A8502 データシートの表示（PDF） - Allegro MicroSystems

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A8502

Wide Input Voltage Range, High Efficiency Fault Tolerant LED Driver

Allegro MicroSystems 

A8502

Wide Input Voltage Range, High Efficiency

Fault Tolerant LED Driver

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

Oscillator Frequency

Oscillator Frequency

FSET/SYNC Pin Voltage

FSET Frequency Range

Synchronization

fSW

VFSET

fFSET

RFSET = 10 kΩ

RFSET = 20 kΩ

RFSET = 35.6 kΩ

RFSET = 10 kΩ

1.8

2

2.2

MHz

0.9

1

1.1

MHz

520

580

640

kHz

−

1.00

−

V

580

−

2500

kHz

Synchronized PWM Frequency

Synchronization Input

Minimum Off-Time

fSWSYNC

tPWSYNCOFF

580

−

2300

kHz

150

−

−

ns

Synchronization Input

Minimum On-Time

tPWSYNCON

150

−

−

ns

SYNC Input Logic Voltage

LED Current Sinks

VSYNC(H)

V

SYNC(L)

FSET/SYNC pin, high level

FSET/SYNC pin, low level

−

−

0.4

V

2.0

−

−

V

LEDx Accuracy

ErrLED ISET = 120 μA

−

−

2

%

LEDx Matching

ΔLEDx ISET = 120 μA

−

−

1

%

LEDx Regulation Voltage

VLED

VLED1 = VLED2 , ISET = 120 μA

620

720

820

mV

ISET to ILEDx Current Gain

ISET Pin Voltage

Allowable ISET Current

VLED Short Detect

AISET

VISET

ISET

VLEDSC

ISET = 120 μA

While LED sinks are in regulation, sensed

from LEDx pin to ground

960

980

1000

A/A

0.988

1.003

1.018

V

40

−

120

μA

4.6

5.1

5.6

V

Soft Start LEDx Current

ILEDSS

Current through each enabled LEDx pin

during soft start

−

3.2

−

mA

Maximum PWM Dimming

Until Off-Time2

tPWML

Measured while PWM/EN = low, during

dimming control and internal references

are powered-on (exceeding tPWML results in

shutdown)

−

32,750

−

fSW

cycles

Minimum PWM On-Time

PWM High to LED-On Delay

tPWMH First cycle when powering-up device

−

0.75

2

μs

tdPWM(on)

Time between PWM enable and LED current

reaching 90% of maximum

−

0.5

1

μs

PWM Low to LED-Off Delay

tdPWM(off)

Time between PWM enable going low and

LED current reaching 10% of maximum

−

360

500

ns

Continued on the next page…

Allegro MicroSystems, Inc.

6

115 Northeast Cutoff

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

1.508.853.5000; www.allegromicro.com

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