TI TL4242DRJR

TL4242
www.ti.com .............................................................................................................................................................. SLVS641A – APRIL 2008 – REVISED MAY 2009
ADJUSTABLE LED DRIVER
FEATURES
1
•
•
•
•
•
•
•
•
DRJ (QFN) PACKAGE
(TOP VIEW)
Adjustable Constant Current
up to 500 mA (±5%)
Wide Input Voltage Range up to 42 V
Low Drop Voltage
Open-Load Detection
Overtemperature Protection
Short-Circuit Proof
Reverse-Polarity Proof
Wide Temperature Range: –40°C to 150°C
PWM
1
8
GND
2 Exposed 7
Thermal
3
6
Pad
REF
4
ST
5
I
NC
Q
D
NC – No internal connection
DESCRIPTION/ORDERING INFORMATION
The TL4242 is an integrated adjustable constant-current source, driving loads up to 500 mA. The output current
level can be adjusted via an external resistor. The device is designed to supply high-power LEDs (for example,
OSRAM Dragon LA W57B) under the severe conditions of automotive applications, resulting in constant
brightness and extended LED lifetime. It is provided in the DRJ (QFN) package. Protection circuits prevent
damage to the device in case of overload, short circuit, reverse polarity, and overheat. The connected LEDs are
protected against reverse polarity as well as excess voltages up to 45 V.
The integrated PWM input of the TL4242 permits LED brightness regulation by pulse-width modulation (PWM).
Due to the high input impedance of the PWM input, the LED driver can be operated as a protected high-side
switch.
The TL4242 is characterized for operation from –40°C to 150°C.
An external shunt resistor in the ground path of the connected LEDs is used to sense the LED current. A
regulation loop holds the voltage drop at the shunt resistor at a constant level of 177 mV (typical). The
constant-current level can be adjusted by selecting the shunt resistance, RREF. Calculate the typical output
current using the equation:
IQ,typ = VREF/RREF
where VREF is the reference voltage (typically 177 mV) (see Reference Electrical Characteristics). The equation
applies for RREF = 0.39 Ω to 10 Ω.
The output current is shown as a function of the reference resistance in Figure 1. With the PWM input, the LED
brightness can be regulated via duty cycle. Also, PWM = L sets the TL4242 in sleep mode, resulting in a very
low current consumption of <1 µA (typical). Due to the high impedance of the PWM input (see Figure 4), the
PWM pin also can be used as an enable input.
ORDERING INFORMATION (1)
PACKAGE (2)
TJ
–40°C to 150°C
(1)
(2)
QFN – DRJ
Reel of 1000
ORDERABLE PART NUMBER
TL4242DRJR
TOP-SIDE MARKING
T4242
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
web site at www.ti.com.
Package drawings, thermal data, and symbolization are available at www.ti.com/packaging.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2008–2009, Texas Instruments Incorporated
TL4242
SLVS641A – APRIL 2008 – REVISED MAY 2009 .............................................................................................................................................................. www.ti.com
TERMINAL FUNCTIONS
NO.
NAME
DESCRIPTION
1
PWM
2
ST
3
GND
Ground
4
REF
Reference input. Connect to a shunt resistor.
Pulse-width modulation input. If not used, connect to I.
Status output. Open-collector output. Connect to an external pullup resistor (RPULLUP ≥ 4.7 kΩ).
5
D
Status delay. To set status reaction delay, connect to GND with a capacitor. If no delay is needed, leave open.
6
Q
Output
7
NC
8
I
Thermal
Pad
No internal connection
Input. Connect directly to GND as close as possible to the device with a 100-nF ceramic capacitor.
The thermal pad must be soldered directly to the PCB. It may be connected to ground or left floating.
FUNCTIONAL BLOCK DIAGRAM
I
PWM
8
1
6
Q
Bias Supply
+
−
Bandgap
Reference
4
REF
Comparator
2
ST
Status
Delay
3
GND
2
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5
D
Copyright © 2008–2009, Texas Instruments Incorporated
TL4242
www.ti.com .............................................................................................................................................................. SLVS641A – APRIL 2008 – REVISED MAY 2009
ABSOLUTE MAXIMUM RATINGS (1)
over operating free-air temperature range (unless otherwise noted)
MIN
MAX
–42
45
V
D
–0.3
7
V
PWM
–40
40
V
REF
–1
16
V
Q
–1
41
V
–0.3
Supply voltage range (2)
VCC
VI
Input voltage range
VO
Output voltage range
IO
ST
Output current range
40
V
PWM
±1
mA
REF
±2
mA
±5
mA
ST
θJA
Thermal impedance, junction to ambient (3)
θJP
Thermal impedance, junction to pad (3)
TJ
Virtual-junction temperature range
Tstg
Storage temperature range
(1)
(2)
(3)
(4)
(5)
UNIT
JESD 51-5 (4)
49.5
JESD 51-7 (5)
114.4
°C/W
4.4
°C/W
–40
150
°C
–50
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating
Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltage values are with respect to the network ground terminal.
Maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable ambient
temperature is PD = (TJ(max) – TA)/θJA. Operating at the absolute maximum TJ of 150°C can affect reliability.
The package thermal impedance is calculated in accordance with JESD 51-5.
The package thermal impedance is calculated in accordance with JESD 51-7.
RECOMMENDED OPERATING CONDITIONS
MIN
MAX
4.5
42
V
16
V
0
40
V
Status delay (D) capacitance
0
2.2
µF
Reference (REF) resistor
0
10
Ω
–40
150
°C
VCC
Supply voltage
VST
Status (ST) output voltage
VPWM
PWM voltage
CD
RREF
TJ
Virtual-junction temperature
UNIT
OVERALL DEVICE ELECTRICAL CHARACTERISTICS
over recommended operating free-air temperature range, VI = 13.5 V, RREF = 0.47 Ω, VPWM,H, TJ = –40°C to 150°C, all
voltages with respect to ground (unless otherwise noted)
TYP
MAX
IqL
Supply current
PARAMETER
VQ = 6.6 V
12
22
mA
IqOFF
Supply current, off mode
PWM = L, TJ < 85°C
0.1
2
µA
Copyright © 2008–2009, Texas Instruments Incorporated
TEST CONDITIONS
MIN
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UNIT
3
TL4242
SLVS641A – APRIL 2008 – REVISED MAY 2009 .............................................................................................................................................................. www.ti.com
OUTPUT ELECTRICAL CHARACTERISTICS
over recommended operating free-air temperature range, VI = 13.5 V, RREF = 0.47 Ω, VPWM,H, TJ = –40°C to 150°C, all
voltages with respect to ground (unless otherwise noted)
PARAMETER
MIN
TYP
MAX
VQ – VREF (1) = 6.6 V
TEST CONDITIONS
357
376
395
VQ – VREF = 6.6 V, RREF = 1 Ω
168
177
185
VQ – VREF = 6.6 V, RREF = 0.39 Ω
431
454
476
VQ – VREF = 5.4 V to 7.8 V, VI = 9 V to 16 V
357
376
395
IQ
Output current
IQmax
Output current limit
RREF = 0 Ω
600
Vdr
Drop voltage
IQ = 300 mA
0.35
(1)
UNIT
mA
mA
0.7
V
VQ – VREF equals the forward voltage sum of the connected LEDs (see Figure 3).
PWM INPUT ELECTRICAL CHARACTERISTICS
over recommended operating free-air temperature range, VI = 13.5 V, RREF = 0.47 Ω, VPWM,H, TJ = –40°C to 150°C, all
voltages with respect to ground (unless otherwise noted)
PARAMETER
VPWM,
TEST CONDITIONS
High-level PWM voltage
MIN
TYP
MAX
2.6
UNIT
V
H
VPWM,
Low-level PWM voltage
0.7
V
500
µA
1
µA
L
IPWM,H High-level PWM input current
VPWM = 5 V
IPWM,L
Low-level PWM input current
VPWM = 0 V
tPWM,O
Delay time, turn on
70% of IQnom, See Figure 6
0
15
40
µs
Delay time, turn off
30% of IQnom, See Figure 6
0
15
40
µs
N
tPWM,O
FF
220
–1
REFERENCE (REF) ELECTRICAL CHARACTERISTICS
over recommended operating free-air temperature range, VI = 13.5 V, RREF = 0.47 Ω, VPWM,H, TJ = –40°C to 150°C, all
voltages with respect to ground (unless otherwise noted)
PARAMETER
TEST CONDITIONS
VREF
Reference voltage
RREF = 0.39 Ω to 1 Ω
IREF
Reference input current
VREF = 180 mV
MIN
TYP
MAX
UNIT
168
177
185
mV
–1
0.1
1
µA
STATUS OUTPUT (ST) ELECTRICAL CHARACTERISTICS
over recommended operating free-air temperature range, VI = 13.5 V, RREF = 0.47 Ω, VPWM,H, TJ = –40°C to 150°C, all
voltages with respect to ground (unless otherwise noted)
PARAMETER
TEST CONDITIONS
VIQL
Lower status-switching threshold
ST = L
VIQH
Upper status-switching threshold
ST = H
VSTL
Low-level status voltage
IST = 1.5 mA
ISTLK
Leakage current
VST = 5 V
MIN
TYP
15
25
30
MAX
UNIT
mV
40
mV
0.4
V
5
µA
STATUS DELAY (D) ELECTRICAL CHARACTERISTICS
over recommended operating free-air temperature range, VI = 13.5 V, RREF = 0.47 Ω, VPWM,H, TJ = –40°C to 150°C, all
voltages with respect to ground (unless otherwise noted)
PARAMETER
TEST CONDITIONS
tSTHL
Delay time, status reaction
CD = 47 nF, ST H→L
tSTLH
Delay time, status release
CD = 47 nF, ST L→H
4
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MIN
TYP
MAX
6
10
14
UNIT
ms
10
20
µs
Copyright © 2008–2009, Texas Instruments Incorporated
TL4242
www.ti.com .............................................................................................................................................................. SLVS641A – APRIL 2008 – REVISED MAY 2009
TYPICAL CHARACTERISTICS
450
700
400
600
IOUT – Output Current – mA
IOUT – Output Current – mA
350
500
400
300
200
250
200
150
100
50
100
0
-50
0
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
0
2.25
10
15
20
25
30
35
VCC – Supply Voltage – V
Figure 1. Output Current vs External Resistor
Figure 2. Output Current vs Supply Voltage
40
60
50
IPWM – PWM Current – µA
178.0
177.5
177.0
176.5
176.0
175.5
-40
5
RREF – 8W
178.5
VREF – Reference Voltage – mV
300
40
30
20
10
0
-10
-20
0
20
40
60
80
100 120 140
TJ – Virtual Junction Temperature – °C
Figure 3. Reference Voltage vs Junction Temperature
Copyright © 2008–2009, Texas Instruments Incorporated
0
10
20
30
40
VPWM – PWM Voltage – V
Figure 4. PWM Pin Input Current vs PWM Voltage
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5
TL4242
SLVS641A – APRIL 2008 – REVISED MAY 2009 .............................................................................................................................................................. www.ti.com
APPLICATION INFORMATION
Figure 5 shows a typical application with the TL4242 LED driver. The three LEDs are driven by a supply current
that is adjusted by the resistor, RREF, preventing brightness variations due to forward voltage spread of the LEDs.
The luminosity spread arising from the LED production process can be compensated via software by an
appropriate duty cycle applied to the PWM pin. Therefore, it is not necessary to select LEDs for forward voltage
or luminosity classes. The minimum supply voltage calculates as the sum of the LED forward voltages, the
TL4242 drop voltage (maximum 0.7 V at a LED current of 300 mA) and the maximum voltage drop at the shunt
resistor RREF of 185 mV (max).
VBAT
I
RO
SI
Microcontroller
Q
RADJ
GND
10 µF
D
10 kΩ
100 nF
PWM
ST
I
Q
TL4242
REF
GND
LED
Dragon
D
47 nF
0.47 Ω
0.25 W
RREF
Figure 5. Application Circuit
The status output of the LED driver (ST) detects an open-load condition, enabling supervision of correct LED
operation. An LED failure is detected as a voltage drop at the shunt resistor (RREF) below 25 mV (typ). In this
case, the status output pin (ST) is set low after a delay time adjustable by an optional capacitor connected to
pin D.
The functionality and timing of ST and PWM are shown in Figure 6. The status delay can be adjusted via the
capacitor connected to pin D. Delay time scales linearly with capacitance, CD:
6
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Copyright © 2008–2009, Texas Instruments Incorporated
TL4242
www.ti.com .............................................................................................................................................................. SLVS641A – APRIL 2008 – REVISED MAY 2009
t STHL,typ +
CD
47 nF
10 ms
t STLH,typ +
CD
47 nF
10 ms
Open
Load
VPWM
Open
Load
VPWM,H
VPWM,L
IQ
t
tPWM,ON
tPWM,OFF
IQ,nom
70%
30%
t
VD
tSTHL
VLD
t
VST
t
Figure 6. Function and Timing Diagram
Copyright © 2008–2009, Texas Instruments Incorporated
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7
PACKAGE OPTION ADDENDUM
www.ti.com
23-Jan-2009
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
TL4242DRJR
ACTIVE
SON
DRJ
Pins Package Eco Plan (2)
Qty
8
1000 Green (RoHS &
no Sb/Br)
Lead/Ball Finish
CU NIPDAU
MSL Peak Temp (3)
Level-3-260C-168 HR
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
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incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
2-Sep-2009
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
TL4242DRJR
Package Package Pins
Type Drawing
SON
DRJ
8
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
1000
180.0
12.4
Pack Materials-Page 1
4.25
B0
(mm)
K0
(mm)
P1
(mm)
4.25
1.15
8.0
W
Pin1
(mm) Quadrant
12.0
Q2
PACKAGE MATERIALS INFORMATION
www.ti.com
2-Sep-2009
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
TL4242DRJR
SON
DRJ
8
1000
190.5
212.7
31.8
Pack Materials-Page 2
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