PT4115E
50V/1.5A Step-down High Brightness
LED Driver
GENERAL DESCRIPTION
FEATURES
The PT4115E 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 50V and provides an externally
adjustable output current of up to 1.5A.
The PT4115E 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 PT4115E is available in SOT89-5 package.
Simple low parts count
Wide input voltage range: 6V to 50V
High efficiency (up to 97%)
Up to 1.5A output current
Single pin on/off and brightness control using DC
voltage or PWM
Up to 1MHz switching frequency
Typical 3% output current accuracy
Inherent open-circuit LED protection
Inherent Rcs open protection
High-Side Current Sense
Hysteretic Control: No need compensation
Adjustable Constant LED Current
Thermal shutdown
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
PT4115EE89E
Tape and Reel
1000 units
PT4115E
xxxxxX
Note:
xxxxxX
Assembly Factory Code
Lot Number
TYPICAL APPLICATION CIRCUIT
RS
DC6-50V
VIN
LED
L
D
CIN
AC12-24V
VIN
DIM
CSN
SW
PT4115E
GND
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PT4115E_DS_Rev EN 1.0
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Page 1
PT4115E
50V/1.5A Step-down High Brightness
LED Driver
PIN ASSIGNMENT
PIN DESCRIPTIONS
SOT89-5 PIN
No.
PIN NAMES
1
SW
2
GND
3
DIM
4
CSN
Current sense input
5
VIN
Input Supply Pin. Must be locally bypassed.
Exposed
DESCRIPTION
Switch Output. SW is the drain of the internal N-Ch MOSFET
switch.
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.
PAD
Internally connected to GND. Mount on board for lower thermal
resistance.
ABSOLUTE MAXIMUM RATINGS (note1)
SYMBOL
ITEMS
VALUE
UNIT
VIN
Supply Voltage
-0.3~55
V
SW
Drain of the internal power switch
-0.3~55
V
CSN
Current sense input (Respect to VIN)
+0.3~(-6.0)
V
DIM
Logic level dimming input
-0.3~6
V
Switch output current
1.5
A
Power Dissipation (Note 2)
1.5
ISW
PDMAX
θJA
W
PTR
Thermal Resistance, SOT89-5
TJ
Operation Junction Temperature Range
-40 to 150
o
C
Storage Temperature
-55 to 150
o
C
TSTG
ESD Susceptibility (Note 3)
CR POWTECH (SHANGHAI) CO., LTD.
PT4115E_DS_Rev EN 1.0
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45
2
o
C /W
kV
Page 2
PT4115E
50V/1.5A Step-down High Brightness
LED Driver
RECOMMENDED OPERATING RANGE
SYMBOL
ITEMS
VIN
VDD Supply Voltage
TOPT
Operating Temperature
VALUE
UNIT
6 ~ 50
V
-40 to +85
o
C
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.
CR POWTECH (SHANGHAI) CO., LTD.
PT4115E_DS_Rev EN 1.0
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Page 3
PT4115E
50V/1.5A Step-down High Brightness
LED Driver
ELECTRICAL CHARACTERISTICS (Note 4, 5)
The following specifications apply for VIN=24V, TA=25 oC, unless specified otherwise.
SYMBOL
VIN
VUVLO
VUVLO_HYS
FSW
ITEMS
CONDITIONS
Input Voltage
Min.
Typ.
6
Max.
UNIT
50
V
Under voltage lock out
VIN rising
4.5
V
UVLO hysterisis
VIN falling
0.3
V
Max. Switching Frequency
1
MHz
206
mV
Current Sense
Mean current sense
VCSN
VCSN_hys
ICSN
threshold voltage
VIN-VCSN
194
Sense threshold hysteresis
CSN Pin Input Current
VIN-VCSN=50mV
200
±15
%
8
µA
Operating Current
ISD
Shutdown supply current
IOFF
Quiescent
supply
current
with output off
60
100
µA
No Switching
0.16
0.3
mA
DIM floating
4.2
DIM Input
VDIM
Internal supply voltage
VDIM_H
DIM input voltage High
V
0.3
0.35
V
50
80
mV
2.5
V
VDIM_HYS
DIM input voltage hysterisis
20
VDIM_DC
DC brightness control
0.5
FDIM_MIN
Min. DIM Frequency
0.1
kHz
FDIM_MAX
Max. DIM Frequency
20
kHz
200
KΩ
RDIM
DIM pull up resistor to
Internal supply voltage
IDIM_H
DIM input leakage high
VDIM = 5.0V
2.8
µA
IDIM_L
DIM input leakage low
VDIM = 0
22
µA
SW On Resistance
VIN=6V~50V
0.4
Ω
Output Switch
RSW
ISWmean
ILEAK
Continuous SW Current
SW Leakage Current
0.5
1.5
A
5
µA
Thermal Shutdown
TSD
Thermal
Shutdown
155
℃
Shutdown
20
℃
Threshold
TSD_HYS
Thermal
hysteresis
Note 4:
Note 5:
Typical parameters are measured at 25˚C and represent the parametric norm.
Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.
CR POWTECH (SHANGHAI) CO., LTD.
PT4115E_DS_Rev EN 1.0
WWW.CRPOWTECH.COM
Page 4
PT4115E
50V/1.5A Step-down High Brightness
LED Driver
SIMPLIFIED BLOCK DIAGRAM
OPERATION DESCRIPTION
The PT4115E in conjunction with current sense resistor (RCS),the inductor (L1), and MOSFET forms a self
oscillating continuous-mode buck converter.
When input voltage VIN is first applied, the initial current in L1 and R CS 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 switch, causing
current to flow from VIN to ground, via RCS, the LED(s),L1 and internal MOSFET. The current rises at a rate
determined by VIN and L1 to produce a voltage ramp (VCSN) across RCS. When (VIN-VCSN) > 230mV, the
output of CS comparator switches low and the switch turns off. The current flowing on the RCS decreases at
another rate. When (VIN-VCSN) < 170mV, the switch turns on again and the mean current on the LED is
determined by 200mV/RCS.
The high-side current-sensing scheme and on-board current-setting circuitry minimize the number of external
components while delivering LED current with ±3% accuracy, using a 1% sense resistor. The PT4115E
allows dimming with a PWM signal at the DIM input. A logic level below 0.3V at DIM forces PT4115E 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 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 RCS. 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.
Additionally, to ensure the reliability, the PT4115E is built with a thermal shutdown (TSD) protection. The TSD
protests the IC from over temperature (155℃).
CR POWTECH (SHANGHAI) CO., LTD.
PT4115E_DS_Rev EN 1.0
WWW.CRPOWTECH.COM
Page 5
PT4115E
50V/1.5A Step-down High Brightness
LED Driver
TYPICAL PERFORMANCE CHARACTERASTICS
VIN=24V,3LEDs,IOUT=1A,TA=25℃,unless otherwise noted.
Efficiency
Steady State
2µS/div
Input Power On
Input Power Off
2mS/div
100mS/div
EN Power On
EN Power Off
400µS/div
CR POWTECH (SHANGHAI) CO., LTD.
PT4115E_DS_Rev EN 1.0
200µS/div
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Page 6
PT4115E
50V/1.5A Step-down High Brightness
LED Driver
TYPICAL PERFORMANCE CHARACTERASTICS(continued)
VIN=24V,3LEDs,IOUT=1A,TA=25℃,unless otherwise noted.
PWM Dimming
PWM Dimming
(2KHz,50%)
(2KHz,1%)
400µS/div
400µS/div
Short LED+ to LED- Protection
Short LED+ to LED- Recovery
20µS/div
Open LED Load Protection
20µS/div
Open LED Load Recovery
2mS/div
CR POWTECH (SHANGHAI) CO., LTD.
PT4115E_DS_Rev EN 1.0
40µS/div
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Page 7
PT4115E
50V/1.5A Step-down High Brightness
LED Driver
TYPICAL PERFORMANCE CHARACTERASTICS(continued)
VIN=24V,3LEDs,IOUT=1A,TA=25℃,unless otherwise noted.
Open RCS Protection
2S/div
APPLICATION NOTES
Setting nominal average output current
with external resistor RCS
Output
control
The nominal average output current in the LED(s)
A Pulse Width Modulated (PWM) signal with duty
is determined by the value of the external current
cycle PWM can be applied to the DIM pin, to adjust
sense resistor (RCS) connected between VIN and
the output current to a value below the nominal
CSN and is given by:
average value set by resistor RCS:
IOUT=0.2/RCS
This equation is valid when DIM pin is float or
I OUT
by
PWM
RCS
(0≤D≤100%,2.5V