ground. Tie directly to local ground plane.

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.

VOUT (Pin 5): Drain of Output Disconnect PMOS. Place

a bypass capacitor from this pin to GND.

CAP (Pin 6): Cathode of the Internal Schottky Diode. Place

a bypass capacitor from this pin to GND.

VREF (Pin 7): Reference Pin. Soft-start can be achieved

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.

FBP (Pin 8): Positive Feedback Pin. This pin is the error

ampliﬁer’s positive input terminal. To achieve the desired

output voltage, choose the FBP pin voltage (VFBP) accord-

ing to the following formula:

VFBP =VOUT

31.85

For protection purposes, the output voltage can not exceed

40V even if VFBP is driven higher than VREF.

Exposed Pad (Pin 9): Pin 9 is ﬂoating but must be ground-

ed for proper shielding.

BLOCK DIAGRAM

–

DISCHARGE

CONTROL

ENABLE

CHIP

1.235V

VREF

VCC

FBP

GND

EXPOSED PAD

(GND)

400k

CAP

MAX

10µA

SWSHDN

12.4M

VOUT

SWITCH

CONTROL

–

TIMING AND PEAK

CURRENT CONTROL

–

1.235V

5 6 4

OUTPUT DISCONNECT

CONTROL

1.235V

–

LT8410/LT8410-1

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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 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

(12.4M/0.4M) from the VOUT pin. The output voltage is set

by the FBP pin voltage, which in turn is set by an external

resistor divider from the VREF pin. The FBP pin voltage can

also be directly biased with an external reference, 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

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 PMOS switch turns off, allowing the VOUT node to

go to ground. This type of disconnect function is often

required in power supplies.

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, while those of the LT8410-1 are approximately

8mA and 4mA, respectively.

APPLICATIONS INFORMATION

Inductor Selection

Several inductors that work well with the LT8410 and

LT8410-1 are listed in Table 1. The tables are not complete,

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.

Inductors with a value of 47μH or higher are recommended

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, the inductor should have a saturation current rating

higher than the peak inductor current. The peak inductor

current can be calculated as:

IPK =ILIMIT +VIN •150 •10–6

where the worst case ILIMIT is 30mA and 10mA for LT8410

and LT8410-1, respectively. L is the inductance value in

henrys and VIN is the input voltage to the boost circuit.

Table 1. Recommended Inductors for LT8410/ LT8410-1

PART

(µH)

DCR

(Ω)

SIZE

(mm)

VENDOR

LQH2MCN680K02

LQH32CN101K53

100

6.6

3.5

2.0 × 1.6 × 0.9

3.2 × 2.5 × 2.0

Murata

www.murata.com

DO2010-683ML

LPS3015-104ML

LPS3015-154ML

LPS3314-154ML

100

150

8.8

3.4

6.1

4.1

2.0 × 2.0 × 1.0

3.0 × 3.0 × 1.4

3.3 × 3.3 × 1.3

Coilcraft

www.coilcraft.com

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

capacitance at the desired output voltage. Generally, a 0603

LT8410/LT8410-1

84101fb

or 0805 size capacitor will be adequate. A 0.1μF to 1μF

capacitor placed on the CAP node is recommended to ﬁlter

the inductor current, while a 0.1μF to 1μF capacitor placed

on the VOUT node will give excellent transient response

and stability. To make the VREF pin less sensitive to noise,

putting a capacitor on the VREF pin is recommended, but not

required. A 47nF to 220nF 0402 capacitor will be sufﬁcient.

Table 2 shows a list of several capacitor manufacturers.

Consult the manufacturers for more detailed information

and for their entire selection of related parts.

Table 2. Recommended Ceramic Capacitor Manufacturers

MANUFACTURER PHONE WEB SITE

Taiyo Yuden (408) 573-4150 www.t-yuden.com

Murata (814) 237-1431 www.murata.com

AVX (843) 448-9411 www.avxcorp.com

Kemet (408) 986-0424 www.kemet.com

TDK (847) 803-6100 www.tdk.com

Setting Output Voltage

The output voltage is set by the FBP pin voltage. VOUT is

equal to 31.85 • VFBP when the output is regulated, as

shown in Figure 1. Since the VREF pin provides a good

reference (1.235V), the FBP voltage can be easily set by

a resistor divider from the VREF pin to ground. The series

resistance of this resistor divider should be kept larger than

200KΩ to prevent loading down the VREF pin. The FBP pin

can also be biased directly by an external reference. For

overvoltage protection, the output voltage is limited to

40V. Therefore, if VFBP is higher than 1.235V, the output

voltage will stay at 40V.

APPLICATIONS INFORMATION

FBP VOLTAGE (V)

OUTPUT VOLTAGE (V)

8410-1 F01

21 1.50.5

Figure 1. FBP to VOUT Transfer Curve

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 VOUT pin.

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

internal feedback resistor divider is connected at the VOUT

pin. The disadvantage of this method is that the CAP node

cannot go to ground during shutdown, but will be limited

to around a diode drop below VCC. Loads connected to the

part should only sink current. Never force external power

supplies onto the CAP or VOUT pins.

Maximum Output Load Current

The maximum output current of a particular LT8410 series

circuit is a function of several circuit variables. The following

method can be helpful in predicting the maximum load

current for a given circuit:

Step 1. Calculate the peak inductor current:

IPK =ILIMIT +VIN •150 •10–6

where ILIMIT is 25mA and 8mA for LT8410 and LT8410-1

respectively. L is the inductance value in henrys and VIN

is the input voltage to the boost circuit.

Step 2. Calculate the inductor ripple current:

IRIPPLE =VOUT +1– VIN

( )

•200 •10–6

LmA

where VOUT is the desired output voltage. If the inductor

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 IRIPPLE < IPK.

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:

IIN(AVG) =IPK –IRIPPLE

LT8410/LT8410-1

84101fb

APPLICATIONS INFORMATION

Step 4. Calculate the nominal output current:

IOUT(NOM) =IIN(AVG) •VIN •0.7

VOUT

Step 5. Derate output current:

IOUT = IOUT(NOM) • 0.8

For low output voltages the output current capability will

be increased. When using output disconnect (load current

taken from VOUT), these higher currents will cause the

drop in the PMOS switch to be higher resulting in lower

output current capability than predicted by the preceding

equations.

Inrush Current

When VCC is stepped from ground to the operating voltage

while the output capacitor is discharged, a high level of

inrush current may ﬂow through the inductor and Schottky

diode into the output capacitor. Conditions that increase

inrush current include a larger more abrupt voltage step

at VCC, a larger output capacitor tied to the CAP pin and

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

large steps at VCC (more than 6V) and/or a large capacitor

is used at the CAP pin, inrush current should be measured

to ensure safe operation.

Soft-Start

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

the feedback loop is saturated due to VOUT being far from

its ﬁnal value. The regulator tries to charge the output

capacitor as quickly as possible, which results in large

peak current.

When the FBP pin voltage is generated by a resistor divider

from the VREF pin, the start-up current can be limited by

connecting an external capacitor (typically 47nF to 220nF)

to the VREF pin. When the part is brought out of shutdown,

this capacitor is ﬁrst discharged for about 70μs (providing

protection against pin glitches and slow ramping), then

an internal 10μA current source pulls the VREF pin slowly

to 1.235V. Since the VOUT voltage is set by the FBP pin

voltage, the VOUT voltage will also slowly increase to the

regulated voltage, which results in lower peak inductor

current. The voltage ramp rate on the pin can be set by

the value of the VREF pin capacitor.

Output Disconnect

The LT8410 series has an output disconnect PMOS that

blocks the load from the input during shutdown. The

maximum current through the PMOS is limited by circuitry

inside the chip, helping the chip survive output shorts.

SHDN Pin Comparator and Hysteresis Current

An internal comparator compares the SHDN pin voltage

with an internal voltage reference (1.3V) which gives a

precise turn-on voltage level. The internal hysteresis of this

turn-on voltage is about 60mV. When the chip is turned on,

and the SHDN pin voltage is close to this turn-on voltage,

0.1μA current ﬂows out of the SHDN pin. This current is

called SHDN pin hysteresis current, and will go away when

the chip is off. By connecting the external resistors as in

Figure 2, a user-programmable enable voltage function

can be realized.

The turn-on voltage for the conﬁguration is:

1.30 •1+R1











and the turn-off voltage is:

1.24−R3 •10−7

( )

•1+R1









−(R1•10−7)

where R1, R2 and R3 are resistance value in Ω.

ENABLE VOLTAGE

R3 CONNECT TO

SHDN PIN

84101 F02

Figure 2. Programming Enable Voltage by Using External Resistors

LT8410/LT8410-1

84101fb

Board Layout Considerations

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

short as possible. To prevent electromagnetic interference

(EMI) problems, proper layout of the high frequency

switching path is essential. The voltage signal of the SW pin

has sharp rising and falling edges. Minimize the length and

area of all traces connected to the SW pin and always use

a ground plane under the switching regulator to minimize

interplane coupling. In addition, the FBP pin and VREF pin

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.

APPLICATIONS INFORMATION

CAPACITOR GROUNDS MUST BE

RETURNED DIRECTLY TO IC GROUND

8410-1 F03

SHDN

GND

VIN SHDN

VCC

GND

FBP

CAP

VREF

VOUT

Figure 3. Recommended Board Layout

LT8410/LT8410-1

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TYPICAL APPLICATIONS

16V Output Converter with 2mm × 2mm Inductor

SW CAP

GND FBP

8410 TA06

LT8410

2.2µF

0.1µF

68µH

0.1µF

VOUT = 16V

VIN

2.5V to 16V

VCC VOUT

VREF

SHDN

301k

210k

TURN ON/OFF

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

* HIGHER CAPACITANCE VALUE IS REQUIRED FOR

C3 WHEN THE VIN IS HIGHER THAN 5V

LOAD CURRENT (mA)

0.01

EFFICIENCY (%)

8410-1 TA08

100100.1 1

VIN = 12V

VIN = 3.6V

VIN = 5V

Efﬁciency vs Load Current

SW CAP

GND FBP

8410-1 TA05

LT8410

2.2µF

0.1µF

100µH

0.1µF

VOUT = 16V

VIN

2.5V to 16V

VCC VOUT

VREF

SHDN

604k

412k

TURN ON/OFF

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: MURATA LQH32CN101K53

* HIGHER CAPACITANCE VALUE IS REQUIRED FOR

C3 WHEN THE VIN IS HIGHER THAN 5V

LOAD CURRENT (mA)

0.01

EFFICIENCY (%)

100

8410-1 TA07

100100.1 1

VIN = 12V

VIN = 3.6V

VIN = 5V

VIN (V) IOUT (mA)

3.6 2.2

5 3.6

12 13

Efﬁciency vs Load Current

Figure 4. 16V Output Converter with Wide Input Voltage

VOUT (V)

RESISTOR DIVIDER

FROM VREF

R1 (kΩ) / R2 ( kΩ)

MAXIMUM OUTPUT CURRENT (mA)

VIN = 2.8V VIN = 3.6V VIN = 5V VIN = 12V

40 NA 0.5 0.7 1.1 3.6

35 110/887 0.7 0.9 1.4 4.4

30 237/768 0.8 1 1.5 5.5

25 365/634 1 1.4 2.1 7.2

20 487/511 1.4 1.9 2.9 9.7

15 619/383 1.6 2.4 4 14

10 750/255 3.3 4.6 7 NA

5 866/127 8 11 17 NA

LT8410 Maximum Output Current vs Output Voltage

LT8410/LT8410-1

84101fb

SW CAP

GND FBP

8410-1 TA09

LT8410

2.2µF

0.1µF

150µH

0.1µF

VOUT = 34V

VIN

2.5V to 16V

VCC VOUT

VREF

SHDN

133k

866k

TURN ON/OFF

C1: 2.2μF, 16V, X5R, 0603

C2: 0.1μF, 100V, X5R, 0603

C3: 0.1μF, 100V, X5R, 0603 *

C4: 0.1μF, 16V, X7R, 0402

L1: COILCRAFT LPS3314-154ML

* HIGHER CAPACITANCE VALUE IS REQUIRED FOR

C3 WHEN THE VIN IS HIGHER THAN 8V

34V Output Converter with Wide Input Voltage Efﬁciency vs Load Current

LOAD CURRENT (mA)

0.01

EFFICIENCY (%)

8410-1 TA10

1010.1

VIN = 12V

VIN = 3.6V

VIN = 5V

VIN (V) IOUT (mA)

3.6 0.8

5 1.2

12 4

TYPICAL APPLICATIONS

VOUT (V)

FEEDBACK RESISTOR

DIVIDER

R1 (kΩ) / R2 ( kΩ)

MAXIMUM OUTPUT CURRENT (mA)

VIN = 2.8V VIN = 3.6V VIN = 5V VIN = 12V

40 NA 0.12 0.16 0.24 0.89

35 110/887 0.14 0.19 0.3 1.1

30 237/768 0.18 0.25 0.38 1.5

25 365/634 0.25 0.35 0.55 2

20 487/511 0.34 0.48 0.76 2.9

15 619/383 0.48 0.69 1.1 3.5

10 750/255 0.84 1.2 2.1 NA

5 866/127 2.3 3.3 3.5 NA

LT8410-1 Maximum Output Current vs Output Voltage

SW CAP

GND FBP

8410-1 TA10a

LT8410-1

2.2µF

10000µF

0.1µF

220µH

1.0µF

VOUT = 16V

VIN

2.5V to 16V

VCC VOUT

VREF

SHDN

604k

412k

TURN ON/OFF

C1: 2.2μF, 16V, X5R, 0603

C2: 1.0μF, 25V, X5R, 0603 *

C3: 10000μF, ELECTROLYTIC CAPACITOR

C4: 0.1μF, 16V, X7R, 0402

L1: COILCRAFT LPS3008-224ML

* HIGHER CAPACITANCE VALUE IS REQUIRED FOR

C2 WHEN THE VIN IS HIGHER THAN 12V

SHDN VOLTAGE

2V/DIV

VOUT VOLTAGE

10V/DIV

INPUT CURRENT

5mA/DIV

INDUCTOR

CURRENT

10mA/DIV

VIN = 3.6V 20s/DIV 8410-1 G10b

Figure 5. Capacitor Charger with the LT8410-1

LT8410/LT8410-1

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PACKAGE DESCRIPTION

DC Package

8-Lead Plastic DFN (2mm × 2mm)

(Reference LTC DWG # 05-08-1719 Rev A)

2.00 ±0.10

(4 SIDES)

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

0.40 ± 0.10

BOTTOM VIEW—EXPOSED PAD

0.64 ± 0.10

(2 SIDES)

0.75 ±0.05

R = 0.115

TYP

R = 0.05

TYP

1.37 ±0.10

(2 SIDES)

PIN 1 BAR

TOP MARK

(SEE NOTE 6)

0.200 REF

0.00 – 0.05

(DC8) DFN 0409 REVA

0.23 ± 0.05

0.45 BSC

0.25 ± 0.05

1.37 ±0.05

(2 SIDES)

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

0.64 ±0.05

(2 SIDES)

1.15 ±0.05

0.70 ±0.05

2.55 ±0.05

PACKAGE

OUTLINE

0.45 BSC

PIN 1 NOTCH

R = 0.20 OR

0.25 × 45°

CHAMFER

LT8410/LT8410-1

84101fb

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.

REVISION HISTORY

REV DATE DESCRIPTION PAGE NUMBER

B 01/11 Corrected Pin Conﬁguration

Revised Note 2 in Electrical Characteristics

(Revision history begins at Rev B)

LT8410/LT8410-1

84101fb

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

 LINEAR TECHNOLOGY CORPORATION 2008

LT 0211 REV B • PRINTED IN USA

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LT3464 85mA (ISW), High Efﬁciency Step-Up DC/DC Converter with

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Boost-Inverting DC/DC Converter

VIN: 2.4V to 16V, VOUT(MAX) = ±40V, IQ = 2.5mA, ISD < 1µA,

DFN Package

LT3473/LT3473A 1A (ISW), 1.2MHz, High Efﬁciency Step-Up DC/DC Converter

with Integrated Schottky Diode and Output Disconnect

VIN: 2.2V to 16V, VOUT(MAX) = 36V, IQ = 100µA, ISD < 1µA,

DFN Package

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DC/DC Converter with Output Disconnect

VIN: 2.1V to 16V, VOUT(MAX) = 40V, IQ = 65µA, ISD < 1µA,

DFN Package

LT3495/LT3495B/

LT3495-1/LT3495B-1

650mA/350mA (ISW), High Efﬁciency, Low Noise Step-Up

DC/DC Converter with Output Disconnect

VIN: 2.3 V to 16V, VOUT(MAX) = 40V, IQ = 60µA, ISD < 1µA,

DFN Package

DANGER HIGH VOLTAGE! OPERATION BY HIGH VOLTAGE TRAINED PERSONNEL ONLY

SW CAP

GND FBP

8410-1 TA11

LT8410

2.2µF

0.1µF

100µH

C3, 0.1µF C5, 0.1µF

0.1µF C4

0.1µF

VIN

2.5V to 16V

VCC VOUT

VREF

SHDN

143k

787k

TURN ON/OFF

C1: 2.2μF, 16V, X5R, 0603

C2 – C7: 0.1μF, 100V, X5R, 0603

C8: 0.1μF, 16V, X7R, 0402

D1 – D4: ON SEMI RB751S40T1G

L1: MURATA LQH32CN101K53

OUTPUT = 100V

0.4mA (VIN = 5V)

1.4mA (VIN = 12V)

D1 D2 D3 D4

FBP VOLTAGE (V)

OUTPUT VOLTAGE (V)

140

120

100

8410-1 TA12

21 1.50.5

VIN = 5V

LOAD CURRENT (mA)

0.01

EFFICIENCY (%)

8410-1 TA13

100.1 1

VOUT = 100V

VIN = 12V

VIN = 5V

Output Voltage vs FBP Voltage Efﬁciency vs Load Current

High Voltage Power Supply Does Not Need a Transformer