TL4242DRJR [TI]
ADJUSTABLE LED DRIVER; 可调LED驱动器
| 型号： | TL4242DRJR |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | ADJUSTABLE LED DRIVER |
| 文件： | 总14页 (文件大小：550K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TL4242
www.ti.com .................................................................................................................................................................................................... SLVS641 –APRIL 2008
ADJUSTABLE LED DRIVER
1
FEATURES
DRJ (QFN) PACKAGE
•
Adjustable Constant Current
up to 500 mA (±5%)
(TOP VIEW)
1
8
7
6
5
PWM
ST
I
•
•
•
•
•
•
•
Wide Input Voltage Range up to 42 V
Low Drop Voltage
2
3
4
NC
Q
D
GND
REF
Open-Load Detection
Overtemperature Protection
Short-Circuit Proof
NC – No internal connection
Reverse-Polarity Proof
Wide Temperature Range: –40°C to 150°C
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 (typ). 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 (typ). 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)
TJ
PACKAGE(2)
ORDERABLE PART NUMBER
TOP-SIDE MARKING
–40°C to 150°C
QFN – DRJ
Reel of 1000
TL4242DRJR
T4242
(1) 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.
(2) 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.
Copyright © 2008, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
TL4242
SLVS641 –APRIL 2008 .................................................................................................................................................................................................... www.ti.com
TERMINAL FUNCTIONS
NO.
1
NAME
PWM
ST
DESCRIPTION
Pulse-width modulation input. If not used, connect to I.
2
Status output. Open-collector output. Connect to an external pullup resistor (RPULLUP ≥ 4.7 kΩ).
3
GND
REF
D
Ground
4
Reference input. Connect to a shunt resistor.
5
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
I
No internal connection
8
Input. Connect directly to GND as close as possible to the device with a 100-nF ceramic capacitor.
FUNCTIONAL BLOCK DIAGRAM
8
1
6
I
Q
Bias Supply
PWM
+
−
Bandgap
Reference
4
2
REF
ST
Comparator
Status
Delay
3
5
GND
D
2
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Copyright © 2008, Texas Instruments Incorporated
TL4242
www.ti.com .................................................................................................................................................................................................... SLVS641 –APRIL 2008
ABSOLUTE MAXIMUM RATINGS(1)
over operating free-air temperature range (unless otherwise noted)
MIN
–42
–0.3
–40
–1
MAX UNIT
VCC
Supply voltage range(2)
Input voltage range
45
7
V
V
D
VI
PWM
40
V
REF
16
V
Q
–1
41
V
VO
Output voltage range
ST
–0.3
40
V
PWM
±1
mA
mA
mA
IO
Output current range
REF
±2
ST
±5
JESD 51-5(4)
JESD 51-7(5)
49.5
114.4
θJA
Thermal impedance, junction to ambient(3)
°C/W
θJP
TJ
Thermal impedance, junction to pad(3)
Virtual-junction temperature range
Storage temperature range
4.4 °C/W
–40
–50
150
150
°C
°C
Tstg
(1) 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.
(2) All voltage values are with respect to the network ground terminal.
(3) 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.
(4) The package thermal impedance is calculated in accordance with JESD 51-5.
(5) The package thermal impedance is calculated in accordance with JESD 51-7.
RECOMMENDED OPERATING CONDITIONS
MIN
MAX UNIT
VCC
VST
Supply voltage
4.5
42
16
V
V
Status (ST) output voltage
VPWM PWM voltage
0
0
40
V
CD
Status delay (D) capacitance
2.2
10
µF
Ω
RREF
TJ
Reference (REF) resistor
0
Virtual-junction temperature
–40
150
°C
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)
PARAMETER
TEST CONDITIONS
VQ = 6.6 V
PWM = L, TJ < 85°C
MIN
TYP
12
MAX UNIT
IqL
Supply current
Supply current, off mode
22
2
mA
IqOFF
0.1
µA
Copyright © 2008, Texas Instruments Incorporated
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3
TL4242
SLVS641 –APRIL 2008 .................................................................................................................................................................................................... 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
TEST CONDITIONS
VQ – VREF(1) = 6.6 V
MIN
357
168
431
357
TYP
376
177
454
376
600
0.35
MAX UNIT
395
VQ – VREF = 6.6 V, RREF = 1 Ω
VQ – VREF = 6.6 V, RREF = 0.39 Ω
VQ – VREF = 5.4 V to 7.8 V, VI = 9 V to 16 V
RREF = 0 Ω
185
mA
476
IQ
Output current
395
mA
IQmax
Vdr
Output current limit
Drop voltage
IQ = 300 mA
0.7
V
(1) 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
High-level PWM voltage
Low-level PWM voltage
TEST CONDITIONS
MIN
TYP
MAX UNIT
VPWM,
H
2.6
V
VPWM,
L
0.7
V
IPWM,H High-level PWM input current
IPWM,L Low-level PWM input current
VPWM = 5 V
220
500
1
µA
µA
VPWM = 0 V
–1
0
tPWM,O
N
Delay time, turn on
70% of IQnom, See Figure 6
15
15
40
40
µs
µs
tPWM,O
FF
Delay time, turn off
30% of IQnom, See Figure 6
0
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
Reference voltage
Reference input current
TEST CONDITIONS
RREF = 0.39 Ω to 1 Ω
VREF = 180 mV
MIN
168
–1
TYP
177
0.1
MAX UNIT
VREF
IREF
185
1
mV
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
Lower status-switching threshold
Upper status-switching threshold
Low-level status voltage
TEST CONDITIONS
MIN
TYP
25
MAX UNIT
VIQL
VIQH
VSTL
ISTLK
ST = L
ST = H
15
mV
30
40
0.4
5
mV
V
IST = 1.5 mA
VST = 5 V
Leakage current
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
Delay time, status reaction
Delay time, status release
TEST CONDITIONS
CD = 47 nF, ST H→L
CD = 47 nF, ST L→H
MIN
TYP
10
MAX UNIT
tSTHL
tSTLH
6
14
20
ms
10
µs
4
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Copyright © 2008, Texas Instruments Incorporated
TL4242
www.ti.com .................................................................................................................................................................................................... SLVS641 –APRIL 2008
TYPICAL CHARACTERISTICS
450
400
350
300
250
200
150
100
50
700
600
500
400
300
200
100
0
0
-50
0
5
10
15
20
25
30
35
40
0
0.25 0.5 0.75
1
1.25 1.5 1.75
RREF – W
Figure 1. Output Current vs External Resistor
2
2.25
VCC – Supply Voltage – V
Figure 2. Output Current vs Supply Voltage
178.5
178.0
177.5
177.0
176.5
176.0
175.5
60
50
40
30
20
10
0
-10
0
10
20
30
40
-40 -20
TJ – Virtual Junction Temperature – °C
Figure 3. Reference Voltage vs Junction Temperature
0
20 40
60 80 100 120 140
VPWM – PWM Voltage – V
Figure 4. PWM Pin Input Current vs PWM Voltage
Copyright © 2008, Texas Instruments Incorporated
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5
TL4242
SLVS641 –APRIL 2008 .................................................................................................................................................................................................... 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).
I
RO
SI
V
BAT
Microcontroller
Q
10 µF
10 kΩ
RADJ GND
D
100 nF
PWM
ST
I
Q
TL4242
REF
LED
Dragon
GND
D
47 nF
0.47 Ω
0.25 W
R
REF
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:
CD
47 nF
tSTHL,typ
+
10 ms
10 ms
CD
47 nF
tSTLH,typ
+
6
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TL4242
www.ti.com .................................................................................................................................................................................................... SLVS641 –APRIL 2008
Open
Load
Open
Load
VPWM
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, Texas Instruments Incorporated
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7
PACKAGE OPTION ADDENDUM
www.ti.com
7-Apr-2008
PACKAGING INFORMATION
Orderable Device
Status (1)
Package Package
Pins Package Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
Qty
Type
Drawing
TL4242DRJR
ACTIVE
SON
DRJ
8
1000 Green (RoHS & CU NIPDAU Level-3-260C-168 HR
no Sb/Br)
(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
7-Apr-2008
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0 (mm)
B0 (mm)
K0 (mm)
P1
W
Pin1
Diameter Width
(mm) W1 (mm)
(mm) (mm) Quadrant
TL4242DRJR
SON
DRJ
8
1000
180.0
12.4
4.3
4.3
1.5
8.0
12.0
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
7-Apr-2008
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SON DRJ
SPQ
Length (mm) Width (mm) Height (mm)
190.5 212.7 31.8
TL4242DRJR
8
1000
Pack Materials-Page 2
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