A4405 Datasheet, PDF (1/27 Pages) Allegro MicroSystems – The A4405 is an automotive power management IC that uses a high frequency constant on-time 5.45 V pre-regulator to supply two internal 5 V linear regulators and a 3.3 V linear DMOS driver.

A4405
Constant On-Time Buck Regulator
With One 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 VIN operating range (50 V maximum);
for start/stop, cold crank, and load dump requirements
• 2.2 MHz constant on-time buck regulator
• Valley current sensing achieves shortest buck on-times
• 50 V absolute maximum input voltage for surges
• 5.5 to 46 V input voltage range
• −40ºC to 150ºC junction temperature range
• Power-on reset (NPOR pin) with adjustable rising delay
• 5 V (V5P pin) internal low dropout tracking
linear regulator with both overcurrent foldback and
short-to-battery protection
Continued on the next page…
Package: 20-pin TSSOP with exposed
thermal pad (suffix LP)
Not to scale
Description
The A4405 is an automotive power management IC that uses a
high frequency constant on-time 5.45 V pre-regulator to supply
two internal 5 V linear regulators and a 3.3 V linear DMOS
driver. Designed to supply CAN and microprocessor power
supplies in high temperature environments, the A4405 is ideal
for under hood applications. Efficient operation is achieved by
using a buck pre-regulator to efficiently drop the input voltage
before supplying the linear regulators; this reduces power
dissipation and increases overall regulator efficiency.
The switching regulator is capable of operating 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 and thermal
shutdown. The V5P output is protected from short-to-battery
events. In case of a shorted load, all regulators feature
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Applications:
Automotive Control Modules, such as:
• Electronic power steering (EPS)
• Transmission control (TCU)
• Antilock braking (ABS)
• Emissions control
Typical Application Circuit
3.3 V
0.22 μF
0.22 μF
R_TON
412 kΩ
C_IN1
C_IN2
4.7 μF 4.7 μF
V_BAT
D_IN
B240A
4.7 kΩ
3.3 V
4.7 kΩ
NPOR
CPOR
C_CPOR
0.22 μF
V_IGN 1 kΩ
100 nF
100 Ω
ENBATS
ENBAT
Enable
5V
VIN(Pin1)
5V
Protected
D2
B240A
A
C_V5P
1 to 2.2 μF
ENB
V5
C_V5
1 to 2.2 μF
V5P
D1
B240A
A4405
PAD
LX
ISEN–
ISEN+
D_BUCK
B240A
R_SENSE
300 mΩ
1_{/4 W}
L1
10 μH, 1.3 A
65 mΩ MAX
VREG
CLV33
G33
V33
C_VREG
10 μF
0.47 μF
R_CL
390 mΩ
1_{/4 W}
R_DROP
1.2 Ω
1_{/2 W}
Q_V33 40 °C/W
175°C MAX
C_V33
1 to 4.7 μF
3.3 V, 400 mA
(500 mA MAX)
A ProtecƟon diodes D1 and D2 are required when the V5P pin is driving a wiring harness (or excessively long
PCB trace) where parasiƟc inductance will cause the voltage at the V5P to momentarily transiƟon above
VIN or below ground during a fault condiƟon.
A4405-DS, Rev. 1