A4407 Datasheet, PDF (1/29 Pages) Allegro MicroSystems – 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,

A4407
2.2 MHz Constant On-Time Buck Regulator
With Two External and Two Internal Linear Regulators
Features and Benefits
• AEC Q100 Grade 0 qualified
• Internal buck pre-regulator followed by LDO outputs
• 5.5 to 36 V V_IN 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 (V_IN - 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
• −40ºC to 150ºC junction temperature range
Package: 24-pin TSSOP with exposed
thermal pad (suffix LP)
Not to scale
Description
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 V_IN 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-by-
pulse 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.TheA4407 features both
a logic level and a high-voltage (current and voltage limited)
enable input.TheA4407 also features a power-on-reset (NPOR)
output with adjustable delay for microprocessor control.
TheA4407 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.
Applications:
Automotive Control Modules, such as:
• Electronic power steering (EPS)
• Transmission control (TCU)
• Antilock braking (ABS)
• Emissions control
Simplified Functional Block Diagram
(VREG)
5. 45 V
PWM
Control
Charge
Pump
(3V3)
External
Controller
with Foldback
(1V2)
External
Controller
with Foldback
( V5 )
5 V LDO
with Foldback
A4407
Soft Start
Thermal
Shutdown
(TSD)
3V3
NPOR
Output
V5
Tracking
Control
2:1 MUX
( V5P )
5 V LDO
with Tracking,
Foldback, and
Short to V_BAT
Protection
A4407-DS, Rev. 2