A4407: 2.2 MHz Constant On-Time Buck Regulator With Two External and Two Internal Linear Regulators
The A4407 is an automotive power management IC that uses a 2.2 MHz constant on-time (COT) buck pre-regulator to supply a 5 V linear regulator, a 5 V tracking/protected linear regulator, a 3.3 V linear FET controller/driver, and a 1.2 V/1.5 V/1.8 V linear FET controller/driver.
The A4407 provides a pin to set the master reference for the 5 V tracking regulator to either the 3.3 V or the 5 V output. The on-time of the buck is internally adjusted as a function of VIN to maintain the 2.2 MHz switching frequency. Efficient operation is achieved by using the buck pre-regulator to drop the input voltage before supplying the linear regulators. Designed to supply CAN and microprocessor power supplies in high temperature environments, the A4407 is ideal for under hood applications.
The switching regulator is designed to operate at a nominal switching frequency of 2.2 MHz. The high switching frequency enables the customer to select low value inductors and ceramic capacitors while avoiding EMI in the AM frequency band. Protection features include: undervoltage lockout, pulse-bypulse current limit, LX short circuit protection, and thermal shutdown. In case of a shorted load all linear regulators feature foldback overcurrent protection. In addition, the V5P output is protected from a short-to-battery event.
The A4407 features both a logic level and a high-voltage (current and voltage limited) enable input. The A4407 also features a power-on-reset (NPOR) output with adjustable delay for microprocessor control.
The A4407 is supplied in a low profile (1.1 mm) 24-lead TSSOP package with exposed pad for enhanced thermal dissipation (suffix LP). The package is lead (Pb) free with 100% matte-tin leadframe plating.
– AEC Q100 Grade 0 qualified
– Internal buck pre-regulator followed by LDO outputs
– 5.5 to 36 V VIN operating range (50 V maximum); for start/stop, cold crank, and load dump requirements
– Constant on-time (COT) buck pre-regulator
– Valley current sensing achieves shortest buck on-times
– 2.2 MHz (VIN – adjusted) switching frequency
– 5 V internal low-dropout tracking linear regulator with foldback short circuit and short-to-battery protections
– 5 V internal low-dropout linear regulator with foldback short circuit protection
– 3.3 V external FET controller/driver with programmable current limit and foldback short circuit protection
– 1.2 V/1.5 V/1.8 V external FET controller/driver with programmable current limit and foldback protection
– Power-on reset (NPOR) with adjustable rising delay
– Logic enable input (ENB) for microprocessor control
– Ignition enable input (ENBAT) for remote startup
– Ignition status indicator (ENBATS) output
– Buck pulse-by-pulse overcurrent protection
– Buck LX short circuit protection (latched)
– Missing asynchronous diode protection (latched)
– UVLO for VIN, charge pump, and the internal rail
– Thermal shutdown protection
– -40℃ to 150℃ junction temperature range