PT4115 Datasheet. Www.s Manuals.com. Pt4115e R2.9 Powtech

User Manual: Datasheets PT4115, PT4115B89E, PT4115B89E-B, PT4115BSOH, PT4115BSOH-B.

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30V, 1.2A Step-down High Brightness

LED Driver with 5000:1 Dimming

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PT4115_DS Rev EN_2.9

PT4115

GENERAL DESCRIPTION

The PT4115 is a continuous conduction mode inductive

step-down converter, designed for driving single or

multiple series connected LED efficiently from a

voltage source higher than the total LED chain voltage.

The device operates from an input supply between 6V

and 30V and provides an externally adjustable output

current of up to 1.2A. Depending upon the supply

voltage and external components, the PT4115can

provide more than 30 watts of output power.

The PT4115 includes the power switch and a high-side

output current sensing circuit, which uses an external

resistor to set the nominal average output current, and a

dedicated DIM input accepts either a DC voltage or a

wide range of pulsed dimming. Applying a voltage of

0.3V or lower to the DIM pin turns the output off and

switches the device into a low current standby state.

The PT4115 is available in SOT89-5 and ESOP8

packages.

FEATURES

- Simple low parts count

- Wide input voltage range: 6V to 30V

- Up to 1.2A output current

- Single pin on/off and brightness control using DC

voltage or PWM

- Up to 1MHz switching frequency

- Typical 5% output current accuracy

- Inherent open-circuit LED protection

- High efficiency (up to 97%)

- High-Side Current Sense

- Hysteretic Control: No Compensation

- Adjustable Constant LED Current

- ESOP8 package for large output power application

- RoHS compliant

APPLICATIONS

- Low voltage halogen replacement LEDs

- Automotive lighting

- Low voltage industrial lighting

- LED back-up lighting

- Illuminated signs

- SELV lighting

- LCD TV backlighting

ORDERING INFORMATION

PACKAGE

TEMPERATURE

RANGE

ORDERING PART

NUMBER

TRANSPORT

MEDIA

MARKING

SOT89-5

-40 oC to 85 oC

PT4115B89E:A type

PT4115B89E-B:B type

Tape and Reel

1000 units

PT4115

xxxxxX

ESOP8

-40 oC to 85 oC

PT4115BSOH:A type

PT4115BSOH-B:B type

Tape and Reel

2500 units

PT4115

xxxxxX

Note:

TYPICAL APPLICATION CIRCUIT

PT4115

PT4115

VIN CSN SW

DIM

GND

RS

L

CIN

VIN

D68uH

100uF

AC12-18V

DC6-30V

0.13Ω

3W

LED

xxxxxX

Assembly Factory Code

Lot Number

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PT4115_DS Rev EN_2.9

PT4115

PIN ASSIGNMENT

PIN DESCRIPTIONS

PIN No.

PIN

NAMES

DESCRIPTION

1

SW

Switch Output. SW is the drain of the internal N-Ch MOSFET switch.

2

GND

Signal and power ground. Connect directly to ground plane.

3

DIM

Logic level dimming input. Drive DIM low to turn off the current regulator.

Drive DIM high to enable the current regulator.

4

CSN

Current sense input

5

VIN

Input Supply Pin. Must be locally bypassed.

-

Exposed PAD

Internally connected to GND. Mount on board for lower thermal resistance.

ESOP8 4,5

NC

No connection

ABSOLUTE MAXIMUM RATINGS (note1)

SYMBOL

ITEMS

VALUE

UNIT

VIN

Supply Voltage

-0.3~45

V

SW

Drain of the internal power switch

-0.3~45

V

CSN

Current sense input (Respect to VIN)

+0.3~(-6.0)

V

DIM

Logic level dimming input

-0.3~6

V

ISW

Switch output current

1.5

A

PDMAX

Power Dissipation (Note 2)

1.5

W

PTR

Thermal Resistance, SOT89-5 θJA

45

oC /W

PTR

Thermal Resistance, ESOP8 θJA

40

oC /W

TJ

Operation Junction Temperature Range

-40 to 150

oC

TSTG

Storage Temperature

-55 to 150

oC

ESD Susceptibility (Note 3)

2

kV

1

2

3

45

6

7

8

PT4115

CSN

VIN

SW

NC NC

GNDP

GNDA

DIM

ESOP8

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PT4115_DS Rev EN_2.9

PT4115

RECOMMENDED OPERATING RANGE

SYMBOL

ITEMS

VALUE

UNIT

VIN

VDD Supply Voltage

6 ~ 30

V

TOPT

Operating Temperature

-40 to +85

oC

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Recommended

Operating Range indicates conditions for which the device is functional, but do not guarantee specific performance

limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which

guarantee specific performance limits. This assumes that the device is within the Operating Range. Specifications are

not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device

performance.

Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA,

and the ambient temperature TA. The maximum allowable power dissipation is PDMAX = (TJMAX - TA)/ θJA or the

number given in Absolute Maximum Ratings, whichever is lower.

Note 3: Human body model, 100pF discharged through a 1.5kΩ resistor.

ELECTRICAL CHARACTERISTICS (Note 4, 5)

The following specifications apply for VIN=12V, TA=25 oC, unless specified otherwise.

SYMBOL

ITEMS

CONDITIONS

Min.

Typ.

Max.

UNIT

VIN

Input Voltage

6

30

V

VUVLO

Under voltage lock out

VIN falling

5.1

V

VUVLO, HYS

UVLO hysterisis

VIN rising

500

mV

FSW

Max. Switching Frequency

1

MHz

Current Sense

VCSN

Mean current sense

threshold voltage

VIN-VCSN

A type

95

98

101

mV

B type

99

102

105

mV

VCSN_hys

Sense threshold hysteresis

±15

%

ICSN

CSN Pin Input Current

VIN-VCSN=50mV

8

µA

Operating Current

IOFF

Quiescent supply current

with output off

VDIM<0.3V

95

µA

DIM Input

VDIM

Internal supply voltage

DIM floating

5

V

VDIM_H

DIM input voltage High

2.5

V

VDIM_L

DIM input voltage Low

0.3

V

VDIM_DC

DC brightness control

0.5

2.5

V

fDIM

Max. DIM Frequency

fOSC=500kHz

50

kHz

DPWM_LF

Duty cycle range of low

frequency dimming

fDIM =100Hz

0.02%

1

Brightness control range

5000:1

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PT4115_DS Rev EN_2.9

PT4115

ELECTRICAL CHARACTERISTICS (Continued) (Note 4, 5)

SYMBOL

ITEMS

CONDITIONS

Min.

Typ.

Max.

UNIT

DIM Input

DPWM_HF

Duty cycle range of high

frequency dimming

fDIM =20KHz

4%

1

Brightness control range

25:1

RDIM

DIM pull up resistor to Internal

supply voltage

200

KΩ

IDIM_L

DIM input leakage low

VDIM = 0

25

uA

Output Switch

RSW

SW On Resistance

VIN=12V

0.6

Ω

VIN=24V

0.4

ISWmean

Continuous SW Current

1.2

A

ILEAK

SW Leakage Current

0.5

5

µA

Thermal Shutdown

TSD

Thermal Shutdown Threshold

160

℃

TSD-hys

Thermal Shutdown hysteresis

20

℃

Note 4: Typical parameters are measured at 25˚C and represent the parametric norm.

Note 5: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.

SIMPLIFIED BLOCK DIAGRAM

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PT4115_DS Rev EN_2.9

PT4115

OPERATION DESCRIPTION

The device, in conjunction with the coil (L1) and

current sense resistor (RS), forms a self oscillating

continuous-mode buck converter.

When input voltage VIN is first applied, the initial

current in L1 and RS is zero and there is no output from

the current sense circuit. Under this condition, the

output of CS comparator is high. This turns on an

internal switch and switches the SW pin low, causing

current to flow from VIN to ground, via RS, L1 and the

LED(s). The current rises at a rate determined by VIN

and L1 to produce a voltage ramp (VCSN) across RS.

When (VIN-VCSN) > 115mV, the output of CS

comparator switches low and the switch turns off. The

current flowing on the RS decreases at another rate.

When (VIN-VCSN) < 85mV, the switch turns on again

and the mean current on the LED is determined by

85 115

2

( )/ 100 /

SS

mV R mV R

+=

.

The high-side current-sensing scheme and on-board

current-setting circuitry minimize the number of

external components while delivering LED current with

±5 % accuracy, using a 1% sense resistor.

The PT4115 allow dimming with a PWM signal at the

DIM input. A logic level below 0.3V at DIM forces

PT4115 to turn off the LED and the logic level at DIM

must be at least 2.5V to turn on the full LED current.

The frequency of PWM dimming ranges from 100Hz to

more than 20 kHz.

The DIM pin can be driven by an external DC voltage

(VDIM) to adjust the output current to a value below the

nominal average value defined by RS. The DC voltage

is valid from 0.5V to 2.5V. When the dc voltage is

higher than 2.5V, the output current keeps constant.

The LED current also can be adjusted by a resistor

connected to the DIM pin. An internal pull-up resistor

(typical 200KΩ) is connected to a 5V internal regulator.

The voltage of DIM pin is divided by the internal and

external resistor.

The DIM pin is pulled up to the internal regulator (5V)

by a 200KΩ resistor. It can be floated at normal

working. When a voltage applied to DIM falls below

the threshold (0.3V nom.), the output switch is turned

off. The internal regulator and voltage reference remain

powered during shutdown to provide the reference for

the shutdown circuit. Quiescent supply current during

shutdown is nominally 95uA and switch leakage is

below 5uA.

Additionally, to ensure the reliability, the PT4115 is

built with a thermal shutdown (TSD) protection and a

thermal pad. The TSD protests the IC from over

temperature (160℃). Also the thermal pad enhances

power dissipation. As a result, the PT4115 can handle a

large amount of current safely.

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PT4115_DS Rev EN_2.9

PT4115

TYPICAL PERFORMANCE CHARACTERISTICS

810 12 14 16 18 20 22 24 26 28 30

75%

80%

85%

90%

95%

100%

Efficiency

Supply Voltage Vin(V)

Efficiency1,3 and 7 LEDs

L=47uH

Rs=0.13ohm

1LED

3 LEDs

7LEDs

510 15 20 25 30

4.5

4.6

4.7

4.8

4.9

5.0

5.1

5.2

5.3

5.4

5.5

Vdim(V)

Supply Voltage Vin(V)

Vdim vs Supply Voltage

-40 -20 0 20 40 60 80 100 120

5.00

5.05

5.10

5.15

5.20

5.25

5.30

Vdim(V)

Temperature(Deg C)

Vdim vs Temperature

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PT4115_DS Rev EN_2.9

PT4115

515 25 35

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Rsw (ohm)

Supply Voltage Vin(V)

Rsw vs Supply Voltage

0 5 10 15 20 25 30

0

50

100

150

200

250

Iin (uA)

Supply Voltage Vin(V)

Supply Current vs Supply Voltage

0 1 2 3 4 5

0

100

200

300

400

500

600

700

800

R=0.33ohm

LED current (mA)

Dim Pin Voltage (V)

LED Current vs Vdim

R=0.13ohm

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PT4115_DS Rev EN_2.9

PT4115

510 15 20 25 30

1.10

1.12

1.14

1.16

1.18

1.20

1.22

1.24

7LEDs

6LEDs

5LEDs

4LEDs

3LEDs

2LEDs

Output Current

Supply Voltage(V)

Output Current L=27uH Rcs=0.0825ohm

1LED

510 15 20 25 30

-8%

-7%

-6%

-5%

-4%

-3%

-2%

-1%

0%

1%

2%

3%

7LEDs

5LEDs 6LEDs

4LEDs

3LEDs

Output Current Deviation

Supply Voltge(V)

Output Current L=27uH Rcs=0.0825ohm

1LED

2LEDs

510 15 20 25 30

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

7LEDs

6LEDs

5LEDs

3LEDs

4LEDs

2LEDs

Duty Cycle

Supply Voltage Vin(V)

Duty Cycle L=27uH R=0.0825ohm

1LED

510 15 20 25 30

0

100

200

300

400

500

600

700

800

900

1000

7LEDs

2LEDs 3LEDs

5LEDs 6LEDs

4LEDs

Switching Frequency(kHZ)

Supply Voltage Vin(V)

Switching Frequency L=27uH R=0.0825ohm

1LED

510 15 20 25 30

710

720

730

740

750

760

770

780

790

800

7LEDs

3LEDs

5LEDs

2LEDs 6LEDs

4LEDs

Output Current(mA)

Supply Voltage Vin(V)

Output Current L=47uH Rcs=0.13ohm

1LED

510 15 20 25 30

-6%

-4%

-2%

0%

2%

4%

6%

2LEDs

4LEDs 6LEDs

7LEDs

5LEDs

3LEDs

1LED

Output Current Deviation

Supply Voltage(V)

Output Current L=47uH Rcs=0.13ohm

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PT4115_DS Rev EN_2.9

PT4115

810 12 14 16 18 20 22 24 26 28 30

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

7LEDs

6LEDs

5LEDs

4LEDs

3LEDs

Duty Cycle

Supply Voltage Vin(V)

Duty Cycle L=47uH Rcs=0.13ohm

1LED

2LEDs

810 12 14 16 18 20 22 24 26 28 30

0

100

200

300

400

500

600

700

800

900

7LEDs

6LEDs

5LEDs

4LEDs

3LEDs

2LEDs

1LED

Switch Frequency(kHz)

Supply Voltage Vin(V)

Switch Frequency L=47uH Rcs=0.13ohm

510 15 20 25 30

-6%

-4%

-2%

0%

2%

4%

6%

8%

7LEDs

3LEDs 6LEDs

5LEDs

4LEDs

2LEDs

1LED

Output Current Deviation

Supply Voltage

Output Current L=100uH Rcs=0.33ohm

510 15 20 25 30

0%

10%

20%

30%

40%

50%

60%

70%

80%

90% 7LEDs

6LEDs

5LEDs

4LEDs

3LEDs

Duty Cycle

Supply Voltage Vin(V)

Duty Cycle L=100uH R=0.33ohm

1LED

2LEDs

510 15 20 25 30

0

100

200

300

400

500

600

700

800

900

1000

7LEDs

6LEDs

5LEDs

4LEDs

3LEDs

2LEDs

1LED

Switch Frequency(kHz)

Supply Voltage Vin(V)

Switch Frequency L=100uH R=0.33ohm

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PT4115_DS Rev EN_2.9

PT4115

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PT4115_DS Rev EN_2.9

PT4115

APPLICATION NOTES

Setting nominal average output current with

external resistor RS

The nominal average output current in the LED(s) is

determined by the value of the external current sense

resistor (RS) connected between VIN and CSN and is

given by:

RsIOUT /1.0

)082.0( Rs

This equation is valid when DIM pin is float or applied

with a voltage higher than 2.5V (must be less than 5V).

Actually, RS sets the maximum average current which

can be adjusted to a less one by dimming.

Output current adjustment by external DC control

voltage

The DIM pin can be driven by an external dc voltage

(VDIM), as shown, to adjust the output current to a

value below the nominal average value defined by RS.

PT4115

PT4115

VIN CSN SW

DIM

GND

RS

L

D68uH

0.13Ω

3W

LED

VIN

The average output current is given by:

Rs

V

IDIM

OUT 



5.2

1.0

)5.25.0( VVV DIM 

Note that 100% brightness setting corresponds to:

)55.2( VVV DIM 

Output current adjustment by PWM control

A Pulse Width Modulated (PWM) signal with duty

cycle PWM can be applied to the DIM pin, as shown

below, to adjust the output current to a value below the

nominal average value set by resistor RS:

Rs

D

IOUT



1.0

)55.2%,1000( VVVD pulse 

Rs

DV

Ipulse

OUT 



5.2

1.0

)5.25.0%,1000( VVVD pulse 

PT4115

PT4115

VIN CSN SW

DIM

GND

RS

L

D68uH

0.13Ω

3W

LED

VIN

PWM dimming provides reduced brightness by

modulating the LED’s forward current between 0% and

100%. The LED brightness is controlled by adjusting

the relative ratios of the on time to the off time. A 25%

brightness level is achieved by turning the LED on at

full current for 25% of one cycle. To ensure this

switching process between on and off state is invisible

by human eyes, the switching frequency must be

greater than 100 Hz. Above 100 Hz, the human eyes

average the on and off times, seeing only an effective

brightness that is proportional to the LED’s on-time

duty cycle. The advantage of PWM dimming is that the

forward current is always constant, therefore the LED

color does not vary with brightness as it does with

analog dimming. Pulsing the current provides precise

brightness control while preserving the color purity.

The dimming frequency of PT4115 can be as high as 20

kHz.

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PT4115_DS Rev EN_2.9

PT4115

Shutdown mode

Taking the DIM pin to a voltage below 0.3V will turn

off the output and the supply current will fall to a low

standby level of 95μA nominal.

Soft-start

An external capacitor from the DIM pin to ground will

provide additional soft-start delay, by increasing the

time taken for the voltage on this pin to rise to the

turn-on threshold and by slowing down the rate of rise

of the control voltage at the input of the comparator.

Adding capacitance increases this delay by

approximately 0.8ms/nF.

Inherent open-circuit LED protection

If the connection to the LED(s) is open-circuited, the

coil is isolated from the SW pin of the chip, so the

device and LED will not be damaged.

Capacitor selection

A low ESR capacitor should be used for input

decoupling, as the ESR of this capacitor appears in

series with the supply source impedance and lowers

overall efficiency. This capacitor has to supply the

relatively high peak current to the coil and smooth the

current ripple on the input supply. A minimum value of

4.7uF is acceptable if the DC input source is close to

the device, but higher values will improve performance

at lower input voltages, especially when the source

impedance is high. For the rectified AC input, the

capacitor should be higher than 100uF and the tantalum

capacitor is recommended. The input capacitor should

be placed as close as possible to the IC.

For maximum stability over temperature and voltage,

capacitors with X7R, X5R, or better dielectric are

recommended. Capacitors with Y5V dielectric are not

suitable for decoupling in this application and should

NOT be used.

A suitable Murata capacitor would be

GRM42-2X7R475K-50.

The following web sites are useful when finding

alternatives:

www.murata.com

www.t-yuden.com

www.avxcorp.com

Inductor selection

Recommended inductor values for the PT4115 are in

the range 27uH to 100uH.

Higher values of inductance are recommended at lower

output current in order to minimize errors due to

switching delays, which result in increased ripple and

lower efficiency. Higher values of inductance also

result in a smaller change in output current over the

supply voltage range. (See graphs). The inductor should

be mounted as close to the device as possible with low

resistance connections to the SW and VIN pins.

The chosen coil should have a saturation current higher

than the peak output current and a continuous current

rating above the required mean output current.

Following table gives the guideline on inductor

selection:

Load current

Inductor

Saturation current

Iout>1A

27-47uH

1.3-1.5 times of load

current

0.8A<Iout≤1A

33-82uH

0.4A<Iout≤0.8A

47-100uH

Iout≤0.4A

68-220uH

Suitable coils for use with the PT4115 are listed in the

table below:

Part

No.

L

(uH)

DCR

(Ω)

ISAT

(A)

Manufacturer

MSS1038-333

27

0.089

2.48

CoilCraft

www.coilcraft.com

MSS1038-333

33

0.093

2.3

MSS1038-473

47

0.128

2

MSS1038-683

68

0.213

1.6

MSS1038-104

100

0.304

1.3

The inductor value should be chosen to maintain

operating duty cycle and switch 'on'/'off' times within

the specified limits over the supply voltage and load

current range.

The following equations can be used as a guide.

SW Switch 'On' time

)( swavgLEDIN

ON RrLRsIVV

IL

T





SW Switch 'Off' time

)( rLRsIVV

IL

T

avgDLED

OFF 





Where:

L is the coil inductance (H)

rL is the coil resistance (Ω)

RS is the current sense resistance (Ω)

Iavg is the required LED current (A)

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PT4115_DS Rev EN_2.9

PT4115

ΔI is the coil peak-peak ripple current (A) {Internally

set to 0.3 x Iavg}

VIN is the supply voltage (V)

VLED is the total LED forward voltage (V)

RSW is the switch resistance (Ω) {=0.6Ω nominal}

VD is the diode forward voltage at the required load

current (V)

Diode selection

For maximum efficiency and performance, the rectifier

(D1) should be a fast low capacitance Schottky diode

with low reverse leakage at the maximum operating

voltage and temperature.

They also provide better efficiency than silicon diodes,

due to a combination of lower forward voltage and

reduced recovery time.

It is important to select parts with a peak current rating

above the peak coil current and a continuous current

rating higher than the maximum output load current. It

is very important to consider the reverse leakage of the

diode when operating above 85°C. Excess leakage will

increase the power dissipation in the device and if close

to the load may create a thermal runaway condition.

The higher forward voltage and overshoot due to

reverse recovery time in silicon diodes will increase the

peak voltage on the SW output. If a silicon diode is

used, care should be taken to ensure that the total

voltage appearing on the SW pin including supply

ripple, does not exceed the specified maximum value.

The following web sites are useful when finding

alternatives: www.onsemi.com

Reducing output ripple

Peak to peak ripple current in the LED(s) can be

reduced, if required, by shunting a capacitor CLED

across the LED(s) as shown below:

PT4115

PT4115

VIN CSN SW

DIM

GND

RS

L

D68uH

0.13Ω

3W

LED

VIN

A value of 1uF will reduce the supply ripple current by

a factor three (approx.). Proportionally lower ripple can

be achieved with higher capacitor values. Note that the

capacitor will not affect operating frequency or

efficiency, but it will increase start-up delay and reduce

the frequency of dimming, by reducing the rate of rise

of LED voltage.

By adding this capacitor the current waveform through

the LED(s) changes from a triangular ramp to a more

sinusoidal version without altering the mean current

value.

Operation at low supply voltage

The internal regulator disables the drive to the switch

until the supply has risen above the startup threshold

(VUVLO). Above this threshold, the device will start to

operate. However, with the supply voltage below the

specified minimum value, the switch duty cycle will be

high and the device power dissipation will be at a

maximum. Care should be taken to avoid operating the

device under such conditions in the application, in

order to minimize the risk of exceeding the maximum

allowed die temperature. (See next section on thermal

considerations). The drive to the switch is turned off

when the supply voltage falls below the under-voltage

threshold (VUVLO-0.5V).

This prevents the switch working with excessive 'on'

resistance under conditions where the duty cycle is

high.

Thermal considerations

When operating the device at high ambient

temperatures, or when driving maximum load current,

care must be taken to avoid exceeding the package

power dissipation limits. The graph below gives details

for power derating. This assumes the device to be

mounted on a 25mm2 PCB with 1oz copper standing in

still air.

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PT4115_DS Rev EN_2.9

PT4115

Note that the device power dissipation will most often

be a maximum at minimum supply voltage. It will also

increase if the efficiency of the circuit is low. This may

result from the use of unsuitable coils, or excessive

parasitic output capacitance on the switch output. When

the application is limited by the internal power

dissipation of the device, the ESOP8 package is

recommended because of its enhanced power

dissipation ability.

Thermal compensation of output current

High luminance LEDs often need to be supplied with a

temperature compensated current in order to maintain

stable and reliable operation at all drive levels. The

LEDs are usually mounted remotely from the device

so，for this reason, the temperature coefficients of the

internal circuits for the PT4115 have been optimized to

minimize the change in output current when no

compensation is employed. If output current

compensation is required, it is possible to use an

external temperature sensing network - normally using

Negative Temperature Coefficient (NTC) thermistors

and/or diodes, mounted very close to the LED(s). The

output of the sensing network can be used to drive the

DIM pin in order to reduce output current with

increasing temperature.

Thermal shutdown protection

To ensure the reliability, the PT4115 is built with a

thermal shutdown (TSD) protection function. The TSD

protests the IC from over temperature (160℃). When

the chip temperature decreases (140℃), the IC recovers

again.

Layout considerations

Careful PCB layout is critical to achieve low switching

losses and stable operation. Use a multilayer board

whenever possible for better noise immunity. Minimize

ground noise by connecting high-current ground returns,

the input bypass-capacitor ground lead, and the

output-filter ground lead to a single point (star ground

configuration).

SW pin

The SW pin of the device is a fast switching node, so

PCB tracks should be kept as short as possible. To

minimize ground 'bounce', the ground pin of the device

should be soldered directly to the ground plane.

Coil and decoupling capacitors and current sense

resistor

It is particularly important to mount the coil and the

input decoupling capacitor as close to the device pins as

possible to minimize parasitic resistance and inductance,

which will degrade efficiency. It is also important to

minimize any track resistance in series with current

sense resistor RS. It’s best to connect VIN directly to

one end of RS and CSN directly to the opposite end of

RS with no other currents flowing in these tracks. It is

important that the cathode current of the Schottky diode

does not flow in a track between RS and VIN as this

may give an apparent higher measure of current than is

actual because of track resistance.

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PT4115_DS Rev EN_2.9

PT4115

TYPICAL APPLICATION CIRCUIT

PT4115

PT4115

VIN CSN SW

DIM

GND

RS

L

CIN

VIN

D

100u

H

100uF

AC12-18V

DC6-30V

0.286Ω

LED

1W

Fig1 ：1W application

PT4115

PT4115

VIN CSN SW

DIM

GND

RS

L

CIN

VIN

D68uH

100uF

AC12-18V

DC6-30V

0.286Ω

LED

1W

Fig 2： 3W application

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PT4115_DS Rev EN_2.9

PT4115

TYPICAL APPLICATION CIRCUIT (Continued)

Fig 3 DEMO board for mass production

30V, 1.2A Step-down High Brightness

LED Driver with 5000:1 Dimming

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PT4115_DS Rev EN_2.9

PT4115

PACKAGE INFORMATION

SOT89-5 Package

SYMBOL

MILLIMETERS

INCHES

MIN

MAX

MIN

MAX

A

1.400

1.600

0.055

0.063

b

0.320

0.520

0.013

0.020

b1

0.360

0.560

0.014

0.022

c

0.350

0.440

0.014

0.017

D

4.400

4.600

0.173

0.181

D1

1.400.

1.800

0.055

0.071

E

2.300

2.600

0.091

0.102

E1

3.940

4.250

0.155

0.167

e

1.500 TYP.

0.060 TYP.

e1

2.900

3.100

0.114

0.122

L

0.900

1.100

0.035

0.043

D

D1

b1

b

e

e1

L

E1

E

A

c

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PT4115_DS Rev EN_2.9

PT4115

PACKAGE INFORMATION

ESOP-8 Package

SYMBOL

DIMENSIONS IN MILLIMETERS

DIMENSIONS IN INCHES

MIN

MAX

MIN

MAX

A

1.350

1.750

0.053

0.069

A1

0.050

0.150

0.004

0.010

A2

1.350

1.550

0.053

0.061

b

0.330

0.510

0.013

0.020

c

0.170

0.250

0.006

0.010

D

4.700

5.100

0.185

0.200

D1

3.202

3.402

0.126

0.134

E

3.800

4.000

0.150

0.157

E1

5.800

6.200

0.228

0.244

E2

2.313

2.513

0.091

0.099

e

1.270(BSC)

0.050(BSC)

L

0.400

1.270

0.016

0.050

θ

0°

8°

0°

8°

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