A8521 datasheet(7/35 Pages) ALLEGRO

7 / 35 page

Wide Input Voltage Range, High Efficiency

Fault Tolerant LED Driver

A8521

Allegro MicroSystems, Inc.

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

ELECTRICAL CHARACTERISTICS1,2 (continued) Valid at VIN = 16 V, TA = 25°C,

indicates specifications guaranteed by design

and characterization over the full operating temperature range with TA = TJ = –40°C to 125°C; unless otherwise noted

Characteristics

Symbol

Test Conditions

Min.

Typ.

Max.

Unit

GATE Pin

GATE Pin Sink Current

IGSINK

VGS = VIN

−−104

−μA

Gate Fault Shutdown Greater than

2X Current2

tGFAULT2

−−

μs

Gate Fault Shutdown Greater than

1–2X Current

tGFAULT1

−

10,000

−

fSW

cycles

Gate Voltage

VGS

Gate to source voltage measured when gate

is on

−

–6.7

−

VSENSE Pin

VSENSE Pin Sink Current

IADJ

18.8

20.3

21.8

μA

VSENSE Trip Point

VSENSEtrip1

Measured between VIN and VSENSE,

RADJ = 0 Ω

104

114

VSENSE 2X Trip2

VSENSEtrip2

2X VSENSEtrip, instantaneous shutdown,

RADJ = 0 Ω

−

180

−

¯F¯¯A¯¯U¯¯L¯¯T¯ Pin

¯F¯¯A¯U¯¯L¯¯T¯ Pull-Down Voltage

VFAULT

IFAULT = 1 mA

−−

0.5

¯F¯¯A¯U¯¯L¯¯T¯ Pin Leakage Current

IFAULTLKG VFAULT = 5 V

−−

μA

Thermal Protection (TSD)

Thermal Shutdown Threshold2

TSD

Temperature rising

−

165

−

ºC

Thermal Shutdown Hysteresis2

TSDHYS

−

ºC

1For 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).

2Ensured by design and characterization, not production tested.

3Minimum VIN = 5 V is only required at startup. After startup is completed, the IC is able to function down to VIN = 4 V.

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