ST STLA01 User Manual

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

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.

STLA01

50 mA stand-alone linear

LED driver

DFN6 (2 x 2 mm)

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 Ground

2 NC Not connected

3LED

4VCCInput supply voltage. The input range is from 3.75 V to 6 V.

5 PROG Current limitation program.

6 EN Enable pin. Tie to VCC if unused.

Exposed

Pad

1. The PROG pin is a high impedance pin, It is possible to connect only the programming resistor.

GND

This pin provide an accurate output limited current. In shutdown mode no current can flow to the LED.

(1)

To be connected to PCB ground plane for optimal electrical and thermal performance.

4/16

STLA01 Maximum ratings

3 Maximum ratings

Table 3. Absolute maximum ratings

Symbol Parameter Value Unit

V

PROG

V

I

LED

I

PROG

CC

LED

EN

Input supply voltage From -0.3 to 7 V

LED pin voltage From -0.3 to 7 V

PROG pin voltage From -0.3 to 3 V

EN pin voltage From -0.3 to 7 V

LED pin current 80 mA

PROG pin current 800 µA

LED short-circuit duration Continuous

Power dissipation Internally limited

Max junction temperature 125 °C

Storage temperature range -65 to 125 °C

Operating junction temperature range -40 to 85 °C

Lead temperature (10 sec) 260 (JEDEC 020C) °C

T

P

T

D

T

J

STG

OP

T

L

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 Parameter Value Unit

R

thJA

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.

Thermal resistance junction-ambient 100

(1)

°C/W

Table 5. ESD performance

Symbol Parameter Test conditions Value Unit

HBM (EIA/JESD22/A114) 3 kV

ESD ESD protection voltage

MM (EIA/JESD22/A115) 200 V

5/16

Application STLA01

4 Application

Figure 3. Typical application

I

V

CC

OFF

C

ON

4

V

CC

IN

6

EN

STLA01

GND

1

PROG

LED

3

I

LED

5

R

PROG

6/16

STLA01 Electrical characteristics

5 Electrical characteristics

Table 6. Electrical characteristics (V

CC

= V

= 5 V, C

EN

= 1 µF, TJ = -40° to 85°C unless otherwise

IN

specified)

Symbol Parameter Test conditions Min. Typ. Max. Unit

V

CC

I

CC

I

LED-MIN

I

LED

V

PROG

V

EN

R

EN

R

ON

Supply voltage 3.75 6 V

= 2.4 kΩ 750

R

PROG

(1)

= GND 5 10

EN

=65 kΩ,

PROG

=2.4 kΩ,

PROG

(1)

=6.2 kΩ,

=12.4 kΩ,

47.5 50 52.5

19 20 21

9.5 10 10.5

0.3 0.92 1.2 V

300

200

2mA

0 ±1 µA

1.22

R

= 6.2 kΩ

Supply current

PROG

R

PROG

=12.4 kΩ

Shutdown mode V

Minimum LED pin current

Current mode R

=3 V

V

LED

Current mode R V

=3 V

LED

Current mode R V

=3 V

LED pin current

LED

Current mode R

=3 V

V

LED

Shutdown mode VEN=GND, TJ = 25 °C

R

= 2.4 kΩ 1.22

PROG

PROG pin voltage

PROG

R

PROG

= 6.2 kΩ

= 12.4 kΩ

EN threshold high

V

= 3.75 V to 6 V

EN hysteresis 120 mV

EN pin input resistance V

Power FET ON resistance (between VCC and LED)

CC

= 5 V 2 MΩ

EN

= 50 mA 8 Ω

I

LED

µA

mA

VR

1. Guaranteed by design, but not tested in production.

7/16

Application information STLA01

6 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 I

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 (R

If unused, the pin should be tied to V

EN

).

.

CC

LED

= 0.

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:

R

= 100 x (1.22 V / I

PROG

LED

)

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

OG

7 Typical performance characteristics

Figure 4. LED pin current vs temperature Figure 5. LED pin current vs temperature

25

55

55 54

54 53

53 52

52 51

51

[mA]

50

LED

49

I

48

48 47

47 46

46 45

45

-50 -25 0 25 50 75 100

VEN=VCC=5 V, CIN=1 µF , V

T [°C]

LED

=3 V, R

PROG

=2.4 kohm

25 24

24 23

23 22

22 21

21

[mA]

20

LED

19

I

18

18 17

17 16

16 15

15

-50 -25 0 25 50 75 100

VEN=VCC=5 V, CIN=1 µF, V

T [°C]

LED

=3 V, R

PROG

=6.2 kohm

Figure 6. LED pin current vs temperature Figure 7. LED pin current vs R

15

15 14

14 13

13 12

12 11

11

[mA]

10

LED

9

I

8

8 7

7 6

6 5

5

-50 -25 0 25 50 75 100

Figure 8. Supply current vs temperature Figure 9. Supply current vs R

800

700

600

500

[ µA]

400

CC

I

300

200

100

0

-50 -25 0 25 50 75 100

VEN=VCC=5 V, CIN=1 µF, V

T [°C]

VEN=VCC=5 V, CIN=1 µF, V

T [°C]

LED

=3 V, R

=12.4 kohm

PROG

LED

R

PROG

R

PROG

R

PROG

=3 V

=2.4 kohm

=6.2 kohm

=12.4 kohm

60

50

40

[mA]

30

LED

I

20

10

0

0 10203040506070

600

500

400

[µA]

300

CC

I

200

100

0

0 102030405060

VEN=VCC=5 V, CIN=1 µF, V

[kohm]

R

PR

VEN=VCC=5 V, CIN=1 µF, V

R

[kohm]

R

[kohm]

PR

=3 V, T= -40 °C to 85 °C

LED

PROG

=3 V, T= -40 °C to 85 °C

LED

PROG

9/16

Typical performance characteristics STLA01

OG

Figure 10. PROG pin voltage vs temperature Figure 11. PROG pin voltage vs R

1.4

1.26

1.25

1.24

1.23

[V]

1.22

PROG

V

1.21

1.2

1.19

1.18

-50 -25 0 25 50 75 100

VEN=VCC=5 V, CIN=1 µF, V

R

PROG

R

PROG

R

PROG

T [°C]

=3 V

LED

=2.4 kohm

=6.2 kohm

=12.4 kohm

1.4

1.35

1.3

1.25

[V]

1.2

PROG

V

1.15

1.1

1.05

1

0 10203040506070

VEN=VCC=5 V; CIN=1 µF ; V

R

PR

[kohm]

PROG

=3 V, T = -40 °C to 85 °C

LED

Figure 12. Enable pin voltage vs temperature Figure 13. Enable pin input resistance vs

1.4

1.2

1

0.8

[V]

EN

0.6

V

0.4

0.2

0

-50 -25 0 25 50 75 100 125 150

VCC=5 V; CIN=1 µF; V

V

CC

T [°C]

=5 V; CIN=1 µF; V

=3 V

LED

ON

OFF

6

5

4

[Mohm]

3

EN

R

2

1

0

-50 -25 0 25 50 75 100

temperature

VEN=5 V, VCC=5 V, CIN=1 µF, V

T [°C]

=3 V

LED

Figure 14. RON vs temperature

14

12

10

8

[Ohm]

ON

6

R

4

2

0

-50 -25 0 25 50 75 100

VEN=VCC=5 V, CIN=1 µF, I

T [°C]

LED

=50 mA

10/16

STLA01 Package mechanical data

8 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 0.327.99.8 12.6

D1.90 2.00 2.10 74.8 78.7 82.7

D2 1.22 1.37 1.47 48.0 53.9 57.9

E1.90 2.00 2.10 74.8 78.7 82.7

E2 0.41 0.56 0.66 16.1 22.0 26.0

e 0.50 19.7

L0.30 0.40 0.50 11.8 15.7 19.7

12/16

7733060B

STLA01 Package mechanical data

Tape & reel QFNxx/DFNxx (2x2 mm) mechanical data

mm. inch.

Dim.

Min. Typ. Max. Min. Typ. Max.

A180 7.087

C 12.8 13.2 0.504 0.519

D 20.2 0.795

N60 2.362

T 14.4 0.567

Ao 2.3 0.09 1

Bo 2.3 0.09 1

Ko 1.0 0.039

Po 4 0.157

P 8 0.3 15

13/16

Package mechanical data STLA01

Figure 15. DFN6 (2x2 mm) footprint recommended data

14/16

STLA01 Revision history

9 Revision history

Table 7. Document revision history

Date Revision Changes

27-Nov-2007 1 Initial release.

15/16

STLA01

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16/16

ST STLA01 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Table 1. Device summary

1 Diagram

2 Pin configuration

Figure 2. Pin connections (top view)

Table 2. Pin description

3 Maximum ratings

Table 3. Absolute maximum ratings

Table 4. Thermal data

Table 5. ESD performance

4 Application

Figure 3. Typical application

5 Electrical characteristics

6 Application information

6.1 VCC pin

6.2 EN pin

6.3 Programming charge current

6.4 Power dissipation

7 Typical performance characteristics

Figure 10. PROG pin voltage vs temperature Figure 11. PROG pin voltage vs R

Figure 12. Enable pin voltage vs temperature Figure 13. Enable pin input resistance vs

Figure 14. RON vs temperature

8 Package mechanical data

Figure 15. DFN6 (2x2 mm) footprint recommended data

9 Revision history

Table 7. Document revision history