TM1903

TM1903 is a single-wire three-channel LED constant-current driver IC. It accepts digital input via the DIN interface and supports daisy-chaining through the DO pin, allowing an external controller to drive the chip using only a single wire. The chip integrates an MCU single-wire single-channel digital interface, data latch, LED constant-current driver, and PWM brightness control circuitry. The VDD pin incorporates an internal 5V Zener regulator, minimizing external component count. Suitable for LED decorative products such as guardrail tubes and point light sources.

Applications

• Guard rail tubes
• LED decorative products such as point light sources

Key features

• Power CMOS process; OUT port withstand voltage: 24V
• VDD built-in 5V Zener diode; supports 6~24V supply with series resistor
• Fixed constant current output: 14mA
• PWM brightness control circuit; 256-level adjustable brightness
• Single-wire single-channel serial cascade interface: data input via DIN pin, D0 forwards cascaded data
• Oscillation method: built-in RC oscillator with clock synchronization based on data line signal; after receiving the current unit's data, automatically regenerates subsequent data and transmits to the next stage via data output — no signal distortion or attenuation over cascaded distance
• Built-in power-on reset circuit; all registers initialized to zero after power-on reset
• Data transfer rate: 800KHz
• Package: SOP8, SOT23-8