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A6271 Datasheet Preview

A6271 Datasheet

Automotive High-Current LED Controller

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A6271
Automotive, High-Current LED Controller
FEATURES AND BENEFITS
• Automotive AEC-Q100 qualified
• Constant-current LED drive
• 4.2 to 50 V supply
• 53.3 V maximum LED string voltage
• Boost, buck-boost, and buck switching converters
• Programmable switching frequency 70 to 700 kHz
• PWM-controlled PMOS driver allows accurate LED
current control at low duty cycles
• Dimming via external PWM, internal PWM and/or
analog dimming
• Frequency dither scheme for effective spread spectrum to
reduce EMI
• Comprehensive fault protection and fault flag
PACKAGE:
16-Pin eTSSOP (LP)
with Exposed Thermal Pad
DESCRIPTION
The A6271 is a DC-DC converter controller, providing a
programmable constant-current output for driving high-power
LEDs in series. The controller is based on a programmable
fixed-frequency, peak current-mode control architecture. The
DC-DC converter can be configured in a myriad of different
switching configurations including boost, buck-boost, and
buck (ground-referenced switch).
TheA6271 provides a cost-effective solution using an external
logic-level MOSFET and minimum additional external
components. The maximum LED current is set with a single
external sense resistor and can be accurately modulated using
a current reference input (analog control). External PWM
dimming is possible via the PWMIN input, which also provides
a shutdown mode.As an alternative, an internal PWM dimming
circuit can be used by programming the PWMIN and DR pins.
Either PWM scheme controls the PWMOUT output which
drives an external p-channel MOSFET connected in series
with the LED string. This MOSFET is also used to isolate the
load during certain fault conditions, including output shorts
to ground.
Continued on next page...
Not to scale
APPLICATIONS
• Automotive high-power LED lighting systems
• Fog lights, reversing lights, daytime running lights,
position lights, headlights
VBAT
C1
4.7 µF
C2
4.7 µF
L1 56 µH
C7
47 nF
R5
150 Ω
D2
R6
1.35 Ω
A6271-DS, Rev. 7
MCO-0000359
R1
C3
1 µF
2.7 kΩ
PWM Control
C4
22 nF
VREG VIN
LP LN PWMOUT
GND
FAULTn
DR
PWMIN
IREF
OSC
A6271
DITH
OVUV
SG
SP
COMP
R8
12 Ω
R9
1.3 kΩ
M1
R7
4.3 kΩ
C8
4.4 µF
R11
240 kΩ
R2
73.2 kΩ
R3
110 kΩ
R4
39 Ω
C5
680 nF
C6
22 pF
R10
75 mΩ
GND
Boost Switcher Driving 14 LEDs at 150 mA
M2
LED1
LED14
January 15, 2019




Allegro MicroSystems

A6271 Datasheet Preview

A6271 Datasheet

Automotive High-Current LED Controller

No Preview Available !

A6271
Automotive, High-Current LED Controller
Description (continued)
TheA6271 has been carefully designed to minimize electromagnetic
emissions through distributed decoupling and an externally
programmable frequency dither circuit configured for the EMI
specification CISPR 25. It is also possible to program the fundamental
switching frequency below 150 kHz where most EMI standards begin.
TheA6271 has a comprehensive set of integrated protection features
to protect the IC, the LED driver system, and the LED string against
faults. Fixed-output overvoltage protection ensures no maximum
voltage rating violations, even under a single point failure of the
programmable-output overvoltage protection circuit. Other protection
features include: LED overload (boost), output undervoltage (buck
or buck-boost), input supply (VIN) undervoltage, 5 V regulator
(VREG) output undervoltage, high-side supply (PWM PMOS)
undervoltage, and thermal protection.
SPECIFICATIONS
SELECTION GUIDE
Part Number
A6271KLPTR-T
Packing [1]
4000 pieces per 13-in. reel
[1] Contact Allegrofor additional packing options.
Package
16-pin TSSOP with exposed thermal pad
ABSOLUTE MAXIMUM RATINGS [2]
Characteristic
Symbol
VIN
PWMOUT, LP, LN, OVUV
VIN
OSC, DITH, COMP, FAULTn, SG, SP,
IREF, PWMIN, DR, VREG
LP
Maximum Continuous Junction
Temperature
VLP
TJ(max)
Storage Temperature Range
Tstg
[2] With respect to GND.
With respect to LN
Notes
THERMAL CHARACTERISTICS
Characteristic
Symbol
eTSSOP Package
RθJA
Test Conditions [3]
4-layer PCB based on JEDEC standard
2-layer PCB with 3.8in2 of copper area each side
RθJC
Junction to thermal pad
[3] Additional thermal information available on the Allegro website.
Rating
–0.3 to 55
–0.3 to 58
–0.3 to 6.5
–0.5 to 0.5
150
–55 to 150
Unit
V
V
V
V
°C
°C
Value
34
43
2
Unit
°C/W
°C/W
°C/W
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
2


Part Number A6271
Description Automotive High-Current LED Controller
Maker Allegro MicroSystems
Total Page 30 Pages
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