Datenblatt-pdf.com


A6267 Schematic ( PDF Datasheet ) - Allegro

Teilenummer A6267
Beschreibung Automotive High Current LED Controller
Hersteller Allegro
Logo Allegro Logo 




Gesamt 17 Seiten
A6267 Datasheet, Funktion
A6267
Automotive High Current LED Controller
Features and Benefits
AEC Q100 Grade 0 Automotive Qualified
Constant current LED drive
6.5 to 50 V supply
Boost or buck-boost modes
Drives up to 15 LEDs in series
Programmable switching frequency 100 to 700 kHz
Open LED overvoltage indication and protection
Single and multiple LED short indication
LED short to ground and supply protection
PWM dimming control
10 μA shutdown current including LED leakage
Applications:
Automotive high power LED lighting systems
Fog lights, reversing lights, daytime running lights
Headlights
Package: 16-pin TSSOP with exposed
thermal pad (suffix LP)
Not to scale
Description
The A6267 is a DC-to-DC converter controller, providing a
programmable constant current output for driving high power
LEDs in series. Driving the LEDs in series ensures identical
currents and uniform brightness. For automotive applications,
optimum performance is achieved when driving up to 15 LEDs
at currents up to 1 A.
TheA6267 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 modified using a current
reference input. Direct PWM control is possible via the Enable
input, which also provides a shutdown mode.
This DC-DC converter can be configured as a ground-referenced
boost converter or as a supply-referenced boost converter
providing buck-boost capability.The buck-boost topology used
ensures that there is no leakage path through the LEDs when
in shutdown and no inrush current at power-up.
Integrated diagnostics and two fault outputs give indication of
undervoltage, chip overtemperature, output open circuit, LED
short circuit and LED undercurrent, and can be configured to
provide short to supply and short to ground protection for the
LED connections. A unique feature is the ability to detect one
or more shorted LEDs.
The device is provided in a 16-pinTSSOPpackage with exposed
thermal pad (suffix LP). It is lead (Pb) free, with 100% matte
tin leadframe plating.
Typical Application Diagrams
VBAT 12 V or 24 V (50 V max)
Power net
Buck Boost Mode
VBAT(min)
(V)
Maximum
Quantity of
LEDs
7 10
8 11
9 13
Vf of each LED = 3.5 V,
D(max) = 85%
Fault
Flags
Enable
VIN
VREG
FF1
FF2
A6267
LN
LP
LF
EN
SG
IREF
CKOUT
SP
OSC
SN
GND LA
VBAT 12 V or 24 V (50 V max)
Power net
Boost Mode
VBAT(min)
(V)
Maximum
Quantity of
LEDs
7 12
8 13
9 15
Vf of each LED = 3.5 V,
D(max) = 85%
Fault
Flags
Enable
VIN
VREG
LN
LP
FF1
FF2
A6267 LF
EN
SG
IREF
CKOUT
SP
OSC
GND
SN
LA
Buck-Boost Mode
(Supply-referenced boost)
A6267-DS, Rev. 3
Boost Mode
Free Datasheet http://www.datasheet4u.com/






A6267 Datasheet, Funktion
A6267
Automotive High Current LED Controller
ELECTRICAL CHARACTERISTICS1 (continued) Valid at TJ = –40°C to 150°C, VIN = 8 to 40 V; unless otherwise noted
Characteristics
Symbol
Test Conditions
Min. Typ. Max.
Oscillator (continued)
OSC Watchdog Period
CKOUT Output High Voltage
CKOUT Output Low Voltage
LED Current Sense
tOSWD
VCOH
VCOL
Between successive rising edges
IOH = –1 mA
IOL = 1 mA
7
VREG – 1
VREG
0.4
Input Bias Current LN (BB mode)3
Input Bias Current LP (BB mode)3
Input Bias Current LN (B mode)3
Input Bias Current LP (B mode)3
Differential Input Voltage (Active)
Input Common-Mode Range (BB mode)3
Input Common-Mode Range (B mode)3
Current Error
Switch Current Sense
ILN
ILP
ILN
ILP
VIDL
VCMLH
VCMLL
EISL
LP = LN = VIN
LP = LN = VIN
LP = LN = 0 V
LP = LN = 0 V
EN = High, VIDL = VLP – VLN
VLP = VLN
VLP = VLN
[(10 × ILED × RSL) – 1] × 100
–6–
– 220 –
– –2 –
– –25 –
– 100 –
VIN – VIN + 1
0– 1
–5 –
5
Input Bias Current
Maximum Differential Input Voltage4
Input Source Current
Input Common-Mode Range
Diagnostics and Protection
IBIASS
VIDS
IINS
VCMS
SP = SN = 0 to 2 V
VIDS = VSP – VSN with D = 50%
VIDS = 120 mV
VSP = VSN
–30 –
110 145 180
– 120 –
0– 2
Fault Blank Timer5
VREG Undervoltage Turn-Off
VREG Undervoltage Hysteresis
LED String Short Voltage
Non-Reference LED Short Offset
Voltage
tFB
VREGUV
VREGUVhys
VSCL
Start-up
Decreasing VREG
VSCO
–3–
4.1 4.3 4.5
130 150 160
430 505 580
160 200 240
Reference LED Short Offset Voltage
VSCOR
430 505
LED Open Voltage
VOCL
5 5.5
LF Bias Current (BB mode)3
ILF LF = LA = VIN + 1.7 V
– 46
LA Bias Current (BB mode)3
ILA LF = LA = VIN + 1.7 V
– 170
LF Bias Current (B mode)3
ILF LF = 1.7 V
–8
LA Bias Current (B mode)3
ILA LA = 1.7 V
– 34
LED Undercurrent Voltage Difference6
VUCL
–1
Open Fault Time-Out
tOTO
fOSC = 350 kHz
– 94
Overtemperature Warning Threshold
TJF Temperature increasing
– 170
Overtemperature Hysteresis
TJhys
Recovery = TJF – TJhys
– 15
1For input and output current specifications, negative current is defined as coming out of (sourcing) the specified device pin.
2Function is correct but parameters are not guaranteed below the general limit (8 V).
3BB mode = buck-boost (supply-referenced) mode, B mode = boost (ground-referenced) mode.
4Parameters guaranteed by design.
5Fault Blank timer not enabled for open-LED condition.
6Undercurrent when VSENSEL < VIDL– VUCL, where VSENSEL is the voltage across the LED current sense resistor RSL.
580
6
Unit
μs
V
V
μA
μA
μA
μA
mV
V
V
%
μA
mV
μA
V
ms
V
mV
mV
mV
mV
V
μA
μA
μA
μA
mV
ms
ºC
ºC
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
Free Datasheet http://www.datasheet4u.com/

6 Page









A6267 pdf, datenblatt
A6267
Automotive High Current LED Controller
Two pull-up resistors are used to limit the voltage across the gate-
source junction during high input voltages or load dump condi-
tions. If the battery voltage is restricted, one resistor across the
gate-source junction can be used. The FF1 provides a sink current
of up to 1.3 mA.
This circuit can be used to avoid most hazardous conditions and
protect the circuit components from over-stress. Note that under
extreme cases, the circuit cannot protect against certain fault con-
ditions. For example, when any of the following occurs:
• In boost mode:
If the cathode end of the LED string is shorted to VBAT, the
LED sense resistor effectively appears between VBAT and
ground. Depending on the current limit of the source supply or
the input fuse rating, the fault current may damage the resistor.
If the LF node is shorted to VBAT, the reference LED and
the LED sense resistor effectively appear between VBAT and
ground. Depending on the current limit of the source supply or
the input fuse rating, the fault current may damage the resistor
and /or the reference LED.
If the cathode end of the LED string is shorted to ground. A
fault current determined by the impedance of the shorting link
(now effectively the LED sense resistor) flows through the
power circuit. The fault current will either: be limited by the
maximum switch current sense, VIDS, or if the source supply
cannot maintain this current, be limited by the source supply.
(The source supply will either: fold back, or if the current
exceeds the input fuse rating, the fuse will blow, creating an
open circuit).
• In buck-boost mode:
If the cathode end of the LED string is shorted to ground, the
LED sense resistor effectively appears between VBAT and
ground. Depending on the current limit of the source supply or
the input fuse rating, the fault current may damage the resistor.
If the LF node is shorted to ground, the reference LED and
the LED sense resistor effectively appear between VBAT and
ground. The reference LED will be reversed biased and will
probably be damaged.
If the cathode end of the LED string (LP) is shorted to VBAT,
the impedance of the short appears in parallel with the series
combination of the series protection MOSFET and the LED
sense resistor. This will tend to reduce the effective impedance
of the LED sense resistor and correspondingly increase the
LED current.
To ensure the A6267 inputs (LP and LN) are not damaged dur-
ing any of the above faults, it is necessary to add a differential
resistor in series with the LN connection (between the sense
resistor and the LN pin). This resistor value should be approxi-
mately 150 Ω.
If an output short is detected but it is necessary to keep the output
active, the FF1 output can be pulled low. This will override the
output disable but will not clear the fault.
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
12
Free Datasheet http://www.datasheet4u.com/

12 Page





SeitenGesamt 17 Seiten
PDF Download[ A6267 Schematic.PDF ]

Link teilen




Besondere Datenblatt

TeilenummerBeschreibungHersteller
A6260High Brightness LED Current RegulatorAllegro MicroSystems
Allegro MicroSystems
A6261Protected LED Array DriverAllegro MicroSystems
Allegro MicroSystems
A6262Automotive LED Array DriverAllegro MicroSystems
Allegro MicroSystems
A6264Automotive Stop/Tail LED Array DriverAllegro MicroSystems
Allegro MicroSystems
A6266High Current LED ControllerAllegro MicroSystems
Allegro MicroSystems

TeilenummerBeschreibungHersteller
CD40175BC

Hex D-Type Flip-Flop / Quad D-Type Flip-Flop.

Fairchild Semiconductor
Fairchild Semiconductor
KTD1146

EPITAXIAL PLANAR NPN TRANSISTOR.

KEC
KEC


www.Datenblatt-PDF.com       |      2020       |      Kontakt     |      Suche