STLA01 STMICROELECTRONICS | Alldatasheet
Document overview
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- PDF pages: 16
Technical content
Datasheet sections
- 1 Diagram
- 2 Pin configuration
- 3 Maximum ratings
- 4 Application
- 5 Electrical characteristics
- 6 Application information
- 6.1 V CC pin
- 6.2 EN pin
- 6.3 Programming charge current
- 6.4 Power dissipation
- 7 Typical performance characteristics
- 8 Package mechanical data
- 9 Revision history
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. 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. DFN6 (2 x 2 mm) Table 1. Device summary
1 Diagram
Figure 1. Block diagram
2 Pin configuration
Figure 2. Pin connections (top view) Table 2. Pin description
1 GND Ground
2 NC Not connected
4V CC Input supply voltage. The input range is from 3.75 V to 6 V. 6 EN Enable pin. Tie to V CC if unused.
- The PROG pin is a high impedance pin, It is possi ble to connect only the programming resistor.
3 Maximum ratings
Note: Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Table 3. Absolute maximum ratings Table 4. Thermal data
- This value depends on whether the exposed backside of the pack age is soldered to the PC board. If it is not, the value
could be considerably higher. Table 5. ESD performance
4 Application
Figure 3. Typical application
5 Electrical characteristics
Table 6. Electrical characteristics (VCC = VEN = 5 V, CIN = 1 µF , TJ = -40° to 85°C unless otherwise
- Guaranteed by design, but not tested in production.
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 V CC 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 (R EN). 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: R PROG = 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.
7 Typical performance characteristics
Figure 4. LED pin current vs temperature Figure 5. LED pin current vs temperature Figure 6. LED pin current vs temperature Figure 7. LED pin current vs R PROG Figure 8. Supply current vs temperature Figure 9. Supply current vs R PROG
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.
Dim. mm. inch. A3 0.20 7. 9 e 0.50 1 9.7 DFN6 (2x2 mm) mechanical data 7733060B
Dim. mm. inch. A1 80 7.0 87 C 12. 8 13.2 0.504 0.51 9 D 20.2 0.7 95 N6 0 2 . 362 T 14.4 0.567 Ao 2. 3 0.091 Bo 2. 3 0.091 Ko 1.0 0.0 39 Po 4 0.157 P 8 0.315 Tape & reel QFNxx/DFNxx (2x2 mm) mechanical data
Figure 15. DFN6 (2x2 mm) footprint recommended data
9 Revision history
Table 7. Document revision history 27-Nov-2007 1 Initial release.