A4402_12 Datasheet, PDF (1/17 Pages) Allegro MicroSystems – The A4402 is a dual-output regulator, combining in a single package a constant on-time buck regulator and a linear regulator (LDO)—each with adjustable output voltages.

A4402
Constant On-Time Buck Converter
With Integrated Linear Regulator
Features and Benefits
▪ 2 MHz switching frequency
▪ Adjustable soft start timer
▪ Watchdog input
▪ Power-on reset output
▪ Adjustable buck and linear regulators
▪ Enable input
▪ 6 to 50 V supply voltage range
▪ Overcurrent protection
▪ Undervoltage lockout (UVLO)
▪ Thermal shutdown protection
Applications:
AUTOMOTIVE (“K” VERSION)
• Power steering control units
• Transmission control units
• Lighting control units
• Infotainment
• Cluster
• Centerstack
• Other body control
COMMERCIAL (“E” VERSION)
• Photo and inkjet printers
• Industrial controls
• Distributed power systems
• Networking applications
• Point-of-sale
• Security systems
Package: 16-pin TSSOP with exposed
thermal pad (suffix LP)
Description
The A4402 is a dual-output regulator, combining in a single
package a constant on-time buck regulator and a linear regulator
(LDO)—each with adjustable output voltages. It is ideal for
applications that require two regulated voltages, such as in
microcontroller- or DSP-based applications requiring core
and I/O voltage rails.
The buck regulator output supplies the adjustable linear
regulator to reduce power dissipation and increase overall
efficiency. The switching regulator is capable of operating
above 2 MHz, allowing the use of small low value inductors
and capacitors while avoiding sensitive EMI frequency bands
such as AM radio in automotive applications.
Protection features include undervoltage lockout and thermal
shutdown. In case of a shorted load, each regulator features
overcurrent protection.
The device has an integrated power-on reset with adjustable
delay to monitor LDO output voltage and provide a signal that
can be used to reset a DSP or microcontroller. It also includes
a watchdog circuit.
The A4402 is provided in a 16-pin TSSOP, with exposed pad
for enhanced thermal dissipation. It is lead (Pb) free, with
100% matte tin leadframe plating.
Not to scale
Typical Application
C_TSET
TSET
0.15 μF
C_POR
POR
0.33 μF
TON
A 4402
V_O2
20 kΩ
4.7 kΩ
NPOR
ENB
WDI
GND
VIN1
BOOT
LX
ISEN
GND
GND
FB1
VIN2
VO2
FB2
R_ton
750 kΩ
V_BAT
0.1 μF
10 μF
0.01 μF
L1
33 μH
R_SENSE
R1
31.6 kΩ
4.7 μF
Switching Regulator Output
V_SW
5V
R2
9.76 kΩ
R3
10 kΩ
Linear Regulator Output
V_LIN
3.3 V
250 mA
1 μF
R4
5.62 kΩ
Efficiency vs. Output Current
90
5
85
3.3
80
75
VOUT (V)
70
65
60
0
200 400 600 800 1000 1200
I_OUT (mA)
4402-DS, Rev. 9
Data is for reference only. Efficiency data from circuit shown in left panel.