Low IQ synchronous buck converter with versatile I2C interface from Diodes
Diodes has introduced the AP61406Q, a new 5.5V, 4A member with I2C interface of its low quiescent current (IQ), automotive-compliant synchronous buck converters. The I2C interface allows the programming of various parameters enabling it to meet the growing demand for compact design and high efficiency in various automotive point-of-load (POL) applications, including infotainment, instrument clusters, telematics, and advanced driver assistance systems (ADAS).
A key advantage of the AP61406Q is its I2C 3.0-compatible serial interface, which supports SCL clock rates up to 3.4MHz. This interface enables programmability for various parameters, including PFM/PWM modes, frequencies (1MHz, 1.5MHz, 2MHz, 2.5MHz), and output currents (1A/2A/3A/4A). The device also provides 20mV increment VOUT adjustability and provides fault status reports.
Optimised for high power density automotive POL applications, the AP61406Q is available in a W-QFN1520-8/SWP (Type UX) package, enabling it to operate at high ambient temperatures. The device also features a proprietary gate driver scheme that effectively resists switching node ringing without compromising MOSFET turn-on and turn-off times, thereby reducing high frequency radiated EMI noise.
The AP61406Q operates with an input voltage range of 2.3V to 5.5V. It integrates a 75mΩ high-side and a 33mΩ low-side power MOSFET to provide high-efficiency step-down DC-DC conversion. Its adoption of constant on-time (COT) control minimises external component count, facilitates loop stabilisation, and results in low output voltage ripple
The multi-function enable (EN) input also provides control of the mode of operation. This capability enables flexibility for low IQ (20µA), high-load efficiency in fixed PFM mode or equal ripple across load conditions in PWM mode. Additional features include an accurate power good (PG) indicator with an internal 5MΩ pull-up resistor with a ±5% window comparator circuit, which reduces bill-of-materials (BOM) costs.
The AP61406Q has high-side and low-side current sense protection during output short circuits, increasing its reliability in automotive POL applications. Other protection features include undervoltage lockout (UVLO), VIN overvoltage protection (OVP), peak and valley current limiting, and thermal shutdown.
