A8287 データシートの表示（PDF） - Allegro MicroSystems

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A8287

LNB Supply and Control Voltage Regulator

Allegro MicroSystems 

A8285/A8287

LNB Supply and Control Voltage Regulator

ELECTRICAL CHARACTERISTICS at TA = +25°C, VIN = 10 to 16 V (unless otherwise noted)

Characteristics

Set-point Accuracy, load and line

regulation

Supply Current

Symbol

Test Conditions

VO1

Relative to target voltage selected, with:

ILOAD = 0 to 500 mA

ICC ENB = Low, LNB output disabled

ICCEN ENB = High, LNB output enabled, ILOAD = 0mA

Min. Typ. Max. Units

-4.5 0 4.5 %

–

–

7

mA

–

– 15 mA

Boost Switch-On Resistance

Switching Frequency

RDSBOOST TJ = 25 °C, ILOAD = 500mA

fo –

– 400 500 mΩ

320 352 384 kHz

Switch Current Limit

–

VIN = 12 V

2.0 3 4.0 A

Linear Regulator Voltage Drop

ΔVREG VBOOST – VLNB, no tone signal, ILOAD = 500 mA

400 600 800 mV

Slew Rate Current on TCAP

ICAP Charging

Discharging

–12.5 –10 –7.5 μA

7.5 10 12.5 μA

Output Voltage Slew Period

tslew VLNB = 13 to 18 V, TCAP = 6.8 nF, ILOAD = 500 mA – 500 –

μs

Output Reverse Current

IOR ENB = Low, VLNB = 28 V with C4 fully charged

–

1

5

mA

Ripple and Noise on LNB Output VRN See notes 1 and 2

–

–

50 mVpp

Protection Circuitry

Overcurrent Limit

ILIM

High limit

Low limit

550 700 850 mA

400 500 600 mA

Overcurrent Disable Time

VIN Undervoltage Threshold

tDIS

UVOFF

–

Guaranteed turn-off

1.2 – 1.7 ms

8.65 9.15 9.65 V

VIN Turn-On Threshold

Power-Not-Good Flag Set

UVON Guaranteed turn-on

PNGset –

8.75 9.25 9.75 V

77 85 93 %VLNB

Power-Not-Good Flag Reset

PNGreset –

82 90 98 %VLNB

Thermal Shutdown Threshold

TJ See note 1

– 165 –

°C

Thermal Shutdown Hysteresis

ΔTJ See note 1

– 20 –

°C

Continued on next page

3

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Worcester, Massachusetts 01615-0036 (508) 853-5000

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