STLA01PUR

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 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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