5.5V, 4A, low IQ synchronous Buck converter with versatile I2C Interface

Diodes Incorporated introduces the AP61406Q, a new 5.5V, 4A member with I²C interface of its low quiescent current (I_Q), 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 V_OUT adjustability and provides fault status reports.

Optimized 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 minimizes external component count, facilitates loop stabilization, 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 I_Q (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), V_IN overvoltage protection (OVP), peak and valley current limiting, and thermal shutdown.