UCN5829 データシートの表示（PDF） - Allegro MicroSystems

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UCN5829

9-BIT SERIAL-INPUT, LATCHED SINK DRIVER

Allegro MicroSystems 

5829

9-BIT SERIAL-INPUT,

LATCHED SINK DRIVER

TYPICAL APPLICATION

Shown is a typical application with the UCN5829EB controlling

a chop current of 1 A through a 3 mH, 9 Ω load. To check the duty

cycle and IOUT(asym)/IOUT(P) restrictions

where vd = VHSD + VDIODE ≈ 1.5 + 1.5 = 3

vc = VBB - VOUT(SAT) - VHSD = 36 - 1.5 - 1.5 = 33

IOUT(asym) = vc / RL = 33 / 9 = 3.67

then

IOUT(asym) / IOUT(P) = 3.67 / 1 = 3.67

The condition of IOUT(asym) / IOUT(P) > 2.5 is met and the duty cycle will

be within the proscribed limits. The actual duty cycle is

dc = IOUT(P) /IOUT(asym) + vd/vc = 1.0/3.67 + 2.5/33

1 + vd/vc

1 + 2.5/33

= 32%

For a 50 kHz chopping frequency and a 250 µs print enable time, the

remaining component values are

with

then

and

CC = 250 pF and CEN = 0.01 µF

RC = 1/(2 fch CC) = 1/(2 x 50 x 103 x 250 x 10-12) = 40 kΩ

REN = tEN / CEN = 250 x 10-6 / 10 x 10-9 = 25 kΩ

115 Northeast Cutoff, Box 15036

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

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