A4481 Datasheet

A4481
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
FEATURES AND BENEFITS
•
•
•
•
•
Automotive AEC-Q100 qualified
5.25 to 40 VIN operating range, 50 V load dump rating
5 V ±1% internal LDO regulator
Foldback short-circuit protection
Short-to-battery protection (to 32 V, independent of VIN)
for harness faults
• Power OK (POK) flag
• High-voltage logic level enable input (ENB) for
microprocessor control or connection directly to battery
• Pin-to-pin and pin-to-ground tolerant at every pin
Package:
8-pin SOIC with exposed thermal pad (suffix LJ)
DESCRIPTION
The A4481 is a single low-dropout linear regulator with
complete control, diagnostics, and protection features that
address many requirements of automotive applications. It
regulates input voltages from 5.25 to 40 V, down to 5 V ±1%
output voltage and is able to supply up to 50 mA of load current.
Diagnostic output from the A4481 includes Power OK (POK)
output to alert the microprocessor that a fault has occurred.
Protection features include input undervoltage lockout (UVLO),
foldback overcurrent protection, output undervoltage and
overvoltage protections (UV/OVP), and thermal shutdown
(TSD). In addition, the output is protected from a short-tobattery event up to 32 V.
The A4481 device is available in an 8-pin SOIC package with
exposed pad for enhanced thermal dissipation. It is lead (Pb)
free, with 100% matte-tin leadframe plating.
APPLICATIONS
Power supplies for:
• Microcontrollers
• Transceivers (CAN, LIN, etc.)
• Sensors
Not to scale
Typical Application Circuit
VIN
VIN
VOUT
A4481
Enable
A4481-DS
POK
ENB
GND
VOUT = 5 V, IOUT = 50 mA
VCC
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
A4481
SELECTION GUIDE
Part Number
Temperature Range (ºC)
Package
Packing*
A4481KLJTR-T
–40 to 150
8-pin eSOIC with exposed thermal pad
3000 pieces per 7-in. reel
*Contact Allegro for additional packing options.
ABSOLUTE MAXIMUM RATINGS*
Characteristic
Symbol
VIN, ENB Pins
Notes
VIN, VENB
VOUT Pin
VOUT
Independent of VIN
All other pins
Rating
Unit
–0.3 to 50
V
–0.3 to 32
V
–0.3 to 7
V
Junction Temperature Range
TJ(max)
–40 to 165
°C
Storage Temperature Range
Tstg
–40 to 150
°C
*Stresses beyond those listed in this table may cause permanent damage to the device. The absolute maximum ratings are stress
ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the Electrical Characteristics table is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability
THERMAL CHARACTERISTICS:* May require derating at maximum conditions; see application section for optimization
Characteristic
Package Thermal Resistance
(Junction to Ambient)
Symbol
RθJA
Test Conditions*
eSOIC-8 (LJ) package
Value
Unit
35
ºC/W
*Additional thermal information available on the Allegro website.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
A4481
Functional Block Diagram
Foldback
Short to
VBAT
Protection
5V
LDO
VIN
LDO
VOUT
VCC
ENB
POK
VOUT UV/OV
OCP
TSD
Pin-Out Diagram
GND
Terminal List Table
Number
Name
Function
VIN 1
8 VOUT
1
VIN
Input voltage pin
VIN 2
7 GND
2
VIN
Input voltage pin
3
NC
No connect
4
ENB
Logic enable input from a microcontroller or
DSP
5
POK
Open-drain regulator fault detection output
6
GND
Ground
7
GND
Ground
8
VOUT
5 V regulator output
NC 3
ENB 4
PAD
6 GND
5 POK
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
A4481
ELECTRICAL CHARACTERISTICS1: Valid at 5.25 V ≤ VINx ≤ 40 V, −40ºC ≤ TA = TJ ≤ 150ºC, unless otherwise specified
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Units
ENB high
5.25
5.35
40
V
Input Voltage
Operating Input Voltage
VIN
VIN UVLO Start Voltage
VIN(START)
VIN rising, ENB high
4.75
–
5.2
V
VIN UVLO Stop Voltage
VIN(STOP)
VIN falling, ENB high
4.55
–
5
V
VIN UVLO Hysteresis
VIN(HYS)
VIN(START) – VIN(STOP)
–
0.2
–
V
IQ
VIN = 5.25 V, ENB high
–
3.4
–
mA
IQ(SLEEP)
VIN = 5.25 V, ENB low
–
1
10
µA
4.95
5
5.05
V
–1
–
+1
%
3
4.7
10
µF
0.7
1.5
2.3
ms
Input Current
Input Quiescent Current1
Input Sleep Supply
Current1
5 V Linear Regulator
Accuracy
VOUT
Load Regulation
IOUT = 25 mA, VIN = 5.25 V
5 mA < IOUT < 50 mA, VIN = 5.25 V
Output Capacitance Range2
COUT
Startup Time2
tSTART
COUT ≤ 4.7 µF, Load = 100 Ω ±5% (50 mA)
VENB(H)
VENB rising
–
–
2
V
VENB(L)
VENB falling
0.8
–
–
V
RENB
–
100
–
kΩ
td(EN,FILT)
10
15
25
µs
Login Enable (ENB) Input
ENB Threshold
ENB Resistance
ENB Filter/Deglitch Time
Overcurrent Protection (OCP)
Current Limit1
ILIM
VOUT = 5 V
−55
−80
−140
mA
IFBK
VOUT = 0 V
−3
−15
−27
mA
Thermal Shutdown Threshold2
TTSD
TJ rising
165
−
−
ºC
Hysteresis2
THYS
−
15
−
ºC
Foldback
Current1
Thermal Protection (TSD)
Thermal Shutdown
VOUT OV/UV Protections
VOUT OV Thresholds
VOUT OV Hysteresis
VOUT UV Thresholds
VOUT UV Hysteresis
VOUT Output Disconnect Threshold
VOV(H)
VOUT rising
5.15
5.33
5.5
V
VOV(L)
VOUT falling
–
5.3
–
V
VOV(HYS)
VOV(H) – VOV(L)
15
30
50
mV
VUV(H)
VOUT rising
–
4.71
–
V
VUV(L)
VOUT falling
4.5
4.68
4.85
V
VUV(H) – VUV(L)
15
30
50
mV
VOUT rising
–
7.2
–
V
ENB high, VIN ≥ 5.25 V, IPOK = 4 mA
–
150
400
mV
VUV(HYS)
VDISC
POK Outputs
POK Output Low Voltage
POK Leakage
Current1
OV and UV Filter/Deglitch Times2
VPOK(L)
IPOK(LKG)
td(FILT)
VPOK = 3.3 V
–
–
2
µA
Applies to undervoltage of the VOUT voltages
10
15
20
µs
For input and output current specifications, negative current is defined as coming out of the node or pin (sourcing), positive current is defined as going into the node or pin
(sinking).
2 Ensured by design and characterization, not production tested.
1
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
A4481
5.05
5.04
5.03
5.02
5.01
5
4.99
4.98
4.97
4.96
4.95
Input/Output Differential (mV)
Output Voltage (V)
TYPICAL PERFORMANCE CHARACTERISTICS
-50
-25
0
25
50
75
Temperature (°C)
100
125
160
140
120
100
80
60
40
20
0
0
150
6.00
80
5.00
70
3.00
2.00
50
50
40
30
20
1.00
10
0
0
10
20
30
40
50
60
Output Current (mA)
70
80
90
102
300
400
500 600
Time (µs)
700
105
106
107
800
900 1000
Load Transient Response
(VIN = 12 V, IOUT = 5 mA to 50 mA, COUT = 4.7 µF)
VOUT
(20 mV/div)
5V
VIN
(20 V/div)
VOUT
(20 mV/div)
IOUT
(20 mA/div)
0A
200
104
Ripple Rejection
5V
100
103
Frequency (Hz)
Foldback Current Limit
0
40
60
4.00
0.00
20
30
Output Current (mA)
Dropout Voltage vs. Output Current
PSRR (dB)
Output Voltage (V)
Output Voltage vs. Temperature
10
0
0V
100
200 300 400
500 600 700
800 900 1000
Time (ms)
Load Dump Characteristics
(VIN = 12 to 50 V, IOUT = 50 mA, COUT = 4.7 µF)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
A4481
FUNCTIONAL DESCRIPTION
Enable (ENB) Input
Power OK (POK) Output
The A4481 has an enable (ENB) logic level input pin. To get the
A4481 to operate, the ENB pin must be a logic high (>2 V). The
ENB pin is rated to 50 V, allowing the ENB pin to be connected
directly to VIN if there is no suitable logic signal available to
wake up the A4481. When ENB transitions low, the A4481 waits
approximately 15 µs before shutting down. This delay provides
plenty of filtering to prevent the A4481 from prematurely shutting down because of any small glitch coupling onto the PCB
trace or ENB pin.
The Power OK (POK) output is an open-drain output, so an
external pull-up resistor must be connected. An internal comparator monitors the voltage at the VOUT pin and controls the opendrain device at the POK pin. POK remains low until the voltage
at the VOUT pin is within 10% of the final regulation voltage.
The POK output is pulled low if: (1) the ENB pin transitions low,
(2) UVLO occurs, (3) TSD occurs, or (4) UV/OVP occurs.
VIN
The following timing diagram shows the basic operation and fault
handling of the A4481:
VIN(START)
VIN(STOP)
VENB(H)
ENB
td(EN,FILT)
VENB(L)
VDISC
VOV(H)
VUV(H)
VOV(L)
VUV(L)
VOUT
POK
POK
undefined in
this region
POK
undefined in
this region
td(FILT) td(FILT)
VOUT UV/
Overload at
Output
td(FILT)
td(FILT)
Enable glitch
POK
undefined in
this region
UVLO
Stop
UVLO
Start
td(FILT)
td(FILT)
VOUT OV
Figure 1: Timing Diagram (not to scale)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
A4481
APPLICATION INFORMATION
Capacitor Selection
Output Capacitor (COUT): The A4481 is designed to be stable
with all types of output capacitors, but it must meet the minimum
and maximum capacitance requirement of 3 μF and 10 μF at
the intended operating temperature and working voltage. For a
ceramic capacitor, X5R or X7R dielectrics with 10 V or higher
voltage rating are recommended. However, if the part needs to
survive short-to-battery events (e.g. to supply off-board sensors),
then 50 to 100 V voltage-rated capacitors are recommended.
Input Capacitor (CIN): A 2.2 μF or larger capacitor is recommended for an input bypass capacitor. Similarly, choose a capacitor that offers plenty of safety margins for known input voltage
applications.
rent cannot be ensured for all combinations of ambient temperature and input voltage. The maximum allowable power dissipation in the IC is as follows:
PMAX =
(TJ(MAX ) − TA )
R θ JA
where TJ(MAX) = maximum junction temperature,
TA = ambient air temperature, and RθJA thermal = resistance from
junction to ambient. (35°C/W for the 8-pin eSOIC).
The power dissipated by the IC can be calculated according to the
following equation:
PDISS = (VIN – VOUT) × IOUT + VIN × IQ
Thermal Considerations
where VIN = input voltage, VOUT = output voltage, IOUT = output
current, and IQ = input quiescent current (3.4 mA typical).
The A4481 remains fully operational to 40 V. However, owing to
power dissipation characteristics of the package, full output cur-
Figure 2 shows current de-rating plot at selected input voltages
based on the above calculations.
60
Output Current – mA
50
40
30
20
10
0
65
70
75
80
85
90
95 100 105 110 115 120 125 130 135 140 145 150
Ambient Temperature – °C
VIN = 5.35 V
VIN = 10 V
VIN = 14 V
VIN = 20 V
VIN = 32 V
VIN = 40 V
Figure 2: Output Current De-Rating vs. Input Voltage
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
A4481
PCB LAYOUT GUIDELINES
Place the input and output capacitors as close as possible and on
the same side of the PCB and IC.
Place thermal vias directly under the device in a tight pattern, as
shown in Figure 4, to improve dissipation.
Ground
Input
Capacitor
VIN
Tie directly to VIN to
automatically enable
the A4481
µP Enable
Output
Capacitor
VIN
1
8
VOUT
VIN
2
7
GND
VOUT
PAD
NC
3
6
GND
ENB
4
5
POK
PowerOK
Output
Figure 3: A4481 Layout Example
Signal traces
LJ package
footprint
0.7 mm
0.7 mm
LJ package
exposed
thermal pad
Top-layer
exposed copper
Ø0.3 mm via
Figure 4: Suggested PCB layout for thermal optimization
(maximum available bottom-layer copper recommended)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
A4481
PACKAGE OUTLINE DRAWING
4.90 ±0.10
0.65
8°
0°
8
B
A
1
3.90 ±0.10
6.00 ±0.20
0.25 BSC
SEATING PLANE
GAUGE PLANE
Branded Face
SEATING
PLANE
0.10 C
1.27 BSC
1
1.27
0.40
3.30 NOM
0.51
0.31
2.41
1.04 REF
2
8X
C
5.60
2
3.30
C
PCB Layout Reference View
For Reference Only; not for tooling use (reference MS-012BA)
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
1.70 MAX
0.15
0.00
1.27
1.75
0.25
0.17
2.41 NOM
8
A Terminal #1 mark area
B
Exposed thermal pad (bottom surface); dimensions may vary with device
C
Reference land pattern layout (reference IPC7351
SOIC127P600X175-9AM); all pads a minimum of 0.20 mm from all
adjacent pads; adjust as necessary to meet application process
requirements and PCB layout tolerances; when mounting on a multilayer
PCB, thermal vias at the exposed thermal pad land can improve thermal
dissipation (reference EIA/JEDEC Standard JESD51-5)
Figure 5: Package LJ, 8-Pin eSOIC
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
A4481
5 VOUT, 50 mA Automotive Linear Regulator
with 50 V Load Dump and Short-to-Battery Protection
Revision History
Revision
Revision Date
–
October 9, 2015
Description of Revision
Initial Release
Copyright ©2015, Allegro MicroSystems, LLC
Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to
permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that
the information being relied upon is current.
Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of
Allegro’s product can reasonably be expected to cause bodily harm.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its
use; nor for any infringement of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
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