PT4115E.pdf

PT4115

30V, 1.2A Step-down High Brightness

LED Driver with 5000:1 Dimming

GENERAL DESCRIPTION

FEATURES



Simple low parts count

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.



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

TEMPERATURE

RANGE

ORDERING PART

NUMBER

TRANSPORT

MEDIA

PACKAGE

MARKING

PT4115B89E:A type

PT4115B89E-B:B type

Tape and Reel

1000 units

PT4115

xxxxxX

-40 o C to 85 o C

SOT89-5

PT4115BSOH:A type

PT4115BSOH-B:B type

Tape and Reel

2500 units

PT4115

xxxxxX

-40 o C to 85 o C

ESOP8

Note:

xxxxxX

Assembly Factory Code

Lot Number

TYPICAL APPLICATION CIRCUIT

R S

DC6-30V

V IN

LED

0.13Ω

68uH

C IN

100uF

AC12-18V

VIN

CSN

PT4115

DIM

GND

China Resources Powtech (Shanghai) Limited WWW.CRPOWTECH.COM Page 1

PT4115_DS Rev EN_2.9

PT4115

30V, 1.2A Step-down High Brightness

LED Driver with 5000:1 Dimming

PIN ASSIGNMENT

DIM

CSN

VIN

GNDA

GNDP

4 5

ESOP8

PIN DESCRIPTIONS

NAMES

PIN No.

DESCRIPTION

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

GND

Signal and power ground. Connect directly to ground plane.

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

Drive DIM high to enable the current regulator.

DIM

CSN

Current sense input

VIN

Input Supply Pin. Must be locally bypassed.

Exposed PAD

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

ESOP8 4,5

No connection

ABSOLUTE MAXIMUM RATINGS (note1)

SYMBOL

ITEMS

VALUE

UNIT

V IN

Supply Voltage

-0.3~45

Drain of the internal power switch

-0.3~45

CSN

Current sense input (Respect to VIN)

+0.3~(-6.0)

DIM

Logic level dimming input

-0.3~6

I SW

Switch output current

1.5

Power Dissipation (Note 2)

P DMAX

1.5

Thermal Resistance, SOT89-5 θ JA

o C /W

P TR

Thermal Resistance, ESOP8 θ JA

o C /W

P TR

Operation Junction Temperature Range

-40 to 150

o C

T J

o C

T STG

Storage Temperature

-55 to 150

ESD Susceptibility (Note 3)

China Resources Powtech (Shanghai) Limited WWW.CRPOWTECH.COM Page 2

PT4115_DS Rev EN_2.9

PT4115

30V, 1.2A Step-down High Brightness

LED Driver with 5000:1 Dimming

RECOMMENDED OPERATING RANGE

SYMBOL

ITEMS

VALUE

UNIT

V IN

V DD Supply Voltage

6 ~ 30

o C

T OPT

Operating Temperature

-40 to +85

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 T JMAX , θ JA ,

and the ambient temperature T A . The maximum allowable power dissipation is P DMAX = (T JMAX - T A )/ θ JA 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 V IN =12V, T A =25 o C, unless specified otherwise.

SYMBOL

ITEMS

CONDITIONS

Min.

Typ.

Max.

UNIT

V IN

Input Voltage

V UVLO

Under voltage lock out

V IN falling

5.1

V UVLO, HYS

UVLO hysterisis

V IN rising

500

F SW

Max. Switching Frequency

MHz

Current Sense

A type

101

Mean current sense

threshold voltage

V CSN

V IN -V CSN

B type

102

105

V CSN_hys

Sense threshold hysteresis

±15

I CSN

CSN Pin Input Current

V IN -V CSN =50mV

µA

Operating Cur rent

Quiescent supply current

with output off

I OFF

V DIM <0.3V

µA

DIM Input

V DIM

Internal supply voltage

DIM floating

V DIM_H

DIM input voltage High

2.5

V DIM_L

DIM input voltage Low

0.3

V DIM_DC

DC brightness control

0.5

2.5

f DIM

Max. DIM Frequency

f OSC =500kHz

kHz

Duty cycle range of low

frequency dimming

f DIM =100Hz

0.02%

D PWM_LF

Brightness control range

5000:1

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PT4115_DS Rev EN_2.9

PT4115

30V, 1.2A Step-down High Brightness

LED Driver with 5000:1 Dimming

ELECTRICAL CHARACTERISTICS (Continued) (Note 4, 5)

SYMBOL

ITEMS

CONDITIONS

Min.

Typ.

Max.

UNIT

DIM Input

D PWM_HF

Duty

cycle

range

high

f DIM =20KHz

frequency dimming

Brightness control range

25:1

R DIM

DIM pull up resistor to Internal

supply voltage

200

KΩ

I DIM_L

DIM input leakage low

V DIM = 0

Output Switch

R SW

SW On Resistance

VIN=12V

0.6

VIN=24V

0.4

I SWmean

Continuous SW Current

1.2

I LEAK

SW Leakage Current

0.5

µA

Thermal Shutdow n

T SD

Thermal Shutdown Threshold

160

℃

T SD -hys

Thermal Shutdown hysteresis

℃

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

China Resources Powtech (Shanghai) Limited WWW.CRPOWTECH.COM Page 4

PT4115_DS Rev EN_2.9

PT4115

30V, 1.2A Step-down High Brightness

LED Driver with 5000:1 Dimming

OPERATION DESCRIPTION

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

current sense resistor (RS), forms a self oscillating

continuous-mode buck converter.

(V DIM ) 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 200K Ω ) is connected to a 5V internal regulator.

The voltage of DIM pin is divided by the internal and

external resistor.

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 (V CSN ) across RS.

When (V IN -V CSN ) > 115mV, the output of CS

comparator switches low and the switch turns off. The

current flowing on the RS decreases at another rate.

When (V IN -V CSN ) < 85mV, the switch turns on again

and the mean current on the LED is determined by

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

by a 200K Ω 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.

(

+ = .

115

mVR mVR

) /

100

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

current-setting

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.

circuitry

minimize

the

number

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

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PT4115_DS Rev EN_2.9

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