Power Electronics

3 A, 2 MHz Step-Down (BUCK) LED Driver

Allegro®'s A6210 buck (step-down) LED driver that uses constant on-time with valley current-mode control. This control scheme allows the use of very short switch on-times, making it ideal for applications that require high switching frequencies combined with high input voltages and low output voltages. Its small size and high efficiency makes it suitable for compact applications such as inside small MR16 lamps, while its high current and medium voltage capability serves high-power applications such as street lighting.

System cost is reduced through high switching frequencies of up to 2.0 MHz, allowing small, low-value inductors and capacitors. In addition, few external components are required through high levels of integration, including a 3-amp switch. Optimal drive circuits minimize switching losses, allowing over 90% efficiency in realistic conditions. The switching frequency is maintained constant, as the input voltage modulates the on time. This feed-forward control ensures excellent line correction. An external resistor pulled-up to the input supply programs the on-time.

Allegro's A6210 is supplied in a 4-mm QFN package. It is priced at $0.76 in quantities of 1,000.

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