STMICROELECTRONICS STLA01

STLA01
50 mA stand-alone linear
LED driver
Features
■
Programmable LED current up to 50 mA with ±
5% accuracy
■
No external sense resistor
■
Constant current source
■
Supply voltage range from 3.75 V to 6 V
■
Single LED
■
10 µA max supply current in shutdown mode
■
DFN6 (2 x 2 mm) package
DFN6 (2 x 2 mm)
Description
The STLA01 is a constant current LED driver.
No external sense resistor is required and the
DFN6 2 x 2 mm package makes it ideal for
portable applications.
The LED current limitation can be programmed
using a single resistor connected between the
PROG pin and GND. Using the enable pin the
device can be put into shutdown mode, reducing
the supply current to less than 10 µA.
Table 1.
Device summary
Part number
Order code
Package
STLA01
STLA01PUR
DFN6 (2x2 mm)
November 2007
Rev 1
1/16
www.st.com
18
Contents
STLA01
Contents
1
Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4
Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1
VCC pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.2
EN pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.3
Programming charge current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.4
Power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2/16
STLA01
Diagram
1
Diagram
Figure 1.
Block diagram
3/16
Pin configuration
STLA01
2
Pin configuration
Figure 2.
Pin connections (top view)
Table 2.
Pin description
Pin n°
Symbol
Name and function
1
GND
2
NC
Not connected
3
LED
This pin provide an accurate output limited current. In shutdown mode no current
can flow to the LED.
4
VCC
Input supply voltage. The input range is from 3.75 V to 6 V.
5
PROG
6
EN
Exposed
Pad
GND
Ground
Current limitation program. (1)
Enable pin. Tie to VCC if unused.
To be connected to PCB ground plane for optimal electrical and thermal
performance.
1. The PROG pin is a high impedance pin, It is possible to connect only the programming resistor.
4/16
STLA01
Maximum ratings
3
Maximum ratings
Table 3.
Absolute maximum ratings
Symbol
Parameter
Value
Unit
VCC
Input supply voltage
From -0.3 to 7
V
VLED
LED pin voltage
From -0.3 to 7
V
PROG pin voltage
From -0.3 to 3
V
VEN
EN pin voltage
From -0.3 to 7
V
ILED
LED pin current
80
mA
PROG pin current
800
µA
VPROG
IPROG
LED short-circuit duration
PD
Power dissipation
TJ
Max junction temperature
Continuous
Internally limited
125
°C
TSTG
Storage temperature range
-65 to 125
°C
TOP
Operating junction temperature range
-40 to 85
°C
260 (JEDEC 020C)
°C
TL
Lead temperature (10 sec)
Note:
Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Table 4.
Thermal data
Symbol
RthJA
Parameter
Value
Unit
Thermal resistance junction-ambient
(1)
°C/W
100
1. This value depends on whether the exposed backside of the package is soldered to the PC board. If it is not, the value
could be considerably higher.
Table 5.
Symbol
ESD
ESD performance
Parameter
Test conditions
Value
Unit
HBM (EIA/JESD22/A114)
3
kV
MM (EIA/JESD22/A115)
200
V
ESD protection voltage
5/16
Application
STLA01
4
Application
Figure 3.
Typical application
VCC
4
VCC
CIN
6/16
3
ILED
STLA01
6
OFF ON
LED
PROG
EN
GND
1
5
RPROG
STLA01
Electrical characteristics
5
Electrical characteristics
Table 6.
Electrical characteristics (VCC = VEN = 5 V, CIN = 1 µF, TJ = -40° to 85°C unless otherwise
specified)
Symbol
VCC
Parameter
Test conditions
Supply voltage
Min.
Typ.
3.75
RPROG = 2.4 kΩ
ICC
ILED-MIN
ILED
Supply current
Minimum LED pin current
LED pin current
PROG pin voltage
µA
5
Current mode RPROG=65 kΩ,
VLED=3 V
2
10
mA
Current mode RPROG=2.4 kΩ,
VLED=3 V
47.5
50
52.5
Current mode RPROG=6.2 kΩ,
VLED=3 V (1)
19
20
21
Current mode RPROG=12.4 kΩ,
VLED=3 V (1)
9.5
10
10.5
0
±1
RPROG = 2.4 kΩ
1.22
RPROG = 6.2 kΩ (1)
1.22
kΩ (1)
EN threshold high
EN hysteresis
V
200
Shutdown mode VEN = GND
RPROG = 12.4
VEN
6
300
(1)
Shutdown mode VEN=GND,
TJ = 25 °C
VPROG
Unit
750
RPROG = 6.2 kΩ (1)
RPROG =12.4 kΩ
Max.
µA
V
1.22
0.3
VCC = 3.75 V to 6 V
mA
0.92
1.2
V
120
mV
REN
EN pin input resistance
VEN = 5 V
2
MΩ
RON
Power FET ON resistance
(between VCC and LED)
ILED = 50 mA
8
Ω
1. Guaranteed by design, but not tested in production.
7/16
Application information
6
STLA01
Application information
The STLA01 is a single LED driver using a constant-current topology. It can deliver up to 80
mA of output current.
If a 1% program resistor is connect from the PROG pin to the GND pin and the EN pin is
higher than 0.92 V, the device will supply the LED with the programmed constant current.
Putting the EN pin below 0.80 V results in no current flow into the LED diode.
6.1
VCC pin
A positive input supply voltage provides power to the driver. VCC can range from 3.75 V to 6
V and should be bypassed with at least a 1 µF capacitor. In shutdown mode, the ILED = 0.
6.2
EN pin
The enable input pin is used to shut down the device when the value of the pin is below
0.80 V. In shutdown condition, the device has less than 10 µA supply current. The enable pin
has an internal pull down (REN).
If unused, the pin should be tied to VCC.
6.3
Programming charge current
The LED current is programmed using a single resistor from the PROG pin to ground. The
LED current is 100 times the current out of the PROG pin. The program resistor and the led
current are calculated using, in first approximation, the following equations:
RPROG = 100 x (1.22 V / ILED)
6.4
Power dissipation
A good thermal PCB layout is very important to maximize the available output current. The
thermal path for the heat generated by the IC is from the die to the copper lead frame
through the package leads and exposed pad to the PC board copper. The PC board copper
acts as the heat sink. The copper pad footprints should be as wide as possible and expand
to larger copper areas in order to spread and dissipate the heat to the surrounding ambient.
Feed-through vias to inner or backside copper layers are also useful in improving the overall
thermal performance of the device. Other heat sources on the board, not related to the
device, must also be considered when designing a PC board layout because they will affect
overall temperature rise and the maximum output current.
8/16
STLA01
Typical performance characteristics
Typical performance characteristics
Figure 4.
LED pin current vs temperature
55
54
53
52
51
50
49
48
47
46
45
Figure 5.
VEN=VCC=5 V, CIN=1 µF , VLED=3 V, RPROG=2.4 kohm
ILED [mA]
ILED [mA]
7
-50
-25
0
25
50
75
LED pin current vs temperature
25
24
23
22
21
20
19
18
17
16
15
VEN=VCC=5 V, CIN=1 µF, VLED=3 V, RPROG=6.2 kohm
-50
100
-25
0
25
T [°C]
LED pin current vs temperature
15
14
13
12
11
10
9
8
7
6
5
Figure 7.
100
LED pin current vs RPROG
VEN=VCC=5 V, CIN=1 µF, VLED=3 V, T= -40 °C to 85 °C
50
40
30
20
10
0
-50
-25
0
25
50
75
0
100
10
20
30
Figure 8.
Supply current vs temperature
Figure 9.
800
50
60
70
Supply current vs RPROG
600
VEN=VCC=5 V, CIN=1 µF, VLED=3 V
700
40
RPROG [kohm]
T [°C]
VEN=VCC=5 V, CIN=1 µF, VLED=3 V, T= -40 °C to 85 °C
500
500
RPROG=2.4 kohm
400
RPROG=6.2 kohm
300
RPROG=12.4 kohm
200
ICC [µA]
600
ICC [ µA]
75
60
VEN=VCC=5 V, CIN=1 µF, VLED=3 V, RPROG=12.4 kohm
ILED [mA]
ILED [mA]
Figure 6.
50
T [°C]
400
300
200
100
100
0
0
-50
-25
0
25
T [°C]
50
75
100
0
10
20
30
40
50
60
RPROG [kohm]
9/16
Typical performance characteristics
STLA01
Figure 10. PROG pin voltage vs temperature
Figure 11. PROG pin voltage vs RPROG
1.4
1.26
1.3
VPROG [V]
1.24
VPROG [V]
VEN=VCC=5 V; CIN=1 µF ; VLED=3 V, T = -40 °C to 85 °C
1.35
VEN=VCC=5 V, CIN=1 µF, VLED=3 V
1.25
1.23
1.22
1.21
RPROG=2.4 kohm
1.2
1.2
1.15
1.1
RPROG=6.2 kohm
1.19
1.25
1.05
RPROG=12.4 kohm
1.18
-50
-25
0
25
50
75
1
100
0
10
20
30
40
50
60
70
T [°C]
RPROG [kohm]
Figure 12. Enable pin voltage vs temperature
Figure 13. Enable pin input resistance vs
temperature
6
1.4
VEN=5 V, VCC=5 V, CIN=1 µF, VLED=3 V
VCC=5 V; CIN=1 µF; VLED=3 V
5
REN [Mohm]
1.2
VEN [V]
1
0.8
0.6
4
3
2
0.4
ON
0.2
1
OFF
0
-50
-25
0
25
50
75
100
125
150
0
-50
T [°C]
-25
0
25
T [°C]
Figure 14. RON vs temperature
14
VEN=VCC=5 V, CIN=1 µF, ILED=50 mA
RON [Ohm]
12
10
8
6
4
2
0
-50
-25
0
25
T [°C]
10/16
50
75
100
50
75
100
STLA01
8
Package mechanical data
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a lead-free second level interconnect. The category of
second level lnterconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com.
11/16
Package mechanical data
STLA01
DFN6 (2x2 mm) mechanical data
mm.
inch.
Dim.
Min.
Typ.
Max.
Min.
Typ.
Max.
A
0.70
0.75
0.80
27.6
29.5
31.5
A1
0
0.02
0.05
0.0
0.8
2.0
A3
0.20
7.9
b
0.20
0.25
0.32
7.9
9.8
12.6
D
1.90
2.00
2.10
74.8
78.7
82.7
D2
1.22
1.37
1.47
48.0
53.9
57.9
E
1.90
2.00
2.10
74.8
78.7
82.7
E2
0.41
0.56
0.66
16.1
22.0
26.0
e
L
0.50
0.30
0.40
19.7
0.50
11.8
15.7
19.7
7733060B
12/16
STLA01
Package mechanical data
Tape & reel QFNxx/DFNxx (2x2 mm) mechanical data
mm.
inch.
Dim.
Min.
Typ.
A
Max.
Min.
Typ.
180
13.2
7.087
C
12.8
D
20.2
0.795
N
60
2.362
T
Max.
0.504
0.519
14.4
0.567
Ao
2.3
0.091
Bo
2.3
0.091
Ko
1.0
0.039
Po
4
0.157
P
8
0.315
13/16
Package mechanical data
Figure 15. DFN6 (2x2 mm) footprint recommended data
14/16
STLA01
STLA01
Revision history
9
Revision history
Table 7.
Document revision history
Date
Revision
27-Nov-2007
1
Changes
Initial release.
15/16
STLA01
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16/16