Triple Output Step-Down Switching Regulator
A4491
2
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Selection Guide
Part Number Packing
Operating Temperature Range
(°C)
A4491EESTR-T 1500 pieces per 7-in. reel –40 to 85
Thermal Characteristics may require derating at maximum conditions, see application information
Characteristic Symbol Test Conditions* Value Units
Package Thermal Resistance
R
θJA
On 4-layer PCB based on JEDEC standard 37 ºC/W
*Additional thermal information available on the Allegro website.
Absolute Maximum Ratings (reference to GND)
Characteristic Symbol Notes Rating Units
Load Supply Voltage V
BB
24 V
LX1, LX2, and LX3 Pins V
LXn
–1 to 24 V
PORZ and VDD Pins V
IN
–0.3 to 7 V
ENBx Pin Input Current I
ENBx
Driven by a current-limited voltage source 1 mA
Operating Ambient Temperature T
A
Range E –40 to 85 ºC
Maximum Junction Temperature T
J
(max) 150 ºC
Storage Temperature T
stg
–55 to 150 ºC
Recommended Operating Conditions
Characteristic Symbol Conditions Min. Typ. Max. Units
Load Supply Voltage V
BB
To operate at V
BB
< 6 V, connect V
DD
supply to the V
BB
supply. See Powering
Configurations section.
4.5 – 23 V
LX1, LX2, and LX3 Pins V
LXn
–0.7 – 23 V
Operating Ambient Temperature T
A
–40 – 85 ºC
Junction Temperature T
J
–40 – 125 ºC
Description (continued)
The POR flag also indicates when the input voltage drops below
specification, giving the system controller advance warning while
the switchers continue to operate down to the shutdown level.
Internal diagnostics provide comprehensive protection against
overloads, input undervoltages, and overtemperatures.
Output current capability is ≈ 4.5A total for all 3 outputs, depending
on the combinations of V
IN
and each V
OUT
level.
The A4491 is provided in a 20-contact, 4 mm × 4 mm, 0.75 mm
nominal overall height QFN, with exposed pad for enhanced
thermal dissipation. It is lead (Pb) free, with 100% matte tin
leadframe plating.
