A8450
Automotive Multioutput Voltage Regulator
Package LB 24-pin SOIC
VBB
CP2
CP1
VCP
VREG11
GND
GND
ENB
CPOR
CLADJ
VADJBD
FB
1
2
3
4
5
6
7
8
9
10
11
12
Buck
Converter
Charge
Pump
Soft
Start
3.3 V
Lin Reg
Control
24
23
22
21
20
19
18
17
16
15
14
13
LX
ENBAT
V33
V33BD
CL33
GND
GND
VREG
V5D
NFAULT
NPOR
V5A
5V
Dig/Anlg
Lin Reg
1.2 V to
3.3 V
Lin Reg
Control
5 V Reg
Track
Control
The A8450 is a multioutput power supply intended for automotive
applications. The A8450 operates from a wide input supply range and
is designed to satisfy the requirements of high ambient temperature
environments.
Four regulated voltage outputs provide multiple options. The 3.3 V
regulator and the 1.2 to 3.3 V adjustable regulator can be used to power
microcontroller or DSP cores, or for I/O, sensing, and A-to-D conver-
sion. Two 5 V outputs, one digital and the other analog, feature output
tracking within 0.5% of each other over the operating temperature
range. In addition, the analog regulator is protected against short-to-
battery conditions. All four regulators feature foldback current limit
protection.
The device can be enabled or disabled using two input pins. The
high voltage input, on the ENBAT pin, allows enable/disable using an
engine ignition or battery switch signal. The logic-level input, on the
ENB pin, allows enable/disable by microcontroller or DSP signals.
When disabled, the A8450 draws less than 10 µA of current. A POR
(power-on-reset) block monitors the supply voltages and provides a
reset signal, with an adjustable delay, for microcontroller or DSP resets.
A separate fault pin signals TSD (thermal shutdown), 5 V analog short-
to-supply, and 5 V analog or digital undervoltage.
The A8450 is supplied in a 24-pin SOIC package (part number
suffix LB) with fused power ground pins for enhanced thermal perfor-
mance. This provides an R
θJA
of 35°C/W on a 4-layer board (see chart
on p. 4).
Approximate Scale 1:1
FEATURES
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage, V
BB
..................................45
V
Analog Output, Pin V5A........................–1
V to 45 V
Logic Input Signal
Pin ENBAT .................................–0.3
V to 45 V
Pin ENB .....................................–0.3
V to 6.5 V
Pin LX....................................................
–2 V to V
BB
Operating Temperature Range
Ambient Temperature, T
A
............
–40°C to 135°C
Junction Temperature, T
J(MAX)
.....................
150°C
Storage Temperature, T
S
....................
–55°C to 150°C
6 V to 45 V input range
dc-to-dc buck converter with 5.7 V output
Overcurrent protection with foldback, and undervoltage lockout (UVLO)
Dual 5 V outputs
– Digital 5 V ±2%, 200 mA
– Analog 5 V, 200 mA
– Short-to-supply protection on analog regulator
– Analog to digital regulator output tracking < 0.5%, throughout
operating temperature range
3.3 V linear regulator, with foldback current limit
Adjustable 1.2 V to 3.3 V linear regulator, adjustable foldback current limit
Ignition switch enable; Sleep mode
100% duty cycle operation for low input voltages
Power OK output
–40°C to 135°C ambient operating temperature range
Use the following complete part number when ordering:
Part Number
A8450KLB
Package
24-pin, SOIC
Description
Webbed Leadframe
A8450KLB-DS, Rev. 1
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
