A8450
Automotive Multioutput Voltage Regulator
Features and Benefits
▪
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
Description
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 conversion. 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
Continued on the next page…
Package: 24 pin SOIC (suffix LB)
Continued on the next page…
Not to scale
Typical Application
H.V.
VIN
D2
C8
L1
VBB
CP2
CP1
C7
C10
VCP
VREG11
GND
GND
ENB
C9
R4
VADJ
Q2
R1
R2
CPOR
CLADJ
VADJBD
FB
LX
ENBAT
V33
V33BD
CL33
GND
GND
VREG
V5D
NFAULT
NPOR
V5A
C2
C1
Q1
D1
COUT
C3
R3
CIN
A8450
C4
A8450-DS, Rev. 8
A8450
Automotive Multioutput Voltage Regulator
Features and Benefits (continued)
▪
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
Description (continued)
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-W package (part number
suffix LB) with internally-fused power ground pins for enhanced
thermal performance. This provides an R
θJA
of 35°C/W on a 4-layer
board (see chart on p. 5). The lead (Pb) free version has 100% matte
tin leadframe plating.
Selection Guide
Part Number
A8450KLBTR-T
Pb-free
Yes
Packing
1000 pieces per 13-in. reel
Terminals
24
Package
SOIC-W surface mount, internally
fused power ground pins (6-7, 18-19)
Absolute Maximum Ratings
Parameter
Load Supply Voltage
Analog Output
Logic Input Signal
LX Voltage
Operating Temperature Range
Junction Temperature
Storage Temperature Range
Symbol
V
BB
V
5A
V
ENBAT
V
ENB
V
LX
T
A
T
J
(max
)
T
stg
VBB pin
V5A pin
Conditions
Rating
– 40
–1 to 45
–0.3 to 45
–0.3 to 6.5
–2 to V
BB
–40 to 135
150
–55 to 150
Units
V
V
V
V
V
°C
°C
°C
ENBAT pin input
ENB pin input
LX pin
K range
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A8450
Automotive Multioutput Voltage Regulator
Functional Block Diagram
D2
VIN
L1
C8
High
Voltage
Switch
C7
CIN
D1
COUT
CP1
CP2
VCP
VBB
LX
VREG
R3
VREG11
C10
Charge Pump
Soft Start
CPOK
VBB
ENBAT
High V
Protection
VREG
C3
R4
Internal
Reference
V
REF
1.2 V to 3.3 V
Adjustable Linear
Regulator Control
CLADJ
VADJBD
FB
R1
Buck Converter with
Switching Regulator
3.3 V Linear
Regulator Control
CL33
V33BD
V33
Q1
ENB
Q2
VADJ
R2
NPOR
VREG
5 V Digital Linear
Regulator
V5D
C4
V
UVLOREG
V
UVLOADJ
V
UVLO33
CPOR
C9
Adjustable
Delay
POR Block
C1
5V Analog
Linear Regulator
and V5D to V5A
Tracking Control
Current
Limiting
V5A
NFAULT
C2
GND
Fault
TSD Warning
V5A Short to Supply
UVLO V5D, V5A
Short-to-Supply
Protection
ID
C1, C2, C3, C4
COUT
CIN
C7, C8
C10
D1, D2
L1
Q1, Q2 pass transistors
Characteristics
1
μF,
25 V ceramic X7R
100
μF,
35 V low-ESR electrolytic
47
μF,
63 V electrolytic
0.1
μF,
50 V ceramic X7R (for 14 V applications), or
0.1
μF,
100 V ceramic X7R (for 42 V applications)
0.22
μF,
10 V X7R
1 A, 40 V Schottky (for 14 V applications)
100
μH,
1.2 A
npn transistor, h
FE
> 50
Representative Device
UHC1V101M, Nichicon
EKO4, Sanken
D03316HT, Coilcraft
MPSW06
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A8450
Automotive Multioutput Voltage Regulator
ELECTRICAL CHARACTERISTICS
at T
A
= –40ºC to 135°C, V
BB
= 6 to 45 V, V
ENB
= 5 V, unless otherwise noted
Characteristics
Symbol
Test Conditions
Enabled mode: V
ENBAT
or V
ENB
= HIGH,
I
OUT
= 0 mA: V
BB
= 14 V
Enabled mode: V
ENBAT
or V
ENB
= HIGH,
I
OUT
= 0 mA; V
BB
= 6 V
Disabled mode: V
ENBAT
and V
ENB
= LOW
I
LOAD
= 550 mA = I
LOADV5D
+ I
LOADV5A
+ I
LOADV33
+ I
LOADVADJ
; V
BB
> 6.5 V
Dropout: 6 V
≤
V
BB
< 6.5 V
T
J
= 25°C
T
J
= 135°C
V
BB
= 14 V
V
BB
= 14 V
HIGH input level
LOW input level
HIGH input level, V
ENBAT
= 45 V
HIGH input level, V
ENBAT
= 14 V
LOW input level, V
ENBAT
= 0.8 V
HIGH input level
LOW input level
HIGH input level, V
ENB
≥
2.7 V
LOW input level, V
ENB
≤
0.8 V
1 mA
≤
I
LOADV5D
≤
200 mA
1 mA
≤
I
LOADV5A
≤
200 mA
50 mA
≤
I
LOADV5A
, I
LOADV5D
≤
200mA;
V
BB
> 6.5 V
Min.
–
–
–
5.50
5.00
–
–
1.0
–
5
2.7
–0.3
–
–
–1
2.7
–0.3
–
–1
Typ.
6
10
–
–
–
415
650
1.2
4.75
10
–
–
–
–
–
–
–
–
–
Max.
10
15
10
5.80
5.80
500
750
2.2
–
15
45
0.8
300
70
10
6.5
0.8
50
10
Units
mA
mA
μA
V
V
mΩ
mΩ
A
μs
ms
V
V
μA
μA
μA
V
V
μA
μA
V
V
V
mV
mA
mA
mA
V
nA
Supply Quiescent Current
I
BB
Regulated Output Voltage
Buck Switch On-Resistance
Buck Switch Current Limit
DC-to-DC Fixed Off-Time
Soft Start Time
Logic Inputs
ENBAT Logic Input Voltage
V
REG
R
DSON
I
DSLIM
t
OFF
t
SS
V
ENBAT
I
ENBAT
V
ENB
I
ENB
V
OUTV5D
V
OUTV5A
V
OUTV33
V
TRACK
I
OUTV5DLIM
I
OUTV5ALIM
I
BD
V
FB
I
FB
ENBAT Input Current
ENB Logic Input Voltage
ENB Input Current
Linear Regulator Outputs
*
V5D Output Voltage
V5A Output Voltage
V33 Output Voltage
V5A to V5D Tracking
V5D Current Limit
V5A Current Limit
Base Drive Output Current
Feedback Voltage
Feedback Input Bias Current
Continued on next page
4.9
5.0
5.1
4.9
5.0
5.1
3.234 3.300 3.366
–25
200
200
–
300
300
10.0
1.20
–100
25
–
–
16.0
1.24
100
1 V
≤
V
OUTVADJ
, V
OUTV33
≤
4 V
5.0
1.16
–400
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A8450
Automotive Multioutput Voltage Regulator
ELECTRICAL CHARACTERISTICS (continued)
at T
A
= –40ºC to 135°C, V
BB
= 6 to 45 V, V
ENB
= 5 V, unless
otherwise noted
Characteristics
Protection
Symbol
V
ERRON
I
ERROFF
t
POR
V
UVLOV33
V
HYSV33
V
UVLOV5
V
HYSV5
V
UVLOVADJ
V
FB
rising
V
FB
falling
At FB pin
V5A, V5D rising
V5A, V5D falling
Test Conditions
Fault asserted;
I
NFAULT
, I
NPOR
= 1 mA
V
NFAULT
, V
NPOR
= 5 V
C9 = 0.47
μF
V
33
rising
V
33
falling
Min.
–
–
65
2.80
2.75
–
4.36
4.24
–
1.02
0.97
–
175
4.94
–
–
–
Typ.
–
–
100
2.95
2.90
80
4.50
4.38
125
1.07
1.02
70
200
5.15
160
175
15
Max.
400
1
135
3.10
3.05
–
4.75
4.63
–
1.12
1.07
–
225
5.36
–
–
–
Units
mV
μA
ms
V
V
mV
V
V
mV
V
V
mV
mV
V
°C
°C
°C
NFAULT, NPOR Output Voltage
NFAULT, NPOR Leakage Current
POR Delay
V33 Undervoltage Threshold
V33 Hysteresis
V5A, V5D Undervoltage Threshold
V5A, V5D Hysteresis
VADJ Undervoltage Threshold
VADJ Hysteresis
V
HYSVADJ
VADJ, V33 Overcurrent Threshold
V
OC
VREG Undervoltage Threshold
V
UVLOVREG
Thermal Warning Threshold
T
JTW
T
J
rising
Thermal Shutdown Threshold
T
JTSD
T
J
rising
Thermal Shutdown Hysteresis
T
HYSTSD
Recovery period = T
JTSD
– T
JTW
*
Linear regulator output specifications are only valid when V
REG
is in regulation (V
BB
≥
6.5).
Power Dissipation Versus Ambient Temperature
4.5
4.0
Power Dissipation, P
D
(W)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
4-Layer PCB*
(R
θJA
= 35 ºC/W)
60
80
100
120
140
160
Ambient Temperature (°C)
*In still air; mounted on PCB based on JEDEC high-conductance standard PCB
(JESD51-7; High Effective Thermal Conductivity Test Board for Leaded Surface Mount
Packages); data on other PCB types is provided on the Allegro Web site.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
20
40
5
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