The LM2796 is a charge-pump based white-LED driver that is ideal for mobile phone display backlighting. It can drive up to 7 LEDs in parallel with up to 20mA through each LED. Regulated internal current sources deliver excellent current and brightness matching in all LEDs. The LED-driver current sources are split into two independently controlled groups. The primary group (4 LEDs) can be used to backlight the main phone display. The second group (3 LEDs) can be used to backlight a secondary display or to provide other lighting features (keypad LEDs, for example). Brightness of the two groups can be adjusted independently with pulse- width modulated (PWM) digital signals. The LM2796 works off an extended Li-Ion input voltage range (2.7V to 5.5V). Voltage boost is achieved with a high- efficiency 3/2x-gain charge pump. The LM2796 is available in National’s chip-scale 18-bump micro SMD package.
The LM2796 is a charge‑pump based white‑LED driver designed for mobile phone display backlighting. It can drive up to seven LEDs (four for the main display and three for a secondary display or keypad) with independent PWM dimming control. The device operates from a Li‑ion input voltage of 2.7 V to 5.5 V and uses a high‑efficiency 3/2× gain charge pump.
Typical applications include mobile phone display and keypad lighting, PDAs, and general LED illumination. The driver is supplied in an 18‑bump thin micro‑SMD package (2.1 mm × 2.4 mm × 0.6 mm) and includes internal soft‑start and thermal protection circuitry.
| Input voltage range | 2.7 V to 5.5 V |
|---|---|
| Maximum LED count | 7 LEDs (4 + 3 groups) |
| LED current per output | up to 20 mA |
| PWM dimming frequency | 100 Hz to 1 kHz |
| Charge‑pump gain | 1.5× (below 4.75 V) or 1× (above 4.75 V) |
| Package | 18‑bump Thin Micro SMD (2.1 mm × 2.4 mm × 0.6 mm) |
| Thermal shutdown temperature | 160 °C (typ.) |
The LM2796 operates from 2.7 V up to 5.5 V.
It can drive up to seven white LEDs, each up to 20 mA.
The recommended PWM frequency is between 100 Hz and 1 kHz.
It is supplied in an 18‑bump thin micro‑SMD package measuring 2.1 mm × 2.4 mm × 0.6 mm.