LP3943 is an integrated device capable of independently driving 16 LEDs. This device also contains an internal precision oscillator that provides all the necessary timing required for driving each LED. Two prescaler registers along with two PWM registers provide a versatile duty cycle control. The LP3943 contains the ability to dim LEDs in SMBUS/I2C applications where it is required to cut down on bus traffic. Traditionally, to dim LEDs using a serial shift register such as 74LS594/5 would require a large amount of traffic to be on the serial bus. LP3943 instead requires only the setup of the frequency and duty cycle for each output pin. From then on, only a single command from the host is required to turn each individual open drain output ON, OFF, or to cycle a programmed frequency and duty cycle. Maximum output sink current is 25 mA per pin and 200 mA per package. Any ports not used for controlling the LEDs can be used for general purpose input/output expansion.
The LP3943 from National Semiconductor is an integrated LED driver capable of independently controlling up to 16 LEDs. It includes an internal precision oscillator, two prescaler registers and two PWM registers for flexible duty‑cycle control, and supports SMBus/I²C communication to reduce bus traffic.
The device provides 16 open‑drain outputs (up to 25 mA per pin, 200 mA total), a power‑on reset, and optional GPIO expansion on unused pins. It is suited for RGB/white/blue LED applications such as cellular‑phone accessories, toys, and general‑purpose lighting.
| Number of LED channels | 16 |
|---|---|
| Supply voltage (Vop) | 2.3 V to 5.5 V |
| Power dissipation limit | 400 mW |
It can drive up to 16 LEDs, each with an independent open‑drain output.
The device operates with a Vop supply voltage between 2.3 V and 5.5 V.
The LP3943 has an internal power‑on reset that holds the chip in reset until Vpp reaches Vop; a manual reset can be performed by pulling the RST pin low.