© Semiconductor Components Industries, LLC, 2014
August, 2017 − Rev. 7
1Publication Order Number:
NSI50350AS/D
NSI50350AST3G,
NSV50350AST3G
Constant Current Regulator
& LED Driver
50 V, 350 mA +10%, 5.8 W Package
The linear constant current regulator (CCR) is a simple, economical
and robust device designed to provide a cost−effective solution for
regulating current in LEDs. The CCR is based on Self−Biased
Transistor (SBT) technology and regulates current over a wide voltage
range. It is designed with a negative temperature coefficient to protect
LEDs from thermal runaway at extreme voltages and currents.
The CCR turns on immediately and is at 20% of regulation with
only 0.5 V Vak. It requires no external components allowing it to be
designed as a high or low−side regulator. The high anode−cathode
voltage rating withstands surges common in Automotive, Industrial
and Commercial Signage applications. The CCR comes in thermally
robust packages and is qualified to AEC−Q101 standard and
UL94−V0 Certified.
Also available in DPAK: NSI50350ADT4G.
Features
•Robust Power Package: 5.8 W
•Wide Operating Voltage Range
•Immediate Turn−On
•Voltage Surge Suppressing − Protecting LEDs
•UL94−V0 Certified
•SBT (Self−Biased Transistor) Technology
•Negative Temperature Coefficient
•NSV Prefix for Automotive and Other Applications Requiring
Unique Site and Control Change Requirements; AEC−Q101
Qualified and PPAP Capable*
•These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
Typical Applications
•Automobile: Chevron Side Mirror Markers, Cluster, Display &
Instrument Backlighting, CHMSL, Map Light
•AC Lighting Panels, Display Signage, Decorative Lighting, Channel
Lettering
•Application Note AND8349/D − Automotive CHMSL
•Application Notes AND8391/D, AND9008/D − Power Dissipation
Considerations
Mechanical Characteristics
•CASE: Void-free, transfer-molded, thermosetting plastic
•FINISH: All external surfaces are corrosion resistant and leads are
readily solderable
•MAXIMUM CASE TEMPERATURE FOR SOLDERING PURPOSES:
260°C for 10 seconds
•LEADS: Modified L−Bend providing more contact area to bond pads
•POLARITY: Cathode indicated by molded polarity notch
•MOUNTING POSITIONS: Any
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MARKING DIAGRAM
(Note: Microdot may be in either location)
Ireg(SS) = 350 mA
@ Vak = 7.5 V
350A = Specific Device Code
A = Assembly Location**
Y = Year
WW = Work Week
G= Pb−Free Package
Device Package Shipping†
ORDERING INFORMATION
NSI50350AST3G SMC
(Pb−Free)
2500 / Tape &
Reel
NSV50350AST3G* SMC
(Pb−Free)
2500 / Tape &
Reel
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specifications
Brochure, BRD8011/D.
SMC 2−LEAD
CASE 403AC
AYWW
350AG
G
**The Assembly Location code (A) is front side
optional. In cases where the Assembly Location is
stamped in the package bottom (molding ejecter pin),
the front side assembly code may be blank.
NSI50350AST3G, NSV50350AST3G
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2
MAXIMUM RATINGS (TA = 25°C unless otherwise noted)
Rating Symbol Value Unit
Anode−Cathode Voltage Vak Max 50 V
Reverse Voltage VR500 mV
Operating and Storage Junction Temperature Range TJ, Tstg −55 to +175 °C
ESD Rating: Human Body Model
Machine Model
ESD Class 3B (8000 V)
Class C (400 V)
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise noted)
Characteristic Symbol Min Typ Max Unit
Steady State Current @ Vak = 7.5 V (Note 1) Ireg(SS) 315 350 385 mA
Voltage Overhead (Note 2) Voverhead 1.8 V
Pulse Current @ Vak = 7.5 V (Note 3) Ireg(P) 405.5 460 516.5 mA
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
1. Ireg(SS) steady state is the voltage (Vak) applied for a time duration ≥ 300 sec, using 900 mm2 DENKA K1, 1.5 mm Al, 2kV Thermally
conductive dielectric, 2 oz. Cu (or equivalent), in still air.
2. Voverhead = Vin − VLEDs. Voverhead is typical value for 70% Ireg(SS).
3. Ireg(P) non−repetitive pulse test. Pulse width t ≤ 360 msec.
Figure 1. CCR Voltage−Current Characteristic
NSI50350AST3G, NSV50350AST3G
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3
THERMAL CHARACTERISTICS
Characteristic Symbol Max Unit
Total Device Dissipation (Note 4) TA = 25°C
Derate above 25°C
PD3112
20.75
mW
mW/°C
Thermal Resistance, Junction−to−Ambient (Note 4) RθJA 48.2 °C/W
Thermal Reference, Junction−to−Tab (Note 4) RψJL 8.7 °C/W
Total Device Dissipation (Note 5) TA = 25°C
Derate above 25°C
PD4225
28.17
mW
mW/°C
Thermal Resistance, Junction−to−Ambient (Note 5) RθJA 35.5 °C/W
Thermal Reference, Junction−to−Tab (Note 5) RψJL 8.0 °C/W
Total Device Dissipation (Note 6) TA = 25°C
Derate above 25°C
PD5119
34.13
mW
mW/°C
Thermal Resistance, Junction−to−Ambient (Note 6) RθJA 29.3 °C/W
Thermal Reference, Junction−to−Tab (Note 6) RψJL 7.2 °C/W
Total Device Dissipation (Note 7) TA = 25°C
Derate above 25°C
PD5859
39.06
mW
mW/°C
Thermal Resistance, Junction−to−Ambient (Note 7) RθJA 25.6 °C/W
Thermal Reference, Junction−to−Tab (Note 7) RψJL 6.9 °C/W
Total Device Dissipation (Note 8) TA = 25°C
Derate above 25°C
PD3061
20.41
mW
mW/°C
Thermal Resistance, Junction−to−Ambient (Note 8) RθJA 49 °C/W
Thermal Reference, Junction−to−Tab (Note 8) RψJL 15.1 °C/W
NOTE: Lead measurements are made by non−contact methods such as IR with treated surface to increase emissivity to 0.9.
Lead temperature measurement by attaching a T/C may yield values as high as 30% higher °C/W values based upon empirical
measurements and method of attachment.
4. 400 mm2, see below PCB description, still air.
5. 900 mm2, see below PCB description, still air.
6. 1600 mm2, see below PCB description, still air.
7. 2500 mm2, see below PCB description, still air.
(For NOTES 4−7: PCB is DENKA K1, 1.5 mm Al, 2kV Thermally conductive dielectric, 2 oz. Cu, or equivalent).
8. 1000 mm2, FR4, 3 oz Cu, still air.
NSI50350AST3G, NSV50350AST3G
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4
TYPICAL PERFORMANCE CURVES
(Minimum DENKA K1 @ 900 mm2, 1.5 mm Al, 2kV Thermally conductive dielectric, 2 oz. Cu, or equivalent)
Figure 2. Steady State Current (Ireg(SS)) vs.
Anode−Cathode Voltage (Vak)
Figure 3. Pulse Current (Ireg(P)) vs.
Anode−Cathode Voltage (Vak)
Figure 4. Steady State Current vs. Pulse
Current Testing
Vak, ANODE−CATHODE VOLTAGE (V)
Ireg(P), PULSE CURRENT (mA)
Figure 5. Current Regulation vs. Time
TIME (s)
300250200100500
390
410
430
Ireg, CURRENT REGULATION (mA)
150 350
340
370
Figure 6. Power Dissipation vs. Ambient
Temperature @ TJ = 1755C
TA, AMBIENT TEMPERATURE (°C)
80 1200−40
2000
3000
5000
PD, POWER DISSIPATION (mW)
40
2500 mm2, Denka K1, 2 oz
4000
1000
6000
8000
7000
380
400
420
360
Vak, ANODE−CATHODE VOLTAGE (V)
450
440
9000
0
1600 mm2, Denka K1, 2 oz
900 mm2, Denka K1, 2 oz
1000 mm2, FR4, 3 oz
96543
50
150
200
250
Ireg(SS), STEADY STATE CURRENT (mA)
710
DC Test Steady State, Still Air
8
100
TA = 25°C
210
300
450
350
0
400
11 12 13 14 15
TA = 85°C
TA = −40°C
TJ, maximum die temperature limit 175°C
≈−0.773 mA/°C typ
≈−0.847 mA/°C typ
10987654
150
250
300
520480460
310
320
330
Ireg(P), PULSE CURRENT (mA)
Ireg(SS), STEADY STATE CURRENT (mA)
200
340
350
3
350
400
360
370
400 440
380
390
450
550
21
TA = 25°C
Non−Repetitive Pulse Test
11 12 13 14 15
420 490470410 450430
Vak @ 7.5 V
TA = 25°C
Vak @ 7.5 V
TA = 25°C
500
500 510
350
400 mm2, Denka K1, 2 oz
NSI50350AST3G, NSV50350AST3G
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5
APPLICATIONS INFORMATION
The CCR is a self biased transistor designed to regulate the
current through itself and any devices in series with it. The
device has a slight negative temperature coefficient, as
shown in Figure 2 – Tri Temp. (i.e. if the temperature
increases the current will decrease). This negative
temperature coefficient will protect the LEDS by reducing
the current as temperature rises.
The CCR turns on immediately and is typically at 20% of
regulation with only 0.5 V across it.
The device is capable of handling voltage for short
durations of up to 50 V so long as the die temperature does
not exceed 175°C. The determination will depend on the
thermal pad it is mounted on, the ambient temperature, the
pulse duration, pulse shape and repetition.
Single LED String
The CCR can be placed in series with LEDs as a High Side
or a Low Side Driver. The number of the LEDs can vary
from one to an unlimited number. The designer needs to
calculate the maximum voltage across the CCR by taking the
maximum input voltage less the voltage across the LED
string (Figures 7 and 8).
Figure 7.
Figure 8.
Higher Current LED Strings
Two or more fixed current CCRs can be connected in
parallel. The current through them is additive (Figure 9).
Figure 9.
NSI50350AST3G, NSV50350AST3G
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6
Other Currents
The adjustable CCR can be placed in parallel with any
other CCR to obtain a desired current. The adjustable CCR
provides the ability to adjust the current as LED efficiency
increases to obtain the same light output (Figure 10).
Figure 10.
Dimming using PWM
The dimming of an LED string can be easily achieved by
placing a BJT in series with the CCR (Figure 11).
Figure 11.
The method of pulsing the current through the LEDs is
known as Pulse Width Modulation (PWM) and has become
the preferred method of changing the light level. LEDs being
a silicon device, turn on and off rapidly in response to the
current through them being turned on and off. The switching
time is in the order of 100 nanoseconds, this equates to a
maximum frequency of 10 MHz, and applications will
typically operate from a 100 Hz to 100 kHz. Below 100 Hz
the human eye will detect a flicker from the light emitted
from the LEDs. Between 500 Hz and 20 kHz the circuit may
generate audible sound. Dimming is achieved by turning the
LEDs on and off for a portion of a single cycle. This on/off
cycle is called the Duty cycle (D) and is expressed by the
amount of time the LEDs are on (Ton) divided by the total
time of an on/off cycle (Ts) (Figure 12).
Figure 12.
The current through the LEDs is constant during the period
they are turned on resulting in the light being consistent with
no shift in chromaticity (color). The brightness is in proportion
to the percentage of time that the LEDs are turned on.
Figure 13 is a typical response of Luminance vs Duty Cycle.
Figure 13. Luminous Emmitance vs. Duty Cycle
DUTY CYCLE (%)
10
0
908070605040
0
1000
3000
ILLUMINANCE (lx)
2000
30
4000
6000
20100
5000
Lux
Linear
Reducing EMI
Designers creating circuits switching medium to high
currents need to be concerned about Electromagnetic
Interference (EMI). The LEDs and the CCR switch
extremely fast, less than 100 nanoseconds. To help eliminate
EMI, a capacitor can be added to the circuit across R2.
(Figure 11) This will cause the slope on the rising and falling
edge on the current through the circuit to be extended. The
slope of the CCR on/off current can be controlled by the
values of R1 and C1.
The selected delay / slope will impact the frequency that
is selected to operate the dimming circuit. The longer the
delay, the lower the frequency will be. The delay time should
not be less than a 10:1 ratio of the minimum on time. The
frequency is also impacted by the resolution and dimming
steps that are required. With a delay of 1.5 microseconds on
the rise and the fall edges, the minimum on time would be
30 microseconds. If the design called for a resolution of 100
dimming steps, then a total duty cycle time (Ts) of
3 milliseconds or a frequency of 333 Hz will be required.
NSI50350AST3G, NSV50350AST3G
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7
Thermal Considerations
As power in the CCR increases, it might become
necessary to provide some thermal relief. The maximum
power dissipation supported by the device is dependent
upon board design and layout. Mounting pad configuration
on the PCB, the board material, and the ambient temperature
affect the rate of junction temperature rise for the part. When
the device has good thermal conductivity through the PCB,
the junction temperature will be relatively low with high
power applications. The maximum dissipation the device
can handle is given by:
PD(MAX) +TJ(MAX) *TA
RqJA
Referring to the thermal table on page 2 the appropriate
RqJA for the circuit board can be selected.
AC Applications
The CCR is a DC device; however, it can be used with full
wave rectified AC as shown in application notes
AND8433/D and AND8492/D and design notes
DN05013/D and DN06065/D. Figure 14 shows the basic
circuit configuration.
Figure 14. Basic AC Application
NSI50350AST3G, NSV50350AST3G
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8
PACKAGE DIMENSIONS
J
SMC 2−LEAD
CASE 403AC
ISSUE B
J
*For additional information on our Pb−Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
RECOMMENDED
E
b
D
c
L
A1
A
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANME Y14.5M, 1994.
2. CONTROLLING DIMENSION: INCHES.
3. DIMENSIONS D AND E DO NOT INCLUDE MOLD FLASH. MOLD
FLASH SHALL NOT EXCEED 0.254mm PER SIDE.
4. DIMENSIONS D AND E TO BE DETERMINED AT DATUM H.
5. DIMENSION b SHALL BE MEASURED WITHIN THE AREA
DETERMINED BY DIMENSION L.
TOP VIEW
SIDE VIEW END VIEW
H
DETAIL A
DETAIL A
SOLDERING FOOTPRINT*
8.750
0.344
3.790
0.149
2.250
0.089 ǒmm
inchesǓSCALE 4:1
DIM
A2
MIN MAX MIN
MILLIMETERS
1.90 2.41 0.075
INCHES
A1 0.05 0.20 0.002
b2.90 3.20 0.114
c0.15 0.41 0.006
D5.55 6.25 0.219
E6.60 7.15 0.260
L0.75 1.60 0.030
0.095
0.008
0.126
0.016
0.246
0.281
0.063
MAX
7.75 8.15 0.305 0.321
HE
2X
2X
E
A2
A1.95 2.61 0.077 0.103
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