The power supply provides regulated 5-V output to power the system microcontroller and drive eight low-side switches. The ac zero-detect circuitry is monitoring the crossover voltage of the mains ac supply. The resultant signal is a low-frequency clock output on the ZVS terminal, based on the ac-line cycle. This information allows the microcontroller to reduce in-rush current by powering loads on the ac-line peak voltage.
A serial communications interface controls the eight low-side outputs; each output has an internal snubber circuit to absorb the energy in the inductor at turn OFF. Alternatively, the system can use a fly-back diode to VIN to help recirculate the energy in an inductive load at turn OFF.
FEATURES
• Eight Low-Side Drivers With Internal Clamp for Inductive Loads and Current Limiting for Self Protection
– Seven Outputs Rated at 150 mA and Controlled Through Serial Interface
– One Output Rated at 150 mA and Controlled Through Serial Interface and Dedicated Enable Pin
• 5-V ± 5% Regulated Power Supply With 200-mA Load Capability at VIN Max of 18 V
• Internal Voltage Supervisory for Regulated Output
• Serial Communications for Control of Eight Low-Side Drivers
• Enable/Disable Input for OUT1
• 5-V or 3.3-V I/O Tolerant for Interface to Microcontroller
• Programmable Power-On Reset Delay Before RST Asserted High, Once 5 V Is Within Specified Range (6 ms Typ)
